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MX2010012009A - Metal utilization in supported, metal-containing catalysts. - Google Patents

Metal utilization in supported, metal-containing catalysts.

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Publication number
MX2010012009A
MX2010012009A MX2010012009A MX2010012009A MX2010012009A MX 2010012009 A MX2010012009 A MX 2010012009A MX 2010012009 A MX2010012009 A MX 2010012009A MX 2010012009 A MX2010012009 A MX 2010012009A MX 2010012009 A MX2010012009 A MX 2010012009A
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MX
Mexico
Prior art keywords
metal
further characterized
catalyst
support
deposition bath
Prior art date
Application number
MX2010012009A
Other languages
Spanish (es)
Other versions
MX304650B (en
Inventor
Kam-To Wan
Original Assignee
Monsanto Technology Llc
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Filing date
Publication date
Application filed by Monsanto Technology Llc filed Critical Monsanto Technology Llc
Publication of MX2010012009A publication Critical patent/MX2010012009A/en
Publication of MX304650B publication Critical patent/MX304650B/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
    • B01J23/622—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead
    • B01J23/626—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead with tin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8906—Iron and noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8913—Cobalt and noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8926—Copper and noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/392—Metal surface area
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/396—Distribution of the active metal ingredient
    • B01J35/397—Egg shell like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/617—500-1000 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B01J37/0203—Impregnation the impregnation liquid containing organic compounds
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C227/00—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton
    • C07C227/02—Formation of carboxyl groups in compounds containing amino groups, e.g. by oxidation of amino alcohols
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic Table
    • C07F9/02—Phosphorus compounds
    • C07F9/28—Phosphorus compounds with one or more P—C bonds
    • C07F9/38—Phosphonic acids [RP(=O)(OH)2]; Thiophosphonic acids ; [RP(=X1)(X2H)2(X1, X2 are each independently O, S or Se)]
    • C07F9/3804—Phosphonic acids [RP(=O)(OH)2]; Thiophosphonic acids ; [RP(=X1)(X2H)2(X1, X2 are each independently O, S or Se)] not used, see subgroups
    • C07F9/3808—Acyclic saturated acids which can have further substituents on alkyl
    • C07F9/3813—N-Phosphonomethylglycine; Salts or complexes thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/18—Carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B01J2235/15—X-ray diffraction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B01J2235/30—Scanning electron microscopy; Transmission electron microscopy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/66—Pore distribution
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B01J37/0205—Impregnation in several steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B01J37/0211—Impregnation using a colloidal suspension
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Generalmente, la presente invención se refiere a mejoras en la utilización de metal en catalizadores soportados que contienen metal; por ejemplo, la presente invención se refiere a métodos para dirigir y/o controlar la deposición de metal sobre las superficies de sustratos porosos; la presente invención también se refiere a métodos para preparar catalizadores en donde se deposita un primer metal sobre un soporte (por ejemplo, un soporte de carbono poroso) para proveer una o más regiones de un primer metal en la superficie del soporte, y se deposita un segundo metal en la superficie de las una o más regiones del primer metal; en general, la electropositividad del primer metal (por ejemplo, cobre o hierro) es mayor que la electropositividad del segundo metal (por ejemplo, un metal noble tal como platino) y el segundo metal se deposita en la superficie de las una o más regiones del primer metal por desplazamiento del primer metal; la presente invención también se refiere a sustratos tratados, estructuras precursoras del catalizador y catalizadores preparados por dichos métodos; la invención también se refiere al uso de catalizadores preparados según se detalla aquí en reacciones de oxidación catalítica, como por ejemplo oxidación de un sustrato que se selecciona entre el grupo que consiste en ácido N-(fosfonometil)iminodiacético o una sal del mismo, formaldehído, y/o ácido fórmico.Generally, the present invention relates to improvements in the use of metal in supported catalysts containing metal; for example, the present invention relates to methods for directing and / or controlling the deposition of metal on the surfaces of porous substrates; The present invention also relates to methods for preparing catalysts wherein a first metal is deposited on a support (for example, a porous carbon support) to provide one or more regions of a first metal on the surface of the support, and deposited a second metal on the surface of the one or more regions of the first metal; in general, the electropositivity of the first metal (for example, copper or iron) is greater than the electropositivity of the second metal (for example, a noble metal such as platinum) and the second metal is deposited on the surface of the one or more regions of the first metal by displacement of the first metal; The present invention also relates to treated substrates, catalyst precursor structures and catalysts prepared by said methods; The invention also relates to the use of catalysts prepared as detailed herein in catalytic oxidation reactions, such as oxidation of a substrate which is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde. , and / or formic acid.

Description

USE OF METAL IN SUPPORTED CATALYSTS THAT CONTAIN METAL FIELD OF THE INVENTION In general, the present invention relates to improvements in the use of metal in supported catalysts containing metal. For example, the present invention relates to methods for directing and / or controlling the deposition of metal on the surfaces of porous substrates. More particularly, some embodiments of the present invention relate to methods for treating porous substrates (e.g., porous carbon substrates or porous metal substrates) to provide treated substrates with one or more desirable properties (e.g., lower surface area). which can be attributed to pores with a nominal diameter within a predefined range) that can be used as supports for catalysts containing metal., ..
The present invention also relates to methods for preparing catalysts where a first metal is deposited on a support (e.g., a porous carbon support) to provide one or more regions of a first metal on the surface of the support, and a second metal on the surface of the one or more regions of the first metal. In general, the electropositivity of the first metal (for example, copper or iron) is greater than the electropositivity of the second metal (for example, a noble metal such as platinum) and the second metal is deposited on the surface of the one or more regions of the first metal by displacement of the first metal.
The present invention also relates to treated substrates, catalyst precursor structures and catalysts prepared by these methods.
The invention also relates to the use of catalysts prepared as detailed herein in catalytic oxidation reactions, such as for example oxidation of a substrate selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde , and / or formic acid.
BACKGROUND OF THE INVENTION N- (phosphonomethyl) glycine (known in the agrochemical industry as glyphosate) is described in Franz, U.S. Pat. N °: 3,799,758. The glyphosate and its salts are conveniently applied as a herbicide. of, post emergency in aqueous formulations. It is a very effective broad spectrum herbicide of commercial importance, useful for eliminating or controlling the growth of a wide variety of plants, including germinating seeds, emerging seedlings, woody and herbaceous maturing and established vegetation, and aquatic plants.
Various methods for producing glyphosate are known in the art, including various methods using catalysts that They contain noble metals on carbon supports. See, for example, U.S. Pat. N °: 6.417.133 of Ebner et al. and Wan et al. International Publication No. WO 2006/031938. In general, these methods include the liquid phase oxidative cleavage of N- (phosphonomethyl) iminodiacetic acid (ie, PMIDA) in the presence of a noble metal-containing catalyst on carbon support. Along with the glyphosate product, various by-products can be formed, such as formaldehyde, formic acid (which is formed by the oxidation of the formaldehyde by-product); aminomethylphosphonic acid (AMPA) and acid 10-methylaminomethylphosphonic acid (MAMPA), which are formed by the oxidation of N- (phosphonomethyl) glycine; and iminodiacetic acid (IDA), which is formed by the dephosphonomethylation of PMIDA. These side products can reduce the yield of glyphosate (for example, AMPA and / or MAMPA) and can introduce toxicity problems (for example, formaldehyde). By Consequently, it is preferred to avoid significant product formation ·. · .... · secondary. . ...,. < ·, -.,.
It is generally known in the art, including, for example, the description of Ebner et al. U.S. 6,417,133 and of Wan et al. in International Publication No. WO 2006/031938, that carbon catalyses primarily the 20 Oxidation of PMIDA in glyphosate and that the noble metals primarily catalyze the oxidation of the by-product formaldehyde into carbon dioxide, and water. The catalysts of Ebner et al. U.S. 6,417,133 and Wan et al. WO 2006/031938 have proven to be extremely catalytic advantageous and effective for the oxidation of PMIDA in glyphosate and the oxidation of by-products formaldehyde and formic acid in carbon dioxide and water without excessive leaching of noble metals from the carbon support. These catalysts are also effective in the operation of a continuous process for the production of glyphosate by oxidation of PMIDA. Although these catalysts are effective in the oxidation of PMIDA and are generally resistant to the leaching of noble metals under the oxidation conditions of PMIDA, there is the possibility of improving them.
For example, the pore distribution and / or size of the porous substrates used in the catalysts containing noble metals can affect the performance of the catalyst and the use of metals. Methods for introducing compounds (i.e., pore-blocking compounds) into the pores of the substrates to modify the deposition of metals are known in the art. See, for example, U.S. Pat. No.: 5,439,859 of Durante et al.
An object of the present invention comprises the development of efficient catalysts for the oxidation of PMIDA, formaldehyde and / or formic acid, which more efficiently use the expensive noble metals, and methods for their preparation. A more efficient use of metals can provide more active catalysts than conventional catalysts. Another object of the present invention comprises the development of methods for preparing efficient catalysts which require a reduced proportion of expensive noble metals compared to conventional catalysts, while still exhibiting adequate activity.
BRIEF DESCRIPTION OF THE INVENTION This invention provides catalysts and methods for preparing catalysts that are useful in heterogeneous oxidation reactions, including the preparation of glyphosate by the oxidation of PMIDA.
Therefore, briefly, the present invention is directed to oxidation catalysts comprising a support of particulate carbon, a first metal and a second metal, where the support presents on its surface particles comprising the first metal and the second metal.
In at least one embodiment, the distribution of the second metal within at least one of the particles characterized by means of analysis by linear scanning of X-ray energy dispersion (EDX) as described in protocol B produces a second signal of the metal that varies by no more than about 25% throughout the sweep region having a dimension having at least about 70% of the largest dimension of said at least one particle. In a further embodiment, the distribution of the second metal within at least one of the particles characterized by means of EDX linear scan analysis as described in protocol B produces a second metal signal that varies no further that about 20% in the entire sweep region having a dimension having at least about 60% of the largest dimension of said at least one particle. In another embodiment, the distribution of the second metal within at least one of the particles characterized by means of EDX linear scan analysis as described in protocol B produces a second metal signal that varies by no more than about 15% in the entire sweep region having a dimension having at least about 50% of the largest dimension of said at least one particle.
The present invention is also directed to an oxidation catalyst comprising a particulate carbon support, copper and platinum, where said support presents on its surface particles comprising copper and platinum. The distribution of platinum within at least 70% (numerical basis) of the particles characterized by EDX linear sweep analysis as described in protocol B produces a platinum signal that varies by - not more than about 25% throughout the swept region which has a dimension that presents at least about 70% of the largest dimension of said particles.
The present invention is further directed to an oxidation catalyst comprising a support of particulate carbon, a first metal and a noble metal, wherein said support has on its surface metal particles comprising the first metal and the noble metal. The catalyst is characterized by a chemisorption of at least 975 μ ???β of CO per gram of catalyst per gram of noble metal during Cycle 2 of the chemosorption analysis of static carbon monoxide, as described in protocol A.
The present invention is also directed to an oxidation catalyst comprising a support of particulate carbon, a first metal and a noble metal, where said support has on its surface metal particles comprising the first metal and the noble metal, wherein the metal particles comprise a core comprising the first metal and a coating at least partially surrounding the core and comprising the noble metal, wherein at least about 70% of the noble metal is present within the particle coating.
In a further embodiment, the present invention is directed to an oxidation catalyst comprising a support of particulate carbon, platinum and copper, wherein said support has on its surface metal particles comprising platinum and copper, wherein the percentage of Platinum on the surface of the particles is at least one. 10% approximately.
In still another embodiment, the present invention is directed to an oxidation catalyst comprising a support of particulate carbon, a first metal and a noble metal, wherein said support has on its surface metal particles comprising the first metal and the metal noble, wherein the metal particles comprise a core comprising the first metal and a coating that surrounds at least partially to the core and comprising the noble metal; and wherein the catalyst is characterized by a chemisorption of at least 975 μ ?? ?? de de of CO per gram of catalyst per gram of noble metal during Cycle 2 of the chemosorption analysis of static carbon monoxide as described in the protocol TO.
In another embodiment, the present invention is directed to an oxidation catalyst comprising a support of particulate carbon, platinum and copper, where the support has on its surface metal particles comprising platinum and copper, wherein the percentage of platinum atoms 10 on the surface of the particles is at least about 5%; and the catalyst is characterized by a chemisorption of at least 500 μg of CO per gram of catalyst per gram of noble metal during Cycle 2 of the chemosorption analysis of static carbon monoxide, as described in protocol A .
In still another embodiment, the present invention is - = directed to an oxidation catalyst - comprising a support of particulate carbon, a first metal and a noble metal, where the support has on its surface metal particles comprising the first metal and the noble metal, where the metal particles they comprise a nucleus that 20 comprises the first metal and a coating at least partially surrounding the core and comprising the noble metal; wherein the noble metal constitutes less than 5% by weight of the catalyst; and the catalyst is characterized by a chemisorption of at least about 800 μ ???? of CO per gram of catalyst per gram of noble metal during Cycle 2 of the chemosorption analysis of static carbon monoxide as described in protocol A.
The present invention is also directed to an oxidation catalyst comprising a particulate carbon support having metal particles on the surface thereof comprising a first metal and a second metal, wherein the electropositivity of the first metal is greater than the electropositivity. of the second metal and the second metal is deposited by ion displacement of the first metal of one or more regions of the first metal of a catalyst precursor structure; and the weight ratio of the second metal to the first metal is at least about 0.25: 1.
The present invention is also directed to processes for oxidizing a substrate selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde and formic acid .. In general, the process comprises putting the substrate in contact with an agent oxidant in the presence of an oxidation catalyst prepared by the methods detailed herein and / or as described herein. For example, in one embodiment the catalyst comprises a first metal, a noble metal and a porous carbon support, wherein the catalyst comprising one or more regions of the first metal on the surface of the carbon support and one or more regions of the noble metal on the surface of said one or more regions of the first metal, wherein the first metal has an electropositivity greater than the electropositivity of the noble metal.
The present invention is further directed to various methods for preparing a catalyst comprising a first metal, a second metal and a porous support having a surface comprising pores of a nominal diameter within a predefined range and pores of a nominal diameter outside the predefined interval.
In one embodiment, the method comprises disposing a pore-blocking agent within the pores of the porous support having a nominal diameter within the predefined range, wherein the pore-blocking agent having at least one dimension relative to the pore openings with a nominal diameter within the predefined range such that the pore-blocking agent is preferentially retained within the pores; placing the support in contact with a deposition bath of a first metal comprising an aqueous medium and ions of the first metal, thereby depositing the first metal on the surface of the porous support within the pores that they have, a nominal diameter outside the predefined range to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support between the pores of a nominal diameter outside the predefined range; and placing the catalyst precursor structure in contact with a deposition bath of the second metal comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure.
In another embodiment, the method comprises contacting the support and a deposition bath of a first metal comprising an aqueous medium, ions of the first metal and a coordination agent forming a compound coordinated with the first metal having at least one dimension larger than the nominal diameter of the pores within the predefined range, thereby depositing the first metal on the support surface within the pores having a nominal diameter outside the predefined range to form a precursor structure of the catalyst having a or more regions of the first metal deposited on the surface of the support; and placing the catalyst precursor structure in contact with a deposition bath of the second metal comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure.
The present invention is also directed to methods for preparing catalysts comprising a first metal, a second metal and a porous carbon support. ^ In one embodiment, the method comprises placing the porous carbon support in contact with a deposition bath of a first metal comprising ions of the first metal, said first metal thereby deposited on the surface of the porous carbon support to form a structure precursor of the catalyst having one or more regions of the first metal deposited on the surface of the support, wherein the first metal has a greater electropositivity than the electropositivity of the second metal; placing the catalyst precursor structure in contact with a deposition bath of the second metal comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure by displacing the first metal from one or more of the regions; and heating the catalyst precursor structure on whose surface the first and second metals have been deposited to a temperature of at least about 500 ° C in a non-oxidizing environment.
In a further embodiment, the method comprises placing the porous carbon support in contact with a deposition bath of a first metal comprising ions of the first metal, said first metal thereby depositing on the surface of the porous carbon support to form a precursor structure of the catalyst having one or more regions of the first metal deposited on the surface of the support, wherein the carbon support has a Langmuir surface area of at least about 500 m2 / g and the first metal has an electropositivity greater than. the electropositivity of the second ... metal; and put the structure. catalyst precursor in contact with a deposition bath of the second metal comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure by displacing the first metal from one or more of the regions.
The present invention is also directed to methods for preparing a catalyst comprising a first metal, a noble metal and a porous support. In one embodiment, the method comprises contacting the support and a deposition bath of a first metal comprising an aqueous medium, ions of the first metal and a coordinating agent that forms a compound coordinated with the first metal, depositing in that way the first metal on the surface of the support to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support, wherein the first metal has an electropositivity greater than the electropositivity of the noble metal; and placing the catalyst precursor structure in contact with a bath of 10 deposition of the noble metal comprising ions of said noble metal, the noble metal thereby being deposited on the surface of the catalyst precursor structure by displacement of the first metal from one or more of the regions.
In an additional modality, the method comprises putting the 15 support in contact with a deposition bath of a first metal which: ... comprises an aqueous medium. and ions.of the first metal, thereby depositing the first metal on the surface of the support to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support, wherein the first metal 20 has a higher electropositivity than the electropositivity of the noble metal; and placing the catalyst precursor structure in contact with a noble metal deposition bath comprising ions of said noble metal, thereby depositing the noble metal on the surface of the metal. precursor structure of the catalyst by displacement of the first metal from one or more of the regions, wherein substantially all the noble metal is deposited by the displacement, or the noble metal ions consist essentially of noble metal ions with an oxidation number of 2. .
In another embodiment, the method comprises placing the support in contact with a deposition bath of a first metal comprising an aqueous medium, ions of the first metal and a pore blocking agent, thus providing the pore-blocking agent within the pores of the pore. substrate having a nominal diameter within a predefined range, wherein the pore-blocking agent has at least one dimension relative to the opening of the pores of the predefined interval sufficient for the pore-blocking agent to be retained preferentially within the pores. pores, and the first metal being deposited on the surface of the support within the pores having a nominal diameter outside the predefined range, thus forming a precursor structure of the catalyst having one or more regions of the first metal deposited on the surface, of the support, where the first metal has a greater electropositivity than the electropositivity of the noble metal; and placing the catalyst precursor structure in contact with a noble metal deposition bath comprising ions of the noble metal, thereby depositing the noble metal on the surface of the catalyst precursor structure by displacing the first metal from one or more of the regions.
The present invention is also directed to methods for preparing a catalyst comprising a first metal, a noble metal and a porous support having a surface comprising pores of a nominal diameter within a predefined range and pores of a nominal diameter outside the predefined range. In one embodiment, the method comprises contacting the support and a deposition bath of a first metal comprising an aqueous medium, ions of the first metal and a coordination agent that forms a compound coordinated with the first metal having at least one dimension larger than the nominal diameter of the pores within the predefined range, thereby depositing the first metal on the support surface within the pores having a nominal diameter outside the predefined range to form a precursor structure of the catalyst having a or more regions of the first metal deposited on the surface of the support; and placing the catalyst precursor structure in contact with a noble metal deposition bath comprising ions of the noble metal, thereby depositing the noble metal on the surface of. the precursor structure of the catalyst ... ... ...
The present invention is also directed to methods for preparing catalysts comprising copper, platinum and a porous carbon support.
In one embodiment, the method comprises placing the support in contact with a copper deposition bath comprising copper ions and a coordination agent in the absence of an externally applied voltage, thereby depositing copper on the surface of the copper. porous carbon support to form a catalyst precursor structure having one or more regions deposited with copper on the surface of the support; and placing the catalyst precursor structure in contact with a platinum deposition bath comprising platinum ions, platinum thereby being deposited on the surface of the catalyst precursor structure by displacement of the copper from one or more of the regions.
In another embodiment, the method comprises contacting the support and a copper deposition bath comprising copper ions in the absence of an externally applied voltage, thereby depositing copper on the surface of the carbon support to form a precursor structure. of the catalyst having one or more copper regions deposited on the surface of the support, wherein the carbon support has a Langmuir surface area of at least about 500 m2 / g prior to the deposition of copper thereon; and the contact of the catalyst precursor structure and a platinum deposition bath comprising platinum ions, platinum thereby being deposited on the surface of the catalyst precursor structure by displacement of the copper from one or more of the regions.
In a further embodiment, the method comprises contacting the support and a copper deposition bath comprising copper ions in the absence of an externally applied voltage, thereby depositing copper on the surface of the carbon support to form a catalyst precursor structure having one or more copper regions deposited on the surface of the support; the contact of the catalyst precursor structure and a platinum deposition bath comprising platinum ions, platinum thereby deposited on the surface of the catalyst precursor structure by displacement of copper from one or more of the regions; and heating the surface of the catalyst precursor having platinum on the surface of one or more copper regions to a temperature of at least about 500 ° C in a non-oxidizing environment.
The present invention is also directed to methods for preparing catalysts comprising iron, platinum and a porous carbon support.
In one embodiment, the method comprises placing the support in contact with an iron deposition bath comprising iron ions and a coordination agent in the absence of an externally applied voltage. iron being deposited in this way on the surface of the. porous carbon support to form a catalyst precursor structure having one or more regions deposited with iron on the surface of the support; and placing the catalyst precursor structure in contact with a platinum deposition bath comprising platinum ions, platinum thereby being deposited on the surface of the catalyst precursor structure by displacement of the iron from one or more of the regions.
In another embodiment, the method comprises contacting the support with an iron deposition bath comprising iron ions in the absence of an externally applied voltage, thereby depositing iron on the surface of the carbon support to form a precursor structure. of the catalyst having one or more regions with iron deposited on the surface of the support, wherein the carbon support has a Langmuir surface area of at least about 500 m2 / g prior to deposition of iron thereon; and placing the catalyst precursor structure in contact with a platinum deposition bath comprising platinum ions, platinum thereby being deposited on the surface of the catalyst precursor structure by displacement of iron from one or more of the regions.
In a further embodiment, the method comprises contacting the support with an iron deposition bath comprising iron ions in the absence of an externally applied voltage, iron being deposited on the surface of the carbon support to form a catalyst precursor structure having one or more regions with iron deposited on the surface of the support; contacting the catalyst precursor structure with a platinum deposition bath comprising platinum ions, platinum thereby being deposited on the surface of the catalyst precursor structure by iron displacement from one or more of the regions; and heating the surface of the catalyst precursor with platinum on the surface of said one or more regions with iron in a non-oxidizing environment.
The present invention is also directed to methods of treating a porous substrate to prepare a modified porous substrate with a reduced surface area attributable to pores having a nominal diameter within a predefined range.
In one embodiment, the method comprises disposing a pore-blocking agent within the pores of the porous substrate having a nominal diameter within the predefined range, wherein said pore-blocking agent has at least one dimension relative to the aperture opening of the pores. pores with a nominal diameter within the predefined interval sufficient for said pore-blocking agent to be retained preferentially within the pores.
In another embodiment, the method comprises introducing a pore-blocking compound into the pores of the porous substrate, wherein said pore-blocking compound is susceptible to a conformational change in a way that the blocking compound. Pores are retained within the pores of the porous substrate having a diameter within the predefined range.
In a further embodiment, the method comprises introducing into the pores having a nominal diameter within a predefined range compounds capable of forming a pore-blocking compound with at least one dimension such that the pore-blocking compound is retained within the pores that have a nominal diameter within a range predefined The present invention is also directed to methods for treating porous substrates having micropores and pores of larger diameter to prepare a modified porous substrate with a reduced micropore surface area.
In one embodiment, the method comprises disposing a pore-blocking agent within the micropores of the porous substrate, wherein said pore-blocking agent has at least one dimension relative to the micropore openings such that said pore-blocking agent is preferentially retained within the pores In another embodiment, the method comprises introducing a pore-blocking compound into the micropores of the porous substrate, wherein the pore-blocking compound is susceptible to a conformational change such that said pore-blocking compound is retained within the micropores of the porous substrate.
In an additional mode ,. he. method comprises entering. in the micropores of the substrate compounds capable of forming a pore-blocking compound with at least one dimension such that said pore-blocking compound is retained within the micropores.
In yet another embodiment, the method comprises introducing a pore-blocking composition into the micropores of the porous substrate, wherein said pore-blocking composition comprises a substituted cyclohexane derivative.
The present invention is also directed to methods for preparing a catalyst comprising a metal on the surface of a porous substrate wherein said metal is preferentially excluded from the pores of the porous substrate having a nominal diameter within a predefined range. In one embodiment, the method comprises (i) introducing one or more precursors of a pore-blocking compound into the pores of the porous substrate, wherein: at least one of the precursors of the pore-blocking compound is susceptible to a conformational change to forming a pore-blocking compound that is retained within the pores of the porous substrate having a nominal diameter within the predefined range, or at least two precursors of the pore-blocking compound have the ability to form a pore-blocking compound having at least a dimension such that the pore-blocking compound is retained within the pores of the porous substrate having a nominal diameter within a predefined range; (I) preferentially removing the pore-blocking compound from the pores of the porous substrate having a nominal diameter outside the predefined range for preparing a modified porous substrate with a reduced surface area attributable to pores having a nominal diameter within the predefined interval; and (iii) placing the surface of the modified porous substrate in contact with a solution containing the metal.
In another embodiment, the present invention is directed to a porous substrate containing a pore-blocking compound within the pores of the porous substrate having a nominal diameter within a predefined range. The pore-blocking compound is retained within the pores having a nominal diameter within a predefined range due to the pore-blocking compound having at least one dimension that is greater than pore openings having a nominal diameter within a predefined range, or pore-blocking compound that exhibits a conformation that prevents the pore-blocking compound from escaping through openings in pores having a nominal diameter within the predefined range.
The present invention is directed to treated porous substrates containing a pore-blocking compound within the micropores of the porous substrate. In one embodiment, the micropore surface area of said treated substrate represents no more than about 70% of the micropore surface area of the porous substrate prior to treatment. In another embodiment, the pore-blocking compound is selected from the group consisting of, i, del. - condensation product ... of a substituted cydohexane-substituted and a glycol, the condensation product of a bis-substituted cydohexane derivative and a glycol and combinations thereof.
Other objects and characteristics will be evident and in part will be indicated from here on.
BRIEF DESCRIPTION OF THE FIGURES Figures 1A-1C are graphic representations of pore blockers in accordance with the present invention.
Figure 1 D illustrates a conformational change of a pore blocker according to the present invention.
Figure 2 shows the heat treatment of a support impregnated with a first and second metal according to the present invention.
Figures 3A / 5A and 3B / 5B show the results of electron transmission microscopy (TEM) as described in example 3.
Figures 4A and 4B provide the pore volume and surface area for the treated and untreated substrates described in example 4.
., --.- ,. · Figure 5C provides the porosity data for the analyzed catalysts described in example 19.
Figure 5D provides the pore volume results for the analyzed catalysts described in example 20.
Figures 6-13 are micrographs generated by scanning electron microscopy and transmission (STEM) analysis for a carbon support and impregnated supports with metals as described in example 21.
Figure 14 provides the results of a linear sweep analysis for a support impregnated with metals as described in Example 21.
Figures 15 and 16 are STEM micrographs for the catalysts described in Example 21.
Figures 17 and 18 are the results of an energy dispersion spectroscopy (EDS) analysis of the catalysts as described in example 2.
Figures 19-21 are STEM micrographs for the catalysts evaluated for their reactivity as described in Example 21.
Figure 22 provides the results of a linear scan analysis for a catalyst evaluated for its reactivity as described in Example 21.
Figures 23 and 24 are STEM micrographs for the catalysts evaluated for their reactivity as described in example 21.
. Figure .25 provides the results, of. a linear scan analysis for a catalyst evaluated for its reactivity as described in example 21.
Figures 26 and 27 are the EDS spectra for the catalysts evaluated for their reactivity as described in example 21.
Figures 28 and 29 are TEM and STEM images for supports impregnated with metals as described in example 22.
Figures 30-31, 32-33, 34-35 and 36-37 are TEM images and the corresponding results of a linear scan analysis for supports impregnated with metals as described in example 22.
Figures 38 and 39 are TEM and STEM images for the catalysts described in Example 22.
Figure 40 indicates the catalyst portion analyzed by linear scan analysis as described in example 22.
Figure 41 provides a linear sweep analysis for the portion of the support identified in Figure 40.
Figure 42 indicates the catalyst portion analyzed by linear scan analysis as described in example 22.
Figure 43 provides a linear sweep analysis for the portion of the support identified in Figure 40.
Figures 44 and 45 are TEM images used in the particle size analysis as described in example 23.
Figure 46 provides the particle size distribution data for the catalyst. analyzed as described in the example .23.
Figures 47 and 48 are TEM images used in the particle size analysis as described in example 23.
Figure 49 provides the particle size distribution data for the catalyst analyzed as described in example 23.
Figures 50 and 51 are the results of X-ray diffraction for a catalyst analyzed as described in example 24.
Figures 52-55 are the results of a nanodifraction for a metal particle analyzed as described in example 24.
Figures 56 and 57 provide the reactivity evaluation data as described in example 25.
Figure 58 provides the data for the evaluation of the reactivity of example 26.
Figures 59-62 provide the data for the evaluation of the reactivity of example 27.
Figures 63-65 provide the data for the evaluation of the reactivity of example 28.
Figures 66-68 provide the data for the evaluation of the reactivity of Example 29.
Figures 69-71 provide the data for the evaluation of the reactivity of example 30.
Figures 72-78 provide the data for the evaluation of the reactivity of Example 31.
.. Figures 79-84. provide the data of the evaluation of the reactivity of example 32.
Figure 85 provides the data for the evaluation of the reactivity of example 33.
Figures 86-90 provide the data for the evaluation of the reactivity of example 34.
Figures 91 -95 provide the data for the evaluation of the reactivity of example 35.
Figures 96-98 provide the data for the evaluation of the reactivity of Example 36.
Figure 99 provides the data for the evaluation of the reactivity of Example 37.
Figure 100 provides the data for the evaluation of the reactivity of example 38.
Figures 101 and 102 provide the data of the reactivity evaluation of example 39.
Figure 103 provides the site density data for platinum as described in example 20.
Figure 104 provides the evaluation data of the reactivity of example 41.
Figures 105 and 106 provide the data of the reactivity evaluation of example 42.
Figure 107 provides the evaluation data of the reactivity of example 43. .. .... . . .. ..,: · .._. ·. .
Figure 108 provides the evaluation data of the reactivity of example 44.
Figure 109 provides the results of an X-ray diffraction (XRD) for the catalyst described in Example 45.
Figures 110 and 11 1 provide the XRD results for the catalyst described in Example 46.
Figure 1 1 1 A provides the platinum leaching data for the catalysts described in examples 46 and 48.
Figures 1 12-115 provide the XRD results for the catalysts described in Example 50.
Figure 1 16 is a scan and electron transmission microscopy (STEM) micrograph as described in Example 55.
Figures 17 and 18 are the results of the X-ray energy dispersion spectroscopy (EDX) linear scan that is described in Example 55.
Figures 1 19 and 120 are the STEM photomicrographs described in Example 55.
Figure 121 is a STEM micrograph that is described in Example 55.
Figure 122 provides the results of the linear scan of an electron energy loss spectroscopy (EELS) that is described in Example 55.
Figure 123 is a STEM micrograph that is described in Example 55.
Figure 124 provides the results of the EELS linear scan that is described in Example 55.
Figure 125 is a STEM micrograph that is described in Example 55.
Figure 126 provides the results of the EELS linear scan that is described in Example 55.
Figure 127 provides photomicrographs of high resolution electron microscopy (HRE) as described in example 57.
Figure 128 provides the STEM micrographs that are described in Example 57.
Figure 129 is a STEM micrograph that is described in Example 57.
Figure 130 provides the results of a linear scan analysis of EDX as described in example 57.
Figure 131 is a STEM micrograph that is described in Example 57.
Figure 132 provides the results of a linear scan analysis of EDX as described in example 57.
Figure 133 is a STEM photomicrograph as described in example 57.
Figure 134 provides the results of an EELS linear scan analysis as described in example 57.: .....
Figures 135-137 are HREM photomicrographs as described in example 57.
Figure 138 provides the XRD results that are described in Example 57.
Figure 139 is a STEM micrograph that is described in Example 60.
Figure 140 provides the results of the linear sweep analysis EELS that is described in example 60.
Figure 141 is a STEM micrograph that is described in Example 60.
Figure 142 provides the results of a linear scan analysis of EDX as described in Example 60.
Fig. 143 is a STEM micrograph that is described in Example 60.
Figure 144 provides the results of the EELS linear scan analysis that is described in Example 60.
Figure 145 provides the results of a linear scan analysis of EDX as described in Example 60.
Figure 146 is a STEM micrograph that is described in Example 60.
Figure 147 provides the results of a linear scan analysis of EDX as described in Example 60.
Figure 148 provides the XRD results that are described in Example 60.
Figures 149 and 150 are the STEM micrographs that are described in Example 60.
Figure 151 provides the results of a linear scan analysis of EDX as described in Example 60.
Figure 152 is a STEM micrograph that is described in Example 60.
Figure 153 provides a scanning EDX linear scan as described in Example 60.
Figures 154 and 155 provide the results of XRD as described in example 61.
Figures 155A and 155B provide the results of microscopy for a finished catalyst as described in Example 65.
Figures 155C-155F provide the microscopy results for a finished catalyst as described in example 65.
DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention describes catalyst preparation methods that provide improvements in the use of metals in supported catalysts containing metal. In general, various embodiments of the present invention include controlling and / or directing the deposition of metals on the surface of a porous substrate. The ability to control or direct the deposition of metals can be used to treat one or more of the problems associated with the preparation of conventional metal-containing supported catalysts.
For example, a potential disadvantage associated with conventional platinum-on-carbon catalysts is the susceptibility of relatively small platinum-containing particles to leaching during catalytic oxidation reactions in liquid phase compared with particles that contain larger metals. Excessive leaching of metal particles results in a loss of the metal and represents an inefficient use of the metal. Furthermore, in the case of oxidation of PMIDA, it is believed that these relatively small platinum-containing crystallites contribute to an undesired formation of by-product (eg, IDA). It is also believed that relatively small platinum-containing crystallites are more susceptible to deactivation than larger particles (eg, by deactivation of active sites containing metals in the presence of the reaction medium and / or by coking the catalyst) . It is believed that a significant portion of the relatively small metal particles is located on the surface of the carbon support within relatively small pores and that small pores can trap and prevent the agglomeration of these relatively small platinum crystallites into larger particles than in general, they are resistant to leaching and in general do not promote the formation of: IDA .. In addition, it is believed that. Metal deposited on the surface of a porous substrate within relatively small pores is less accessible to reactants than the metal deposited within larger pores and thereby contributes less to the activity of the catalyst.
The various methods described herein for directing and / or controlling the deposition of metals in general comprise treating the porous substrates by disposing or introducing one or more pore-blocking compounds into the pores of an interval. of predefined size. The methods described herein can be used to selectively block pores within a given size domain without significantly affecting the other pores of the substrate to thereby provide an advantageous catalytic surface area. As detailed herein, including the examples, the various embodiments of the present invention provide a porous substrate that includes a pore-blocking compound disposed, and preferentially retained, within relatively small pores (e.g., micropores or pores having a nominal diameter of less than about 20A). The presence of the pore-blocking compound within the pores of the substrate may be indicated by a reduced proportion of surface area attributable to relatively small pores (e.g., a reduced proportion of micropores surface area) and / or by a lower contribution to the porosity of the substrate through the relatively small pores. It is believed that the presence of the .poros blocking compound within the micropores of the treated substrate reduces. . And, preferably, substantially prevents the deposition of metals on the substrate surfaces within these pores, thereby directing the deposition of metals to other surfaces of the substrate and within larger pores. Therefore, it is currently believed that the presence of the pore blocker reduces the formation of small crystallites of metals within the micropores, which are resistant to agglomeration, rapidly leached and / or deactivated, and represent an inefficient use of metals.
In addition to or apart from the effect of controlling or directing the location of metal deposition (for example, by arranging or introducing a pore-blocking compound into the pores of a substrate), the manner of performing metal deposition may also promote a use most efficient of metals. For example, the various catalysts described herein include and / or are prepared from a support having one or more regions of a first metal on the surface of the support and a second metal on the surface of said one or more regions of the first metal.
The first metal is selected such that it has a greater electropositivity than the second metal and the second metal is deposited on the surface of said one or more regions of the first metal by displacement of the first metal of said one or more regions on the surface of the metal. support. Most particularly, the second metal can be deposited by a nearly atom-by-atom replacement of the first metal by the second metal. It is currently believed that this way of depositing * metals promotes the formation of a relatively thin layer comprising atoms of the second metal and can in fact form virtually a monolayer of atoms of the second metal deposited on the surface of the regions of the first metal ( example, a layer of atoms of the second metal on the surface of one or more regions of the first metal of not more than about 3 atoms in thickness). The heating of the carbon support containing on it to the first and second metals, it forms metal particles comprising the first and second metals. The metal particles formed contain the second metal in a form that represents a more efficient utilization of the second metal. For example, the composition of a significant fraction of the metal particles is generally rich in the content of the first metal, thus providing a relatively low proportion of the second unexposed metal in all the particles (for example, a bimetallic alloy rich in a first metal); In addition, or alternatively, the metal particles formed with subsequent heating may have a relatively thin coating comprising the second metal (e.g., a layer no more than about 3 atoms thick) that at least partially surrounds a core which predominantly comprises the first metal.
I. Porous substrate treatment The deposit and / or introduction of a pore-blocking agent or compound (also referred to as a "pore blocker" in the present) into the pores of a porous substrate generally comprises putting the substrate in contact with the agent or compound, or a precursor (or precursors) thereof. In one embodiment, the pore-blocking compound is retained preferentially within the pores of the substrate in a domain of selected size (e.g., micropores) by virtue of having at least one dimension larger than the openings of the pores, inhibiting that way the agent exit from the selected pores. In In various embodiments, the pore-blocking agent can be formed from one or more precursors of pore-blocking agents introduced into the pores of the substrate. In addition, or alternatively, and irrespective of whether the pore-blocking agent is introduced into the pores or formed in situ (i.e., formed from one or more precursors of agents introduced into the pores), the agent can remain retained within the pores of the substrate in a domain of selected size by virtue of a conformational change induced in the pore-blocking agent such that the exit of selected pores of the pore-blocking agent is inhibited by a matter of dimensions. A conformational change in the pore-blocking agent can be induced in the selected pores by virtue of the interactions between the pore-blocking agent and the pore walls. According to one embodiment, the pore blocking agent is arranged, and preferably retained, within the micropores of the porous substrate to produce a treated substrate for the deposition of metals that exhibit a lower micropores surface area ratio.
It will be understood that the reference to one or more precursors contemplates compositions that will ultimately function as a pore-blocking agent upon entry into the pores (eg, by virtue of at least one dimension of the compound and / or by virtue of a change in conformation in the compound after entering the pores). In addition, or alternatively, the reference to one or more precursors may refer to one or more compounds that combine or react to form the pore-blocking agent once disposed and / or introduced into the pores of the substrate. Regardless of whether a compound that will eventually function as the pore blocker is introduced or disposed within the pores of the substrate, or if the components that combine to form the pore blocker are introduced or disposed within the pores, the mechanism by which is believed to function as the pore blocker (ie, by virtue of having at least one dimension larger than the pore openings, either initially or after a conformational change) is the same.
In various embodiments, the pore blocker comprises a compound having at least one dimension such that, after entering the pores, said pore blocker is retained preferentially within those pores that fall within a domain of selected size.
Of course, it will be understood that the pore blocker typically also has at least one dimension that allows its entry into the pores, but.;; - ..... it is currently believed that the pore blocker typically assumes an orientation and / or conformation within the pores such that the larger dimension of the pore opening prevents the exit of the pore-blocking compound from the pore.
As previously indicated, according to one embodiment, the pore blocker is retained preferentially within the micropores of the substrate. However, this does not exclude the possibility that the pore blocker, or one or more precursors thereof, also enter pores of a size that is not within this predefined range after its contact with the porous substrate. For example, the pore blocker can enter the pores having a nominal diameter greater than about 20A (for example, pores having a nominal diameter of between about 20A and about 3000A, commonly known as meso- and macropores), but the blocker of pores tend to exit after and not be retained preferentially within these pores, although the pore-blocking agent may remain in a smaller pore portion outside the micropore range.
A. Porous substrate In general, the porous substrate or support structure for the metal-containing catalytic active phase can comprise any material suitable for the deposition of one or more metals thereon. Preferably ,. the porous substrate is found. in the form of a carbon support. In general, the carbon supports used in the present invention are well known in the art including, for example, those described in U.S. Pat. N °: 6.417.133 of Ebner et al. and in Wan et al. in WO 2006/031938 (the complete contents of which are incorporated herein by reference for all relevant purposes). Preferred are activated carbon supports, non-graphitized for the noble-carbon-on-metal catalysts used for the oxidation of PMIDA and are provided to the catalyst a robust mechanical integrity and a high surface area for the active phase containing the metal. However, activated, non-graphitized carbon supports are not necessarily preferred in all cases and it should be understood that suitable catalysts for various other applications can be prepared using non-activated and / or non-graphitized carbon supports. In various particularly preferred embodiments, the supports are in the form of particulates (eg, powders).
In various preferred embodiments (for example, the catalysts used for the oxidation of PMIDA), the carbon support contains a relatively low proportion of oxygen-containing functional groups (for example, carboxylic acids, ethers, alcohols, aldehydes, lactones, ketones, esters, amine oxides and amides). These functional groups can increase the leaching of noble metals and can potentially increase noble metal agglomeration and particle growth during liquid phase oxidation reactions and thus reduce the ability of the catalyst to oxidize oxidizable substrates (eg PMIDA). and / or formaldehyde). As used herein, an oxygen-containing functional group is "on the surface of the carbon support" if it is attached to a carbon support atom and if it can interact chemically or physically with the compositions in each reaction mixture. or with the metal atoms deposited on the carbon support. As described in U.S. Pat. No. 6,417,133 and in Wan et al. in WO 2006/031938, many of the oxygen-containing functional groups that reduce the resistance to the leaching and sintering of noble metals and reduce the activity of the catalyst are desorbed from the carbon support as carbon monoxide when the catalyst is heated to a high temperature (for example, 900 ° C) in an inert atmosphere (for example, helium or argon). Thus, measuring the amount of CO desorption of a freshly prepared catalyst (ie, a catalyst that has not previously been used in a liquid phase oxidation reaction) under high temperatures constitutes a method that can be used to analyze the catalyst surface to predict the retention of noble metals and the maintenance of catalyst activity. One way to measure CO desorption is to use thermogravimetric analysis with mass spectroscopy ("TGA-MS") online. Preferably, no more than about 1.2 mmol of carbon monoxide per gram of the catalyst of the present invention is desorbed when a dry sample of the catalyst is heated, after having heated it to a temperature of 500 ° C for about 1 hour. under an atmosphere of hydrogen and before it has been exposed to an oxidant after heating under a hydrogen atmosphere, under a helium atmosphere and is then subjected to a temperature which increases from about 20 ° C to about 900 ° C at a rate of about 10 hours. ° C per minute, and then kept constant at about 900 ° C for about 30 minutes. Most preferably, do not get desorbed more than 0.7 Approximately mmoles of carbon monoxide per gram of freshly prepared catalyst under such conditions, even more preferably no more than about 0.5 mmol of carbon monoxide per gram of freshly prepared catalyst is desorbed and more preferably no more than about 0.3 mmoles are desorbed. carbon monoxide per gram of freshly prepared catalyst. A catalyst is considered to be "dry" when said catalyst has a moisture content of less than about 1% by weight. Typically, the catalyst can be dried by placing it under a vacuum with an N2 purge of about 25 inches Hg and at a temperature of 120 ° C for about 16 hours.
As also described in U.S. Pat. No. 6,417,133 and in Wan et al. in WO 2006/031938, the measurement of the number of oxygen atoms on the surface of a freshly prepared catalyst support constitutes another method for analyzing the catalyst in order to predict metal-noble retention and maintenance of lar, activity- catalytic To analyze a surface layer of the approximately 50 A support, for example, X-ray photoelectron spectroscopy can be used. Preferably, this analysis for a support suitable for use in relation to the oxidation catalysts described in FIG. the present indicates a ratio of carbon atoms to oxygen atoms on the support surface of at least about 20: 1. Most preferably, the ratio is at least 30: 1 approximately, still most preferably at least about 40: 1, still most preferably at least about 50: 1 and most preferably at least about 60: 1. In addition, the ratio of oxygen atoms to metal atoms on the surface is preferably less than about 8: 1. Most preferably, the ratio is less than about 7: 1, still most preferably less than about 6: 1 and more preferably less than about 5: 1.
Typically, a support in the form of particles can comprise a wide distribution of particle sizes. For the powders, preferably at least about 95% of the particles have between about 2 and about 300 μm in their largest dimension, most preferably at least about 98% of the particles have between about 2 and about 200 μm in their larger dimension and very preferably still, at least 99% approximately. -the particles have between about 2 and .-, about 150 pm where about 95% of the particles have between about 3 and about 100 pm in their largest dimension. Particles larger than about 200 μm in their largest dimension tend to fracture to give superfine particles (ie, less than 2 μm in their largest dimension) which may be more difficult to recover.
In the following description, areas are typically provided Surface specific carbon supports and catalysts measured in terms of the well-known Langmuir method using N2. It will be understood that these values in general correspond to the values measured by the well-known Brunauer-Emmett-Teller 5 (B.E.T.) method using N2.
The specific surface area of the carbon support before any treatment (e.g., disposition or introduction of a pore-blocking compound within the pores of a substrate) in accordance with the present invention is generally at least 500 m2 / g. approximately, at least 750 m2 / g approximately, at least 1000 m2 / g approximately or at least 1250 m2 / g approximately. Typically, the specific surface area of the carbon support comprises between about 10 and about 3000 m2 / g, more typically between about 500 and about 2100 m2 / g and even more typically 5 between about 750 and about 1900 m2 / g or between, .-. .... approximately 1000 and approximately 1900 m2 / g. In certain embodiments, the preferred specific surface area comprises between about 1000 and about 1700 m2 / g, between about 1000 and 1500 m2 / g, between about 1100 and about 0 1500 m2 / g, between about 1250 and about 1500 m2 / g, between approximately 1200 and approximately 1400 m / g is approximately 1400 m2 / g. In addition, in accordance with the present invention, the porous carbon support generally has a pore volume of at least 0.1 ml / g approximately, at least 0.2 ml / g approximately or at least 0.4 ml / g approximately. Typically, the porous carbon support has a pore volume of between about 0.1 and about 2.5 ml / g, more typically between about 0.2 and about 2.0 ml / g and, even more typically, between about 0.4 and about 1.5 ml / g.
It should be noted that the present disclosure is focused on a blocking treatment of the pores to reduce the micropore surface area of the porous carbon substrates or supports for use in catalysts containing noble metals suitable for use in the oxidation of PMIDA. However, it will be understood that methods of treating a porous substrate by introducing a pore blocking compound as described herein are generally applicable to the preferential blocking of other pore size domains, other types of porous catalyst supports and / or porous carbon substrates used as, metal supports, other than noble metals. For example, the methods of the present invention are suitable for the treatment of porous Raney metals or alloys often known as sponges, such as those described in US Pat. No.:7,329,778 to Morgenstern et al. and used as supports for copper-containing catalysts used in the dehydrogenation of primary amino alcohols. By way of further example, the methods of the present invention are also suitable for the treatment of other non-carbonaceous porous supports such as, for example, silica dioxide (SiO2), aluminum oxide (AI2O3), zirconium oxide (Zr03), titanium oxide (Ti02) and combinations thereof.
B. Locking pores In accordance with the present invention, the pore blocker used to selectively block micropores can be selected from a variety of compounds including, for example, various sugars (e.g., sucrose), compounds containing 5 or 6 membered rings (e.g. , cyclohexanes 1, 3- and 1,4-disubstituted) and combinations thereof. Suitable compounds for use in the selective blocking of micropores include 1,4-cyclohexanedimethanol (1,4-CHDM), bis (ethylenic ketal) of 1,4-cyclohexanedione, 1,3- or 4-cyclohexanedicarboxylic acid, acetal monoethylene of 1,4-cyclohexanedione and combinations thereof.
In various embodiments, the pore blocker may comprise the product of a reaction (e.g., a condensation reaction) between one or more precursors of the pore-blocking compound. Once formed, the resulting pore blocking compound can be retained preferentially within the selected pores of the substrate by virtue of the fact that they have at least one dimension that prevents the exit of the pore-blocking compound from the pores.
For example, it has been observed that the coupling product of a cyclohexane derivative and a glycol can be used as an agent micropores blocker for particulate carbon substrates used as a support for a noble metal or other metal catalyst. Most particularly, the pore-blocking agent can be the coupling product of a disubstituted, trisubstituted or tetrasubstituted cyclohexane derivative and a glycol. In particular, the cyclohexane derivative can be selected from the group consisting of 1,4-cyclohexanedione, 1,3-cyclohexanedione, 1,4-cyclohexanebis (methylamine) and combinations thereof. The glycol is generally selected from the group consisting of ethylene glycol, propylene glycol and combinations thereof.
In general, the substrate is contacted with a liquid comprising the pore-blocking agent or one or more precursors of the pore-blocking agent. Typically, the substrate to be treated is contacted with a mixture or solution comprising one or more compounds or precursors of pore blockers dispersed or dissolved in the liquid contact medium (e.g., deionized water). For example, the substrate can be contacted with a mixture or solution that includes a cyclohexane derivative and a glycol, or a liquid contact medium consisting essentially of the cyclohexane derivative and glycol. The substrate can also take contact successively with liquids or liquid media comprising one or more of the precursors. The composition of the liquid that includes the pore-blocking agent or one or more precursors thereof that makes contact with the porous substrate is not absolutely critical and can be easily selected and / or optimized by the person skilled in the art.
As already indicated, regardless of whether a compound is introduced that will eventually function as a pore blocker in the pores of the substrate or if precursors are introduced which form the blocking compound in the substrate, the pore blockers may be preferentially retained within the selected substrate pores (eg, micropores) by virtue of the conformational arrangement assumed by the pore-blocking agent once it was disposed or formed within the pores. For example, it is currently believed that several pore-blocking molecules are transformed from a more linear saddle conformation to a bulkier can conformation, which causes the compound to be trapped within the micropores. In particular, it is currently believed that various pore-blocking agents that include a terminal hydrophilic group will favor a can-like conformation within the micropores of a porous carbon support due to the nature of the carbon support (ie, the can-like conformation will be favored in a pore-blocking compound containing terminal hydrophilic groups due to the relatively hydrophobic nature of the carbon support surface). Examples of pore-blocking compounds comprising a terminal hydrophilic group include 1,4-cyclohexanedicarboxylic acid and 1,4-cyclohexanedimethanol (CHDM).
It is also possible to promote or induce a conformational change in a pore blocker by manipulating the liquid medium comprising the pore-blocking agent in contact with the skin. substrate including, for example, adjusting the pH and / or adjusting the temperature of the liquid medium.
Figures 1A-1C provide graphical representations of preformed pore block molecules and pore blocker molecules formed from precursors within the pore (i.e., in situ coupling) undergoing a conformational change within the pore to block or selectively plugging smaller pores. A conformational change of a cyclohexane pore blocker is generally shown in Figure 1 D. These representations are offered for illustrative purposes only and are not intended to limit the present invention.
As already indicated, it is believed that contacting the substrate with the pore-blocking agent, or precursors thereof, results in the introduction or disposition of the pore-blocking agent within the micropores of the substrate and within larger pores outside of the pores. this predefined range. In order to provide a treated substrate in which the micropores of the predefined interval have been preferentially blocked, a. The substrate is then contacted with a washing liquid to remove the blocking agent from the pores outside the micropore domain (ie, those pores in which the pore-blocking agent is not to be preferentially retained by virtue of the fact that the agent has at least one dimension larger than the opening of the pore). The precise composition of the washing liquid and the way it makes contact with the substrate are not strictly critical, but for this purpose the substrate can conveniently be Take contact with deionized water.
C. Treated substrates As already indicated, the method of treating the substrate of the present invention is suitable for introducing a pore-blocking agent into the micropores of porous substrates (eg, a particulate carbon support) and preferentially retaining the pore-blocking agent in the pores. micropores The preferential retention of the pore-blocking agent within the micropores can be represented by the proportion of micropores in which the agent is retained. Typically, the pore blocking compound remains at least about 2%, at least about 5%, at least about 10%, or at least about 20% of the micropores, based on the total amount of micropores in the substrate. .
The preferential retention of the pore-blocking compound within the micropores is also indicated by the surface area of the treated substrate provided by the micropores and provided by the larger pores. It is believed that the presence of the pore-blocking compound within the micropores will cause at least a portion of these "blocked" pores to appear as a non-porous portion of the treated substrate during surface area measurement methods (eg, the recognized method of Langmuir surface area measurement), thus reducing the proportion of surface area that would otherwise be attributable to micropores if not They were blocked. This preferential locking of the pores sought results in a reduction in the surface area supplied by the micropores (ie, the surface area of the micropores). For example, in various embodiments, the surface area of the micropores of the treated substrate generally represents no more than about 70%, no more than about 60%, or no more than about 50% of the surface area of the micropores of the substrate. before treatment by contact with the pore blocker. Preferably, the micropore surface area of the treated substrate represents no more than about 40%, most preferably no more than about 30% and, most preferably, no more than about 20% of the surface area of the micropores of the substrate before of the treatment.
D. Methods for preparing catalysts using treated substrates ... .r¿ ..;; .........
As detailed herein, the catalysts can be prepared by a process which generally comprises depositing one or more noble metals and, optionally, one or more promoter metals on the surface of a treated (i.e., blocked pore) substrate such as a porous carbon support, and heating the carbon support containing the noble metals and the optional promoters deposited thereon in a non-oxidizing environment.
The noble metal is generally selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, silver, osmium, gold and combinations thereof. In various preferred embodiments, the noble metals comprise platinum and / or palladium. In still other preferred embodiments, the noble metal is platinum. Said one or more promoter metals are generally selected from the group consisting of tin, cadmium, magnesium, manganese, nickel, aluminum, cobalt, bismuth, lead, titanium, antimony, selenium, iron, rhenium, zinc, cerium, zirconium, tellurium , germanium and combinations thereof, on the surface of the porous substrate and / or a noble metal surface.
The noble metal can be deposited in accordance with conventional methods known in the art including, for example, liquid phase deposition methods such as reactive deposition techniques (eg, deposition by reduction of noble metal compounds and deposition by hydrolysis of noble metal compounds), ion exchange techniques, impregnation in excess of solution and impregnation of incipient humidity; vapor phase methods such as physical deposition and chemical deposition; precipitation; electrochemical deposition; and non-electrolytic deposition as described in U.S. Patent No. 6,417,133 and by Wan et al. in International Publication No. WO 2006/031938. In various preferred embodiments, the noble metals are deposited by means of a reactive deposition technique comprising the contact of the carbon support with a solution comprising a salt of the noble metals and then the hydrolysis of the salt. An example of a suitable platinum salt relatively inexpensive is hexachloroplatinic acid (H2PtCl6).
The promoter or promoters can be deposited on the surface of the carbon support treated before, simultaneously or after the deposition of the noble metals on the surface. The methods for depositing a promoter metal are generally known in the art and include the methods indicated above with respect to the deposition of noble metals.
Once the carbon support has been impregnated with one or more noble metals and optional promoters, the surface of the catalyst is preferably heated to elevated temperatures, for example, in a heat treatment or a calcining operation. For example, the calcination can be carried out by placing the catalyst in an oven (for example, rotary stoves, tunnel stoves and vertical calciners), by passing it through a heat treatment atmosphere.
In general, the surface of the treated support impregnated with one or more metals is heated to a temperature of at least about 700 ° C, at least about 800 ° C, at least about 850 ° C, at least about 900 ° C or minus 950 ° C approximately. Typically, the metal-impregnated support is heated to a temperature of between about 800 ° C and about 1200 ° C, preferably between about 850 ° C and about 1200 ° C, most preferably between about 900 ° C and about 1200 ° C, still very preferably between about 900 ° C and about 1000 ° C and especially between about 925 ° C and about 975 ° C.
The period of time that the impregnated support is subjected to high temperatures (including the time by which the support is heated to the maximum temperature) is not strictly critical. Typically, in commercial-scale apparatus, the metal-impregnated support is heated to the maximum temperature of the heat treatment for at least about 10 minutes (eg, at least about 30 minutes).
Preferably, the support impregnated with metals is heated in a non-oxidizing environment. Said non-oxidizing environment may comprise or consist essentially of inert gases, such as N2, noble gases (eg, argon, helium) or mixtures thereof. In certain embodiments, the non-oxidizing environment comprises a reducing environment and includes a gaseous phase reducing agent, such as, for example, hydrogen, carbon monoxide or combinations thereof. The non-oxidizing environment in which the catalyst is heated may include other components such as ammonia, water vapor and / or an oxygen-containing compound as described, for example, in Wan et al. in International Publication No. WO 2006/031938. In one embodiment, the heat treatment after metal deposition preferably comprises a gas phase reduction at elevated temperature to remove the oxygen-containing functional groups from the catalyst surface, thereby obtaining a catalyst that exhibits the characteristics of monoxide desorption. from carbon and / or the surface ratio of carbon atoms to oxygen atoms that are described in Ebner et al. Patent of the U.S.A. N °: 6.417.133.
In various preferred embodiments, the noble metals form alloys with at least one promoter to form alloys of metal particles. For example, noble metal particles on a carbon bearing surface may comprise noble metal atoms forming alloys with promoter metal atoms. In several other preferred embodiments, the noble metals form alloys with two promoters (e.g., iron and cobalt). Catalysts comprising a noble metal forming an alloy with one or more promoters often exhibit a higher resistance to metal leaching and greater stability (for example, from one cycle to another) with respect to the oxidation of formaldehyde and formic acid . It will be understood that the term "alloy" as used herein generally encompasses any metal particle comprising a noble metal and at least one promoter (eg, intermetallic compounds, substitution alloys, multiphasic alloys, segregated alloys, and alloys). interstitial as described in Wan et al., in International Publication No. WO 2006/031938).
The heat treatment of the metal-impregnated support generally provides agglomeration and / or sintering of metal particles on the surface of the support. The use of substrates with treated blocked micropores results in impregnated media having a reduced proportion of particles containing relatively small metals in the surface of the support within the domain of micropores, which in general are more susceptible to leaching and / or deactivation, compared to particles containing noble metals of larger size. In addition, or alternatively, metal-containing particles on the surface of the substrate outside the micropore domain are generally more accessible to the reactants. By virtue of either or both of these effects, it is believed that the treated substrates of the present invention provide a more efficient metal utilization (eg, an increase in the effective catalytic surface area of the metal per unit weight) in the catalyst.
It should be taken into account that the persistence of the pore blocker in the treated substrate after heat treatment of post-deposition of metals is not critical to obtain the advantages indicated previously. In fact, it is currently believed that the pore blocker most likely decomposes and / or otherwise removes from the surface of the substrate during calcination. But currently it is also believed that it is possible to obtain a .o. more of the mentioned advantages provided that the pore blocker is preferentially retained in the pores selected on the surface of the support during the deposition of metals in order to promote the desired metal dispersion.
E. Catalysts prepared using treated substrates The substrates treated in accordance with the method herein (ie, blocked pore substrates) can be used as supports for catalysts containing metals including, for example, catalysts that include one or more noble metals (eg, a noble metal such as platinum) deposited on a particulate carbon support. In addition, catalysts containing noble metals prepared using the substrates treated according to the present invention may include one or more promoters and may be prepared in a manner that exhibits one or more of the properties as described, for example, in US Pat. No. 6,417,133, in International Publication No. WO 2006/031938 and in the US Patent. No.: 6,956,005, the contents of which are incorporated herein in their entirety as a reference for all relevant purposes.
In general, the noble metal constitutes less than about 8% by weight of the catalyst, typically less than about 7% by weight of the catalyst, more typically less than about 6% by weight of the catalyst. In various embodiments, the noble metal typically constitutes between about 1% and about 8% by weight of the catalyst, more typically between about 2% and about 7% by weight of the catalyst and, even more typically, between about 3% and about 6% by weight of the catalyst.
As already indicated, the particulate carbon supports treated in accordance with the present invention to preferentially block micropores offer a more efficient use of metals. Therefore, effective catalysts containing noble metals can be prepared in an amount below the indicated limits preceding and / or at or near the lower limits of one or more of the ranges indicated previously. For example, in various embodiments, the noble metal constitutes less than about 5% by weight of the catalyst, less than about 4% by weight of the catalyst or even less than about 3% by weight of the catalyst. By way of further example, in various embodiments the noble metal typically constitutes between about 1% and about 5% by weight of the catalyst, more typically between about 1.5% and about 4% by weight of the catalyst and, even more typically, between about 2% and about 3% by weight of the catalyst. However, it should be understood that the present invention does not require the use of a substrate treated in the preparation of a catalyst containing noble metals, including a lower proportion of noble metals, compared to conventional catalysts. That is, the preparation of a catalyst that includes a porous treated substrate that provides a more efficient metal utilization to conventional noble metal fillers, also represents an advance in the art (for example, it is currently believed that the treated substrates of the present invention provide a smaller proportion of relatively small metal particles that are susceptible to leaching and represent inefficient metal utilization, thus contributing to improvements in catalytic activity and a reduction in the formation of unwanted side products (eg, IDA)) .
In general, according to some modalities, at least a promoter (eg, iron) constitutes less than about 2% by weight of the catalyst, less than about 1.5% by weight of the catalyst, less than about 1% by weight of the catalyst, less than about 0.5% by weight of the catalyst or approximately 0.4% by weight of the catalyst. Typically, at least one promoter constitutes less than about 1% by weight of the catalyst, preferably between about 0.25% and about 0.75% by weight of the catalyst and, most preferably, between about 0.25% and about 0.6% by weight of the catalyst. In various preferred embodiments, the catalyst includes iron as a promoter. In addition, or alternatively, the catalyst includes cobalt as a promoter.
In various particularly preferred embodiments, the catalyst comprises iron and cobalt promoters. The use of iron and cobalt in general provides the benefits associated with the use of iron (for example, activity and stability with respect to the oxidation of formaldehyde and formic acid). However, compared to the presence of iron only as a promoter, the presence of cobalt tends to reduce the formation of certain side products during the oxidation of a PMIDA substrate (eg, IDA). Moreover, it is believed that the formation of IDA is directly related to the total iron content of the catalyst. Accordingly, in various embodiments of iron / cobalt co-promoters, the iron content is essentially replaced by Cobalt to reduce the formation of IDA and other byproducts however provides sufficient activity for the oxidation of formaldehyde and formic acid. For example, compared to a platinum-on-carbon catalyst containing 0.5% by weight of iron in the absence of cobalt, a similar catalyst containing 0.25% by weight of iron and 0.25% by weight of cobalt typically provides comparable activity for the oxidation of PMIDA, formaldehyde and formic acid, while minimizing the formation of secondary products.
In co-promoter iron / cobalt modalities, the The amount of each promoter on the surface of the carbon support (either associated with the carbon surface itself, with noble metals or a combination thereof) typically comprises at least about 0.05% by weight, at least about 0.1% by weight or at least 0.2% by weight approximately. In addition, the amount of iron on the 15 surface of the carbon support typically comprises between "... about 0.1 and about 4% by weight of catalyst, preferably between about 0.1 and about 2% by weight of the catalyst, most preferably between about 0.1 and about 1% by weight of the catalyst and, even more preferably, 20 between about 0.1 and about 0.5% by weight of the catalyst.
Similarly, the amount of cobalt on the surface of the carbon support typically comprises between about 0.1 and about 4% by weight of the catalyst, preferably between about 0.1 and about 2% by weight of the catalyst, most preferably between about 0.2 and about 1% by weight of the catalyst and, even more preferably, between about 0.2 and about 0.5% by weight of the catalyst. In such a mode, the weight ratio of iron to cobalt in the catalyst in general is between about 0.1: 1 and about 1.5: 1 and preferably between about 0.2: 1 and about 1: 1. For example, the catalyst may comprise about 0.1 wt% of iron and about 0.4 wt% of cobalt or about 0.2 wt% and about 0.2 wt% of cobalt.
As will be understood by those skilled in the art, the metal content of the catalysts can be freely controlled within the ranges described herein (eg, by adjusting the concentration and relative proportions of the metal sources used in a deposition bath. reagent in liquid phase).
II. Catalysts containing a first and a second metal Various preferred embodiments of the present invention are directed to catalysts comprising and / or being prepared from a porous substrate or from a support containing one or more regions of a first metal on its surface, and a second metal on the surface of said one or more regions of the first metal. In these modalities, a first metal whose electropositivity is greater than the electro-positivity of the second metal (that is, the first metal is greater than the second metal in the electromotive series). Oxidation of the first metal provides electrons for the reduction of the ions of the second metal present in the deposition bath in order to deposit the atoms of the second metal on the surface of said one or more regions of the first metal. The oxidation of the first metal and the reduction of the second metal and the deposition take place substantially simultaneously and the atoms of the second metal are deposited on the surface of said one or more regions of the first metal by displacement of the ions of the first metal of said metals. one or more regions towards the deposition bath. This form of metal deposition can be termed spontaneous or deposition by redox displacement. (See, for example, U.S. Patent No. 6,670,301 to Adzic et al., And U.S. Patent Nos. 6,376,708, 6,706,662, and 7,329,778 to Morgenstern et al.) Preferably, the first sacrificial metal is less expensive than the second metal.
. . As detailed in the present the deposition of the second metal by displacement deposition is preferably conducted and controlled in a manner that allows a preferential deposition of the second metal on the surface of said one or more regions of the first metal. That is, the second metal is preferentially deposited on one or more regions of the surface of the first metal by deposition by displacement on the deposition of the second metal on the support surface and / or deposition of the second metal on the surface of the second metal. metal already deposited.
Without taking into account a particular theory, it is currently believed that the source of the ions of the second metal can promote a preferential deposition of the second metal over said one or more regions of the first metal. Most notably, it is now believed that sources of the second metal that provide ions of the second metal at lower oxidation numbers (eg, +2) provide a slower, more controlled deposition of the metals compared to the sources that they provide ions of noble metals with higher oxidation numbers (for example, +4). It is believed that the ions of the second metal at said higher oxidation numbers can be reduced more rapidly in the presence of the electrons generated by the oxidation of the first metal that provides a greater driving force for the deposition of the second metal. It is believed that this greater driving force increases the rate of deposition of the second metal which, in turn, is believed to promote a less discriminated deposition of the second metal. Very particularly ,; HE . believes that the greater-driving force for the deposition of ions of the second metal promotes the deposition of the atoms of the second metal on the support and / or on the surface of the atoms of the second metal already deposited. Therefore, it is currently believed that as the oxidation state of the ions of the second metal decreases, there is a preferential (eg, selective) deposition of the noble metal directed over one or more regions of the first metal by displacement of the atoms of the first metal of the deposition on the carbon support and / or they generally increase the atoms of the second metal already deposited.
In addition, it is currently believed that the deposition of the atoms of the second metal using sources that supply ions at relatively low oxidation numbers occurs in a manner that generally reduces the complexity of the displacement deposition process to promote the desired preferential deposition of the second. metal directed on the regions of the first metal. For example, displacement deposition using sources supplying ions of the second metal at relatively low oxidation numbers easily occurs in the absence of precise control of the concentration of the source of the second metal and / or the deposition time.
In accordance with the present invention, it is currently believed that a significant fraction, if not substantially all, of the second metal deposited by controlled displacement of a first metal provides domains or regions on the surface of one or more regions of the first metal - characterized by , a relatively thin layer of atoms of the second metal (for example, no more than about 5 atoms thick or not more than about 3 atoms thick), rather than agglomerate to form metal-containing particles. In certain preferred embodiments, the preparation of the catalyst by the method herein can provide virtually a monolayer of the second metal (e.g., a layer of atoms of the second metal of not more than about 3 atoms in thickness, not more than 2 carbon atoms). thickness approximately and preferably between approximately one and approximately two atoms in thickness).
Also according to the present invention, it is currently believed that the deposition of the second metal by displacement of the atoms of the first metal of one or more regions of the first metal provides a structure (eg, a catalyst precursor structure) which, after heat treatment at elevated temperatures, provides metal particles that include the second metal in a form that represents a more efficient utilization of the second metal. In various embodiments, the metal particles are typically rich in the first metal (i.e., they contain an excess of atoms of the first metal before the atoms of the second metal) and it is currently believed that the particles include one or more bimetallic alloys. In contrast, conventional noble metal-containing catalysts typically include particles comprising an atomic excess of noble metal atoms. Thus, it is believed that the particles rich in the first metal include the noble metal (ie, the second metal) in a form that represents a reduced proportion of noble metal distributed throughout the particle and, therefore, represents atoms of exposed bare metal and potentially unused for the entire structure of the particle. But an excess of the first metal is not required to provide an improvement in the use of metals. However, to the extent that the ratio of the first metal to the second metal increases, improvements in the use of the second metal can be achieved. Therefore, various modalities of present invention contemplate the selection of combinations of a first and second metal that are malleable for the formation of alloys that include at least an equivalent atomic ratio of first metal (M-i) to second metal (M2). More particularly, in various embodiments there is a preference for the selection of combinations of a first and second metal that provide bimetallic alloys of said first and second metals, M x M 2y, where the atomic ratio of x: y is greater than or equal to 1. In accordance further with these and various other preferred embodiments, the metal particles include bimetallic alloys in which the atomic ratio of x: y is greater than about 2 or greater than about 3. For example, in the case of a first and second copper and platinum metals, respectively, the metal particles on the support surface may include bimetallic CuPt and / or Cu3Pt alloys. By way of further example, in the case of one and second tin and platinum metals, respectively, at least some of the metal particles may include bimetallic alloys of Pt2Sn3, PtSn2.and / or PtSn4, In the case of a primer: and second iron and platinum metals, respectively, the metal particles on the support surface may include, for example, FesPt, FePt, In addition, or alternatively, it is also currently believed that at least part of the metal particles on support produced after calcination of a catalyst precursor structure prepared by displacement of a noble metal (ie, second metal) as detailed herein include a relatively thin layer or coating comprising atoms of the second metal (e.g., a layer of atoms of the second metal of no more than about 3 atoms in thickness) that at least partially surrounds a core comprising to the first metal. The core generally comprises a relatively high concentration of the first metal (eg, greater than about 50 atom percent). The combination of a core rich in a first metal and a coating containing the second metal provides a relatively low proportion of the second unexposed metal and, therefore, provides improvements in the surface area of the exposed metal per unit weight of the metal. It is currently believed that the particles exhibiting said core-coating arrangement can generally provide a greater improvement in the use of the second metal compared to conventional noble metal supported catalysts as compared to particles generally characterized as rich in the first metal ( that is, a greater increase in the surface area of the second exposed metal per unit weight of the second metal). Accordingly, as the fraction of core-coating particles increases on the surface of the support, the use of metals in the catalyst also increases. Therefore, in various preferred embodiments, the catalyst includes a predominant fraction of metal particles that exhibit a core-shell arrangement. However, it should be noted that although they obtain improvements in the use of metals by virtue of the presence of particles of metal in general rich in the content of the first metal, independently of the presence of any particle characterized by exhibiting a core-coating arrangement.
It should be noted that the reference to a porous substrate such as a carbon support on which a first and second metals (i.e., a support containing a first and second metal) has been deposited as a catalyst precursor structure is not it excludes the catalytic activity of these impregnated supports in the absence of subsequent heat treatment. In fact, experimental evidence indicates that supports impregnated with metals prepared in this way can function as effective catalysts. Therefore, elsewhere in the present (including the claims) porous substrates on which a first metal (eg, a first support impregnated with metals) has been deposited are also known as catalyst precursor structures. But in various preferred embodiments, the support impregnated with a first and second metal is heated to elevated temperatures to provide the catalyst (sometimes known as the catalyst finished herein).
Experimental evidence indicates that the catalysts (ie both the catalyst precursor structures and the finished catalysts) prepared as detailed herein using a noble metal and a first sacrificial metal layer are at least as active as the catalysts. conventional noble metals on carbon on a unit weight basis of the metal. Without taking into account a particular theory, it is currently believed that the active sites or domains of the second metal provided by the method of the present invention provide an increase in the catalytic surface area per unit weight of the metal compared to conventional catalysts containing metal prepared by methods that do not include deposition by displacement of the second metal over one or more regions of a first sacrificial metal.
Conventional noble metal catalysts on carbon in general include particles containing noble metals on the surface of the support formed by agglomeration and / or sintering of the noble metal atoms and / or particles containing noble metals. This agglomeration typically occurs during post-deposition heat treatment of a support impregnated with noble metal at relatively high temperatures. Metal particles of conventional noble metal catalysts formed by agglomeration of the metal deposited on the surface of a support, typically include the noble metals distributed throughout the particle (for example, the particles exhibit a composition profile of a relatively constant noble metal concentration). The stability of the particles (for example, resistance to leaching and / or deactivation under the reaction conditions) generally increases with increasing particle size, but the catalytic surface area of the exposed metal per unit weight of the metal typically decreases in the largest particles. Therefore, a In spite of the greater stability, the abundance of relatively large noble metal-containing particles and the catalytic surface area of the metal per unit weight of the consequently lower metal represent less efficient metal utilization. Advantageously, the particles rich in the first metal and / or the metal particles comprising a coating containing a noble metal (ie, the second metal) and a core containing the first metal prepared in accordance with various embodiments of the present invention invention generally represent a more efficient utilization of metals. For example, as already indicated, it is believed that particles rich in the first metal include the second metal in a form (e.g., a bimetallic alloy that includes an atomic excess of the first metal) that supplies a reduced proportion of the second metal not exposed.
In addition, or alternatively, and as detailed elsewhere herein, the larger, more stable metal particles in accordance with the present invention are not associated with an unacceptable decrease in the effective catalytic surface area of the given second metal. that an increase in particle size in general is associated with an increase in the size of the core rich in the first metal. For example, experimental evidence indicates a relatively constant thickness of the coating that contains the second metal over a range of particle sizes. Therefore, as the particle size increases, in general it increases the fraction (atom and / or weight) of the particle provided by the core rich in the first metal, while the particle fraction provided by the coating that contains the second metal generally decreases. However, the exposed surface area of the second metal increases with a larger particle size. For example, compared to a particle that includes a core of 1 nm in diameter, at constant thickness values of the coating of the second metal, a particle that includes a core 10 nm in diameter can provide an increase of up to 100 times in the area exposed surface of the coating containing the second metal.
A mechanism for the deactivation of conventional noble-carbon-on-carbon catalysts prepared by deposition of noble metals in the absence of a sacrificial metal comprises an over-oxidation of platinum as a result of charge accumulation between the active sites comprising particles of carbon atoms. noble metals agglomerated. It is currently believed that metal-containing particles in which there is a coating containing a second metal that at least partially surrounds a core containing a first metal results in a lower over-oxidation of the catalyst. In this way, the shape of the catalyst provides an improvement in activity. With respect to a catalyst precursor structure, it is currently believed that the preferential deposition of the second metal by displacement of the first metal to form domains or active sites less subject to agglomeration to form metal-containing particles than metals deposited in the absence of a metal of sacrifice provides a greater dispersion of load between the active sites and, consequently, a reduction in the deactivation of the catalyst by over-oxidation of the metal.
It should be noted that there is a certain degree of agglomeration of the second metal by primarily forming particles containing the second metal in the catalysts containing a first and second metal prepared in accordance with the present invention. However, it is currently believed that such agglomeration occurs to a much lesser extent than that observed in catalysts prepared without a first sacrificial metal and, in any case, it is considered that there is no agglomeration of the second metal to a significant degree that prevent obtaining the benefits indicated above of a better use of metals.
It is also currently believed that previously described methods using a first sacrificial metal layer can be employed in conjunction with the methods for treating porous substrates detailed elsewhere herein. For example, a first metal can be deposited on a porous support treated first according to the methods detailed herein (for example, a substrate containing a pore-blocking compound arranged and / or preferentially retained within its micropores), followed by deposition of a second metal over one or more regions of the first deposited metal. Thus, it is currently believed that the deposition of one or more regions of the first metal and the subsequent deposition of the second metal thereon are preferentially directed out of the domain of relatively small pores (eg. example, micropores) of the substrate, thereby providing an advantageous dispersion of the first and second metals and contributing to one or more of the benefits indicated above with respect to the use of metals.
A. First metal In those embodiments of the present invention in which the catalyst or precursor includes one or more regions of a first metal on the surface of the support, said first metal is generally selected from the group consisting of vanadium, tungsten, molybdenum, gold, osmium. , iridium, tantalum, palladium, ruthenium, antimony, bismuth, arsenic, mercury, silver, copper, titanium, tin, lead, germanium, zirconium, cerium, nickel, cobalt, iron, chromium, zinc, manganese, aluminum, beryllium, magnesium , lithium, barium, cesium and combinations thereof. In various preferred embodiments, the first metal is selected from the group consisting of copper, iron, tin, nickel, cobalt and combinations thereof. In various additional preferred embodiments, the first metal comprises copper, tin, nickel or a combination thereof. In various additional preferred embodiments, the first metal is tin or the first metal is copper. In still other embodiments, the first metal comprises cobalt, copper, iron and combinations thereof. In various preferred embodiments, the first metal is copper. In various additional preferred embodiments, the first metal is iron. In still other preferred embodiments, the first metal is cobalt.
In general, the support is contacted with a deposition bath comprising ions of the first metal and one or more additional components for depositing the first metal on the surface of the support. At least two events occur during the deposition of the first metal on the surface of the support: (1) nucleation (ie deposition of atoms of the first metal on the surface of the support) and (2) growth of the particle (i.e. agglomeration of the atoms of the first deposited metal). As used herein, the term "one or more regions of the first metal" refers to a group of agglomerated atoms of the first metal on the surface of the support. It is currently believed that the sizes, or dimensions, of these regions (i.e., the ratio of the surface area of the support on which a region of the first metal is deposited) can directly affect the effectiveness / convenience of the catalyst.
For example, the proportion of deposition, or of exchange sites, for the deposition of. second metal decreases together with the decreasing dimensions of the regions of the first metal. In addition, the resistance to leaching and / or deactivation under the reaction conditions generally decreases as one or more size dimensions of the region of the first metal decreases. Accordingly, it is preferred that the dimensions of the regions of the first metal be sufficiently resistant to metal leaching and provide a sufficient proportion of sites for the deposition of the second metal. Therefore, it is preferable to controls one or more conditions of the deposition of the first metal to provide an adequate balance between nucleation and agglomeration (ie, the growth of the particles) and thus provide regions of the first metal of adequate dimensions that provide sufficient exchange sites for the deposition of the second metal, are themselves stable and, therefore, promote the deposition of stable domains or regions of the second metal . For example, as detailed elsewhere herein, supports containing the first and second metals preferably include an excess of the first metal, which contributes in the provision of the second metal in a way that promotes more efficient metal utilization. .
In addition to achieving a desirable balance between nucleation and agglomeration, the location, or dispersion of said one or more regions of the first metal on the surface of the support can affect the use of metals. That is, the aforementioned considerations referred to in general a; - deposition of metals between pores - relatively small are generally also applied to the deposition of one or more regions of the first metal and it is currently believed that the dispersion of these regions between the pores of the porous substrates affects the performance of the catalyst. Therefore, in general one or more conditions of the deposition of the first metal is controlled and / or selected to provide a desired dispersion of the regions of the first metal. Thus, in general, the conditions of the deposition of the first metal preferentially promotes the deposition of the first metal on the surface of the support for supplying regions of the first metal in the support with one or more dimensions that provide a suitable proportion of exchange sites for the deposition of the second metal on the surface of the regions of the first metal. Very particularly, it is currently believed that the dimensions of the regions of the first metal preferably provide a suitable excess of the first deposited metal with respect to the desired proportion of the second metal to be deposited. For example, as detailed elsewhere herein, supports on which a first and second metals have been deposited in accordance with the present invention can be characterized by a minimum ratio of atoms of the first metal to the second metal. 1. Coordination Agents / Pore Blockers In various preferred embodiments, the preferential deposition of the first metal out of relatively small pores of the substrate (e.g., the micropore domain) can be promoted by the presence of one or more components of the deposition bath of the first metal. Very particularly, the dispersion of the first metal in this form can be promoted by the presence of one or more components of the deposition bath referred to herein as coordination agent (s).
It is currently believed that a component of the deposition bath of the first metal can function as a coordination agent by forming one or more coordination bonds with the first metal and that the The coordination compound formed in this way can not enter certain relatively small pores of the substrate, thereby preventing the first coordinated metal from depositing on those portions of the surface of the substrate. It should be understood that the precise form of any coordination link (s) between the compound and the metal, or the precise form of any coordination compound formed in this way are not strictly critical. However, it is currently believed that a coordination compound generally includes an association or a linkage between the first metal ion and one or more binding sites of one or more ligands. The coordination number of a metal ion of a coordination compound generally corresponds to the number of other ligand atoms bound thereto. The ligands can be linked to the central metal ion by one or more covalent coordination bonds in which the electrons involved in the covalent bonds are provided by the ligands (i.e., the central metal ion can be considered as the electron acceptor and the ligand can be considered as the electron donor). Typical donor atoms of the ligand include, for example, oxygen, nitrogen, and sulfur. The ligands can provide one or more potential binding sites; the ligands that offer two, three, four, etc., potential binding sites are called bidentate, tridentate, tetradentate, etc., respectively. Just as a central atom can coordinate with more than one ligand, a ligand with multiple donor atoms can bind with more than one central atom. Coordination compounds that include a metal ion attached to two or more binding sites of a particular ligand are generally referred to as chelates.
Additionally or alternatively, a coordination agent as described herein can promote the dispersion of the first metal on the surface of the support by virtue of the coordination bonds between the coordination agent and the metal to be deposited by retarding or by delaying the reduction of metal ions and the deposition of metal on the surface of the support while promoting the dispersion of the first metal on the surface of the support. The coordination force between the coordination agent and the metal generally influences the effectiveness of the agent in promoting the dispersion of the first metal on the surface of the support. Unless the coordination force reaches a minimum threshold, the effect of the agent on the dispersion will not be noticeable to any significant degree and the degree of coordination prevailing in the deposition bath will essentially mimic the solvation of the water. As the The amount of coordination between the agent and the metal is increased, a higher concentration of reducing agent can be used and / or a relatively more potent reducing agent can be included (for example, a metal hydride) in the deposition bath to promote the reduction of the coordination complex 0 and / or the reduction and deposition of the first metal. The coordination agent and / or ligand (s) deriving therefrom, present in the deposition bath, can function effectively as a pore blocking compound during and / or after the deposition of the first metal. For example, once the Coordination links between the first metal and the coordination agent have been broken, the agent or ligand (s) can be arranged within the micropores of the support.
In accordance with the previous deposition bath components that can function as coordination agents, in these and various other preferred embodiments, such components of the first metal deposition bath can promote desirable dispersion of one or more regions of the first metal under a pore blocking function. That is, in addition to preventing the entry of the first coordinated metal in certain pores of the substrate, the components of the deposition bath of the first metal that are described as coordination agents can be deposited themselves between certain relatively small pores of the porous substrate, thus inhibiting , and preferably substantially preventing the deposition of the first metal within the relatively small pores. Generally, it is believed that these compounds function as blocking compounds during the deposition of the first metal and that preferential deposition of the first metal and blocking of the pore can occur substantially simultaneously to provide a substrate impregnated with the first metal.
But it has been understood that the treatment of the porous substrate in accordance with the methods detailed above for placing within and / or introducing a pore-blocking compound into the pores of the substrate, followed by deposition of the metal, also provides substrates. adequate.
A variety of compounds that function as coordination agents and / or pore blocking compounds can be included in the deposition bath of the first metal to provide one or more of the effects mentioned above. Generally, these compounds are selected from the group consisting of different sugars, compounds containing 5 or 6 membered rings (for example, 1,3 and 1,4 disubstituted cyclohexanes), polyols, Rochelle salts, acids, amines, citrates, and combinations thereof. . For example, the compound may be selected from the group consisting of sucrose, sorbitol, mannitol, xylitol, Rochelle salts (sodium and potassium tartrates), ethylenediaminetetraacetic acid (EDTA), N-hydroxyethylenediaminetetraacetic acid (HEDTA), nitrilotriacetic acid (NTA) ), N, N, N ', N'-tetrakis (2-hydroxypropyl) ethylenediamine, and combinations thereof.
It should be noted that the advantageous effects provided by the presence of these compounds which are referred to herein as coordination agents or pore blockers are based in part on the experimental evidence. Although it is currently believed that one or more of these compounds provides one or both of the coordination or pore-blocking functions, it should be understood that the present invention does not depend on either or both of these theories and does not require one or more compounds that provide one or both of these functions.
In different preferred modalities (for example, those in which the first metal is copper or iron), the deposition bath comprises sucrose which is believed to function as a coordination agent and / or as a pore-blocking compound. In addition to these effects in accordance with the previous discussion, its presence may offer other advantages. For example, as detailed elsewhere herein, the deposition of the first metal can proceed more easily at a higher pH. The coordination effect of sucrose allows the deposition of the first metal at a higher pH since the coordination effect reduces the risk of excessive precipitation of the first metal at a higher pH.
Generally, the coordination agent / pore blocker, or a combination of agents / blockers, is present in the deposition bath of the first metal with a concentration of at least about 10 g / l, at least about 20 g / l, or at least about 30 g / l. Preferably, this component of the deposition bath of the first metal is present in a concentration between approximately. 10 g / l; and approximately 1 15 g / l,. between approximately 25 g / l and approximately 100 g / l, or between approximately 40 g / l and approximately 85 g / l. In addition to these and various other preferred embodiments, the weight ratio of the coordination agent to the first metal in the deposition bath is generally at least about 3: 1, generally at least about 5: 1 and, very typically, at less approximately 8: 1. For example, generally the weight ratio of the coordination agent to the first metal in the The deposition bath is generally between about 3: 1 and about 20: 1, generally between about 5: 1 and about 15: 1 and, very typically, between about 8: 1 and about 12: 1. 2. Non-electrolytic deposition of the first metal Generally and in accordance with the above, the deposition of the first metal on the surface of the support can be carried out in accordance with conventional methods known in the art. In this way, the deposition of the first metal is generally carried out by means of a non-electrolytic deposition in which the support is brought into contact with the deposition bath which generally comprises a source of the first metal in the absence of the application of an external voltage. . Generally the deposition bath comprises a reducing agent that reduces the ions of the first metal to form metal atoms that are deposited on the surface of the support, ... ... · ¾, .. ...
Generally, the source of the first metal is a salt of the first metal which includes, for example, sulfates of the first metal, nitrates of the first metal, chlorides of the first metal, tartrates of the first metal, phosphates of the first metal, and a combination thereof. . The concentration of the first metal in the deposition bath is generally selected by considering the desired content of the first metal. Generally, the source of the first metal is present in a deposition bath with a concentration of at least about 0.25 g / l, at least about 1 g / l, at least about 2.5 g / l, or at least about 4 g / l. For example, the source of the first metal may be present in the deposition bath at a concentration between about 1 and about 20 g / l, between about 2.5 and about 12.5 g / l, or between about 4 and about 10 g / l. 3. Copper deposition The following discussion focuses on the deposition of copper as the first metal on a porous carbon support. However, as detailed elsewhere herein, it should be understood that the present invention further contemplates the deposition of the first metals other than copper on the carbon supports, and the deposition of copper and other first metals on non-carbon supports. . (a) Copper sources. -. ·, ...
Suitable sources of copper ions for use in the methods of the present invention include copper salts such as nitrate, sulfate, chloride, acetate, oxalate, and copper formate salts, and combinations thereof. Generally, copper-containing salts in the divalent state (ie, Cu (II)) are preferred, including, for example, copper sulfate. (b) Copper loading in the deposition bath The loading of the first metal in the deposition bath can affect the quality (for example, the resistance to leaching) and / or the applicability (for example, the dispersion of the first metal over a sufficient portion of the support surface) of the deposition of the first metal. Very particularly, it is currently believed that the relative proportions of the first metal and the support impact the deposition of the first metal. Agglomeration, or particle growth, and the dimensions of the regions of the resulting first metal may increase with the increase in copper loading. As indicated above, the dimensions of the regions of the first metal are preferably controlled to promote an adequate balance between dispersion and stability of the first and second metals. Therefore, the concentration of copper in the deposition bath satisfies the limits mentioned above and / or is within the ranges mentioned above.
For example, copper is generally present in the deposition bath of the first metal with a concentration of at least about 0.25 g / l, very typically at least about 1 g / l, still very typically at least about 2 g / l, and even very typically at least about 3 g / l (eg, at least about 5 g / l). Preferably, the copper is present in the deposition bath of the first metal with a concentration between about 0.25 and about 15 g / l, most preferably between about 1 and approximately 12 g / l and, still very preferably, between approximately 2 and approximately 10 g / l. (c) Reducing agents Suitable reducing agents include those generally known in the art including, for example, sodium hypophosphite (NaH2P02), formaldehyde (CH2O) and other aldehydes, formic acid (HCOOH), formic acid salts, borohydride salts (e.g., borohydride) sodium (NaBH4)), substituted borohydride salts (for example, sodium triacetoxyborohydride (Na (CH3CO2) 3BH)), sodium alkoxides, hydrazine (H2NNH2), and ethylene glycol. In different preferred embodiments, formaldehyde is the preferred reducing agent. For the deposition of copper in non-aqueous deposition baths, gaseous hydrogen is usually the preferred reducing agent since it is generally more readily soluble in organic solvents.
The manner of adding the reducing agent to the deposition bath is not narrowly critical, but in different embodiments the reducing agent is added at a relatively slow rate (eg, for a period of between about 5 minutes and 3 hours, or over a period of time). between about 15 minutes and about 1 hour) to a suspension of the support and the first metal in water or in an alcohol and under an inert atmosphere (for example, N2). In contrast, if the reducing agent is first added to the copper salt, it can preferably be added to the solution containing the copper salt and also the coordinating agent (for example, the chelator). The presence of the chelator inhibits the reduction of the copper ions before the copper salt solution is combined with the support and which, as detailed herein, can further promote the advantageous deposition of the first metal throughout. of the entire surface of the support.
Generally, in the case of formaldehyde as a reducing agent, the reducing agent is present in the deposition bath of the first metal at a concentration of at least about 1 g / l, very typically at least about 2 g / l, even very typically, at least about 5 g / l. For example, in the case of formaldehyde as a reducing agent, formaldehyde is preferably present in the deposition bath at a concentration of between at least about 1 and about 20 g / l, most preferably between about 2 and about 15 g / l, even very preferably, between about 5 and about 10 g / l. .. .
Additionally or alternatively, in the case of a formaldehyde reducing agent, generally the formaldehyde and the first metal (eg, copper) are present in the deposition bath in a weight ratio of formaldehyde to the first metal of at least about 0.5. : 1, and generally at least about 1: 1. For example, in different embodiments, the weight ratio of formaldehyde to the first metal in the deposition bath is between about 0. 5: 1 and about 5: 1, between about 1: 1 and about 3: 1, or between about 1: 1 and about 2: 1. (d) Temperature The temperature of the deposition bath can affect nucleation and agglomeration (eg, particle growth) that occurs during the deposition of the first metal. For example, nucleation (ie, metal deposition) and agglomeration generally increase with increasing temperature of the deposition bath.
In this way, the temperature of the deposition bath preferably does not reach a level which promotes the agglomeration of the metal and / or the leaching of the metal under the reaction conditions to an undesired level. The reduction of the temperature of the deposition bath generally suppresses the nucleation at a higher level than the agglomeration. Therefore, the temperature of the deposition bath is preferably high enough so that the nucleation is not delayed to an unacceptable level. In accordance with the present invention, it is currently believed that depositions of the first metal having a temperature between about 5 ° C and about 60 ° C generally address these concerns and provide a deposition of the first suitable metal. Preferably, the temperature of the deposition bath of the first metal is between about 10 ° C and about 50 ° C; very preferably, the temperature of the deposition bath of the first metal is between about 20 ° C and about 45 ° C. It should be noted that the reference temperature of the deposition bath of the first metal can be related to the temperature of the bath before and / or during the contact of the deposition bath and the support. (e) Agitation Preferably the deposition bath of the first metal is stirred to promote the dispersion of the first metal on the surface of the support. Agitation may also promote diffusion of the reducing agent over the entire support. Experimental evidence indicates that sufficient agitation may contribute to improvements in catalytic activity. However, excessive agitation of the deposition bath can cause the dispersion of copper at a level that provides regions of the first metal that may be less resistant to leaching relative to less dispersed regions. For example, undesirably high dispersion can result in the deposition of a portion of the first metal within the relatively small pores of the support that is less prone to agglomeration to form regions of the first metal generally resistant to leaching.
Additionally, it is currently believed that the type of agitator can impact the deposition of the first metal. Experimental evidence indicates that the first metal (eg, copper) can be deposited on the surface of the agitator resulting in a reduced deposition of the first metal on the carbon surface and, therefore, reduce the sites for the deposition of the second metal. For example, the first metal can be deposited on the surface of agitators that include or are constructed of metal (for example, agitators with metal shells). Thus, in different preferred embodiments, the agitator is constructed of a material that generally prevents, and preferably substantially and completely prevents, the deposition of the first metal on the surface of the agitator. For example, the agitator can preferably be constructed of glass, or another variety of materials that preferably prevent the deposition of the first material on the surface of the agitator. (f) pH of deposition Copper deposition is generally more effective at a higher pH (eg, greater than about 8, greater than about 9, or greater than about 10). In fact, as the pH of the deposition bath increases, the deposition of the copper by means of the reduction and precipitation on the support can occur at a rate that can hinder sufficient dispersion of the first metal on the surface of the support. In addition to the benefits mentioned above, it is currently believed that the presence of a coordination agent such as sucrose delays the precipitation of copper at a high pH and thereby promotes sufficient dispersion of the metal on the surface of the support. The formation of a coordination complex between the first metal and the coordination agent generally increases at the mentioned pH levels previously. However, at certain levels, the pH of the deposition bath can negatively impact the solvation of the first metal ions and the reduction and deposition of the first metal. Therefore, in different preferred embodiments in which the coordination agent is present in the deposition bath, the pH of the deposition bath is between about 8 and about 13, or between about 9 and about 12. 4. Deposition of iron In different preferred embodiments, the first metal is iron.
Generally, deposition of the iron on the surface of the support can be carried out in accordance with conventional methods known in the art (e.g., non-electrolytic deposition). In this way, the deposition of iron is generally carried out by a process comprising contacting the support with the deposition bath comprising a source of the first metal in the absence of an external application voltage. For example, iron can be deposited via a non-electrolytic deposition pathway using methods that are generally known in the art including, for example, those described in the U.S. Patent. No. 6,417,133 and by Wan et al. in International Publication No. WO 2006/031938. In different embodiments, as detailed below, the deposition bath comprises a reducing agent that reduces the ions of the first metal deposited on the surface of the support. (a) Sources of iron Suitable sources of iron include salts such as nitrate, sulfate, chloride, acetate, oxalate, and formate salts, and combinations thereof. In different preferred embodiments, the iron source comprises iron chloride (i.e., FeCl3), iron sulfate (i.e., Fe2 (S04) 3), or a combination thereof.
The concentration of the iron source in the deposition bath is not strictly critical and is generally selected according to the desired metal content and / or the composition of the source. Frequently, the iron source is present in the deposition bath at a concentration of at least about 5 g / l and very typically between about 5 and about 20 g / l. In different embodiments, the complete proportion of the iron source is introduced into the deposition bath before, during, or after the addition of the carbon support to the deposition bath and / or the container containing the deposition bath. Additionally or as an alternative (even as described in the examples of work), the iron source can be measured, or pumped into the deposition bath and / or a container containing the carbon support. In this sense it should be understood that the measured aggregate of the iron source is controlled to provide a deposition of an adequate proportion of iron on the support surface, regardless of the concentration of the iron source in the deposition bath at any point ( s) during the deposition of iron. (b) Iron load in the deposition bath As with other first metals (eg, copper as described above), the iron loading in the deposition bath can affect the quality and / or dispersion of the iron deposition on a sufficient portion of the support surface. The concentration of iron in the deposition bath is generally controlled to address these and other considerations (eg, agglomeration of the first metal). For example, iron is generally present in the deposition bath of the first metal with a concentration of at least about 2 g / l, very typically at least about 3 g / l and, even very typically, at least about 4 g / l. Preferably, the iron is present in the deposition bath in a concentration of between about 2 and about 8 g / l, most preferably between about 3 and about 6 g / l, still most preferably between about 4 and about 5 g / l . (c) Reducing agents To provide a driving force for the deposition of a second metal above, iron is preferably deposited in at least a partially reduced state, for example, as Fe + 2 and / or its totally reduced state as Fe0. Therefore, in different embodiments, the deposition bath of the first iron metal comprises a reducing agent. Any drafting agent is usually used under the conditions previously established in relation to copper deposition (eg, reducing agent concentration, etc.). Suitable reducing agents include sodium hypophosphite (NaH2P02), formaldehyde (CH2O), formic acid (HCOOH), salts of formic acid, sodium borohydride (NaBH), sodium triacetoxyborohydride (Na (CH3CO2) 3BH), sodium alkoxides , hydrazine (H2NNH2), and ethylene glycol. In view of the greater electropositivity of iron compared to copper, stronger reducing agents for the deposition of a first iron metal can be preferred in comparison with those preferred for the deposition of a first copper metal. Therefore, in different preferred embodiments, the reducing agent is sodium borohydride or ethylene glycol.
In those embodiments in which the reducing agent is sodium borohydride and / or ethylene glycol, the molar ratio of reducing agent to iron deposited is generally at least 1, generally at least about 2, and very typically at least about 3. Generally, according to . these embodiments, the molar ratio of sodium borohydride to iron deposited is between about 1 and about 5 and, very typically, between about 2 and about 4. (d) Temperature As with copper deposition, the temperature of the deposition bath affects the nucleation and agglomeration of iron. Generally, the The temperature of the deposition bath is sufficient to provide adequate nucleation and agglomeration, but preferably not at a level that promotes agglomeration of the first metal to an undesired degree. Generally, temperatures of the iron deposition bath can vary in a range between about 5 ° C and about 60 ° C to provide suitable catalysts. Frequently, the temperature of the iron deposition bath is above ambient conditions in order to provide sufficient nucleation and, most particularly, adequate dispersion of the first metal on the support surface. Therefore, generally the temperature of the iron deposition bath is between about 25 ° C and about 60 ° C and, very typically, between about 25 ° C and about 45 ° C. (e) Agitation The deposition bath of the first metal iron is generally It is necessary to promote the dispersion of iron on the surface of the support. As in copper deposition, agitation can also promote diffusion of the reducing agent over the entire support. Any agitation during the deposition of the first metal is generally carried out according to the description above in relation to the copper deposition. (f) pH of deposition As in copper deposition, iron deposition generally proceeds more easily as the pH of deposition increases. Therefore, generally the pH of the iron deposition is at least about 8, at least about 9, or at least about 10. Also as with iron deposition, it is currently believed that the presence of a coordination agent (for example, sucrose) delays the precipitation of iron at high pH and therefore promotes sufficient dispersion of the metal on the surface of the support. As indicated, the formation of a coordination complex between the first metal and a coordination agent is generally enhanced at the pH levels mentioned above. But at certain pH levels, the pH of the deposition bath can adversely affect the solvation or reduction and deposition of the iron ions and the first metal. Therefore, in different preferred embodiments the pH of the iron deposition bath is between about 8 and about 13, or between about 9 and about 12. 5. Atmosphere of deposition of the first metal Regardless of the precise conditions of the deposition of the first metal and the dispersion of the first metal deposited on the surface of the support, oxidation of the deposited first metal can reduce the proportion of the exchange sites of the first metal available for the deposition of the first metal. second metal. Therefore, in different preferred embodiments, the first metal is deposited on the support in the presence of a non-oxidizing environment (eg, a nitrogen atmosphere). Additionally or alternatively, the water and / or other components of the deposition bath are degassed to remove the dissolved oxygen using methods known to those skilled in the art.
B. Second metal Catalysts containing conventional noble metals are generally prepared by deposition of a noble metal on the surface of a support, generally a porous carbon support. The agglomeration of noble metal into particles, hence the reduction of the catalytic surface area of the exposed metal, has been observed with these methods. In particular, an abundance of relatively large metal-containing particles can represent an insufficient use of the metal because these particles provide an area of. catalytic surface relatively little exposed per unit of metal.
In accordance with various embodiments of the present invention, noble metal-containing catalysts are prepared by a method in which the noble metal is deposited in a manner that increases the catalytic surface area of the exposed metal per unit weight of metal. Most particularly, the noble metal is deposited on the surface of one or more regions of the first metal by displacement of the first metal of the metals. regions. It is currently believed that the deposition of the noble metal using a sacrificial first metal produces a reduced noble metal agglomeration. For example, as noted elsewhere, the deposition of the noble metal in this way provides a catalyst precursor structure wherein the noble metal deposited on the surface of one or more regions of a first metal is less prone to agglomeration than the noble metal deposited directly on the surface of a porous support. Presently, it is further believed that the heat treatment of the supports having noble metal deposited on them in this way, will form metal particles that provide improved (second) noble metal utilization (eg, greater exposed catalytic surface area). per unit weight of metal).
Generally, the second metal is deposited on a support impregnated with first metal by contact of the impregnated support with metal and a second metal deposition bath. Most particularly, the second metal is generally deposited by non-electrolytic deposition in which an impregnated support is contacted with a first metal and a deposition bath of a second metal in the absence of an externally applied voltage.
As indicated, in different modalities, the second metal is a noble metal. Typically, the noble metal is selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, silver, osmium, gold, and combinations thereof. In different preferred embodiments, the noble metal comprises platinum. In still other preferred embodiments, the noble metal comprises more than one metal (e.g., platinum and palladium or platinum and gold).
The following discussion focuses on the deposition of platinum as the second metal, but it should be understood that the present invention also contemplates the use of any or all of the noble metals mentioned above as the second metal. Additionally, the applicability of a combination of metals for use in the deposition by displacement of a second metal over one or more regions of a first metal generally depends on its relative electropositivities. Therefore, the present invention is not limited to the deposition of noble metals as the second metal. For example, two metals designated as candidates for first metals elsewhere in the present may provide the first and second metals while their relative electropositivities permit deposition by displacement of the second metal over one or more regions of the first metal.
.. - -. . The . Suitable sources of platinum include those generally known in the art for use in liquid phase deposition of platinum and include, for example, H2PtCI4, H2PtCI6, K2PtCI, Na2PtCI6, and combinations thereof. Therefore, in different embodiments, the deposition bath of the second metal comprises a platinum source which includes a platinum salt comprising platinum in an oxidation state of +2 and / or +4. As indicated, in different preferred embodiments, the platinum source provides platinum ions that exhibit an oxidation state of +2.
However, it should be understood that effective catalysts can be prepared using platinum sources that provide platinum ions that have other oxidation states (eg, +4), and platinum sources that provide platinum ions that comprise platinum ions that exhibit oxidation states other than +2. Similarly, sources of noble metals other than platinum and sources of second metal that generally provide metal ions with low oxidation states are likewise preferred. For example, it is currently believed that palladium provided by Na2PdCU and PdCfe can be used to prepare an active catalyst comprising palladium as the second metal.
Generally, the platinum source is present in the deposition bath of the second metal in a proportion that provides a molar concentration of the ions of the second metal lower than the concentration of the ions of the first metal in the deposition bath of the first metal. Generally, the molar ratio of the copper ions in the first deposition bath, metal to noble metal Jones in the deposition bath of the second metal is greater than 1, very typically at least about 2 and, still very typically at least about 3 (for example, at least about 5). In different preferred embodiments, the molar ratio of copper ions in the deposition bath of the first metal to noble metal ions in the deposition bath of the second noble metal is generally greater than 1 and about 20, very typically between about 2 and about 15. , still very typically between about 3 and about 10 and, even very typically, between about 5 and about 7.5.
Generally, the support impregnated with the first metal is not subjected to high temperatures before contact with the deposition bath of the second metal. That is, the structure of the catalytic precursor is preferably not subjected to temperatures that would facilitate the formation of metal-containing particles (for example, through the agglomeration of particles of the first metal). For example, the support impregnated with the first and second metals is generally subjected to temperatures of no more than about 200 ° C, no more than about 150 ° C, and preferably no more than about 120 ° C before contact with the bath deposition of the second metal.
Typically, the metal impregnated support is contacted with the deposition bath of the second metal at a temperature of at least about 5 ° C, generally at least about 10 ° C and, very typically, at least about 5 ° C. Preferably, the support impregnated with the first metal is brought into contact with the deposition bath of the second metal at a temperature between about 10 ° C and about 60 ° C, between about 20 ° C and about 50 ° C, or between about 25 ° C C and approximately 45 ° C.
Frequently, the deposition bath of the second metal has a pH lower than the pH of the deposition bath of the first metal and is between about 1 and about 12 or between about 1.5 and about 10. In accordance with different embodiments, the pH of the deposition bath is between about 2 and about 7 or between about 3 and about 5. It has been observed that said pH conditions are suitable for the deposition of a noble metal (second) on one or more regions of the first copper metal. In different preferred embodiments, the first metal is iron. Compared to copper, iron can be more easily leached from the surface of the support when the pH of the deposition bath decreases. Therefore, in accordance with those embodiments in which the first metal is iron, the pH of the deposition bath of the noble metal (second) is generally between about 4 and about 9, and preferably between about 5 and about 8 (e.g. , approximately 7).
As indicated above, the first metal is preferably deposited in an environment that prevents oxidation of the first deposited metal that could. reduce the proportion of the exchange sites of the first metal available for the deposition of the second metal. Also, in different preferred embodiments, the second metal is also deposited on the impregnated first metal support in a non-oxidizing environment (eg, a nitrogen atmosphere) to prevent oxidation of the first and second deposited metals.
C. Support impregnated with first and second metals As indicated, preferably the first metal deposited on the surface of the support provides suitable exchange sites for the deposition of the second metal on the surface of one or more regions of the first metal and, very particularly, an excess of exchange sites for the metal. deposition of the second metal. Therefore, generally the atomic ratio between that of the first metal and the second metal of the support impregnated with the first and second metal (ie, structure of the catalytic precursor) is at least about 1.5, very typically at least about 2 and, still very typically, at least about 3 (for example, at least about 4 or at least about 5). Preferably, the atomic ratio between the first metal and the second support metal impregnated with the first and second metals is between about 1.5 and about 15, most preferably between about 2 and about 15, still most preferably between about 3 and about; 1.0 and, still very preferably r between, approximately 4 and approximately 8.
As indicated, the heat treatment of the impregnated support provides particles containing the first and noble (second) metals on the surface of the support including the noble metal (second) in a form that provides advantages over the use of the metal. An excess of atoms of the first metal with respect to the atoms of the second metal on it. impregnated support is believed to result in the formation of said particles. For example, the excess of atoms of the first metal relative to the second metal on the impregnated support provides particles rich in the first metal that include a relatively low proportion of noble metal (second) not exposed in all the particles (for example, a bimetallic alloy). that has an excess of atoms of the first metal).
Additionally or alternatively, and as generally described in Figure 2, the heat treatment of the support impregnated with the first and second metals can form metal particles comprising a core and a coating at least partially surrounding the core. It is currently believed that the composition of the core and coating indicates improvements in the use of the metal and, very particularly, improvements in the use of the second metal (for example, noble metal). For example, the core of these particles is generally rich in the first metal, thus providing a relatively low proportion of unexposed second metal in all the particles.
With the increase of the atomic ratio of the first metal relative to the second metal in the catalytic precursor, the extent to which the first metal-rich core is surrounded by a coating containing a second metal can decrease. For example, a relatively high excess of exchange sites of the first metal for the deposition of the second metal can result in a portion of exchange sites not participating in the deposition by displacement of the noble metal (second). Said particles can be prepared from catalytic precursors in which the ratio Atomic is close to or above the above-mentioned upper limit of the atomic ratios of the first metal with respect to the second metal (eg, about 10 or greater). Although less preferred, it should be understood that a decrease in the degree to which the core is surrounded by a coating containing the second metal does not necessarily indicate a loss of improved utilization of the second metal. These particles can nevertheless provide a utilization of the metal based on, for example, a core rich in the first metal that provides a relatively low proportion of noble (second) metal not exposed, and potentially not used. However, it is currently believed that the structure of the particles can change towards increasing the coverage of the rich core in the first metal by the coating containing the second metal. Most particularly, this change in the shape of the particles can comprise the leaching of the first metal from the metal particle on the surface of the support during the use of the catalyst in the liquid phase reactions.
Also, the. second metal can be removed or leached from the particles, .---. / ... but currently it is believed that the first metal is removed from the particles to a greater extent than the second metal. Therefore, the atomic ratio of the first metal to the second metal approaches more preferred ranges and it is currently believed that as a result of this removal, the particle structure changes to a more preferred (ie, more extensive) coverage of the core. rich in the first metal by the coating that contains the second metal. After a period of use, the leachate of the first metal of the metal particles on the surface of the support generally decreases. After said period of use, it is currently believed that catalysts comprising particles having a more preferred relation of atoms of the first metal with respect to those of the second metal with accompanying change in the structure, then exhibit performance characteristics comparable with the catalysts prepared using the most preferred relationships of the atoms of the first metal with respect to those of the second metal. This "autocorrector" behavior has been observed, for example, related to catalysts in which the first metal is copper and the second metal is platinum.
D. Heat treatment of the supports impregnated with the first and second metal As indicated, it should be understood that the metal impregnated support of the present invention is a suitable catalyst as described in the working examples discussed herein. Nevertheless, generally in accordance with different preferred embodiments, the metal impregnated support is treated at elevated temperatures generally as described elsewhere herein (eg, in the presence of a non-oxidizing environment at temperatures in excess of about 800 ° C. ) to form a finished catalyst. Generally, the metal impregnated support is heated to temperatures between about 400 ° C and about 1000 ° C, very typically between about 500 ° C and about 950 ° C, still very typically between about 600 ° C and about 950 ° C and even very typically between about 700 ° C and about 900 ° C. Submitting metal-impregnated supports to such temperatures provides finished catalysts exhibiting a reduced metal leachate and improved utilization of the metal as detailed elsewhere herein (eg, catalysts comprising particles rich in the first metal and / or particles including a core rich in the first metal at least partially surrounded by a coating rich in the second metal).
Stable metal particles (ie, resistant to leaching) are currently believed to form easily in the case of supports impregnated with the first and second metals wherein the first metal is iron and the second metal is platinum. It has been observed that supports impregnated with iron and platinum (ie, iron-platinum catalyst precursors) exhibit adequate stability during the reaction test. Preferably, however, the iron-platinum catalyst precursor is subjected to elevated temperatures to prepare a finished catalyst. It is currently believed that the heating of the support impregnated with iron-platinum improves the activity. But, in view of the advantageous stability of the supports impregnated with iron and platinum, suitable catalysts derived therefrom can be prepared by heating the catalyst precursor to temperatures within, but at or near the lower limits of the ranges mentioned above. Therefore, of according to certain embodiments, the supports impregnated with platinum-iron are subjected to a maximum temperature of between about 400 ° C and about 750 ° C, or between about 500 ° C and about 650 ° C to prepare a finished catalyst.
As indicated, the degree of alloying of the first and second metals generally increases with the increase in temperature at which the metal impregnated support is subjected. Therefore, it is believed that if the iron / platinum impregnated support is subjected to a relatively low maximum temperature, a relatively low grade of iron and platinum alloy is provided. Although the catalysts of the present invention include the first and second metals in a form that represents efficient utilization of the metal (e.g., an alloy rich in first metal), alloy formation inevitably results in a noble metal (second ) not exposed. Therefore, the preparation of catalysts containing iron and platinum by subjecting the impregnated support with metal at a relatively low temperature can contribute to improved utilization. of metal. However, in this regard it should be noted that the preparation of catalysts containing iron and platinum by subjecting the supports to higher temperatures, for example, in the ranges indicated above such as 700 ° C or higher, likewise is currently believed that provides catalysts that represent a more efficient use of the metal.
E. Platinum and iron deposition protocols Catalysts containing iron and platinum can generally be prepared according to the above discussion in relation to the deposition of iron (first metal) and platinum (second metal), both in accordance with previous expositions concerning the first and second metals generally , and specifically iron and platinum. However, in accordance with the present invention it has been found that advantageous catalysts are provided by combination of particular characteristics of the deposition of iron (first metal) and platinum (second metal).
For example, in different preferred embodiments, the iron deposition bath (first metal) comprises ethylene glycol as a reducing agent, but does not comprise a separate coordination agent (eg, sucrose). However, it should be understood that the ethylene glycol coordination agent can, in fact, function as a coordination agent to a certain degree. ·····; · -. ··.
In still other preferred embodiments, the iron deposition bath comprises a reducing agent and a coordination agent. In these different modalities, ethylene glycol is the reducing agent and sucrose is the coordination agent. In other such embodiments, ethylene glycol and sodium borohydride are used as reducing agents for iron deposition, and the iron deposition bath also comprises sucrose as a coordination agent.
In other different preferred embodiments, the iron deposition bath (first metal) comprises sodium borohydride as a reducing agent generally in accordance with the above discussion. The iron deposition bath does not comprise a separate coordination agent (e.g., sucrose). or F. Catalysts containing first and second metals As indicated, supports impregnated with the first and noble (second) metals generally contain an excess of atoms of the first metal on the atoms of the second metal. In accordance with these and other different embodiments, the first metal generally constitutes at least about 1% by weight, at least about 1.5% by weight, or at least about 2% by weight of the catalyst. Generally the first metal constitutes at least about 3% by weight, at least about 4% by weight, or at least about 5% by weight of the catalyst. For example, preferably the first metal constitutes between about 3% and about 25% by weight of the catalyst, most preferably between about 4% and about 20% by weight of the catalyst and, even more preferably, between about 5% and about 15% by weight of the catalyst. catalyst weight. In several other embodiments (for example, those in which iron is the first metal), the first metal constitutes between about 1% and about 10% by weight, most preferably between about 1.5% and about 8% by weight and, most preferably, between about 2% and about 5% (eg, about 4%) by weight of the catalyst.
According to the above-mentioned, the catalysts of different embodiments of the present invention generally contain at least about 1% by weight noble metal (second), at least about 2% by weight noble metal, or at least about 3% by weight. noble metal weight. Generally, the catalysts contain less than about 8 wt.% Noble metal, very typically less than about 7 wt.% Noble metal and, even very typically, less than about 6 wt.% Noble metal. In accordance with different preferred embodiments, the catalysts contain less than about 5% or less than about 4% by weight of noble metal (eg, between about 1% and about 3% by weight noble metal). The catalysts prepared as detailed herein more efficiently use the noble metal (second) in comparison with conventional catalysts, thereby providing catalysts at least as active or even more active than conventional noble metal-containing catalysts. For example, the catalysts can be prepared to include metal charges similar to catalysts containing conventional noble metals, but are generally more active and, in different preferred embodiments, much more active than the catalysts. that contain conventional noble metals. In this way, the catalytic activity can be increased without an increase in noble metal loading, which may be undesirable due to processing limitations. In different embodiments, active catalysts containing between about 3% and about 6% by weight noble metal, or between about 4% and about 5% by weight noble metal can be prepared.
As an additional example, the more efficient use of the metal by the catalysts of the present invention allows the preparation of catalysts that include a reduced proportion of the second metal compared to conventional catalysts containing noble metal, but which are at least as active and, in different preferred embodiments , more active than conventional catalysts containing noble metal. Thus, the catalysts of the present invention can provide activities equivalent to those provided by conventional catalysts containing noble metal with lower metal loads, noble, or higher catalytic activities at equivalent noble metal loads. For example, in different embodiments, active catalysts containing between about 1% and about 5% by weight, between about 1.5% and about 4% by weight, or between about 2% and about 3% by weight noble metal can be prepared. .
In different modalities, the atomic ratio of the first metal to the second metal in the metal particles on the surface of the Catalyst support generally increases with increasing particle size. It is currently believed that with the increase in particle size, the portion of the particle constituting the rich core in the first metal increases, while the portion (i.e., fraction by weight) of the particles constituting the coating containing the second metal. As previously indicated, the larger metal-containing particles are generally more resistant to leaching from the surface of the catalyst support. However, a significant fraction of larger particles is generally not desired in conventional noble metal catalysts since when the particle size increases, the proportion of noble metal distributed in the particle that does not contribute to the effective catalytic surface area increases. Therefore, a relatively high proportion of large particles comprising a coating rich in the second metal according to the present invention provides increased stability, without sacrificing in the catalytic surface area of the noble (second) exposed metal associated with the relatively large particles in conventional catalysts containing noble metal.
For example, in different embodiments, the catalyst includes metal-containing particles characterized by a particle size, determined using electron microscopy, so that a significant fraction (eg, at least about 80%, at least about 90%, or less about 95%, based on number) of the particles have between about 5 and about 60 nm, or between about 5 and about 40 nm in its longest dimension. Additionally, the thickness of the metal-containing coatings of the particles in these size distributions is generally less than about 3 nm, very typically less than about 2 nm, and preferably less than about 1 nm (eg, less than about 0.8 nm). or less than about 0.6 nm).
Improvements in the use of metal can be characterized by an increase in the proportion of the noble (second) exposed metal of the catalyst. Very particularly, improvements in the use of the metal can be indicated by an increase in the surface area of the noble metal exposed per unit weight of catalyst per unit weight of noble metal. The exposed noble metal surface area of catalysts of the present invention can be determined using chemisorption analysis of static carbon monoxide, including protocol A described in Example 67. The chemo-sorption analysis of carbon monoxide described in the example 67 includes a first and second cycles. The catalysts of the present invention which are subjected to such an analysis are generally characterized as chemisorbing at least about 500 pmoles of carbon monoxide per gram of catalyst per gram of noble metal and, very typically, at least about 600 pmoles of carbon monoxide. per gram of catalyst per gram of noble metal. Generally, the catalysts of the present invention are characterized as chemosorben at least about 700, at least about 800, at least about 900, at least about 975, at least about 1000, or at least about 1 100 pmoles of carbon monoxide per gram of catalyst per gram of noble metal.
An alternative or additional indicator of the effective use of the metal is the proportion of the noble metal (second) of the catalyst that can be found in a coating at least partially surrounding a core rich in first metal. Generally, at least about 10%, at least about 20%, at least about 30%, at least about 40%, or at least about 50% of the noble metal is present in the coating of the metal particles. Typically, at least about 60% and, very typically, at least about 70% (eg, at least about 80% or at least about 90%) of the noble metal is present in the coating of the metal particles. · ...
Additionally or as an alternative, the effective utilization of the metal can be indicated by the proportion of the noble metal (second) on the surface of the metal particles. That is, the efficient use of the metal can be indicated by the proportion of noble metal on the surface of the particles rich in the first metal, for example, the second metal present in an alloy and / or in a coating rich in the second metal. at least partially surrounding a core rich in the first metal. Generally, the The percentage of noble metal atoms on the surface of the particles containing the first and noble metals (second) is at least about 2%, or at least about 5%. Typically, the percentage of noble metal atoms on the surface of the particles containing the first and noble metals is at least about 10%, very typically at least about 20%, even very typically at least about 30%, and preferably at least about 40% (for example, at least about 50%).
The result of the linear scanning analysis of X-ray energy scattering spectroscopy (EDX) for the catalysts of the present invention (for example, as described in protocol B in example 68) also indicates an efficient utilization of the metal. Most particularly, the linear scan analysis results in the catalyst metal particles of the present invention having a noble (second) metal distribution in which a significant fraction of the noble metal (second) is present in the coating at least , partially surrounding a core rich in the first metal. Additionally or alternatively, the linear scan analysis results in the metal particles of the catalysts of the present invention having a noble metal distribution in which a significant fraction of the noble metal is disposed at or near the surface of a metal. or some metal particles.
The efficient use of the metal in the particles of the catalysts of the present invention is indicated by a distribution of the second metal that produces a line sweep signal by EDX that does not vary significantly in a sweep region. As used herein, the term "sweep region" refers to the portion of the largest dimension of the analyzed particle over which a relatively low degree of variation in the second metal signal indicates improved utilization of the metal. A linear sweep signal of the second metal, relatively constant in a sweep region that corresponds to a significant portion of the largest dimension of the particle, indicates that a significant fraction of the second metal is distributed near the surface of the particle instead of all over the metal particle. On the other hand, the last type of distribution would cause the signal of the second metal to increase (decrease) significantly in that portion of the sweep region where the probe is directed to a thicker (thinner) dimension of the particle. For example, in different embodiments, the signal of the second metal generated during the analysis by linear scanning by EDX of a particle on the surface of a catalyst. according to the present invention it varies no. more than about 25%, no more than about 20%, no more than about 15%, no more than about 10%, or no more than about 5% throughout the sweep region which is at least about 70% of the largest dimension of at least one particle. In other embodiments, the second metal signal varies no more than about 20%, no more than about 15%, no more than about 10%, or no more than about 5% throughout the swept region that is at least about 60% of the largest dimension of at least one particle. In still other embodiments, the second metal signal varies no more than about 15%, no more than about 10%, or no more than about 5% throughout the sweep region that is at least about 50% of the dimension larger than at least one particle.
Particles having metal distributions characterized by EDX linear scan analysis as detailed above, are typically rich in the first metal and, very particularly, typically include the second metal and the first metal in an atomic ratio of the second metal to the metal. to the first metal in one or more analyzed particles of less than 1: 1. Typically, the atomic ratio of the second metal to the first metal of the particle (s) is less than about 0.8: 1 and, very typically, less than about 0.6: 1 (eg, less than about 0.5: 1) .
.¾ · .. :: ·. . ... Generally, the first and second metal particle (s) of the catalysts of the present invention having a second metal distribution characterized by linear scanning by EDX indicating efficient utilization of metal have a larger dimension of less about 6 nm, typically at least about 8 nm, very typically at least about 10 nm and, even very typically, at least about 12 nm.
The relative magnitudes of the first and second signals Metal throughout the sweep region may also indicate distributions of the first and second metal in a form indicating the effective utilization of the metal. Very particularly, generally in accordance with different embodiments, the ratio of the maximum signal of the first metal to the maximum signal of the second metal along the sweep region is at least about 1.5: 1, at least about 2: 1, or at least about 2.5.1. Typically, the ratio of the maximum signal of the first metal to the maximum signal of the second metal along the sweep region is at least about 3: 1, at least about 4: 1, or at least about 5: 1.
It should be understood that efficient utilization of the metal can be indicated by the identification of at least one particle on the surface of the catalyst support having a (second) noble metal distribution characterized as described above. That is, the population of metal particles on the surface of the catalyst support can include the particles that satisfy one or more of the particles. distribution characteristics, dek -..- noble metal and those that do not. However, the use of the metal is enhanced as the proportion of the metal particles exhibit these preferred noble metal distribution characteristics and generally a plurality of these metal particles will possess these characteristics. Very typically, the distribution of the second metal of each portion (based on number) of the particles on the surface of the support indicates efficient utilization of the metal. Generally, at least about 1%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, or at least about 25% of the metal particles satisfy the distribution characteristics of the second metal. Typically, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, or at least about 65% of the metal particles satisfy the distribution characteristics of the second metal. The proportion of metal particles that satisfy one or more distribution characteristics of the noble metal is somewhat dependent on the particular combination of the first metal and second metal. For example, it has been observed that catalysts prepared with copper and platinum as the first and second metals, respectively, produce catalysts in which a large portion of metal particles on the surface thereof possess those preferred distribution characteristics of the noble metal. . Therefore, in these and other preferred embodiments, at least about 70%, at least about 75%, at least about 85%, or at least about 90% of the metal particles on the surface of the support satisfy one or more of the distribution characteristics of the second metal determined by linear scanning by EDX.
As previously indicated, in different embodiments of the present invention (for example, in which copper is the first metal and platinum is the second metal) the second metal rich coating can provide a relatively low coating of the core rich in the first metal and, during the subsequent use of the catalyst, the structure of the particles can change towards the increase of the coating of the core rich in the first metal by the coating that contains the second metal. This change generally comprises the leaching of the first metal from the metal particles on the surface of the support. The second metal can be removed or leached from the particles, but to a lesser degree than the removal of the first metal from the particles. It has been observed that this behavior provides a shift towards preferred atomic relationships of first metal to second metal.
It has been observed that the platinum-iron catalysts of the present invention behave as described. That is, during use, the iron and platinum can be leached from the metal particles on the surface of the catalyst and, very particularly, the iron is leached from the particles to a greater extent than platinum. The. Leaching in this way can proceed in accordance with the "autocorrector" mechanism described above in relation to the platinum-copper catalysts. However, or leaching can also proceed to form platinum-iron particles with advantageous structures. Instead of compensating for a relatively low excess of the first metal relative to the second metal to provide a structure in which the atomic ratio of the first metal to the second metal is in a suitable excess, the leaching of the first metal it predominates over any leachate of the second metal to such an extent that one or more particles are provided so that they exhibit minimal, if any, excess of first metal relative to the second metal. In fact, in different embodiments, a catalyst structure is obtained which exhibits an excess of second metal relative to the first metal. Although these particles may not include an alloy rich in the first metal or a core rich in the first metal at least partially surrounded by a coating rich in the second metal, they nevertheless provide improved utilization of metal.
In several such embodiments, the metal particles on the catalyst surface are in the form of a structure comprising a discontinuous coating comprising a layer of first metal atoms and a layer (eg, monolayer) of second metal atoms. on the surface of the atoms of the first metal. The reference to a coating in relation to these embodiments does not indicate the presence of a continuous or discontinuous coating surrounding a relatively continuous core. In contrast, the coating refers to the complete structure of the resulting particle. The structure of the coating may surround an internal region that includes the first metal, but the internal regions of the coating structure are not in the form of a relatively continuous core rich in the first metal surrounded by the outer regions of the coating structure. The discontinuous porous coating generally comprises pores and, most particularly, nanopores (i.e., pores having a size in their largest dimension of between about 1 and i) about 6 nanometers (nm), or between about 2 and about 5 nm). In this way, the structure of the coating can be referred to as a discontinuous nanoporous coating. In accordance with such embodiments, the atomic ratio of iron (first metal) to platinum (second metal) is generally less than 1: 1, generally between about 0.25: 1 and about 0.9: 1, very typically between about 0.4: 1 and approximately 0.75: 1 and, very typically, between about 0.4: 1 and about 0.6: 1 (for example, about 0.5: 1). Further, in accordance with these embodiments, the layer or regions of the first metal generally have a thickness of no more than about 5 atoms of the first metal, generally no more than about 3 atoms of the first metal and, even very typically, no more than about 2 atoms of the first metal. Additionally or alternatively, the layer or regions of the atoms of the second metal generally have a thickness of no more than about 5 atoms of the second metal, ... generally no more than-about 4 atoms of the second metal, very typically no more of about 3 atoms of the second metal and, very typically, no more than about 2 atoms of the second metal.
The extensive leaching of the metal from the catalyst particles to form platinum-iron coating particles has been observed to occur during use under certain conditions (for example, acidic conditions that prevail during PMIDA oxidation). The evidence experimental indicates that catalysts that include platinum-iron coating particles are effective for use in, for example, liquid phase oxidation of PMIDA. Therefore, instead of simply depending on the formation of the coating structure during use, catalysts including platinum-iron coating particles can be prepared by a process generally as described above for the preparation of platinum-iron which also includes the treatment for leaching the metals from one or more catalyst particles before or during the use of the catalyst. Generally, the treatment for the leaching of metal to form platinum-iron coating particles comprises contacting a platinum-iron catalyst with a suitable liquid medium. Generally, the liquid medium is acidic and the catalyst is contacted with the liquid medium at a temperature of at least about 5 ° C, or at least about 15 ° C.
. III. Use of oxidation catalysts ...-. ·,.
The oxidation catalysts of the present invention can be used for the liquid phase oxidation reactions. Examples of such reactions include the oxidation of alcohols and polyols to form aldehydes, ketones, and acids (for example, the oxidation of 2-propanol to acetone, and the oxidation of glycerol to form glyceraldehyde, dihydroxyacetone, or glyceric acid); the oxidation of aldehydes to form acids (for example, the oxidation of formaldehyde to form formic acid, and the oxidation of furfural to form 2-furancarboxylic acid); oxidation of tertiary amines to form secondary amines (e.g., oxidation of nitrilotriacetic acid (NTA) to form iminodiacetic acid (IDA)); the oxidation of secondary amines to form primary amines (for example, the oxidation of IDA to form glycine); and the oxidation of different acids (for example, formic acid or acetic acid) to form carbon dioxide and water.
The catalysts described above are especially useful in liquid phase oxidation reactions at pH levels less than 7, and in particular, at pH levels less than 3. One such reaction is the oxidation of PMIDA or a salt thereof for forming an N- (phosphonomethyl) glycine product in an environment having pH levels in the range of between about 1 and about 2. This reaction is generally carried out in the presence of solvents that solubilize noble metals and, in addition, the reactants , intermediates, or products generally solubilize noble metals. _. ::, · .-. · The oxidation catalyst described herein is particularly suitable for catalyzing the liquid phase oxidation of a tertiary amine to secondary amines, for example in the preparation of glyphosate and related compounds and derivatives. For example, the tertiary amine substrate may correspond to a compound of Formula I having the structure (Formula I) wherein R1 is selected from the group consisting of R5OC (0) CH2- and R5OCH2CH2-, R2 is selected from the group consisting of R5OC (O) CH2-, R5OCH2CH2-, hydrocarbyl, substituted hydrocarbyl, acyl, -CHR6P03R7R8, and -CHR9S03R1 ° , R6, R9 and R11 are selected from the group consisting of hydrogen, alkyl, halogen and -NO2l and R3, R4, R5, R7, R8 and are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl and a metal ion. Preferably, R1 comprises R5OC (0) CH2-, R1 is hydrogen, R5 is selected from hydrogen and an agronomically acceptable cation and R2 is selected from the group consisting of R5OC (0) CH2-, acyl, hydrocarbyl and substituted hydrocarbyl.
. .. As indicated above, the oxidation catalyst of the present invention is particularly suitable for catalyzing the oxidative digestion of a PMIDA substrate to form an N- (phosphonomethyl) glycine product. In said embodiment, the catalyst is effective for the oxidation of the secondary product formaldehyde to formic acid, carbon dioxide and / or water. Most particularly, it is currently believed that the catalysts of the present invention can provide improvements in activity by the oxidation of PMIDA, formaldehyde, and / or formic acid in comparison to conventional catalysts containing noble metal, either generally or on a weight basis of unitary metal.
As recognized in the art, the liquid phase oxidation of N- (phosphonomethyl) iminodiacetic acid substrates can be carried out in a batch, semi-batch or continuous reaction system containing one or more oxidation reaction zones . The oxidation reaction zone or zones may be provided in a suitable manner by different reactor configurations, including those having perfect mixing characteristics, in the liquid phase and optionally also in the gas phase, and those having piston flow characteristics. Suitable reactor configurations having perfect blending characteristics include, for example, stirred tank reactors, loop-type reactors with ejection nozzles (also known as loop-type reactors with Venturi effect) and fl uxed bed reactors. Suitable reactor configurations having piston flow characteristics include those having a packed or fixed catalyst bed (e.g., percolator bed reactors and bubble packed column reactors) and aqueous paste bubble column reactors. Fluidized bed reactors can also be operated in a manner that exhibits piston flow characteristics. The configuration of the oxidation reactor system, including the number of the oxidation reaction zones and the oxidation reaction conditions are not critical to the practice of the present invention. The appropriate oxidation reactor systems and the oxidation reaction conditions for the Catalytic oxidation in liquid phase of an N- (phosphonomethyl) iminodiacetic acid substrate are well known in the art and are described, for example, by Ebner et al., in U.S. Pat. No. 6,417,133, by Leiber et al., U.S. Pat. No. 6,586,621, and by Haupfear et al., U.S. Pat. No. 7,015,351, the full disclosures thereof are incorporated herein by reference.
The description below describes with particularity the use of catalysts described above acting as the catalyst to affect the oxidative digestion of a PMIDA substrate to form an N- (phosphonomethyl) glycine product. It should be recognized, however, that the principles described below are generally applicable to other oxidative reactions in the liquid phase, especially those at pH levels less than 7 and those involving solvents, reagents, intermediates, or products that solubilize noble metals.
To start the oxidation reaction of PMIDA, it is preferable to charge the reactor with the. substrate PMIDA, catalyst,.-... and. a solvent in the presence of oxygen. The solvent is very preferably water, although other solvents (for example, glacial acetic acid) are also suitable.
The reaction can be carried out in a wide variety of batch, semi-batch, and continuous reactor systems. The configuration of the reactor is not critical. Suitable conventional reactor configurations include, for example, stirred tank reactors, fixed bed reactors, percolating bed reactors, fluidized bed reactors, bubble flow reactors, piston-type flow reactors, and parallel flow reactors.
When carried out in a continuous reactor system, the residence time in the reaction zone can vary widely depending on the specific catalyst and the conditions employed. Generally, the residence time may vary in a range of between about 3 and about 120 minutes. Preferably, the residence time is between about 5 and about 90 minutes, and most preferably between about 5 and about 60 minutes. When carried out in a batch reactor, the reaction time generally varies in a range of between about 15 and about 120 minutes. Preferably, the reaction time is between about 20 and about 90 minutes, and most preferably between about 30 and about 60 minutes.
In a broad sense,. the . Oxidation reaction can be carried out in accordance with the present invention over a wide range of temperatures, and at pressures ranging in a sub-atmospheric to super-atmospheric range. The use of mild conditions (for example, ambient temperature and atmospheric pressure) has obvious commercial advantages in that less expensive equipment is used. However, the operation at high temperatures and super-atmospheric pressures, although it increases the capital requirements, tends to improve the phase transfer between the liquid and gas phase and increase the rate of oxidation reaction.
Preferably, the oxidation reaction of PMIDA is carried out at a temperature between about 20 and about 180 ° C, most preferably between about 50 and about 140 ° C, and most preferably between about 80 and about 110 ° C. At temperatures greater than about 180 ° C, the raw materials tend to begin to decompose slowly.
The pressure used during the oxidation of PMIDA generally depends on the temperature used. Preferably, the pressure is sufficient to prevent the reaction mixture from boiling. If a gas containing oxygen is used as the source of oxygen, the pressure is also preferably adequate to cause the oxygen to dissolve in the reaction mixture at a sufficient rate so that the oxidation of PMIDA is not limited due to inadequate input of oxygen. The pressure is preferably at least equal to the atmospheric pressure. Most preferably, la-A,. Pressure is between approximately. 2.1 and about 35.15 kg / cm2 gauge, and most preferably between about 2.1 and about 9.14 kg / cm2 gauge.
The concentration of the catalyst prepared according to the present invention in the reaction mixture is preferably between about 0.1 and about 10% by weight ([catalyst mass ÷ total reaction mass] x 100%). Most preferably, the concentration of the catalyst is preferably between about 0.1 and about 5% by weight, even very preferably between about 0.2 and about 5% by weight and, most preferably, between about 0.3 and about 1.5% by weight. Concentrations greater than about 10% by weight are difficult to filter. On the other hand, lower concentrations of about 0.1% by weight tend to produce unacceptably low reaction rates.
As indicated, catalysts prepared in accordance with the methods of the present invention provide for efficient utilization of the metal. Therefore, the catalysts of the present invention can provide sufficient activity at low catalyst loads compared to fillers associated with conventional noble metal containing catalysts. Therefore, catalyst loads according to the present invention can conveniently be or be close to the lower limits of the ranges mentioned above. However, it should be understood that the use of a low catalyst load is not a critical aspect of the present invention. In fact, another aspect of the present invention involves the use of catalysts of the present invention at fillers similar to those associated with conventional catalysts containing noble metal while providing improved catalytic activity based on improvements in metal utilization. .
The concentration of the PMIDA substrate in the feed stream is not critical. The use of a saturated solution of PMIDA substrate in water, although for ease of operation, the process is also operable at lower or higher concentrations of PMIDA substrate in the feed stream. If the catalyst is present in the reaction mixture in a finely divided form, it is preferred to use a reagent concentration such that all reagents and the N- (phosphonomethyl) glycine product remain in solution so that the catalyst for the catalyst can be recovered. reuse, for example, by filtration. On the other hand, higher concentrations tend to increase reactor performance. Alternatively, if the catalyst is present as a stationary phase through which the reaction medium and oxygen source pass, it may be possible to use higher concentrations of reagents such that a portion of the product N- (phosphonomethyl) glycine precipitates .
Typically, a PMIDA substrate concentration of up to and about 50% by weight ([mass of PMIDA substrate ÷ total reaction mass] x 100%) (especially at a reaction temperature of between about 20 and about ~ 180 ° can be used. C). Preferably, a concentration of PMIDA substrate of up to and about 25% by weight (particularly at a reaction temperature of between about 60 and about 150 ° C) is used. Most preferably, a PMIDA substrate concentration of between about 12 and about 18% by weight (particularly at a reaction temperature of between about 100 and about 130 ° C) is used. Concentrations of PMIDA substrate below 12% by weight they can be used, but are less economical since a relatively low payload of the N- (phosphonomethyl) glycine product occurs in each reactor cycle and more water must be removed and more energy used per unit of product N- (phosphonomethyl) glycine produced. Relatively low reaction temperatures (ie, temperatures less than 100 ° C) often tend to be less advantageous since the solubility of the substrate PMIDA and product N- (phosphonomethyl) glycine are both relatively low at such temperatures.
The oxygen source for the oxidation reaction of PMIDA may be an oxygen-containing gas or a liquid comprising dissolved oxygen. Preferably, the oxygen source is a gas containing oxygen. As used herein, an oxygen-containing gas is a gaseous mixture comprising molecular oxygen that optionally may comprise one or more diluents that are not reactive with oxygen or with the reactant or product under reaction conditions.
Examples of such gases are air, oxygen.molecular. pure, a molecular oxygen diluted with helium, argon, nitrogen, or other non-oxidizing gases. For economic reasons, the oxygen source is most preferably air, oxygen enriched air, or pure molecular oxygen.
The oxygen can be introduced into the reaction medium by any conventional means in a manner that maintains the concentration of dissolved oxygen at a desired level in the reaction mixture. If a The oxygen-containing gas is preferably introduced into the reaction medium in a manner that maximizes the contact of the gas with the reaction solution. Such contact can be obtained, for example, by dispersion of the gas through a diffuser such as a porous glass or by mixing, stirring, or other methods known to those skilled in the art.
The rate of oxygen delivery is preferably such that the oxidation reaction rate of the PMIDA is not limited by the oxygen supply. However, if the concentration of dissolved oxygen is very high, the surface catalyst tends to oxidize detrimentally, which, in turn, tends to lead to greater leaching of the noble metal present in the catalyst and decrease the formaldehyde activity ( which, in turn, leads to increased production of NMG). Generally, it is preferred to use an oxygen supply rate such that at least about 40% of the oxygen is used. Most preferably, the oxygen delivery rate is such that at least about 60% of the oxygen is usedEven very preferably, the oxygen delivery rate is such that at least about 80% of the oxygen is used. Most preferably, the speed is such that at least about 90% of the oxygen is used. As used herein, the percentage of oxygen used is equivalent to: (total oxygen consumption rate ÷ oxygen delivery rate) x 100%. The term "total oxygen consumption rate" means the sum of: (i) the rate of oxygen consumption ("R") of the oxidation reaction of the PMIDA substrate to form the product N- (phosphonomethyl) glycine and formaldehyde, (ii) the rate of oxygen consumption ("R¡¡") of the oxidation reaction of formaldehyde to form formic acid, and (iii) the rate of consumption of oxygen ("R¡¡¡") of the formic acid oxidation reaction to form carbon dioxide and water.
In different embodiments of this invention, oxygen is supplied in a reactor as described above until the mass of PMIDA substrate has been oxidized, and then a reduced delivery rate is used. This reduced delivery rate is preferably used after approximately 75% of the PMIDA substrate has been consumed. Most preferably, the reduced delivery rate is used after approximately 80% of the PMIDA substrate has been consumed. When the oxygen is supplied as pure oxygen or oxygen enriched air, a reduced delivery rate can be achieved by purging the reactor with air (not enriched), preferably at a volumetric delivery rate which is higher. the volumetric velocity in which pure molecular oxygen or air enriched with oxygen was supplied before purging with air. The reduced oxygen delivery rate is preferably maintained between about 2 and about 40 minutes, most preferably between about 5 and about 20 minutes, and most preferably between about 5 and about 15 minutes. While oxygen is supplied at a reduced speed, the The temperature is preferably maintained at the same temperature or at a temperature lower than the temperature at which the reaction was conducted before purging with air. In addition, it is maintained at the same pressure or at a lower pressure than the pressure at which the reaction was conducted before purging with air. The use of a reduced oxygen delivery rate near the end of the PMIDA reaction allows the amount of formaldehyde present in the reaction solution to be reduced without producing harmful amounts of AMPA by oxidation of the N- (phosphonomethyl) glycine product.
The reduced losses of the noble metal can be observed with this invention if a sacrificial reducing agent is maintained or if it is introduced into the reaction solution. Suitable reducing agents include formaldehyde, formic acid, and acetaldehyde. Most preferably, formic acid, formaldehyde, or mixtures thereof are used. Experiments carried out in accordance with this invention indicate that if small amounts of formic acid, formaldehyde, or a combination thereof are added to the reaction solution, the catalyst will preferably perform. . the oxidation of formic acid or formaldehyde before effecting the oxidation of the PMIDA substrate, and later it will be more active in effecting the oxidation of formic acid and formaldehyde during the oxidation of the PMIDA.
Preferably from about 0.01 to about 5% by weight ([formic acid mass, formaldehyde, or a combination of the same total reaction mass x 100%) of reducing agent is added, very preferably it is added between about 0.01 and about 3% by weight of the sacrificial reducing agent, and most preferably between about 0.01 and about 1% by weight of the sacrificial reducing agent is added.
In certain embodiments, formaldehyde and formic acid that do not react are then recycled into the reaction mixture for use in subsequent cycles. In this case, an aqueous recycle stream comprising formaldehyde and / or formic acid can also be used to solubilize the PMIDA substrate in subsequent cycles. Said recycle stream can be generated by evaporating the water, formaldehyde, and formic acid from the oxidation of the reaction mixture to concentrate and / or crystallize the product N- (phosphonomethyl) glycine. The condensate of the top head containing formaldehyde and formic acid may be suitable for recycling.
Typically, the concentration of N- (phosphonomethyl) glycine in the product mixture can be as large as 40% by weight, or greater. Preferably, the concentration of N- (phosphonomethyl) glycine is between about 5 and about 40%, most preferably between about 8 and about 30%, and most preferably between about 9 and about 15%. The formaldehyde concentrations in the product mixture are generally less than about 0.5% by weight, most preferably less than about 0.3%, and most preferably less than about 0.15%.
After oxidation, the catalyst is preferably separated subsequently by leaching. The product N- (phosphonomethyl) glycine can then be isolated by precipitation, for example, by evaporation of a portion of the water and cooling.
In certain embodiments, it must be recognized that the catalyst of this invention has the ability to be reused in several cycles, depending on how oxidized its surface becomes with use. Even after the catalyst becomes very oxidized, it can be reused by reactivation. To reactivate a catalyst having a highly oxidized surface, the surface is preferably washed to remove the organics from the surface. It is then preferably reduced in the same manner in which the catalyst is reduced after the noble metal is deposited on the surface of the support, as described above.
Catalysts containing noble metal including the treated porous substrates prepared by the present method, may also be used in combination with an additional promoter such as is described, for example, in the U.S. Patent. No. 6,586,621, in the. Patent of E.U.A. No. 6,963,009, the entire contents of which are incorporated herein by reference for all relevant purposes.
The N- (phosphonomethyl) glycine product prepared according to the present invention can be further processed according to many methods well known in the art to produce agronomically acceptable salts of N- (phosphonomethyl) glycine commonly used in glyphosate herbicidal compositions. As used herein, a "agronomically acceptable salt" is defined as a salt containing one or more cations which allows an agriculturally and economically useful herbicidal activity of an N- (phosphonomethyl) glycine anion. Said cation can be, for example, an alkali metal cation (for example, a sodium or potassium ion), an ammonium ion, an isopropylammonium ion, a tetra-alkylammonium ion, a trialkylsulfonium ion, a protonated primary amine, a protonated secondary amine , or a protonated tertiary amine.
IV. Additional forms of realization A. Locking pores With regard to the application or deposit of a pore-blocking compound in the pores of a substrate, as described elsewhere in this documentation, it is worth noting that the present invention is not limited to the application or deposit of a compound pore blocker within the pores of the substrate (e.g., micropores). That is, various embodiments of the present invention relate to the application or deposit of a pore blocker within pores with an intermediate or larger size. Thus, in various embodiments of the present invention, additional opportunities are provided to control the size of the pores that are blocked (i.e., additional opportunities to control or adjust the pore block). For example, in addition to the micropores, porous carbon supports that can be treated with the present method have pores with larger dimensions (for example, pores). which have a larger dimension of between about 20A and about 3000A).
The application or deposit of a pore-blocking agent within pores larger than the size range of the micropores is generally carried out in accordance with the method described above. For example, the substrate can be contacted with the pore-blocking compound and / or one or more precursors. Furthermore, in accordance with the method described above, the pore blocker can be retained within the desired pores because it has at least one dimension larger than the desired pore openings. In addition, regardless of the introduction of the pore-blocking agent into the desired pores or their formation in situ, the pore-blocker can be retained within the desired pores due to the conformational arrangement of the pore-blocker.
As mentioned above, when the pore blocker is directed to relatively small pores, the pore-blocker can enter unwanted pores and then exit them (for example, due to contact with a liquid washing medium). . It is worth noting that the targeting of a pore-pore blocker of intermediate and / or larger size may not be effective for pores smaller than the desired pores. However, this does not affect the goal of blocking pores of intermediate and / or larger size.
Currently, it is believed that a variety of compounds are suitable as pore blocking compounds, for the purpose of blocking pores with a size range superior to that of micropores. For example, the pore blocker may be selected from the group consisting of various hydrophilic polymers (eg, various polyethylene glycols) and combinations thereof.
In various embodiments, the pore blocker of intermediate and / or larger size may comprise the product of a reaction between one or more precursors of pore-blocking compounds. For example, it has been observed that the binding product of a ketone and a dihydric alcohol can be used as a pore blocker.
As with the above-mentioned micropores, it is believed that the presence of the pore-blocking compound within the desired pores, outside the micropore domain, will cause at least a portion of the "blocked" pores to appear as a non-porous portion. porous of the substrate during the measurements of surface area, which will reduce the proportion of surface area that the desired pores would present, if they are not blocked. At present, it is believed that this blocking of the desired pores provides a reduction in the surface area of the treated substrate provided by the desired pores. For example, in various embodiments, the surface area of the treated substrate provided by the pores outside the size range of the micropores (ie, above said range) is generally not greater than about 80% or about 70% of the surface area of the substrate. provided by these pores before treatment. Typically, the surface area of the treated substrate provided by the desired pores is not greater than about 60%, and more typically, is not greater than about 50% of the surface area of the substrate provided by these pores prior to the treatment.
B. Pore Blocker for the Pores of a Catalyst As mentioned, the persistence of the pore blocker in the treated substrates of the present invention is not critical to provide the advantages described above (eg, a reduced proportion of metal crystals in the surface of a porous carbon support, between the relatively small pores of the substrate surface). In addition, it is now believed that the pore blocker is likely to decompose and / or be otherwise removed from the surface of the substrate before it is calcined. In various alternative embodiments, methods for treating porous substrates can be applied to the treatment of finished catalysts. For example, the catalysts that. they comprise a noble metal -;. ·. ·. deposited on a carbon support can be treated by depositing a pore blocker on the surface of the catalyst, within its relatively small pores. At present, it is believed that the presence of the pore blocker within the relatively small pores can promote the preferential contact of the reactants with the metal deposited in the pore regions with intermediate and larger sizes, within which the metal deposited it is more accessible to the reactants. This In this way, the conversion of the reactants into the products can be promoted by reducing the proportion of the reagents that come into contact with the metal deposited between the pore regions with relatively small sizes., within which the deposited metal may be relatively inaccessible to the reactants. As a further example, it is currently believed that the treatment of catalysts with carbon supports suitable for the preparation of DSIDA from DEA in accordance with the detailed methods results in catalysts including a reduced proportion of exposed noble metal, and therefore, fewer by-products (eg, glycine and / or oxalate). However, it is to be understood that the treatment of the finished catalyst (ie, one containing carbon or a metal, with the deposit of one or more metals) is not a critical aspect of the invention, and that catalysts have been found to Preparations using substrates treated in accordance with the present methods are effective catalysts.
C. Supports other than coal In addition to the treatment of the porous carbon supports detailed in the present documentation, the method of the present invention for blocking certain pores of a substrate can be used to treat non-carbonaceous soups. Most particularly, the methods detailed in this documentation can be used for the treatment of porous metal alloys which are commonly known as metal sponges.
The alloys of metal sponges that can be treated in accordance with the present method are described, for example, in the U.S. Patent. No. 5627125, the Patent of E.U.A. No. 5916840, the Patent of E.U.A. No. 6376708 and the Patent of E.U.A. No. 6706662, whose complete contents are incorporated in this documentation as a reference for all relevant purposes. At present, it is believed that substrates containing treated metals may have one or more of the properties mentioned above in relation to the treated porous carbon substrates.
D. Preparation of carboxylic acids In addition to oxidation with PMIDA detailed elsewhere in this documentation, it is currently believed that catalysts including treated substrates prepared in accordance with the present method are suitable for use in other reactions. For example, catalysts that include treated substrates prepared according to the present "method can be used in the preparation of carboxylic acids ,. including, for example, the preparation of disodioiminodiacetic acid (DSIDA) by the dehydrogenation of diethanolamine (DEA). Most particularly, the catalysts including the treated substrates of the present invention can be used to solve one or more of the problems observed with the conventional catalysts used in the preparation of carboxylic acids such as DSIDA. For example, appropriate catalysts commonly include copper deposited on the surface of a carbon support having a noble metal (e.g., platinum or palladium) on its surface. At present, it is believed that at least a portion, and possibly a significant portion of the noble metal can remain exposed after the deposit of the copper. It is undesirable that there is an excess of exposed noble metal, as this is believed to promote the formation of various undesirable byproducts (eg, glycine and oxalate). It is believed that a substantial portion, if not practically all, of the exposed noble metal is on the surface of the support, within the relatively small pores which are inaccessible to copper during deposition. Other catalysts suitable for the preparation of carboxylic acids include copper deposited on the surface of metal-containing sponges (eg, nickel). As with the noble metal exposed on the surface of catalysts with carbon supports, it is believed that the surface with the metal support that is not covered by copper, within relatively small pores of the metal sponge, contributes to the formation of undesirable byproducts. At present, it is believed that the selective blocking of relatively small pores of substrates, in accordance with the methods detailed in this documentation, can be used to prepare effective catalysts with carbon and metallic supports, to solve one or more of the problems mentioned previously.
The preparation of DSIDA from DEA using a catalyst comprising a substrate treated as described herein Documentation is generally carried out in accordance with methods known in the art, including, for example, U.S. Pat. No. 5627125, the Patent of E.U.A. No. 5916840, the Patent of E.U.A. No. 6376708 and the Patent of E.U.A. No. 6706662, whose complete contents are incorporated in this documentation as a reference for all relevant purposes.
The present invention is illustrated by the following examples, which are merely provided for illustrative purposes, and are not to be construed as limiting the scope of the invention or the manner in which it may be put into practice.
EXAMPLES The following non-limiting examples are provided to illustrate the present invention in greater detail.
I. Pore coverage EXAMPLE 1 Three carbon supports were treated to determine the effectiveness of candidate pore blocking compounds. Support A had a total Langmuir surface area of approximately 1500 m2 / g (including a total surface area of the micropores of approximately 1279 m2 / g and a total surface area of the macropores of approximately 231 m2 / g). The support B had a total Langmuir surface area of about 2700 m2 / g (including a total surface area of the micropores of approximately 1987 m2 / g and a total surface area of the macropores of approximately 723 m2 / g). The support C had a total Langmuir surface area of about 1100 m2 / g (including a total surface area of the micropores of about 876 m / g and a total surface area of the macropores of about 332 m2 / g).
The candidate pore blocking compounds were 1,4-cyclohexanedione, ethylene glycol and the diketal product of a linking reaction between 1,4-cyclohexanedione and ethylene glycol (ie bis (ethylene ketal) of 1,4-cyclohexanedione).
Samples of the supports (30 g) were contacted with a solution of 1,4-cyclohexanedione in ethylene glycol (6 g / 40 g) at about 25 ° C for about 60 minutes. The pH of the suspension was adjusted to about 1 by the addition of hydrochloric acid, and stirred for about 60 minutes. Then, the pH of the suspension was adjusted to about 8.5 by the addition of a 50% by weight sodium hydroxide solution. Subsequently, the suspension was filtered to isolate the treated support, which was washed using deionized water at a temperature of about 90 ° C (mechanism one).
Samples of the supports (2 g) were also placed in contact with a solution of bis (ethylene ketal) of 1,4-cyclohexanedione in water (0.6 g / 40 g), at approximately 25 ° C for approximately 60 minutes (mechanism two).
As controls, carbon A samples were also treated putting them in contact separately with (1) ethylene glycol and (2) 1, 4- cyclohexanedione.
The treated supports were analyzed with the well-known method of Langmuir to determine its surface area profiles (SA) (for example, total surface area, surface area attributed to micropores and surface area attributed to macropores). The results are detailed in the box 1 TABLE 1 % of the original SA of% of the original SA Support Mechanism micropores macropores Coal To One 24.2 74.9 Coal A Dos 34.4 70.9 Coal A Control one 93.7 98.7 Coal A Control two 68.9 94.4 Carbon B One 55.6 78.7 Carbon B Two 65.4 81.5 Coal C One 17.9 76.8 Coal C Dos 22 72.3 As can be seen, both with mechanism one and with mechanism two, it was possible to obtain a reduction in the surface areas of the micropores and macropores for each of the AC supports, and very particularly, a greater reduction in the surface area of the micropores, in comparison with the reduction in the surface area of the macropores (for example, a reduction three times greater in the surface area of the micropores). It is believed that the percentage reduction in surface area for carbon B is less than that observed for the other two carbons due to its greater surface area. However, it is worth noting that, even so, the percentage of reduction of the surface area of the micropores for coal B corresponds to an absolute reduction of approximately 900 m2 / g.
The evaluation of the control of carbon A with ethylene glycol resulted in a minimal reduction in the surface areas of the micropores and macropores, while the evaluation of the control with 1,4-cyclohexanedione resulted in a greater reduction in the surface areas of the micropores and the macropores, but to a much lesser degree than that observed with mechanism one and mechanism two. Accordingly, it is believed that the components combine to form a pore-blocking compound that provides a greater reduction in surface area than either of the components alone, or that the cumulative reduction provided by both.
EXAMPLE 2 Each of the coals A, B, and C (30 g) described in the Example 1 was treated by putting it in contact with solutions of 1, 4- cyclohexanedione in ethylene glycol (6 g / 40 g), at about 25 ° C during approximately 60 minutes. Each coal was also treated by putting it in contact with solutions of, 3-cyclohexanedione in ethylene glycol (1 g / 50 g), a about 25 ° C for about 120 minutes. The carbon C It was also treated by putting it in contact with a solution of 1, 4- cyclohexanedione in 1,2-propanediol (1 g / 50 g), at about 25 ° C for approximately 60 minutes. The results of the area analysis are detailed in Table 2. As can be seen, each Dione and diol combination resulted in a reduction of the areas surface areas of micropores and macropores, and very particularly, a preferential reduction in the surface area of the micropores.
TABLE 2 % of the SA% of the original original SA of those of the Diona Diol shows micropores macropores Coal A 1, 4-substituted Ethylene glycol 22.6 75.8 Coal A 1, 3-substituted Ethylene glycol 58.4 84 Coal B 1, 4-substituted Ethylene glycol 55.6 78.7 Coal B 1, 3-substituted Ethylene glycol 32.2 39.8 EXAMPLE 3 In this example, the results of electron transmission microscopy (TEM) are provided for a platinum-on-carbon catalyst prepared using carbon B treated as described in example 1 (mechanism one). The catalyst contained approximately 5% by weight of platinum and was prepared in general as detailed herein (for example, by liquid deposition of platinum on the treated carbon support), followed by a treatment at temperatures elevated in a non-oxidative environment. For comparative purposes, a catalyst including 5% by weight of platinum on carbon B that was not treated was also analyzed. The TEM analysis was carried out in general as described by Wan et al. in International Publication No. WO 2006/031198.
The results for the catalyst including the untreated and treated carbons are illustrated in Figures 3A / 5A and 3B / 5B, respectively. From these results, a reduction in relatively small particles containing platinum (for example, those having a particle size less than 4 nm) can be inferred for the catalyst prepared using the treated support.
In general, the results of the TEM correspond to the regions of high density of the substrates, which primarily include the micropores, and from them, it can be concluded that there is a higher density of platinum between these regions for the catalyst that includes the support without try.
EXAMPLE 4 In this example, the results of an analysis of the surface area of a carbon support of the type described in US Patents are provided. No. 4624937 and 4696771, Chou et al. (designated MC-10), treated in accordance with the present invention. Samples of the supports were treated in accordance with mechanism one and mechanism two, described previously in example 1. The support had a surface area of Langmuir. micropores of approximately 1987 m2 / g and an initial Langmuir surface area of the macropores of approximately 723 m2 / g. The retention results related to the surface area of the micropores and the macropores for the treated supports are detailed in Table 3.
TABLE 3 Figures 4A and 4B provide pore volume data for treated and untreated MC-10 supports.
EXAMPLE 5 In this example, the results of the carbon monoxide (CO) chemisorption analysis for the platinum containing catalysts of example 4 are provided. The chemosorption of CO is an appropriate method of analysis for estimating the proportion of exposed metal, and the analysis it was carried out in general in accordance with "Protocol A", described in the example. 67 of the present documentation, and the example ..- 23; -, of WO 2006/031938, incorporated in the present documentation by way of reference.
The results are detailed in Table 4. From the lowest chemosorption of CO present in the catalyst that includes a treated charcoal support (38.6 and 43.3 [mu] μ CO / gram versus 54.7 [mu] t [CO] / catalyst gram), it can be concluded that there is a reduced proportion of noble metal exposed in the platinum containing catalyst prepared using the treated carbon support.
TABLE 4 EXAMPLE 6 Catalysts containing approximately 5% by weight of Pt and approximately 0.5% by weight of Fe were prepared in general as detailed herein, using uncoated MC-10 carbon supports and MC-10 carbon supports treated in accordance with with mechanism one and mechanism two described in example 1. These catalysts were evaluated in an oxidation with PMIDA, generally under the conditions detailed in example 7, and the results are detailed in table 5. The catalyst (1 ) included an untreated support. Each of the catalysts (2) and (3) included supports treated in accordance with mechanism two, described above in example 1. The catalyst (2) was prepared with a method that included filtration of the copper impregnated support before of the platinum deposit. Catalyst (3) was prepared with a method that did not include filtration of the copper-impregnated support before platinum deposition (i.e., a one-pot method, as described in Example 16).
TABLE 5 GLY = glyphosate,. IDA = iminodiacetic acid i FORMIC = formic acid ppm = parts per million II. Precursor catalysts, catalysts containing a first and a second metal, structures of the precursor catalysts In the following examples, the preparation of the catalysts detailed in this documentation is described, its evaluation with various characterization methods and its evaluation in the oxidation with PMIDA. In the following examples, comparisons of the catalysts prepared as detailed in this documentation and other various catalysts containing metals with carbon supports are also provided. For example, in the following examples, comparisons are provided with catalysts with carbon supports including 5% by weight of Pt, 0.1% by weight of Fe and 0.4% by weight of Co, and catalysts with carbon supports including 5% in weight of Pt and 0.5% in weight of Fe. These catalysts were prepared in general as described by Wan et al. in International Publication No. WO 2006/031938.
EXAMPLE 7 The catalysts prepared as described herein and the comparative samples were evaluated under oxidizing conditions with PMIDA, as also generally described by Wan et al. in International Publication No. WO 2006/031938. For example, the. Oxidation cycles with PMIDA were carried out in a glass reactor (200 ml, commercially available from Ace Glass Inc.) containing a reaction mass (approximately 140 g) which included water (approximately 128 g), approximately 8, 2% by weight of PMIDA (approximately 11.48 g) and a catalyst load of approximately 0.18% by weight (0.25 g). In general, the oxidations were carried out at a temperature of approximately 100 ° C, under a pressure of approximately 4.21 kg / cm2 manometric and with an oxygen flow velocity of approximately 100 cc / minute. Unless otherwise indicated, the reaction cycles were carried out to a terminal point determined by the generation of approximately 1600 cm3 of carbon dioxide.
As described in the following examples and the accompanying figures, various data were collected, including cycle length, metal capture, residual formaldehyde content (HCHO), residual formic acid (HCOOH) content, formation of iminodiacetic acid (IDA), the formation of N-methyl-N- (phosphonomethyl) glycine (NMG), the generation of total carbon dioxide (CO2), and so on.
EXAMPLE 8 In this example, the preparation of a catalyst containing a nominal Pt content of approximately 2.5% by weight and a nominal Cu content of approximately 5% by weight, on an activated carbon support with a Langmuir surface area of approximately 500 m2 / g.
A carbon solution (approximately 10 g), a solution of CuSO4-5H2O (approximately 2.07 g), sucrose (approximately 5.67 g), degassed degassed water (approximately 30 g) and degassed 1 M NaOH (70 g) in a mixture were mixed. beaker with partitions. The mixture was stirred under ambient conditions (approximately 25 ° C) for approximately 20 minutes. Formaldehyde (about 2.25 g of a 37 wt% solution) was added to the mixture, the resulting suspension was heated to about 30 ° C and stirred for about 60 minutes.
The resulting suspension was filtered, washed with degassed deionized water, suspended again in deionized water and 1 M HCl was added until a pH of about 1.5 was reached.
A solution of K ^ PtCU (approximately 0.557 g) in degassed water (15 g) was added to the suspension, followed by continuous agitation for 60 minutes under ambient conditions. The suspension was filtered, the support impregnated with recovered metal was washed with water and dried under vacuum at about 10 ° C. A total of 12.12 g of the support impregnated with dry metal was recovered. With elemental analysis, a composition of approximately 2.04% by weight of Pt and approximately 1.93% by weight of Cu in carbon was established.
Then, the catalyst, precursor was heated, at elevated temperatures of up to about 815 ° C, in the presence of a stream of hydrogen / argon (2% / 98%, v / v) for about 60 minutes. With elemental analysis, a final metal content of approximately 2.34% by weight of Pt and approximately 2.22% by weight of Cu was established.
As will be described later, catalysts prepared by heating the impregnated support were also evaluated. with metal at various temperatures. In addition, the catalytic activity of various supports impregnated with metal was also determined.
EXAMPLE 9 (Copper bath at room temperature) Preparation of a catalyst with a nominal content of 2% Pt, 3.45% Cu in activated carbon. The following components were added in a beaker with partitions containing approximately 10 g of activated carbon: CuS04-5H20 solution (1.410 g), 3.866 g of sucrose, 90 g of degassed deionized water and 5.974 g of NaOH 50% by weight. The mixture was stirred at about 22 ° C for about 10 minutes using a mechanical stirrer. After stirring, about 1468 g of a 37% by weight formaldehyde solution was added, and the resulting suspension was stirred at about 22 ° C for 60 minutes. Then, the suspension was filtered and washed twice in the filter, and then it was suspended again in water and the pH was brought up to about 2.0 by the addition of degassed 1.5 M HCl. To this suspension was added a solution of K2PtCI4 (0.444 g) in 15 g of degassed water, followed by stirring for about 60 minutes under ambient conditions. Subsequently, the suspension was heated to about 65 ° C, followed by stirring for another 30 minutes. After, the suspension The resulting product was filtered, washed with water and dried in vacuo at approximately 10 ° C. A total of 1 1389 g of dry material was recovered.
EXAMPLE 10 Preparation of a catalyst with a nominal content 2.5% Pt, 5% Cu in activated carbon. The following components were added to approximately 10 g of activated carbon in a septated beaker: 2.072 g of a CuS04-5H20 solution, 5.694 g of sucrose, 30 g of degassed deionized water and 70 g of 1 M degassed NaOH. The mixture was heated to about 35 ° C using a mechanical stirrer. To this mixture was added 2,249 g of a 37% by weight formaldehyde solution, and the resulting suspension was heated to about 33-35 ° C, followed by continuous agitation for 60 minutes. The suspension was filtered and washed with degassed degassed water in the filter, then re-suspended in water and the pH was brought up to about 1.5 by the addition of 0.5 M HCl. A 0.557 g solution was then added. K2PtCI4 in 15 g of degassed water to the suspension, followed by continuous agitation for 60 minutes under ambient conditions. Subsequently, the suspension was heated to about 60 ° C and stirred another 30 minutes. The resulting suspension was filtered and washed with water, and dried under vacuum at about 10 ° C. A total of 11,701 g of dry material was recovered. After performing a final treatment at a temperature maximum of about 950 ° C, in the presence of an argon / hydrogen atmosphere (2% / 98%) (v / v) for 120 minutes, a final catalyst composition indicative of a weight loss of approximately 12.1% was recovered in Weight during heating.
EXAMPLE 11 (Without washing after depositing the copper) Preparation of a catalyst with a nominal content of 2% Pt, 4% Cu in activated carbon. The following components were added in a septated beaker containing approximately 10 g of activated carbon: 1643 g of a CuSO4-5H2O solution, 4509 g of sucrose, 90 g of degassed deionized water and 4.625 g of 50% NaOH. in weigh. The mixture was heated to about 30 ° C for about 10 minutes with a mechanical stirrer. To this suspension was added 1,706 g of a formaldehyde solution at 37% by weight and the resulting suspension was heated to about 30-35 ° C, followed by continuous stirring for about 90 minutes. Then, the suspension was filtered, and subsequently and without washing, it was suspended again in water and the pH was brought up to 2.02 by the addition of 1 M degassed HCI. Subsequently, a solution of 0.454 g of K2PtCI4 in 10 g of water was added. degassing to the suspension, followed by continuous agitation for 60 minutes under conditions environmental Then, the resulting suspension was heated to about 60 ° C and stirred another 30 minutes. Subsequently, this suspension was filtered and washed with water, and dried under vacuum at about 10 ° C. A total of 11,720 g of dry material was recovered. After performing a heat treatment to a maximum temperature of about 950 ° C, in the presence of an argon / hydrogen atmosphere (2% / 98%) (v / v) for approximately 120 minutes, the sample lost approximately 13.5% of the weight.
EXAMPLE 12 Preparation of a catalyst with a nominal content of 2% Pt, 3.75% Cu in activated carbon. The following components were added in a septated beaker containing approximately 10 g of activated carbon: 1533 g of CuS0 -5H20 solution, 4.210 g of sucrose, 90 g of degassed deionized water and. 4,300 g of 50% by weight NaOH. This mixture was heated to about 30 ° C and stirred for about 10 minutes using a mechanical stirrer. To this mixture was added 1,507 g of formaldehyde at 37% by weight and the suspension was heated to about 30-35 ° C, followed by continuous agitation for 60 minutes. The suspension was filtered and the solids recovered once in the filter were washed, and then suspended again in water and the pH was brought up to 1.97 by the addition of HCl. 1 M degassed. Then, a solution of 0.452 g of K2PtCI4 in 10 g of degassed water was added to the suspension, followed by continuous agitation for 60 minutes under ambient conditions. Subsequently, the suspension was heated to about 60 ° C and stirred another 30 minutes. Then, the suspension was filtered and washed with water, and dried under vacuum at about 110 ° C. A total of 11,413 g of dry material was recovered. Upon heat treatment to a maximum temperature of about 950 ° C, in the presence of an atmosphere of 2% / 98% (v / v) H2 / Ar for 120 minutes, the sample lost approximately 12.5% by weight.
EXAMPLE 13 (Deposit of platinum at higher temperature) Preparation of a catalyst with a nominal content of 2% Pt, 4% Cu in. .activated carbon. The following . The components were added in a beaker with partitions containing 10 g of activated carbon: 1645 g of CuS0-5H20 solution, 4,502 g of sucrose, 90 g of degassed deionized water and 4,636 g of 50% by weight NaOH. The mixture was stirred under ambient conditions for approximately 20 minutes with a mechanical stirrer. Then, 1721 g of 37% formaldehyde were added and the suspension was heated to about 30-35 ° C, followed by continuous stirring for 70 minutes. Subsequently, the The suspension was filtered and washed once in the filter, and then it was suspended again in water and the pH was brought up to 2.95 by the addition of 1 M degassed HCI. Then a solution of 0.455 g of K2PtCI4 in 10 g of water was added. degassed to the suspension, followed by continuous stirring for 45 minutes at 40-45 ° C. Subsequently, the suspension was heated to 60 ° C and stirred for another 30 minutes. The suspension was filtered and the recovered solids were washed with water, and dried under vacuum at about 110 ° C. A total of 12,008 g of dry material was recovered. By performing a heat treatment to a maximum temperature of about 950 ° C, in the presence of an atmosphere of (2% / 98%) (v / v) H2 / Ar for about 120 minutes, the sample lost approximately 12.6% of the weight.
EXAMPLE 14 Preparation of a catalyst with a nominal content of 3% Pt, 6% Cu in activated carbon. The following components were added in a septated beaker containing 10 g of activated carbon: 2,507 g of CuSO4-5H20 solution, 6,878 g of sucrose, 90 g of degassed deionized water and 6,974 g of 50% by weight NaOH. . The mixture was heated to 30 ° C and stirred for about 10 minutes with a mechanical stirrer. Then, 2.444 g of 37% formaldehyde was added and the suspension was heated to about 35-37 ° C, followed by a continuous agitation for 45 minutes. Subsequently, the suspension was filtered and washed twice in the filter, and then it was suspended again in water and the pH was brought up to 1.97 by the addition of 1 M degassed HCI. A solution of 0.700 g of K2PtCI4 was then added in 20 ml. g of degassed water to the suspension, followed by continuous agitation for 60 minutes under ambient conditions. Subsequently, the suspension was heated to 60 ° C and stirred for another 30 minutes. The suspension was filtered and washed with water, and dried under vacuum at about 110 ° C. A total of 1 1868 g of dry material was recovered. When performing a heat treatment up to a maximum temperature of about 950 ° C, in the presence of an atmosphere of (2% / 98%) (v / v) H2 / Ar for 120 minutes, the sample lost approximately 12.5% by weight .
EXAMPLE 15 (Higher content of platinum and higher temperature for the deposit of · ·;, ..; · platinum). ... ..
Preparation of a catalyst with a nominal content of 4% Pt, 8% Cu in activated carbon. The following components were added in a beaker with septa containing approximately 10 g of activated carbon: 3420 g of CuS04-5H20 solution, 9.375 g of sucrose, 100 g of degassed deionized water and 9.675 g of 50% NaOH in weight. The mixture was heated to 30 ° C and stirred for 10 minutes with a mechanical stirrer. Then, 3331 g of 37% formaldehyde were added and the resulting suspension was heated to about 30-35 ° C, followed by continuous agitation for 90 minutes. Subsequently, the suspension was filtered and washed once in the filter, and then it was suspended again in water and the pH was brought up to 1.97 by the addition of 1 M degassed HCI. Then a solution of 0.964 g of K2PtCI4 in 20 ml was added. g of degassed water to the suspension, followed by continuous agitation for 45 minutes at 45 ° C. Subsequently, the suspension was heated to 60 ° C and stirred another 45 minutes. The suspension was filtered and washed with water, and dried under vacuum at about 10 ° C. A total of 12,283 g of dry material was recovered. By performing a heat treatment to a maximum temperature of about 950 ° C, in the presence of an atmosphere of 2% / 98% (v / v) H2 / Ar for 120 minutes, the sample lost approximately 12.6% by weight.
EXAMPLE 16 (Procedure in a single container) Preparation of a catalyst with a nominal content of 2% Pt, 4% Cu in activated carbon. The following components were added in a beaker with partitions including 10 g of activated carbon: 1644 g of CuSO4-5H20 solution, 4509 g of sucrose, 90 g of. degassed deionized water and 4,715 g of 50% by weight NaOH. The The mixture was heated to 30 ° C and stirred for 10 minutes with a mechanical stirrer. Then 1.736 g of 37% formaldehyde was added and the suspension was heated to about 30-35 ° C, followed by continuous agitation for 90 minutes. Subsequently, the suspension was acidified to a pH of 2.98 by the addition of 1 M degassed HCl. Then, a solution of 0.454 g of J ^ PtCU in 10 g of degassed water was added to the suspension, followed by stirring Continues for 60 minutes under environmental conditions. Subsequently, the suspension was heated to 60 ° C and stirred for another 30 minutes. The suspension was filtered and washed with water, and dried under vacuum at about 110 ° C. A total of 11,864 g of dry material was recovered. When performing a heat treatment at approximately 950 ° C, in the presence of an atmosphere of (2% / 98%) (v / v) H2 / Ar for 120 minutes, the sample lost approximately 12.2% by weight.
EXAMPLE 17 Preparation of a catalyst with a nominal content of 2% Pt, 4% Cu in activated carbon. The following components were added in a septated beaker containing 10 g of activated carbon: 1,645 g of CuS04-5H20 solution, 4,509 g of sucrose, 90 g of degassed deionized water and 4,630 g of 50% by weight NaOH. . The mixture was heated to 30 ° C and stirred for 10 minutes with a stirrer mechanic. Then, 1.710 g of 37% formaldehyde was added and the suspension was heated to about 30-35 ° C, followed by continuous agitation for 90 minutes. Subsequently, the suspension was filtered and washed once in the filter, and then it was suspended again in water and the pH was brought up to 2.01 by the addition of 1 M degassed HCI. Then a solution of 0.570 g of H2PtCl6 was added in 15 ml. g of degassed water to the suspension, followed by continuous agitation for 60 minutes under ambient conditions. Subsequently, the suspension was heated to 60 ° C and stirred for another 30 minutes. The suspension was filtered and washed with water, and dried under vacuum at about 10 ° C.
EXAMPLE 18 Preparation of a catalyst with a nominal content of 2% Pt, 4% Cu in activated carbon. The following components were added in a septated beaker containing approximately 10 g of activated carbon: 1.644 g of CuSO4-5H2O solution, 4.517 g of sucrose, 70 g of degassed deionized water and 4.701 g of 50% NaOH. % in weigh. The mixture was heated to 30 ° C and stirred for about 10 minutes with a mechanical stirrer. Then, 1,705 g of 37% formaldehyde diluted to 17.10 g with degassed water was added, and the suspension was heated to about 30-35 ° C, followed by continuous agitation for 60 minutes. Subsequently, the The suspension was filtered and washed once in the filter, and then it was suspended again in water and the pH was brought up to 1.99 by the addition of 1 M degassed HCI. Then a solution of 0.460 g of K2PtCI4 in 10 g of water was added. degassed to the suspension, followed by continuous agitation for 60 minutes under ambient conditions. Subsequently, the suspension was heated to 60 ° C and stirred for another 30 minutes. It was filtered and washed with water, and dried under vacuum at about 110 ° C. A total of 11,203 g of dry material was recovered.
EXAMPLE 19 In this example, analysis of surface area (SA) and chemosorption of CO for catalysts with variable platinum and copper contents that were generally prepared in accordance with the conditions detailed in example 7 in this documentation are detailed. They were evaluated in an oxidation with PMIDA with. 10 cycles, generally. under the conditions detailed in example 7.
TABLE 6 TABLE 7 Figure 5C provides the porosity data for each of the catalysts evaluated.
EXAMPLE 20 In this example, surface area analysis (SA) and pore volume (PV) data are provided for a carbon support treated by contact with sucrose, generally in accordance with the method to be described below. The corresponding results are also provided for a catalyst with a nominal content of 2% Pt / 3.45% Cu / C, prepared using a treated carbon support, by contacting sucrose, generally as will be described below, together with the copper and platinum deposit, generally as described in example 12. The support impregnated with metal was not subjected to elevated temperatures.
A carbon support (10 g) was added to a mixture that included degassed H20 (approximately 100 g), sucrose (approximately 3.8 g), 1 M NaOH (approximately 6.15 g). To prepare the sucrose mixture, the sucrose was first added to the water, followed by the addition of NaOH, which was followed by the addition of about 1.9 g of a 37% by weight formaldehyde solution. After about 60 minutes at about 25 ° C, the mixture was acidified to a pH of about 4.8, by the addition of HCl 2. Then, the mixture was stirred for about 45 minutes at about 25 ° C, then it was filtered to isolate the support, and the latter was dried during about 10 hours in a vacuum oven at a temperature of approximately 1 10 ° C, in the presence of nitrogen. They got better about 1.5 g of treated support.
The surface area and volume of the pores of the catalyst and the treated support, generally as described by Wan et al. in International Publication No. WO 2006/031938. The results of the analysis of the surface area and the volume of the pores are detailed in the tables 8 and 9, respectively. In Figure 5D, the results of the volume of the pores.
TABLE 8 Saccharose Precursor carbon. 2% adsorbed Average description Pt / 3.45% Cu / C in the coal Langmuir SA (nVVg) 1499 957 954 graphic of the SA of the micropores (m2 / g) 1 193 727 726 SA of the meso-macropores (m2 / g) 293,184 222,314 219,061 20-40 175,666 136,964 133,600 40-80 77,937 58,165 58,144 80-150 25.781 17.608 17.651 150-400 1 1,205 7,676 7,743 400-1000 2,159 1,625 1,672 1000-2000 0.396 0.276 0.251 2000-3000 0.04 0.000 0.000 Total SA of the meso-macropores (m2 / g) 293,184 222,314 219,061 TABLE 9 As can be seen in these results, the reductions in the total surface area, the surface area of the micropores and the surface of the meso / macropores were approximately equivalent for the catalyst in which there was sucrose present in the bath for the deposit of copper and for the carbon support treated by contact with-sucrose alone. Based on these results, it is believed that a significant portion, but substantially all of the reduction in surface area for the finished catalyst, relative to the initial support, is based on the presence of sucrose in the bath for the copper deposit.
EXAMPLE 21 In this example, the results of the microscopy are detailed for the following samples: (1) a carbon support having a total Langmuir surface of approximately 1500 m2 / g (including a micropore surface area of approximately 1200 m2 / g and a meso / macropore surface area of approximately 300 m2 / g); (2) the carbon support of (1), which has a nominal copper content of about 3.45% by weight, deposited generally in accordance with example 12; (3) a catalyst with a nominal content of 2% Pt / 3.45% Cu / C including the support (1), prepared generally as described in example 12, but before heating it to elevated temperatures; (4) the catalyst with a nominal content of 2% Pt / 3.45% Cu / C of (3), after heating it at approximately. 950 ° C.
The microscopy analysis was generally performed as described in example 46.
Carbon support Figure 6 is a STEM micrograph of the surface of the carbon support.
Support impregnated with Cu Figures 7 and 8 are STEM micrographs of the surface of the support impregnated with Cu. From these results, it can be concluded that regions of Cu with an irregular morphology and size on the surface of the carbon support were deposited.
Support impregnated with Pt / Cu (before heat treatment) Figures 9-12 are micrographs of the support surface impregnated with Pt / Cu before treatment at elevated temperatures. From these results, it can be concluded that the Cu regions deposited on the surface of the carbon support that already had deposited Pt generally retained the irregular morphology and size of the deposited Cu regions.
In FIG. 13 a STEM micrograph is provided for a portion of the impregnated support. The portion indicated as "spectrum image" was subjected to an analysis. of linear sweep, whose results are shown in Figure 14. As can be seen, with the linear sweep analysis the presence of copper and platinum in the portion of the spectrum image is demonstrated.
Pt / Cu / C Catalyst (after heating) Figure 15 is a photomicrograph of STEM and Figure 16 is a high resolution TEM photomicrograph (HRTEM) of a portion of the Pt / Cu / C catalyst, after heating at elevated temperatures. In these figures a change in the morphology of the Pt / Cu regions is represented. From these results, it can be concluded that spherical particles were formed with sizes ranging from about 1 nm to about 15 nm.
Figures 17 and 18 are EDS spectra for particles of various sizes. As the particle size increases, the ratio between the copper atoms and the platinum atoms increases, from which it can be concluded that there is a relatively constant amount of platinum between the particles. At present, it is believed that the thickness of the platinum layer is relatively constant over a range of particle sizes.
Pt / Cu / C catalyst used in 3 cycles of reaction with PMIDA Figures 19-21 are STEM photomicrographs of a portion of a catalyst used in 3 cycles of reaction with PMIDA under the conditions described above. From these results, it can be concluded that there are stable particles present that have varying sizes, including sizes in the range of about 1-1.5 nm.
Figure 22 provides linear sweep analysis data for the portion of the catalyst surface indicated as "spectrum image" in Figure 21. Based on the detection of Cu throughout the spectrum image, where the content Higher copper is in the center of the particle, while the platinum signal is relatively low, it can be inferred that there is a relatively thin outer layer (ie, no more than 3 atoms thick) containing platinum. That is to say, as in the linear scan analyzes where an X-ray beam with a size of approximately 1 nm (10 A) was used, the presence of a layer containing platinum with a thickness not exceeding 3 platinum atoms can be inferred (the atomic size of platinum is 3Á).
Pt / Cu / C catalyst used in 30 reaction cycles with PMIDA These results correspond to the catalysts evaluated in 30 reaction cycles. The STEM photomicrographs of Figures 23 and 24 indicate the presence of stable particles with varying sizes, including sizes of approximately 1-1.5 nm. Figure 25 provides scan analysis data for the portion indicated as "spectrum image" in Figure 24. From these results, the presence of a relatively thin layer of platinum can also be inferred, since the signals from the Platinum and copper began to be detected at the same point with a beam of X-rays with a size of approximately 1 nm, which again allows inferring the presence of a layer containing platinum with a thickness of less than 1 nm (ie less of 3 platinum atoms).
In Figures 26 and 27, EDS spectra are provided for particles with sizes of approximately 2 nm and 9 nm. As can be seen, the percentage of copper atoms increased significantly with the particle size, including the presence of a copper-rich core.
EXAMPLE 22 In this example, the results of a microscopy analysis, performed in general as described in Example 46, are detailed for (1) a precursor catalyst with a nominal content of 2% Pt / 3.45% Cu / C, prepared as described in example 9, and (2) a catalyst with a nominal content of 2% Pt / 3.45% Cu / C, prepared from the precursor (1) (for example, by heating the precursor to a maximum temperature of approximately 950 ° C).
Figures 28 and 29 are TEM and STEM images of the precursor (1). In Figures 30-37 the TEM images and the corresponding scan data are provided for portions of the precursor surface. As can be seen with the linear scan, it was possible to detect platinum and copper in the particle.
Figures 38 and 39 are TEM and STEM images for the catalyst (2). In Figures 40 and 42 the portion of the surface of the catalyst analyzed with the linear sweep is illustrated, the results of which are illustrated in Figures 41 and 43, respectively. From the results of the linear sweep, the presence of platinum in the particles can be inferred.
EXAMPLE 23 In this example, an analysis of the particle size distribution is provided for a catalyst with a nominal content of 2% Pt / 3.45% Cu / C, prepared as described in example 9. Fifteen images of the type were used. illustrated in Figures 44 and 45 to determine the size of a total of 1177 particles. The size distribution of the measured particles is illustrated in Figure 46. In this example, an analysis of the particle size distribution for the catalyst is also provided, after using it in an oxidation with PMIDA during 4 reaction cycles, under the conditions described in example 7. Fourteen images of the type illustrated in figures 47 and 48 were used to determine the size of 1319 particles. The size distribution of the measured particles is illustrated in Figure 49.
EXAMPLE 24 In this example, the X-ray diffraction results are provided for a catalyst with a nominal content of 2% Pt / 3.45% Cu / C, prepared as described in example 12.
In FIGS. 50 and 51 the diffraction results are provided for a surface area of the catalyst having a diameter of about 1 μ ??, where the diffraction was measured using diffraction electronics in selected areas (SAED). Based on the generation of FCC indices (face-centered cubic) (ie, the results indicated as 1 13, 022, 002 and 1 1 1) and primitive cubic indexes (ie, the results indicated as 300, 221 , 310 and 210), and from the results of SAED, the presence of a CuPt alloy phase (probably Cu3Pt) can be inferred. From the results, the presence of a metallic copper phase can also be inferred.
In figures 52 and 53 the results of the nanodifraction of a single particle on the surface of the support are provided. The results of the nanodifraction are obtained by focusing an X-ray beam having a diameter of about 50 nm on a portion of the surface of the catalyst. From the results obtained from the generation of primitive cubic indices (ie, 010, 100 and 01-1), the presence of a CuPt alloy phase (probably Cu3Pt) can also be inferred. The indices indicated as 200 and 1 1-1 are believed to constitute evidence of the presence of a Cu phase, an Rt phase, or additional evidence of a CuPt alloy phase. Figures 54 and 55 show the results of the nanodifraction (the portions enclosed in circles), from which the presence of a metallic copper phase can be inferred.
In the following Examples 25-42, data is provided on the evaluation of a reaction with various catalysts generally prepared as described in Examples 8-18. Various parameters were modified (for example, metal loading, temperature metal deposit and heat treatment) to determine the effect, if any, on catalyst performance. Unless specifically indicated otherwise, the metal impregnated support was heated to a maximum temperature of about 955 ° C, in the presence of a hydrogen (2%) / argon atmosphere. The catalysts were generally evaluated in an oxidation with PMIDA, under the conditions detailed in example 7.
EXAMPLE 25 Catalysts: (1) 2.5% Pt / 10% Cu, (2) 2.5% Pt / 20% Cu, (3) 2.5% Pt / 7.5% Cu and (4) 5% Pt / 0.1 % Fe / 0.4% Co (nominal compositions).
Figure 56 provides data on the duration of each of (1) - (4), for the nine reaction cycles.
In figure 57 it is. provide data for the platinum capture for (1) and (2), for each of the nine reaction cycles.
EXAMPLE 26 Catalysts: (1) 2.5% Pt / 7.5% Cu, (2) 2.5% Pt / 5% Cu, (3) 5% Pt / 0.1% Fe / 0.4% Co and (4) 720 ° C / 2.5% Pt / 10% Cu (nominal compositions).
Figure 58 provides data on the duration of each of (1) - (4) for the nine reaction cycles.
EXAMPLE 27 Catalysts: (1) 2.5% Pt / 10% Cu and (2) 720 ° C / 2.5% Pt / 10% Cu (nominal compositions).
Each catalyst was evaluated in 10 reaction cycles.
Figure 59 provides data on the duration of the cycles. Figure 60 provides data on the IDA generation.
Figures 61 and 62 provide the residual formaldehyde and formic acid concentration, respectively.
Table 10 provides a comparison of the platinum capture for the two catalysts. As can be seen, less platinum was captured with the catalyst prepared with a process that included heat treatment at 720 ° C. ... ..
TABLE 10 EXAMPLE 28 Catalysts: (1) 2.5% Pt / 7.5% Cu, (2) 815 ° C / 2.5% Pt / 7.5% Cu and (3) 5% Pt / 0.1% Fe / 0.4% Co ( nominal compositions). Each catalyst was evaluated in nine reaction cycles.
Figure 63 provides data on the duration of the cycles of each of (1) - (3) · Figures 64 and 65 provide the residual formaldehyde and formic acid concentration, respectively, for each of (1) - (3).
EXAMPLE 29 Catalysts: (1) 815 ° C / 2.5% Pt / 7.5% Cu, (2) 815 ° C / 2.5% Pt / 7.5% Cu and (3) 5% Pt / 0.1% Fe / 0.4 % Co (nominal compositions). Each catalyst was evaluated in nine reaction cycles.
Figure 66 provides data on the duration of the cycles for each of (1) - (3).
Figures 67 and 68 provide the residual formaldehyde and formic acid concentration, respectively, for each of (D- (3).
EXAMPLE 30 Catalysts: (1) 815 ° C / 2.5% Pt / 7.5% Cu, (2) 815 ° C / 2.5% of ... Pt / 5% Cu, (3). 5 of. Pt / 0.1% Fe / 0.4% de, or (4). 815 ° C / 2.5% Pt / 3% Cu (nominal compositions). Each catalyst was evaluated in ten reaction cycles.
Figure 69 provides the results of the IDA generation for each of (1) - (4).
In Figures 70 and 71 the residual formaldehyde and formic acid concentration, respectively, is provided for each of (1) - (4).
EXAMPLE 31 Catalysts: (1) 815 ° C / 2.5% Pt / 5% Cu, (2) 715 ° C / 2.5% Pt / 5% Cu, (3) 615 ° C / 2.5% Pt / 5% of Cu, and (4) 5% Pt / 0.1% Fe / 0.4% Co (nominal compositions). Each catalyst was evaluated in ten reaction cycles and various parameters were compiled for nine or each of the ten reaction cycles.
In figure 72 the results of the duration of the cycles are provided.
The residual formaldehyde and formic acid concentration, respectively, are provided in Figures 73 and 74.
Figure 75 provides the results of the platinum capture.
Figure 76 provides the results of the IDA generation.
In figure 77 it is. provide the results of the generation of NMG Figure 78 provides the results of the generation of C02 total.
Catalysts: (1) 915 ° C / 2% Pt / 4% Cu (heated in an atmosphere containing hydrogen, ie reduced), (2) 910 ° C / 2% Pt / 4% Cu ( heated in an inert atmosphere, ie, calcined) and (3) 5% Pt / 0.1% Fe / 0.4% Co (nominal compositions). Each catalyst was evaluated in nine reaction cycles.
As can be seen in figure 79, the duration of the cycles was similar for each of (1) - (3), but the duration of the cycles for the catalyst (3) was slightly longer than for cycles 3 to 8.
In figure 80 the results of formaldehyde generation are provided.
In figure 81 the results of the generation of formic acid are provided.
As can be seen in Figure 82, the IDA generation was substantially equivalent for each catalyst. during cycles 3 to 9.
From the results illustrated in Figure 83, it can be concluded that there was a reduced NMG generation for each of the catalysts with 2% Pt, compared to the catalyst with 5% Pt.
Figure 84 provides results of the generation of total CO2.
EXAMPLE 33 In this example, the results of the platinum capture for the following catalysts are provided: (1) 815 ° C / 2.5% Pt / 5% Cu, (2) 815 ° C / 2.5% Pt / 3% Cu, (3) 910 ° C / 2% Pt / 4% Cu, (4) 908 ° C / 2% Pt / 3.6% Cu and (5) 975 ° C / 2% Pt / 3.6% of Cu (nominal compositions). The results are illustrated in figure 85.
EXAMPLE 34 In this example, the results of the evaluation of catalysts are provided for which the copper deposition temperature was altered by approximately 10 ° C (approximately 25 ° C and approximately 35 ° C), while the heat treatment after the deposit of platinum was substantially similar.
Catalysts:. (1) 970 ° C / 2% t / 3.45% Cu / 35 ° C and (2) 965 ° C / 2% Pt / 3.45% Cu / 25 ° C (nominal compositions).
As can be seen in Figures 86 and 87, the generation of formaldehyde and formic acid was slightly lower for the catalyst prepared after the copper bath at higher temperature.
From the results illustrated in Figure 88, it can be concluded that there is a higher initial generation of IDA for the catalyst prepared with the copper bath at higher temperature, but they are obtained Similar results for each catalyst from the third cycle.
As can be seen in Figure 89, the platinum capture was lower for the catalyst prepared with the copper bath at lower temperature, and in Figure 90 the initial reduced copper capture for the catalyst prepared with the copper bath is illustrated. lower temperature.
EXAMPLE 35 In this example, the results of an oxidation evaluation with extended PMIDA for 30 reaction cycles are provided.
The catalysts evaluated included (1) a catalyst with a nominal content of 2% Pt / 3.45% Cu / C prepared as described in example 12; (2) 5% Pt / 0.1% Fe / 0.4% Co; (3) a catalyst with a nominal content of 2% Pt / 3.45% Cu / C prepared as described in example 16; .. (4) a catalyst of 5% Pt / 0.5% Fe.
As can be seen in Figures 91-94, the duration of the cycles, the generation of total C02, the generation of formaldehyde and the generation of formic acid were substantially similar for each of (1) - (4). The catalyst loading was constant for each catalyst. Therefore, when using the catalysts (1) and (3), similar results were obtained with reduced platinum charges, in comparison with the catalysts (2) and (4).
Figure 95 provides the data for the capture of Cu and Fe for the catalysts (1), (3) and (4).
EXAMPLE 36 In this example, oxidation results with PMIDA are provided for catalysts prepared with varying calcination temperatures and varying copper contents. Catalysts: (1) 908 ° C / 2% Pt / 3.6% Cu, (2) 975 ° C / 2% Pt / 3.6% Cu, (3) 910 ° C / 2% Pt / 4% of Cu and (4) 970 ° C / 2% Pt / 3.45% Cu (nominal compositions).
Figure 96 provides the results of the generation of GOING.
In Figures 97 and 98 substantially similar results are provided for the generation of formaldehyde and formic acid.
EXAMPLE 37 In this example, evaluation data are provided in a reactor of catalysts of 2% Pt / 4% Cu / C prepared generally as described in example 1 1. Each catalyst was evaluated in 9 cycles of reaction with PMIDA.
A catalyst was prepared by heating the impregnated support with metal up to a maximum temperature of about 950 ° C in the presence of an inert argon atmosphere. A second catalyst was prepared by subjecting it to a maximum temperature of about 950 ° C, in the presence of a hydrogen / argon atmosphere (2% / 98%) (v / v).
Table 1 1 provides the data for the duration of the cycles and the generation of C02 for the two catalysts. The duration of the cycles for each catalyst is illustrated in Figure 99.
TABLE 11 EXAMPLE 38 In this example, the evaluation data are provided in a reactor for a catalyst of 2% Pt / 4% Cu / C and a support impregnated with metal (precursor) of 2% Pt / 4% Cu / C prepared generally as described in example 11. Catalyst and support impregnated with metal were evaluated in 4 cycles of reaction with PMIDA. The catalyst was prepared by subjecting a support impregnated with metal at a maximum temperature of about 950 ° C, in the presence of a hydrogen / argon atmosphere (2% / 98%) (v / v).
Table 12 provides the data on the duration of the cycles and the generation of C02 for the catalyst and the metal impregnated support. The duration of the cycles for each catalyst is illustrated in Figure 100.
TABLE 12 EXAMPLE 39 In this example, a comparison of 2% Pt / 4% Cu / C catalysts prepared using different platinum sources is provided. Each catalyst was generally prepared as described in Example 11, including heating a metal impregnated backing to a maximum temperature of about 950 ° C. The platinum was deposited by means of a displacement deposit, on copper impregnated supports, using the following platinum sources: (1) K2PtCI4 (ie, Pt + 2 ions) and (2) H2PtCI6 H20 (ie, Pt ions) +4) Table 13 provides the data on the duration of the cycles, the generation of C02 and the difference in activity (based on the duration of the cycles) for each catalyst in 9 reaction cycles. Figures 101 and 102 provide data on the duration of the cycles and the difference in activity.
TABLE 13 EXAMPLE 40 In this example, data for the chemosorption of CO (ie the platinum density at the site) are provided for catalysts with different platinum contents prepared generally as described in examples 8, 11, 14 and 15. In the Table 14 provides chemosorption of CO (generally determined in accordance with the method described in example 67) and in figure 103 a representation of the platinum load is given as a function of the platinum density at the site. The catalysts were evaluated in an oxidation with PMIDA during 10 cycles of reaction, before the analysis of chemosorption of CO.
TABLE 14 With these results, it is shown that there is a linear relationship between the platinum load and the density at the site. Based on these results, it is currently believed that a significant portion of the platinum incorporated in the catalyst is present in the form of a relatively thin layer. On the other hand, a non-linear relationship between platinum loading and site density has been observed for conventional platinum-containing catalysts. It is believed that this is due to the fact that a larger portion of the platinum is distributed in the metal particles. Thus, beyond a certain level of platinum, the density of the platinum loading site does not increase, since the portion of platinum distributed in the particles does not contribute to the surface area of the exposed platinum.
EXAMPLE 41 Catalysts having nominal metal contents of approximately 2% Pt and 4% Cu were prepared, generally as described in Examples 11 and 12. The bath for depositing the metal was kept under a nitrogen atmosphere during the deposition of copper . Figure 104 illustrates the results of a reaction where the Pt / Cu catalysts were compared with a catalyst of 5% Pt / 0.5% Fe. As can be seen, all catalysts showed comparable activities.
EXAMPLE 42 In this example, a reaction is detailed to evaluate catalysts with a nominal content of 3% Pt / 6% Cu, prepared as described in example 14, with various catalyst loads. One catalyst was evaluated with a load of approximately 0.25 g and another was evaluated with a load of approximately 0.17 g. The performance of each catalyst was compared with that of a 5% Pt / 0.5% Fe catalyst, generally prepared as described in the U.S. Patent. No. 6417133, with a load of 0.25 g. The total charges of catalyst and platinum are summarized in Table 15. The results of the generation of total CO2 and the results of the duration of the cycles are illustrated in figures 105 and 106, respectively. From these results and in comparison with the catalyst of 5% Pt / 0.5% Fe, it can be concluded that the catalyst with 3% Pt exhibited an improved activity with an equivalent catalyst load, and an activity at least comparable with a reduced catalyst load. Therefore, the catalysts with 3% Pt of the present invention, or other similar catalysts, can be used to obtain an improvement in catalyst activity or a reduction in working metal capital.
TABLE 15 III. Additional forms of realization Preparation of disodioiminodiacetic acid (DSIDA) EXAMPLE 43 In this example, the analysis and evaluation of (1) a catalyst containing palladium and copper with a carbon support (CuPdC) of the type described in US Patents is detailed. No. 5916840, 5689000 and / or 5627125, and (2) a CuPdC catalyst prepared as described in U.S. Patents. No. 5916840, 5689000 and / or 5627125 which was treated by contact with a mixture containing 1,4-cyclohexane dione and ethylene glycol, as described in Example 1 (mechanism 2).
The treated and untreated catalysts were analyzed to determine their Langmuir surface areas and provide comparisons of the surface areas of the micropores and macropores, before and after the treatment.
TABLE 16 As can be seen in Table 16, the catalyst treatment resulted in a 75% reduction in the surface area of the micropores of the catalyst, while providing a reduction in the surface area of the macropores of less than 20% (i.e. a reduction preferential in the surface area of the micropores approximately 4 times greater than the reduction in the surface area of the macropores).
The conversion of diethanolamine to disodioiminodiacetic acid in the treated and untreated catalysts was also evaluated. Mixtures were heated including water, the catalyst (original or modified) (2% by weight), diethanolamine (1.8% by weight), sodium hydroxide (2.4% by weight) and disodioiminodiacetic (DSIDA) (12.5% by weight) a temperatures that varied between 150 and 160 ° C, in the course of 5 hours and under a pressure of approximately 9.49 kg / cm2 gauge. These conditions were selected to determine the performance of the modified and unmodified catalysts in relation to the formation of oxalate and glycine. The results are illustrated in Figure 107. The modified catalyst resulted in a reduction of approximately 8-10 times in the formation of oxalate and an approximately 4-fold reduction in glycine formation. From these results, it can be inferred that the modified catalyst resulted in the exposure of less noble metal, and it is believed that this contributed to the formation of glycine and oxalate.
EXAMPLE 44 In this example, the evaluation of catalysts containing palladium and copper with carbon supports (CuPdC) in the preparation of DSIDA by dehydrogenation of DEA is detailed. The catalysts are prepared as described in US Pat. No. 5916840, 5689000 and / or 5627125, and were generally evaluated under the conditions described in said publications. Two CuPdC catalysts were prepared in accordance with the method described in one or more of these patents. Each catalyst was prepared so as to include 24% by weight of Cu. A catalyst was prepared using an untreated carbon support, and this resulted in a catalyst that included 3% by weight of Pd (ie, 24% Cu / 3% Pd / C). The second catalyst was prepared using a carbon support treated in accordance with the present method, as described in Example 1, by contacting 1,4-CHDM. This resulted in a catalyst that included approximately 2.4% by weight of Pd (ie, 24% Cu / 2.4% Pd / C). Accordingly, it is believed that the use of the modified support resulted in the deposit of palladium.
Each catalyst was evaluated in the conversion of DEA to DSIDA, generally in accordance with the conditions detailed in the Patents of E.ILA..N0 591.6840, 5689000 and / or 5627125. The results are illustrated in figure 108 and Table 17 As can be seen in Fig. 108, from the second cycle, the duration of the cycles was reduced for the catalyst that included 2.4% of Pd in the treated carbon support. That is, the use of a catalyst prepared using the treated carbon support resulted in an increase in activity of approximately 15-20% for the lower noble metal content.
TABLE 17 As can be seen in table 17, the use of the catalyst with 2.4% Pd on the modified carbon support resulted in a lower generation of oxalic acid and a lower generation of glycine, compared to the catalyst with 3% Pd on the unmodified carbon support (for example, an improvement in the selectivities by oxalic acid and glycine of approximately 15% and 25%, respectively).
IV. Platinum-Iron EXAMPLE 45 This example details the preparation of a catalyst having a nominal platinum content of 2% by weight and a nominal iron content of 4% by weight on an activated carbon support having an area Langmuir surface area of approximately 1500 m2 / g. The following preparation was obtained under nitrogen protection.
Activated carbon (approximately 10,458 g) was mixed with degassed water (approximately 90 g) in a baffle beaker under a nitrogen atmosphere. FeCl 3 »H 2 O (2,007 g) was dissolved in degassed water (40 g) and this solution was pumped into the beaker with a baffle over a period of one hour. The pH of the aqueous paste inside the beaker with baffle was maintained at 4 by introduction of degassed NaOH 2.5 N, according to need. After the addition of the FeC solution was complete, the pH of the aqueous slurry was raised to about 4.5 and the slurry was allowed to mix at room temperature for about 15 minutes. The aqueous paste was then heated to a temperature of about 60 ° C over a period of about 48 minutes, during which time the pH of the aqueous paste was maintained at about 4.5 by the addition of 2.5 N NaOH.
The pH of the aqueous slurry was then raised to about 10.5 over a period of about 30 minutes at a temperature of about 60 ° C, and at a rate of 0.5 pH units per 5 minutes. After adjusting the pH, the aqueous paste was allowed to mix for approximately 10 minutes.
Sodium borohydride (NaBH4) (about 0.686 g) was dissolved in degassed water (approximately 20 g); HE they added seven drops of 2.5 N degassed NaOH to stabilize the NaBH4 solution, and the resulting NaBH4 solution was introduced into the deflector beaker at about 60 ° C over a period of 20 minutes. The aqueous paste was then allowed to mix for another ten minutes at about 60 ° C. The aqueous paste was then filtered and the wet cake was redissolved to re-form an aqueous paste in the beaker with deflector in deionized degassed water (90 g approximately). The pH of the resulting aqueous paste was then lowered to about 5 by introduction of 2 M degassed HCI.
K2PtCI4 (about 0.456 g) was dissolved in degassed water (about 20 g) and the resulting Pt solution was then added to the baffle beaker over a period of three minutes. Then, the resulting aqueous paste was allowed to mix under ambient conditions (about 22 ° C) for about 60 minutes, and then it was heated to a final temperature of 65 ° C over a period of 30 minutes, and then allowed mix at 60 ° C. The resulting aqueous paste was then filtered and washed twice by contact with degassed water (approximately 100 g) at a temperature of about 65 ° C. The washed sample was then dried in a vacuum oven at about 110 ° C for about 12 hours with a small flow of nitrogen to form a precursor of the Pt / Fe catalyst.
The catalyst precursor was then heated to elevated temperatures of up to about 900 ° C in the presence of a flow of hydrogen / argon (2% / 98%; v / v) for approximately 120 minutes.
The 2% Pt / 4% Fe finished catalyst was evaluated in a PMIDA oxidation under the conditions indicated in Example 7. An inductively coupled plasma (ICP) analysis was used to determine platinum and iron leached from the catalyst and present in the reaction mixture. The ICP analysis was conducted using an inductively coupled mass-plasma spectrometer VG PQ ExCelda (ICP-MS) (commercially available from Thermo Jarrell Ash Corp., Thermo Elemental, Franklin, MA). The results are shown in table 18.
Figure 109 provides the results of the XRD analysis (which was conducted as indicated in example 69) for the finished catalyst (i.e., before the reactor test).
TABLE 18 EXAMPLE 46 This example details the preparation of a catalyst having a nominal platinum content of 2% by weight and a nominal iron content of 4% by weight on an activated carbon support having a Langmuir surface area of approximately 1500 m2 / g . The following preparation was obtained under nitrogen protection.
Activated carbon (approximately 10,455 g) was mixed with degassed water (approximately 90 g) in a baffle beaker under a nitrogen atmosphere. Fe2 (SO4) 3 * H2O (2990 g) was dissolved in degassed water (40 g) and this solution was pumped into the beaker with a deflector over a period of one hour. The pH of the aqueous paste within the deflector beaker was maintained at 4 by introduction of 2.5 N degassed NaOH, as needed.
The mixing of the components of the aqueous paste into the baffle beaker took place for a total of about 20 minutes at a pH value of about 4. The pH of the aqueous paste was then raised to 4.5 by the addition of NaOH. The aqueous paste was then heated to a temperature of about 60 ° C over a period of 30 minutes. During the heating, the pH was maintained at 4.5 by introduction of 2.5 N degassed NaOH (as needed). At this elevated temperature, the pH of the slurry was raised to about 6.5 over a period of 20 minutes, by increments in the pH at a rate of approximately 0.5 pH units per 5 minutes.
Sodium borohydride (NaBH) (approximately 0.681 g) was dissolved in degassed water (approximately 20 g) and then pumped into the deflector beaker at approximately 60 ° C over a period of 20 minutes. The aqueous paste was then allowed to mix for another ten minutes at 60 ° C. The aqueous paste was then cooled to 45 ° C and then filtered. The wet cake was resuspended to form an aqueous slurry in beaker with deflector using deionized degassed water (90 g). The pH of the resulting aqueous paste was then lowered to about 5 by introduction of 2 M degassed HCI.
K2PtCI4 (0.460 g approximately) was dissolved in degassed water (approximately 20 g) and the resulting Pt solution was then added to the deflector beaker over a period of five minutes. Then, the resulting aqueous paste was allowed to mix - - ... under ambient conditions (about 22 ° C) for about 60 minutes, then heated to a final temperature of 65 ° C over a period of 30 minutes, and finally allowed to mix at 65 ° C for another 10 minutes. The resulting aqueous paste was then filtered and washed twice by contact with degassed water (approximately 100 g) at a temperature of about 65 ° C. The washed sample was then dried in a vacuum oven at approximately 10 ° C for 12 hours. hours with a small flow of nitrogen to form a precursor of the Pt / Fe catalyst.
The catalyst precursor was then heated to elevated temperatures of up to about 900 ° C in the presence of a flow of hydrogen / argon (2% / 98% v / v) for about 120 minutes.
Table 19 shows the results of an evaluation of the reactivity with PMIDA, the platinum leaching data and the iron leaching data for the finished catalyst of 2% Pt / 4% Fe.
TABLE 19 EXAMPLE 47 This example provides the results of an X-ray diffraction analysis (XRD) for the catalyst prepared as described in example 46. The XRD analysis was conducted as indicated in example 69.
The results are shown in Figures 1 10 and 1 1 1. These results indicate the presence of a bimetallic FeaPt alloy.
EXAMPLE 48 This example details the preparation of a catalyst having a nominal Pt content of 2% by weight and a nominal iron content of 4% by weight on an activated carbon support having a Langmuir surface area of approximately 1500 m2 / g . The following preparation was obtained under nitrogen protection.
Activated carbon (approximately 10,455 g) was mixed with degassed water (approximately 90 g) in a baffle beaker under a nitrogen atmosphere.
FeCl3"6H2O (2,009 g approximately) was dissolved in degassed water (40 g) and this solution was pumped into the beaker with a baffle over a period of one hour. The pH of the aqueous paste inside the beaker with baffle was maintained at 4 by introduction of NaOH 2.5 N degassed, according to need. After the addition of the FeCl3 »6H20 solution to the beaker was completed, the pH of the aqueous paste was raised to about 4.5 by addition of NaOH and the aqueous paste was allowed to mix under ambient conditions (about 22 ° C) for approximately 20 minutes.
The aqueous paste was then heated to a temperature of about 60 ° C over a period of about 50 minutes. During heating, the pH was maintained at 4.5 by the addition of 2.5 N degassed NaOH. At this elevated temperature, the pH of the aqueous slurry was raised to about 10.5 over a period of 30 minutes, by increases in pH at a rate of approximately 0.5 pH units for every 5 minutes.
Sodium borohydride (NaBH4) (approximately 0.69 g) was dissolved in degassed water (approximately 20 g); 7 drops of 2.5N NaOH were added to stabilize the NaBH4 solution. Next, the sodium borohydride solution was pumped into the deflector beaker at approximately 60 ° C over a period of 20 minutes. The aqueous paste was then filtered and the wet cake was resuspended to form an aqueous slurry in the beaker with degassed degassed water baffle (90 g). The pH of the resulting aqueous paste was then lowered to about 5 by introduction of 2 M degassed HCI.
K2PtCI4 (0.460 g approximately) was dissolved in water degassed (approximately 20 g) and the resulting Pt solution was then added to the baffle beaker over a period of three minutes. Then, the resulting aqueous paste was allowed to mix under ambient conditions (about 22 ° C) for about 60 minutes and then heated to a final temperature of about 65 ° C.
The resulting aqueous paste was then filtered and washed twice by contact with degassed water (approximately 100 g) at a temperature of about 65 ° C. The washed sample was then dried in a vacuum oven at about 110 ° C for about 12 hours with a small flow of nitrogen to form a precursor of the Pt / Fe catalyst.
The catalyst precursor was then heated to elevated temperatures of up to about 900 ° C in the presence of a flow of hydrogen / argon (2% / 98%; v / v) for about 120 minutes.
., ... ., In. Table 20 are shown - the results of an evaluation. . of the reactivity with PMIDA, the platinum leaching data and the iron leaching data for the finished catalyst of 2% Pt / 4% Fe.
TABLE 20 Figure 1 1 1 A includes the platinum leach data for the catalysts of Examples 46 and 48, as compared to a 5% Pt / 0.5% Fe (Reference) catalyst prepared as described in Wan et al., in International Publication No. WO 2006/031938.
EXAMPLE 49 The following preparation was carried out under nitrogen protection.
Activated charcoal (approximately 10.456 g) and degassed water (approximately 90 g) were placed in a beaker with baffles and allowed to mix for 20 minutes. FeCl3 * 6H20 (2,009 g) was dissolved in degassed water (approximately 40 g) and this solution was pumped into the beaker with baffles over a period of 30 minutes while maintaining the pH of the aqueous paste at 4 minutes. by adding 2.5 N NaOH. After the addition of the FeCl3 «6H2O solution, the pH was raised to 4.5 and it was left to mix for 10 minutes. The aqueous paste was then heated to about 50 ° C over a period of 30 minutes, while maintaining the pH at pH 4.5. The pH of the aqueous paste was then raised to 8 over a period of 15 minutes, and allowed to mix for about 10 minutes. Then ethylene glycol (approximately 1386 g) was added to the aqueous paste, and allowed to mix at about 60 ° C for about 20 minutes.
After the mixture was completed, the aqueous paste was allowed to cool to 30 ° C.
Then the pH of the solution was lowered to 5 by adding degassed 0.5 M HCl. K2PtCI4 (0.460 g) was dissolved in degassed water (20 g). The Pt solution was then added to the beaker with deflectors over a period of three minutes. The aqueous paste was then allowed to mix under ambient conditions (about 22 ° C) at room temperature for 30 minutes, and then heated to a temperature of 60 ° C over a period of 10 minutes.
The aqueous paste was then filtered, and the wet cake was washed twice hot at 60 ° C with about 100 ml degassed water. The resulting sample was then dried in a vacuum oven at 1 10 ° C for 12 hours with a small stream of nitrogen.
EXAMPLE 50 The following preparation was carried out under nitrogen protection.
Activated carbon (10456 g) and degassed water (approximately 90 g) were placed in a beaker with baffles and left to mix for 20 minutes. FeCl3 »6H20 (2.011 g) was dissolved in degassed water (approximately 40 g) and this solution was pumped into the beaker with deflectors over a period of 34 minutes. while maintaining the pH of the aqueous paste in 4 by adding 2.5 N NaOH.
After the complete addition of the FeCI3 »6H2O solution, the pH was raised to 4.5, and it was left to mix for 10 minutes. The aqueous paste was then heated to about 60 ° C over a period of 34 minutes, while maintaining the pH at 4.5. The pH of the aqueous pulp was then raised to 1 1 over a period of 30 minutes, and then allowed to mix for 10 minutes. Then ethylene glycol (1385 g) was added to the aqueous paste, and allowed to mix at 60 ° C for about 10 minutes.
The pH of the solution was then lowered to 5 by adding degassed 1 M HCl. K2PtCI4 (0.459 g) was dissolved in degassed water (20 g). The Pt solution was then added to the beaker with deflectors over a period of three minutes. The aqueous paste was then allowed to mix under ambient conditions (about 22 ° C) for 30 minutes, and then heated to a temperature of about 60 ° C over a period of 10 minutes.
The aqueous paste was then filtered, and the wet cake was washed twice hot at 60 ° C with about 100 ml degassed water. The resulting sample was then dried in a vacuum oven at 110 ° C for 12 hours with a small stream of nitrogen.
Four catalysts of 2% Pt / 4% Fe were prepared from a precursor which was prepared as already described, which was heated to elevated temperatures in the presence of a hydrogen / argon stream (4% / 96%; v / v) for about 120 minutes. The maximum heating temperatures were: (1) 900 ° C; (2) 750 ° C; (3) 650 ° C; (4) 550 ° C.
Figure 1 12 provides results of an XRD analysis of the catalyst (1); these results indicate the presence of a Fe3Pt phase.
Figure 1 13 provides results of XRD analysis of the catalyst (2); these results indicate the presence of a Fe3Pt phase.
Figure 14 provides XRD analysis results of the catalyst (3); these results indicate the presence of a Fe3Pt phase.
Figure 1 15 provides results of XRD analysis of the catalyst (4); these results indicate the presence of a phase of FePt. ..., - ._ · .. The reaction test data, platinum leaching data, and iron leaching data for the catalyst 900 ° C / 2% Pt / 4% Fe are reported in table 21.
TABLE 21 Reaction test data, platinum leach data, and iron leaching data for the 750 ° C / 2% Pt / 4% Fe catalyst are reported in Table 22.
TABLE 22 Reaction test data, platinum leaching data, and iron leaching data for the 650 ° C / 2% Pt / 4% Fe catalyst are reported in Table 23.
TABLE 23 Reaction test data, platinum leaching data, and iron leaching data for the 550 ° C / 2% Pt / 4% Fe catalyst are reported in Table 24.
TABLE 24 EXAMPLE 51 The following preparation was carried out under nitrogen protection.
Activated charcoal (approximately 10,456 g) and degassed water (approximately 90 g) were placed in a beaker with baffles and allowed to mix for approximately 20 minutes.
FeCl3 »6H20 (2,009 g) was dissolved in degassed water (approximately 40 g) and this solution was then pumped into the beaker with baffles over a period of 30 minutes while maintaining the pH of the aqueous slurry. 4 by adding 2.5 N NaOH. After the complete addition of the FeCl3 solution »6H2O, the pH was raised to 4.5 and the aqueous paste was allowed to mix for 10 minutes. The aqueous paste was then heated at 60 ° C over a period of 30 minutes, while maintaining the pH at pH 4.5. The pH of the aqueous paste was then raised to 6.5 over a period of 10 minutes, and allowed to mix for 10 minutes. Then ethylene glycol (approximately 1384 g) was added to the aqueous paste, and allowed to mix at about 60 ° C for about 10 minutes. The aqueous paste was then filtered, and then a new aqueous paste was formed with the wet cake in degassed deionized water (90 g) and introduced into the beaker with baffles.
Then the pH of the solution was decreased to 5 by adding HCI 1 M degassed (0.841 g). K2PtCI4 (0.459 g) was dissolved in degassed water (20 ml). The resulting Pt solution was then added to the beaker with deflectors over a period of three minutes. The aqueous paste was then allowed to mix under ambient conditions (about 22 ° C) for 30 minutes, and then heated to a temperature of 60 ° C over a period of 10 minutes.
The slurry was filtered, and the wet cake was washed twice hot at 60 ° C with about 100 ml of degassed water. The resulting sample was then dried in a vacuum oven at 110 ° C for 12 hours with a small stream of nitrogen.
The catalyst precursor was then heated at elevated temperatures to about 755 ° C in the presence of a hydrogen / argon stream (4% / 96%; v / v) for about 120 minutes.
EXAMPLE 52 The following preparation was carried out under nitrogen protection.
Activated charcoal (approximately 10.456 g) and degassed water (approximately 90 g) were placed in a beaker with baffles and allowed to mix for 20 minutes. FeCl3 * 6H2O (2.411 g) was dissolved in degassed water (approximately 41 g) and this solution was then pumped into the beaker with deflectors along a 30 minute period while maintaining the pH of the aqueous paste at 4 by adding 2.5 N NaOH. After the complete addition of the FeC ^ h ^ O solution, the pH was raised to 4.5, and allowed to mix for 10 minutes. minutes The aqueous paste was then heated at 60 ° C over a period of 25 minutes while maintaining the pH at pH 4.5. The pH of the aqueous pulp was then raised to 1 1 over a period of 30 minutes, and then allowed to mix for 10 minutes.
Then ethylene glycol (1382 g) was added to the aqueous paste, and allowed to mix at about 60 ° C for about ten minutes. The aqueous paste was then filtered, and then a new aqueous paste was formed with the wet cake in degassed deionized water (90 g) and introduced into the beaker with baffles.
The pH of the solution was then lowered to 5 by adding degassed 1 M HCl degassed (3.7 g). K2PtCI4 (0.552 g) was dissolved in degassed water (20 g) and the Pt solution was introduced into the beaker with baffles over a period of three. minutes The aqueous paste was then allowed to mix under ambient conditions (about 22 ° C) for 30 minutes and then heated to a temperature of 60 ° C over a period of 10 minutes.
The aqueous paste was then filtered, and the wet cake was washed twice hot at 60 ° C with about 100 ml degassed water. The sample was then dried in a vacuum oven at 1 10 ° C for 12 hours with a small stream of nitrogen.
The catalyst precursor was then heated at elevated temperatures to about 650 ° C in the presence of a hydrogen / argon stream (4% / 96%; v / v) for about 120 minutes.
BOX 24A EXAMPLE 53 The following preparation was carried out under nitrogen protection.
Activated carbon (10.456 g) and degassed water were placed (approximately 90 g) in a beaker with deflectors and left to mix for 20 minutes. FeCl3"6H20 (2,009 g) was dissolved in degassed water (approximately 41 g) and the resulting solution was pumped into the beaker with baffles over a period of 30 minutes while maintaining the pH of the aqueous slurry. 4 by adding 2.5 N NaOH. After the addition of the FeCl3 »6H20 solution, the pH was raised to 4.5, and it was left to mix for 10 minutes. The aqueous paste was then heated to about 50 ° C over a period of 32 minutes, while maintaining the pH at pH 4.5. The pH of the slurry was then raised to 8 over a period of 15 minutes, and then allowed to mix for 10 minutes. Then ethylene glycol (1386 g) was added to the slurry, and left to mix at 60 ° C. for ten minutes. The aqueous paste was then filtered, and then a new aqueous paste was formed with the wet cake in degassed deionized water (90 g) and introduced into the beaker with baffles.
The pH of the solution was then lowered to 5 by adding degassed 0.5 M HCl (2.17 g). K2PtCI4 (0.460 g) was dissolved in degassed water (20 g) and the Pt solution was introduced into the beaker. precipitated with deflectors over a period of three minutes. The aqueous paste was then allowed to mix at room temperature for 30 minutes, and then heated to a temperature of 60 ° C over a period of 10 minutes. The aqueous paste was then filtered, and the wet cake was hot washed twice at 60 ° C with about 100 ml of degassed water. The sample was then dried in a vacuum oven at 1 10 ° C for 12 hours with a small stream of nitrogen.
The catalyst precursor was then heated at elevated temperatures to about 550 ° C in the presence of a stream of hydrogen / argon (4% / 96%; v / v) for about 120 minutes.
EXAMPLE 54 This example details the preparation of a catalyst having a nominal Pt content of 2% by weight and a nominal iron content of 4% by weight on a. Activated carbon support having a surface area of Langmuir of approximately 1500 m2 / g. The following preparation was carried out under nitrogen protection.
Activated charcoal (approximately 10,458 g) and degassed water (approximately 90 g) were mixed in a beaker with deflectors under a nitrogen atmosphere.
FeCl3 * 6H20 (about 2028 g) was dissolved in degassed water (20 g) and this solution was pumped into the beaker with deflectors over a period of approximately 25 minutes. The pH of the slurry within the beaker with baffles was maintained at 4 by the introduction of degassed 2.5 N NaOH, as needed. After completing the addition of the FeCl3 »6H2O solution in the beaker, the pH of the aqueous paste was raised to approximately 4.5 by adding NaOH and the aqueous paste was allowed to mix at ambient conditions (approximately 22 ° C) during approximately 10 minutes.
The aqueous paste was then heated to a temperature of about 60 ° C over a period of about 40 minutes. During the heating, the pH was maintained at 4.5 with the addition of degassed 2.5 N NaOH.
The pH of the aqueous paste was then raised to about 7.5 over a period of about 15 minutes at a temperature of about 60 ° C, through the increase in pH at a rate of about 0.5 pH units every 5 minutes. The aqueous paste was then allowed to mix at a pH of about 7.5 for about 10 minutes, and then cooled to ambient conditions (about 22 ° C).
K2PtCI4 (approximately 0.460 g) was dissolved in degassed water (approximately 20 g) and then the resulting Pt solution was added to the beaker with baffles over a period of about 20 minutes. The resulting aqueous paste was left to mix for approximately 30 minutes. The aqueous paste thus mixed is then cooled to approximately 60 ° C over a 45 minute period, and then left to mix at 60 ° C for 15 minutes.
Then the resulting aqueous paste was filtered and then dried in a Vacuum oven at approximately 1 10 ° C for approximately 12 hours with a small stream of nitrogen to form a precursor to Pt / Fe catalyst.
Then the catalyst precursor was heated to temperatures elevated to approximately 950 ° C in the presence of a stream of hydrogen / argon (2% / 98%; v / v) for approximately 120 minutes.
Table 25 reports the results of the reaction test of PMIDA, platinum leaching data, and iron leaching data for the Finished catalyst 2% Pt / 4% Fe.
TABLE 25 Cycle 1 2 3 4 5 Total C02 (CE) 2169.6 2196.5 2147.3 2122.5 2062.5 End point (min) 36.42 36.08 37.83 38.42 40.00 Maximum concentration of C02 (%) 40.5 39.7 37.8 37.5 36.4 PMIDA (% by weight) ND 0.008 0.008 Glyphosate (% by weight) 5,363 5,520 5,461 ADA (% by weight) 0.087 0.030 0.021 0.017 CH20 (ppm) 1408 1 143 1247 HCOOH (ppm) 5283 5733 5993 Pt (ppm) 0.122 0.153 0.155 Fe (ppm) 33.310 0.941 0.491 EXAMPLE 55 This example provides microscopy results (carried out in accordance with protocol B described in example 68) for the catalyst precursor that was prepared as described in example 54.
Figure 116 is a scanning and transmission electron microscopy (STEM) micrograph of a portion of the surface of the precursor, including points 1 and 2. Figures 117 and 1 18 are results of energy dispersive energy spectroscopy analysis. (EDX) for points 1 and 2, respectively. As shown, these portions of the surface of the precursor included well dispersed iron along the entire surface, but not all of the iron had platinum deposited thereon.
Figures 119 and 120 are STEM photomicrographs of a portion of the precursor surface indicating a spatial distribution of metal over the entire carbon particle.
Figures 121 and 122 are a STEM and linear scanning EELS micrograph for a portion of the precursor surface, 1, which is identified in the micrographs. Figures 123 and 124, and 125 and 126 are also pairs of STEL and linear scanning EELS micrographs. These STEM and EELS results indicate the presence of iron over the entire carbon particle.
EXAMPLE 56 This example details the preparation of a catalyst having a nominal Pt content of 2% by weight and a nominal iron content of 4% by weight on an activated carbon support having a surface area of Langmuir of approximately 1500 m2 / g . The following preparation was carried out under nitrogen protection.
Activated carbon support (approximately 10.457 g) was introduced into a beaker with deflectors under a nitrogen atmosphere. FeCl3 »6H20 (approximately 2.013 g) and sucrose (approximately 4.550 g) were dissolved in degassed water (approximately 85 g). 50% by weight NaOH (approximately 5.225 g) was added and mixed with the FeCl3 »6H20-sucrose solution. The solution of FeCl3 * 6H20-sucrose was then added to the beaker with baffles, and allowed to mix. The resulting aqueous paste was then heated to about 60 ° C over a period of about 10 minutes.
Ethylene glycol (approximately 1263 g) was added to the beaker with baffles and allowed to mix with the aqueous pulp for about ten minutes at about 60 ° C. The aqueous paste was then filtered, and then a new aqueous paste was formed with the wet cake in the beaker with deflectors in degassed degassed water (approximately 90 g). Then it was decreased in pH of the aqueous paste resulting at approximately 7 by the addition of degassed 2 M HCl.
I ^ PtCU (0.462 g) was dissolved in degassed water (approximately 20 g) to form a platinum solution which was pumped into the beaker with baffles over a period of about 20 minutes. It was then left to mix the resulting aqueous paste under ambient conditions (about 22 ° C) for about 30 minutes, and then heated to a temperature of about 60 ° C over a period of about 60 minutes. The final aqueous paste was then filtered and the wet cake dried in a vacuum oven at about 110 ° C for about 12 hours with a small stream of nitrogen to form a Pt / Fe catalyst precursor.
The catalyst precursor was then heated at elevated temperatures to about 900 ° C in the presence of a stream of hydrogen / argon (2% / 98%; v / v) for about 120 minutes.
Table 26 reports the results of the PMIDA reaction test, platinum leaching data, and iron leaching data for the 2% Pt / 4% Fe catalyst.
TABLE 26 EXAMPLE 57 This example details the results of microscopy analysis (carried out in accordance with protocol B described in example 68) for the final catalyst that was prepared as described in example 56.
Figures 127 to 132 include microscopy results for the catalyst after its use in PMIDA oxidation assays as described in example 56.
Figure 127 includes four high resolution electronic photomicrographs (HREM) for different portions of the spent surface of the catalyst. These indicate the formation of graphite and iron oxide on the outer regions of the metal particles. Figure 128 includes three STEM micrographs, which indicate the presence of nanoporous platinum regions.
The . Figure 129 is a STEM myogram that shows different portions of the spent surface of the catalyst that were analyzed by EDX analysis. The results of the EDX analysis are shown in Figure 130, which indicates the presence of a composition rich in platinum.
Figure 131 is also a STEM mimeogram and the figure 132 are the results of the EDX analysis for portions of the spent surface of the catalyst. These results indicate the presence of varied metal compositions.
Figures 133 to 137 include microscopy results for the final catalyst that was prepared as described in example 56, but before the reaction test.
Figure 133 in a STEM photomicrograph identifying a particle to be analyzed by EELS linear scan analysis, the results of which are shown in Figure 134. As shown in Figure 134, a partial coating of iron oxide was detected.
Figure 135 is an HREM photomicrograph that highlights regions of Pt lattice. As shown in Figure 135, the identified particle included no more than about 4 Pt lattice margins. It is currently believed that each lattice margin corresponds to a lattice. layer of platinum atoms. That is, the identified particle included a platinum layer with no more than about 4 platinum atoms in thickness.
Figures 136 and 137 are photomicrographs by HREM that identify two layers of platinum atoms.
. Figure 138 provides analysis results by XRD, which indicate the formation of a phase of Fe0.75Pt0.25.
EXAMPLE 58 This example details the preparation of a catalyst precursor having a nominal Pt content of 2% by weight and a nominal iron content of 4% by weight on a carbon support activated which has a surface area of Langmuir of approximately 1500 m2 / g. The following preparation was carried out under nitrogen protection. Activated carbon support (approximately 10.456 g) was introduced into a beaker with deflectors under a nitrogen atmosphere. FeCl3 * 6H2O (approximately 2.011 g) and sucrose (approximately 4.511 g) were dissolved in degassed water (approximately 91.1 g). 50% by weight NaOH (approximately 5.214 g) was added and mixed with the FeCl3 * 6H20-sucrose solution. The solution of FeCl3 »6H20-sucrose was then added to the beaker with baffles, and allowed to mix with the activated carbon support. The resulting aqueous paste was then heated to about 40 ° C over a period of about 10 minutes.
Ethylene glycol (approximately 1309 g) was added to the beaker with baffles and allowed to mix with the aqueous slurry for about ten minutes at about 40 ° C. The aqueous paste was then filtered, and then a new aqueous paste was formed with the wet cake, in the beaker with deflectors, in degassed degassed water (90 g). The pH of the resulting aqueous paste was then adjusted / decreased to approximately 7 by the addition of degassed 2 M HCl (1.52 g).
K2PtCI4 (approximately 0.461 g) was dissolved in degassed water (20 g) to form a platinum solution which was introduced into the beaker with baffles over a period of 3 minutes. Then it was left to mix the resulting aqueous paste about 25 ° C for about 30 minutes, and then heated to a temperature of about 60 ° C over a period of about 40 minutes.
The final aqueous paste was then filtered and the wet cake was washed twice by contact with degassed water (approximately 100 g) at a temperature of about 60 ° C. The wet cake was dried in a vacuum oven at about 110 ° C for about 12 hours with a small stream of nitrogen to form a Pt / Fe catalyst precursor.
EXAMPLE 59 This example details the preparation of a catalyst having a nominal Pt content of 2% by weight and a nominal iron content of 4% by weight on an activated carbon support having a surface area of. Langmuir of approximately 150.0. . m2 / g. The following preparation was carried out under nitrogen protection.
Activated carbon support (approximately 10.456 g) was introduced into a beaker with deflectors under a nitrogen atmosphere. FeCl3 »6H20 (approximately 2.01 g) and sucrose (approximately 4.513 g) were dissolved in degassed water (approximately 91 g). 50% by weight NaOH (approximately 5.25 g) was added and mixed with the FeCl3 »6H20-sucrose solution. The solution of FeCl3 »6H2O-sucrose was then added to the beaker with baffles, and allowed to mix with the activated carbon support.
Ethylene glycol (approximately 1.31 g) was added to the baffle beaker and the resulting aqueous slurry was heated to a temperature of about 30 ° C over a period of about 15 minutes. The slurry was then filtered, and then a new slurry was formed with the wet cake in the baffled beaker in cold degassed deionized water (90 g) at a temperature of about 12 ° C. The pH of the resulting solution was then lowered to approximately 7 by the addition of 2 M HCl (approximately 0.645 g) and 1 M HCl (approximately 0.461 g) degassed.
K2PtCI4 (approximately 0.461 g) was dissolved in cold degassed water (approximately 20 g) at a temperature of about 12 ° C. Then the platinum solution was pumped into the »« beaker with. deflectors over a period of about 20 minutes.
The final aqueous paste was then filtered and the wet cake dried in a vacuum oven at about 110 ° C for about 12 hours with a small stream of nitrogen to form a Pt / Fe catalyst precursor.
The catalyst precursor was then heated at elevated temperatures to about 755 ° C in the presence of a stream of hydrogen / argon (4% / 96%; v / v) for approximately 120 minutes.
Table 27 reports the results of the PMIDA reaction test, platinum leaching data, and iron leaching data for the final catalyst of 2% Pt / 4% Fe.
TABLE 27 EXAMPLE 60 Figures 139 to 148 include microscopy results (carried out in accordance with protocol B described in example 68) for the final catalyst that was prepared as described in example 59.
Figure 139 is a STEM micrograph that identifies the particle that was analyzed by EELS linear scan analysis, the results of which are shown in Figure 140. As shown in Figure 139, the ratio of FE: Pt atoms of the analyzed particle it was 85.99 / 14.01. The results of the linear sweep of Figure 140 indicate the formation of an outer layer of iron oxide.
Figure 141 is a STEM micrograph that indicates the particle that was analyzed by linear scan analysis by EDX, whose results are shown in Figure 142. The linear sweep results show a relatively constant platinum signal, suggesting a very thin platinum coating, that is, varying by no more than about 25% during the sweep as length of the particle (e.g., between about 17.5 nm and about 46 nm along the scan line.) As also shown in Figure 142, the variation in the magnitude of the iron signal during scanning through the particle is proportionally greater than the variation in the platinum signal during the sweep through the particle (that is, in the order of at least approximately 1.5: 1).
Fig. 143 is a STEM micrograph and Figs. 144 and 145 are the corresponding linear scan analyzes by EELS and linear scan analysis by EDX, respectively. The results of linear scanning by EELS indicate the presence of an iron oxide layer. The results of linear scanning by EDX indicate the presence of a thin coating of platinum.
Figure 146 is a STEM micrograph and Figure 147 is the corresponding linear scan analysis by EDX. The linear scan results show a relatively constant platinum signal, that is, in the range of no more than about 25% during scanning through the particle, between about 9 nm and about 35 nm along the line of sweep and greater variation in the magnitude of the iron signal compared to the variation in the platinum signal (ie, in the order of approximately 1.5: 1).
Figure 148 provides XRD results of the analysis that was carried out as described in example 69. These results indicate the formation of a phase of Feo.75Feo.25- Figures 149-153 are results of microscopy for the spent catalyst (that is, after the assay in the oxidation of PMIDA).
Figure 149 is a STEM micrograph showing different porous metal particles on the spent surface of the catalyst.
Figure 150 is a STEM micrograph and Figure 151 is the corresponding results of linear scan analysis by EDX. The figure 152 is a STEM micrograph and Figure 153 is the corresponding results of the linear scan analysis by. These results indicate a platinum-rich composition throughout all the analyzed particles due to the leaching of iron from the core, that is, from the internal regions of the particles to form particles rich in porous platinum.
EXAMPLE 61 This example details the preparation of a catalyst precursor having a nominal Pt content of 2% by weight and a nominal iron content of 3.5% by weight on an activated carbon support having a surface area of Langmuir of approximately 1500 m2 / g. The following preparation was carried out under nitrogen protection.
Activated charcoal support (approximately 10.457 g) was introduced into a beaker with baffles under an atmosphere of nitrogens-Be dissolved FeCl3"6H2O (approximately 1753 g) and sucrose (approximately 4.455 g) in degassed water (approximately 90 g) . 50% by weight NaOH (approximately 4.613 g) was added and mixed with the FeCl3 solution «6H20-sucrose. The solution of FeCl3 «6H20-sucrose was then added to the beaker with baffles, and allowed to mix with the activated carbon support. The aqueous paste was then heated to a temperature of about 60 ° C over a period of 10 minutes.
Ethylene glycol (approximately 1200 g) was added to the beaker with baffles and allowed to mix with the slurry for about ten minutes at about 60 ° C. The aqueous paste was then filtered, and then a new aqueous paste was formed with the wet cake in degassed deionized water (90 g) and introduced into the beaker with baffles. The pH of the resulting aqueous paste was then lowered to approximately 6 by the addition of degassed 1 M HCl (3.6 g).
K2PtCI4 (about 0.452 g) was dissolved in degassed water (approximately 20 g) to form a platinum solution which was introduced into the beaker with baffles over a period of about 3 minutes. It was then left to mix the resulting aqueous paste under ambient conditions (about 22 ° C) for about 15 minutes, and then heated to a temperature of about 40 ° C over a period of about 12 minutes. , - .. - .. · .| ·. -. ....
The final aqueous paste was then filtered and the wet cake was washed twice warmly by contact with degassed water (about 100 g) at a temperature of about 60 ° C. The resulting sample was then dried in a vacuum oven at about 10 ° C for about 12 hours with a small stream of nitrogen.
Then the catalyst precursor was heated to temperatures elevated to about 755 ° C in the presence of a hydrogen / argon stream (4% / 96%; v / v) for about 120 minutes.
Figure 154 provides results of XRD analysis for the final catalyst of 2% Pt / 3.5% Fe, which indicate the formation of a Fe3Pt phase.
Table 28 reports the results of the PIDA reaction test, platinum leaching data, and iron leaching data for the finished catalyst. Figure 155 provides results of XRD analysis for the catalyst after the reaction test (ie, the spent catalyst). These results indicate the formation of a Pt phase.
TABLE 28 EXAMPLE 61 A This example details the preparation of a catalyst having a nominal Pt content of 2% by weight and a nominal iron content of 4% by weight on an activated carbon support having a surface area of Langmuir of approximately 1500 m2 / g . The following preparation was carried out under nitrogen protection.
Activated charcoal (approximately 10.456 g) and degassed water (approximately 90 g) were mixed in a beaker with baffles and allowed to mix for 20 minutes.
FeCl3'6H20 (approximately 2,009 g) was dissolved in degassed water (40 g) and this solution was then pumped into the beaker with baffles over a period of 30 minutes while maintaining the pH of the aqueous slurry in 4 with 2.5 N NaOH, as needed. After the addition of the FeCl 3 »6H 20 solution in the beaker, the pH of the aqueous paste was raised to 4.5 and it was left to mix for 10 minutes.
The aqueous paste was then heated to about 60 ° C over a period of about 30 minutes. During the heating, the pH was maintained at 4.5. The pH of the aqueous paste was then raised to 11 over a period of 30 minutes, and then allowed to mix for 10 minutes. Then ethylene glycol (1388 g) was added to the aqueous paste, and allowed to mix at about 60 ° C during approximately 10 minutes. The aqueous paste was then filtered, and then a new aqueous cake was formed with the wet cake, in the beaker with deflectors, in degassed degassed water (approximately 90 g).
The pH of the solution was then decreased to 7 by adding degassed 0.5 M HCl. K2PtCI4 (0.460 g) was dissolved in 20 ml of degassed water. The Pt solution was then pumped into the beaker with deflectors over a period of 30 minutes. It was then left to mix the resulting aqueous paste under ambient conditions (about 20 ° C) for about 30 minutes, and then heated to a temperature of about 60 ° C over a period of 10 minutes.
The resulting aqueous paste was then filtered and washed twice by contact with degassed water (approximately 100 g) at a temperature of about 60 ° C. The sample was then dried in a vacuum oven at approximately 110 ° C for 12 hours with one. small nitrogen stream to form a Pt / Fe catalyst precursor.
The catalyst precursor was then heated at elevated temperatures to about 650 ° C in the presence of a hydrogen / argon stream (4% / 96%; v / v) for about 120 minutes.
V. Platinum-Cobalt EXAMPLE 62 This example details the preparation of a catalyst having a nominal platinum content of approximately 2% by weight and a nominal cobalt content of approximately 4% by weight on an activated carbon support having a surface area of Langmuir of approximately 1500 m2 / g. The following preparation was carried out under nitrogen protection.
CoCl2 (1686 g) and sucrose (4,499 g) were dissolved in degassed water (89.4 ml) in a screw-capped flask that had been gassed rapidly with nitrogen. To this mixture was added 50% by weight of sodium hydroxide (5,209 g), the bottle was quickly gassed with nitrogen, and then the solution was mixed for one minute.
Activated carbon support (10,458 g) was added. to a baffled beaker of 400 ml and then the CoCl2 solution was added to the beaker with baffles, the beaker was quickly gassed with nitrogen, and the components were allowed to mix at room temperature for about five minutes . The resulting solution was then heated to about 60 ° C over a period of about forty minutes. Then ethylene glycol (approximately 1272 g) was added, and the resulting solution was left to mix about 60 ° C for about twenty minutes.
After the solution was filtered on a fritted glass filter, the resulting wet cake was returned to the beaker with deflectors. The pH of the solution was reduced to approximately 4.7 by the addition of HCl (2M).
K2PtCI4 (approximately 0.460 g) was dissolved in degassed water (20 ml) and the platinum solution was added to the beaker with drop baffles over a period of about three minutes. The resulting solution was allowed to mix at about 25 ° C for about sixty minutes. The solution was then heated to approximately 60 ° C over a period of about twenty minutes. The resulting solution was then filtered, and the filtrate was washed hot twice with degassed water (120 ml) at about 60 ° C. The sample was then dried in a vacuum oven at 1 10 ° C for 12 hours under a stream of nitrogen. ..... < , .. The catalyst precursor was then heated to temperatures. elevated to about 900 ° C in the presence of a hydrogen / argon stream (4% / 96%; v / v) for about 120 minutes.
EXAMPLE 63 This example details the preparation of a catalyst precursor having a nominal platinum content of 2% by weight and a cobalt content of 4% by weight on an activated carbon support having a surface area of Langmuir of approximately 1500 m2 / g. The following preparation was carried out under nitrogen protection.
Activated charcoal (10.458 g) was placed in a beaker with deflectors. CoCl2 »6H20 (1685 g) and sucrose (4.566 g) were mixed with degassed water (89.2 ml) and allowed to dissolve. 5.154 g of 50% by weight sodium hydroxide was added to the cobalt solution and allowed to mix. The resulting CoCl2 6H20 solution was then added to the beaker with carbon baffles, and allowed to mix.
The resulting aqueous paste was then heated to approximately 60 ° C over a period of twenty minutes. Sodium borohydride (approximately 0.558 g) was dissolved in degassed water (20 ml) to which then degassed 2.5 N NaOH (0.329 g) was added. The sodium borohydride solution was added to the beaker with deflectors at about 60 ° C over a period of about twenty minutes, and then allowed to mix for an additional ten minutes. The aqueous paste was then filtered, and the wet cake was washed twice at about 60 ° C. Then an aqueous paste was re-formed with the wet cake in degassed deionized water (90 g).
The pH of the solution was reduced to approximately 5 by the addition of degassed 2 M HCl. K2PtCI4 (0.459 g) was dissolved in degassed water (20 ml). The Pt solution was then added to the beaker with deflectors over a period of about three i minutes The aqueous paste was then allowed to mix at about 25 ° C for about 40 minutes, and then heated to a temperature of about 40 ° C.
The resulting aqueous paste was then filtered, and the wet cake was washed twice with hot water (about 100 ml) at about 60 ° C. The resulting sample was then dried in a vacuum oven at approximately 1 10 ° C for 12 hours with a small stream of nitrogen.
SAW. Platinum-Tin EXAMPLE 64 The following preparation was carried out under nitrogen protection. Activated charcoal (10.457 g) was placed in a beaker with deflectors and mixed with degassed water (100 ml).
SnCl4 * 5H20 (2.545 g) and K2PtCI4 (0.463 g) were dissolved in degassed water (20 ml). The Sn / Pt solution was then pumped into the beaker with baffles over a period of approximately twenty-three minutes. The temperature and pH of the Sn / Pt solution were raised simultaneously to approximately 60 ° C and approximately 7, respectively, over a period of about forty-five minutes. The solution was left to mix for approximately thirty minutes.
NaBH4 (1310 g) was dissolved in degassed water (10 ml) and this solution was added to the beaker with deflectors in a period of twenty minutes. It was then left to mix the resulting aqueous paste for about twenty minutes, the slurry was filtered, and the wet cake was washed twice hot with about 100 ml of degassed water at about 60 ° C. The resulting sample was then dried in a vacuum oven at 1 10 ° C for 12 hours with a small stream of nitrogen.
Then the catalyst precursor was heated at elevated temperatures to about 545 ° C in the presence of a stream of hydrogen / argon (2% / 98% v / v) for about 120 minutes.
VII. Platinum-Copper EXAMPLE 65 The following preparation was carried out under nitrogen protection.
Preparation of nominal 2% Pt 4% nominal Cu on activated carbon: the following was added to a beaker with baffles with approximately 10 g of activated carbon: 1.64 g of CuS04 solution «5H20, 4.51 g of sucrose, 90 g of deionized water degassed, and 4.63 g of 50% by weight NaOH. The mixture was heated to about 40 ° C and stirred for about 10 minutes with a mechanical stirrer. To this aqueous paste was added 1.71 g of 37% formaldehyde diluted with 17.1 g with degassed deionized water. The resulting aqueous paste was heated to about 40 ° C together with continuous stirring for about 30 minutes (or until the solution became colorless). Then, the aqueous paste was filtered, washed once on the filter, and then the aqueous paste was again formed in water at pH 2.02 by adding degassed 1 M HCl. Then a solution of 0.454 g of I ^ PtCU in 10 g of degassed water was added to the slurry, together with continuous stirring for about 30 minutes at ambient conditions. The aqueous paste was then heated to about 60 ° C and stirred for about 30 more minutes. The aqueous paste was then filtered and washed with water, and dried under vacuum at about 10 ° C under a small stream of nitrogen. A total of 11,720 g of dry material was recovered. During the heat treatment at a maximum temperature of about 950 ° C in the presence of an argon / hydrogen atmosphere (2% / 98%) (v / v) for approximately 120 minutes, the sample lost 13.5% by weight.
Figures 155A and 155B include microscopy results for the final catalyst. Figures 155C to 155F include microscopy results for the catalyst after the oxidation assay of PMIDA.
EXAMPLE 66 This example details the preparation of a catalyst having a nominal Pt content of 2% by weight and a nominal copper content of 3.75% by weight on an activated carbon support having a Langmuir surface area of approximately 1500 m2 / g . The following preparation was carried out under nitrogen protection.
Activated carbon support (approximately 10.457 g) was introduced into a beaker with deflectors under a nitrogen atmosphere. CuSO4"5H2O (approximately 1540 g) and sucrose (approximately 4.225 g) were dissolved in degassed water (approximately 91 g). 50% by weight NaOH (approximately 4370 g) was added and mixed with the CuSO-5H2O-sucrose solution, and the resulting solution was then added to the beaker with baffles, and allowed to mix with the activated carbon support. a temperature of about 29 ° G for about 20 minutes.
Formaldehyde (37%) (approximately 1604 g) was added to the beaker with baffles and allowed to mix with the slurry for about eighty-four minutes at about 29 ° C. The aqueous paste was then filtered, and then a new aqueous paste was formed with the wet cake in degassed deionized water (90 g) and introduced into the beaker. Then it was decreased in pH of the resulting aqueous paste to approximately 4 by adding 1 M HCl degassed.
K2PtCI4 (approximately 0.427 g) was dissolved in degassed water (approximately 20 g) to form a platinum solution which was introduced into the beaker with baffles over a period of about 3 minutes. It was then left to mix the resulting aqueous paste under ambient conditions (about 22 ° C) for about 30 minutes, and then it was heated to a temperature of about 60 ° C, and then mixed for about 30 additional minutes.
The final aqueous paste was then filtered and the wet cake was washed twice hot at 60 ° C by contact with degassed water (approximately 100 g). The resulting sample was dried in a vacuum oven at about 10 ° C for about 12 hours with a small stream of nitrogen.
The catalyst precursor was then heated at elevated temperatures to about 950 ° C in the presence of a hydrogen / argon stream (2% / 98% v / v) for about 120 minutes.
Table 29 reports the results of the PMIDA reaction test, platinum leaching data, and iron leaching data for the finished catalyst.
TABLE 29 VIII. Test Protocols EXAMPLE 67 Protocol A The following example details the chemisorption analysis of CO that was used to determine the exposed metal surface areas of the catalysts that were prepared as described in this documentation. The method described in this example is referred to in this specification and the appended claims as "Protocol A." This protocol submits an individual sample to two sequential cycles of CO chemisorption.
Cycle 1 measures the initial exposed noble metal in the zero-valent state. The sample is degassed by vacuum treated with oxygen. Then, the residual, non-adsorbed oxygen is removed, and the catalyst is then exposed to CO. The volume of CO taken irreversibly is used to calculate the initial site density of the noble metal (eg, Pt °).
Cycle 2 measures the total exposed noble metal. Without altering the sample after cycle 1, it is degassed again under vacuum and then treated with hydrogen flow, and degassed again. Then the sample is treated with oxygen. Finally, the residual, non-adsorbed oxygen is removed and the catalyst is exposed again to CO. The volume of CO taken in the form Irreversible is used to calculate the density of exposed total sites of the noble metal (eg, Pt °). See, for example, Webb et al., Analytical Methods in Fine Particle Technology, Micromeritics Instrument Corp., 1997, for a description of the chemisorption analysis. The preparation of the sample, including degassing, is described, for example, between pages 129 and 130.
Equipment Static chemosorption instrument Micromeritics (Norcross, GA) ASAP 2010 ~ Gases required: hydrogen UHP; carbon monoxide; helium UHP; oxygen (99.998%); sample tube for passage of Quartz fluid with filling rod; two plugs; two internal quartz wool plugs; Analytical balance.
Preparation Insert an internal plug of quartz wool without pressing on the bottom of a sample tube. Obtain the tare weight of the sample tube with the first internal wool plug. Pre-weigh approximately 0.25 grams of sample and then add it to the top of the first internal quartz wool plug. Accurately measure the initial sample weight. Insert the second internal quartz wool plug over the sample and gently press down to contact the sample mass, then add the filler rod and insert two plugs. Measure the total weight (before degassing): Transfer the sample tube to the degassing port of the instrument and then apply vacuum of < 10 μg Hg while heating under vacuum at 150 ° C for approximately between 8 and 12 hours. Release the vacuum Cool to room temperature and weigh again. Calculate the weight loss and the final degassed weight (use this weight in the calculations).
Cycle 1 Secure the sample tube in the analysis port of the static chemosorption instrument. Make helium flow (approximately 85 cm3 / minute) at room temperature and atmospheric pressure through the sample tube, then heat at 150 ° C to 5 ° C / minute. Maintain at 150 ° C for 30 minutes. Cool to 30 ° C.
Evacuate the sample tube to < 10 pm Hg at 30 ° C. Keep at 30 ° C for 15 minutes. Close the sample tube to the vacuum pump and run the loss test. Evacuate the sample tube while heating at 70 ° C to 5 ° C / min. Keep for 20 minutes at 70 ° C. .-. . . .
Make oxygen flow (approximately 75 cm3 / minute) through the sample tube at 70 ° C and atmospheric pressure for 50 minutes.
Evacuate the sample tube at 70 ° C for 5 minutes.
Make helium flow (approximately 85 cm3 / minute) through the sample tube at atmospheric pressure and increase to 80 ° C at 5 ° C / minute. Keep at 80 ° C for 15 minutes.
Evacuate the sample tube at 80 ° C for 60 minutes and keep under vacuum at 80 ° C for 60 minutes. Cool the sample tube to 30 ° C and continue the evacuation at 30 ° C for 30 minutes. Close the sample tube to the vacuum pump and run the loss test.
Evacuate the sample tube at 30 ° C for 30 minutes and keep under vacuum at 30 ° C for 30 minutes.
For a first analysis with CO, the CO uptake is measured under conditions of static chemosorption at 30 ° C and initial collector pressures of 50, 100, 150, 200, 250, 300, 350 and 400 mm Hg (manometric) for determine the total amount of CO absorbed (ie, both chemisorbed and physiadsorbed).
Pressurize the collector to the initial pressure (for example, 50 mm Hg). Open the valve between the manifold and the sample tube allowing the CO to come in contact with the sample in the sample tube. Allow the pressure in the sample tube to equilibrate. The pressure reduction from the initial collector pressure to the equilibrium pressure in the sample tube indicates the volume of uptake of .CO per part of the sample.
Close the valve between the collector and the sample tube and pressurize the collector to the next initial pressure (for example, 100 mm Hg). Open the valve between the manifold and the sample tube allowing the CO to come in contact with the sample in the sample tube. Allow the pressure in the sample tube to equilibrate to determine the volume of CO uptake by the sample. Carry out the procedure for each initial collector pressure.
Evacuate the sample tube at 30 ° C for 30 minutes.
For a second CO analysis, CO uptake is measured under conditions of static chemosorption at 30 ° C and initial collector pressures of 50, 100, 150, 200, 250, 300, 350 and 400 mm Hg (manometric) as it was previously described during the first CO analysis to determine the total amount of fisiadsorbed CO.
Cycle 2 After the second CO analysis of Cycle 1, flow helium (approximately 85 cm3 / minute) at 30 ° C and atmospheric pressure through the sample tube, then heat at 150 ° C at 5 ° C / minute. Maintain at 150 ° C for 30 minutes.
Cool to 30 ° C. Evacuate the sample tube to < 10 pm Hg at 30 ° C for 15 minutes. Maintain at 30 ° C for 5 minutes.
Close the sample tube to the vacuum pump and run the test. lost. . , ... "- -.
Evacuate the sample tube at 30 ° C for 20 minutes.
Run hydrogen (approximately 150 cm3 / minute) through the sample tube at atmospheric pressure while heating to 150 ° C at 10 ° C / min. Maintain at 150 ° C for 15 minutes.
Evacuate the sample tube at 150 ° C for 60 minutes. Cool the sample tube to 70 ° C. Maintain at 70 ° C for 15 minutes.
Make oxygen flow (approximately 75 cm3 / minute) through of the sample tube at atmospheric pressure and 70 ° C for 50 minutes.
Evacuate the sample tube at 70 ° C for 5 minutes.
Make helium flow (approximately 85 cm3 / minute) through the sample tube at atmospheric pressure and increase the temperature to 80 ° C to 5 ° C / minute. Keep at 80 ° C for 15 minutes. Evacuate the sample tube at 80 ° C for 60 minutes. Maintain under vacuum at 80 ° C for 60 minutes.
Cool the sample tube to 30 ° C and continue the evacuation at 30 ° C for 30 minutes. Close the sample tube to the vacuum pump and run the loss test.
Evacuate the sample tube at 30 ° C for 30 minutes and hold for 30 minutes.
For a first CO analysis, CO uptake is measured under conditions of static chemosorption at 30 ° C and initial collector pressures of 50, 100, 150, 200, 250, 300, 350 and 400 mm Hg (manometric) for determine the total amount of CO absorbed (ie, both chemisorbed and physiadsorbed).
Pressurize the collector to the initial pressure (for example, 50 mm Hg). Open the valve between the manifold and the sample tube allowing the CO to come in contact with the sample in the sample tube. Allow the pressure in the sample tube to equilibrate. The pressure reduction from the initial collector pressure to the equilibrium pressure in the sample tube indicates the volume of CO uptake by the sample.
Close the valve between the manifold and the sample tube and pressurize the collector until the next initial pressure (for example, 100 mm Hg). Open the valve between the manifold and the sample tube allowing the CO to come in contact with the sample in the sample tube. Allow the pressure in the sample tube to equilibrate to determine the volume of CO uptake by the sample. Carry out the procedure for each initial collector pressure.
Evacuate the sample tube at 30 ° C for 30 minutes.
For a second CO analysis, CO uptake is measured under conditions of static chemosorption at 30 ° C and initial collector pressures of 50, 100, 150, 200, 250, 300, 350 and 400 mm Hg (manometric) as it was previously described during the first CO analysis to determine the total amount of fisiadsorbed CO.
Calculations Plot the lines of the first and second analyzes in each cycle: volume of physically adsorbed CO and chemisorbed (ler analysis) and volume of CO physically adsorbed (2nd analysis) (cm3 / g to STP) versus objective pressures of CO (mm Hg). Graph the difference between the lines of the First and Second analyzes at each target pressure of CO. Extrapolate the line of difference to its intercept with the Y axis. In cycle 1, exposed total PtO (pmoles of CO / g) = Intercept of the Y with the difference line / 22,414 X 1000. In cycle 2, total exposed Pt Emoles of CO / g) = Intercept of the Y axis with the difference line / 22,414 X 1000. < EXAMPLE 68 (Microscopy): Protocol B This example details analysis by microscopy of catalyst samples of the present invention.
High Resolution Electronic Micro-Chrads (HREM) HREMs were generated for different catalyst samples using a transmission electron microscope (TEM) with Jeol 2100 field emission trigger (FEG) operated at an acceleration voltage of 200 keV. The samples were placed in the support as it is without carbon interference (ie, the samples were not cut with a microtome, they were not embedded in a material containing organic compounds such as an epoxy), and under conditions that identified marginal reticulum rings.
Atomic layer measurements The grating spaces d were measured in the catalyst particles identified by TEM. These measurements were calibrated based on the known d space (3.84 A) of an individual silicon crystal (110) that was also analyzed using the Jeol 2100 FEG TEM at the same magnification and acceleration voltage (200 KeV). The measurements were recorded and analyzed using the DigitalMicrograph program. The number of layers was determined atomic platinum for the particles analyzed based on the number of repetitive marginal reticular rings that were observed in the HREM micrographs.
Analysis by linear sweep Linear scan analysis by x-ray energy dispersive spectroscopy (EDX) was carried out using the Jeol 2100 FEG TEM operated in scanning and transmission electron microscopy (STEM) mode. The probe size was 1 nm.
The linear scanning analysis of electronic energy loss spectroscopy (EELS) was carried out using the Jeol 2100 FEG TEM operated in STEM mode with a probe size of 0.5 nm.
EXAMPLE 69 (X-ray diffraction) This example details the method that was used during the X-ray Diffraction (XRD) analysis for the results reported in this documentation. The powder samples (less than about 0.2 g) were compacted using a pellet press to form pellets of samples for analysis. The sample pellet was placed on a plastic sample holder for analysis on a Bruker D8 Discover Diffractometer.
CuKocX radiation (CuKo = 1.5418 A) was produced in a sealed tube of Cu at 40 kV and 40 mA. Before the experiment, a korundum sample was used to adjust for any peak misalignment.
The sample holder was placed on the XYZ platform and analyzed in locked coupled-scan mode; the angles of the trigger and the detector were kept in the same value (that is, T1 = T2). The XRD data were collected using a LynxEye® Position Sensitive Detector (PSD) that is 103 times more sensitive than the conventional XRD. For each sample, an XRD spectrum was collected within the range between 0 and 90 ° 2T with a step size of 0.02 ° and a total measurement time of about 3 hours.
EXAMPLE 70 (Analysis of pore volume and surface area) In general, different "supports and catalysts impregnated in metal were analyzed to determine surface area and pore volume data as reported herein using a Micromeritics 2010 Micropore analyzer with a torr transducer and a Micromeritics 2020 Accelerated Surface Area and Porosimetry System, also with a torr transducer These analytical methods are described in, for example, Analytical Methods in Fine Partiole Technology, First Edition, 1997, Micromeritics Instrument Corp, Atlanta, Georgia (USA), and Principies and Practice of Heterogeneous Catalysis, 1997, VCH Publishers, Inc .; New York, NY (E.U.A.).
The present invention is not limited to the above modalities and can be modified in different ways. The above description of the preferred embodiments, including the examples, is only intended to bring other experts in the field up to date with respect to the invention, its principles, and its practical application so that other experts in the field can adapt and applying the invention, in its many forms, in the way that best suits the requirements of a particular use.
With reference to the use of the word (s) comprising or comprising, or comprising, this entire specification (including the subsequent claims), unless the context otherwise requires, those words are used on the base and the clear understanding that they should be interpreted in an inclusive manner, rather than exclusively, and the applicants intend that each of those words be interpreted in that way in the understanding of this complete descriptive memory.
When introducing the elements of the present invention or of the preferred embodiment (s) thereof, the articles "a / a", "a / a", "the / the / s / the "and" said / a / os / as "are meant to mean that there is one or more of the elements. The terms "comprising (n)", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than those items that are listed.
In view of the foregoing, it will be noted that the different objects of the invention are achieved and that other advantageous results are achieved.

Claims (1)

  1. NOVELTY OF THE INVENTION CLAIMS 1. - An oxidation catalyst comprising a support of particulate carbon, a first metal, and a second metal, where the support has on its surface particles comprising the first metal and the second metal, where: the distribution of the second metal within at least one of said particles characterized by linear scanning by EDX as described in protocol B produces a second metal signal that does not vary more than about 25% through a swept region of which one dimension is at least approximately 70% of the largest dimension of the at least one particle. 2. - The oxidation catalyst according to claim 1, further characterized in that the second metal signal varies by no more than about 20%, no. more than about 15%, no more than about 10%, or no more than about 5% across the swept region. 3. - An oxidation catalyst comprising a support of particulate carbon, a first metal, and a second metal, where the support has on its surface particles comprising the first metal and the second metal, where: a distribution of the second metal within at least one of said particles characterized by linear scanning by EDX according to described in protocol B produces a second metal signal that does not vary more than about 20% through a swept region of which one dimension is at least about 60% of the largest dimension of the at least one particle. 4. - The oxidation catalyst according to claim 3, further characterized in that the second metal signal varies by no more than about 15%, no more than about 10%, or no more than about 5% through the swept region. 5. - An oxidation catalyst comprising a support of particulate carbon, a first metal, and a second metal, where the support has on its surface particles comprising the first metal and the second metal, where: the distribution of the second metal within at least one of said particles characterized by linear scanning by EDX as described in protocol B produces a second metal signal that does not vary more than about 15% through a swept region of which one. dimension is at least about 50% of the largest dimension of the at least one particle. 6. - The oxidation catalyst according to claim 5, further characterized in that the second metal signal varies by no more than about 10%, or no more than about 5% through the swept region. 7. - The oxidation catalyst according to any of claims 1 to 6, further characterized by the atomic ratio of the second metal to the first metal of the at least one particle is less than 1: 1, less than about 0.8: 1, less than about 0.6.1, or less than about 0.5: 1. 8 -. 8 - The oxidation catalyst according to any of claims 1 to 7, further characterized in that the at least one particle has a larger dimension of at least about 6 nm, at least about 8 nm, at least about 10 nm, or at least about 12 nm. 9 -. 9 - The oxidation catalyst according to any of claims 1 to 8, further characterized in that the at least one particle constitutes at least about 1%, at least about 5%, at least about 10%, so less about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 85%, or at least about 90% of the metal particles on the surface of the carbon support. 10. - The oxidation catalyst according to any of claims 1 to 9, further characterized in that the distribution of the first metal in the at least one metal particle characterized by linear scanning by EDX as described in protocol B produces a first metal signal, where the ratio of the maximum of the first metal signal to the maximum of the second signal metal through the swept region is at least about 1.5: 1, at least about 2.1, at least about 2.5: 1, at least about 3: 1, at least about 4: 1, or at least about 5: 1. 1 1 - An oxidation catalyst comprising a support of particulate carbon with metal particles in a surface thereof comprising a first metal and a second metal, wherein: the electropositivity of the first metal is greater than the electropositivity of the second metal and the second metal is deposited by ion displacement of the first metal from one or more regions of the first metal of a catalyst precursor structure; and the weight ratio of the second metal to the first metal is at least about 0.25: 1. . . . ....... 12. - The oxidation catalyst according to any of claims 1 to 1, further characterized in that the first metal is selected from the group consisting of vanadium, tungsten, molybdenum, gold, osmium, iridium, tantalum, palladium, ruthenium, antimony , bismuth, arsenic, mercury, silver, copper, titanium, tin, lead, germanium, zirconium, cerium, nickel, cobalt, iron, chromium, zinc, manganese, aluminum, beryllium, magnesium, lithium, barium, cesium, and combinations of the same. 13. - The oxidation catalyst according to claim 12, further characterized in that the first metal is selected from the group consisting of copper, tin, nickel, cobalt, and combinations thereof. 14. - The oxidation catalyst according to claim 12, further characterized in that the first metal is selected from the group consisting of cobalt, copper, iron, and combinations thereof. same. 15. - The oxidation catalyst according to claim 12, further characterized in that the first metal is copper. 16. - The oxidation catalyst according to claim 12, further characterized in that the first metal is iron. 17. - The oxidation catalyst according to claim 12, further characterized in that the first metal is cobalt. 18. - The oxidation catalyst according to any of claims 1 to 17, characterized. furthermore because the first metal, ... constitutes at least about 1% by weight, at least about 1.5% by weight, at least about 2% by weight, at least about 3% by weight, per at least about 4% by weight, or at least about 5% by weight of the catalyst. 19. - The oxidation catalyst according to any of claims 1 to 17, further characterized in that the first metal constitutes between about 1% and about 10% by weight of the catalyst, between about 1.5% and about 8% by weight of the catalyst, between about 2% and about 5% by weight of the catalyst, or about 4% by weight of the catalyst. 20. - The oxidation catalyst according to any of claims 1 to 19, further characterized in that the second metal is a noble metal. 21. - The oxidation catalyst according to claim 20, further characterized in that the noble metal is selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, silver, osmium, gold, and combinations thereof. 22. - The oxidation catalyst according to claim 20, further characterized in that the noble metal comprises platinum, palladium, or platinum and palladium. 23. - The oxidation catalyst according to claim 20, further characterized in that the noble metal is platinum. ... ~ 24. The oxidation catalyst according to any of claims 1 to 23, further characterized in that the second metal constitutes at least about 1% by weight, at least about 2% by weight, or at least less about 3% by weight of the catalyst. 25. - The oxidation catalyst according to any of claims 1 to 23, further characterized in that the second metal constitutes less than about 8% by weight, less than about 7% by weight, less than about 6% by weight, less than about 5% by weight, or less than about 4% by weight of the catalyst. 26. - The oxidation catalyst according to any of claims 1 to 23, further characterized in that the second metal constitutes between about 3% and about 6% by weight, or between about 4% and about 5% by weight of the catalyst. 27. - The oxidation catalyst according to any of claims 1 to 23, further characterized in that the second metal constitutes between about 1% and about 5% by weight, between about 1.5% and about 4%, or between about 2% and about 3% by weight of the catalyst. 28 -. 28 - The oxidation catalyst according to any of claims 20 to 27, further characterized in that the catalyst is characterized by chemisorber at least about 500, at least about 600, at least about 700, at least about 800 , at least about 900, at least about 1000, or at least about 1 100 μ ?? ee of CO per gram of catalyst per gram of noble metal during Cycle 2 of the static chemosorption analysis of carbon monoxide as described in protocol A. 29 -. 29 - The oxidation catalyst according to any of claims 1 to 28, further characterized in that the particles of The metal on the surface of the carbon support comprises a core comprising the first metal and a coating which at least partially surrounds the core and which comprises the second metal. 30. - The oxidation catalyst according to claim 29, further characterized by at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the second metal is present within the coating of the metal particles. 31. - The oxidation catalyst according to any of claims 1 to 30, further characterized in that the percentage of atoms of the second metal on the surface of the first and second particles containing metal on the surface of the carbon support is at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 20%, at least about 30%, at least about 40%, or at least approximately 50%. 32. - An oxidation catalyst comprising a support of particulate carbon, a first metal, and a noble metal, where the support has on its surface metal particles comprising the first metal and the noble metal, where the catalyst is characterized by quimisorber by least 975 CO2 rimols per gram of catalyst per gram of noble metal during Cycle 2 of the static chemosorption analysis of carbon monoxide as described in protocol A. 33. - The oxidation catalyst according to claim 32, further characterized in that the first metal is selected from the group consisting of vanadium, tungsten, molybdenum, gold, osmium, iridium, tantalum, palladium, ruthenium, antimony, bismuth, arsenic, mercury, silver, copper, titanium, tin, lead, germanium, zirconium, cerium, nickel, cobalt, iron, chromium, zinc, manganese, aluminum, beryllium, magnesium, lithium, barium, cesium, and combinations thereof. 34. - The oxidation catalyst according to claim 33, further characterized in that the first metal is selected from the group consisting of copper, tin, nickel, cobalt, and combinations thereof. 35. - The oxidation catalyst according to claim 33 † further characterized in that the first metal is selected from the group consisting of cobalt, copper, iron, and combinations thereof. 36. - The oxidation catalyst according to claim 33, further characterized in that the first metal is copper. 37. - The oxidation catalyst according to claim 33, further characterized in that the first metal is iron. 38. - The oxidation catalyst in accordance with the claim 33, further characterized in that the first metal is cobalt. 39. - The oxidation catalyst according to any of claims 32 to 38, further characterized in that the first metal constitutes at least about 1% by weight, at least about 1.5% by weight, at least about 2% by weight, at least about 3% by weight, at least about 4% by weight, or at least about 5% by weight of the catalyst. 40. - The oxidation catalyst according to any of claims 32 to 38, further characterized in that the first metal constitutes between about 1% and about 10% by weight of the catalyst, between about 1.5% and about 8% by weight of the catalyst, between about 2% and about 5% by weight of the catalyst, or about 4% by weight of the catalyst. 41. - The oxidation catalyst according to any of claims 32 to 40, further characterized in that the noble metal is. selects from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, silver, osmium, gold, and combinations thereof. 42. - The oxidation catalyst according to claim 41, further characterized in that the noble metal comprises platinum, palladium, or platinum and palladium. 43. - The oxidation catalyst according to claim 41, further characterized in that the noble metal is platinum. 44. - The oxidation catalyst in accordance with any of claims 32 to 43, further characterized in that the noble metal constitutes at least about 1% by weight, at least about 2% by weight, or at least about 3% by weight of the catalyst. 45. - The oxidation catalyst according to any of claims 32 to 43, further characterized in that the noble metal constitutes less than about 8% by weight, less than about 7% by weight, less than about 6% by weight, less than about 5% by weight, or less than about 4% by weight of the catalyst. 46 -. 46 - The oxidation catalyst according to any of claims 32 to 43, further characterized in that the noble metal constitutes between about 3% and about 6% by weight, or between about 4% and about 5% by weight of the catalyst. 47. - The oxidation catalyst according to any of the. claims 32 to 43, further characterized, that the noble metal constitutes between about 1% and about 5% by weight, between about 1.5% and about 4%, or between about 2% and about 3% by weight of the catalyst. 48. - The oxidation catalyst according to any of claims 32 to 47, further characterized in that the catalyst is characterized by chemisorber at least about 1000, or at least about 1 100 μ? P? Is of CO per gram of catalyst by gram of noble metal during Cycle 2 of the analysis of static chemosorption of carbon monoxide as described in protocol A. 49. - The oxidation catalyst according to any of claims 32 to 48, further characterized in that the metal particles on the surface of the carbon support comprise a core comprising the first metal and a coating surrounding at least partially the core and comprising the noble metal. fifty - . 50 - The oxidation catalyst according to claim 49, further characterized by at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50% , at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the noble metal is present within the coating of the metal particles. ;: ¾-; ·: ......... 51.- The oxidation catalyst of. according to any of claims 32 to 50, further characterized in that the percentage of noble metal atoms on the surface of the particles containing the first metal and noble metal on the surface of the carbon support is at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 20%, at least about 30%, at least about 40%, or at least about 50%. 52. - An oxidation catalyst comprising a support of particulate carbon, copper, and platinum, where the support has on its surface particles comprising copper and platinum, where: the distribution of platinum within at least 70% (on a numerical basis ) of said particles characterized by linear scanning by EDX as described in protocol B produces a platinum signal that does not vary more than about 25% through a swept region of which one dimension is at least about 70%. % of the largest dimension of said particles. 53. - An oxidation catalyst comprising a support of particulate carbon, a first metal, and a noble metal, where the support has on its surface metal particles comprising the first metal and the noble metal, where: the metal particles comprise a a core comprising the first metal and a coating at least partially surrounding the core and comprising the noble metal, where at least about 70% ¾del. Noble metal is present within the coating of the particle. 54. - An oxidation catalyst comprising a support of particulate carbon, a first metal, and a noble metal, where the support has on its surface metal particles comprising the first metal and the noble metal, where: the metal particles comprise a a core comprising the first metal and a coating at least partially surrounding the core and comprising the noble metal; the noble metal it constitutes less than 5% by weight of the catalyst; and the catalyst is characterized by chemisorbing at least about 800 μ ?? ee of CO per gram of catalyst per gram of noble metal during Cycle 2 of the static chemosorption analysis of carbon monoxide as described in protocol A. 55. - An oxidation catalyst comprising a support of particulate carbon, platinum, and copper, where the support has on its surface metal particles comprising platinum and copper, where the percentage of platinum atoms on the surface of the particles is at least approximately 10%. 56. - An oxidation catalyst comprising a support of particulate carbon, platinum, and copper, where the support has on its surface metal particles comprising platinum and copper, where: the percentage of platinum atoms on the surface of the particles is at least about 5%; and the catalyst is characterized by chemisorbing at least 500 μ? t ??? ße of GO per gram of catalyst per gram of noble metal during Cycle 2 of the static chemosorption analysis of carbon monoxide as described in protocol A. 57. - The oxidation catalyst according to any of claims 1 to 56, further characterized in that the carbon support has a specific surface area of at least about 500 m2 / g, at least about 750 m2 / g, at least approximately 1000 m2 / g, or at least approximately 1250 m2 / g. 58. - The oxidation catalyst according to any of claims 1 to 56, further characterized in that the carbon support has a specific surface area of between about 10 and about 3000 m2 / g, between about 500 and about 2100 m2 / g, between about 750 and about 1900 m2 / g, between about 1000 and about 1900 m2 / g, between about 1000 and about 1700 m2 / g, 1000 and about 1500 m / g, between about 1 100 and about 1500 m / g, between about 1250 and approximately 1500 m2 / g, between approximately 1200 and approximately 1400 m2 / g, or approximately 1400 m2 / g. 59. - A process for oxidizing a substrate that is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde, and acid, formic, the process comprising: contacting the substrate with a oxidizing agent in the presence of an oxidation catalyst comprising a first metal, a noble metal, and a porous carbon support, wherein the catalyst comprises one or more regions of the first metal on the surface of the carbon support and one or more regions of the noble metal on the surface of the one or more regions of the first metal, where the first metal has an electropositive character greater than the electropositivity of the noble metal. 60. - The process of claim 59, further characterized in that the oxidation catalyst is prepared by a process comprising contacting the carbon support with one or more regions of the first metal on its surface with a noble metal deposition bath comprising ions of the noble metal, thereby depositing the noble metal by displacing the first metal from one or more of said regions. 61. - A process for oxidizing a substrate that is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde, and formic acid, the process comprising: contacting the substrate with an oxidizing agent in the presence of an oxidation catalyst comprising a support of particulate carbon, a first metal, and a second metal, where the support has on its surface particles comprising the first metal and the second metal, where: the distribution of the second metal within at least one of said particles characterized by linear scanning by EDX as described in protocol B produces a second metal signal, which does not vary more than about 25% through a swept region of which one dimension is at least about 70% of the largest dimension of the at least one particle. 62. - A process for oxidizing a substrate that is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde, and formic acid, the process comprising: contacting the substrate with an oxidizing agent in the presence of a catalyst oxidation comprising a support of particulate carbon, a first metal, and a second metal, where the support has on its surface particles comprising the first metal and the second metal, where: the distribution of the second metal within at least one of said particles characterized by linear scanning by EDX as described in protocol B produces a second metal signal that does not vary more than about 20% through a swept region of which one dimension is at least about 60% of the largest dimension of the at least one particle. 63. - A process for oxidizing a substrate that is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde, and formic acid, the process comprising: contacting the substrate with an oxidizing agent in the presence of an oxidation catalyst comprising a particulate carbon support, a first metal, and a second metal, where the support has on its surface particles comprising the first metal and the second metal, where: the distribution of the second metal within at least one of said particles characterized by linear scanning by EDX according to described in protocol B produces a second metal signal that does not vary more than about 15% through a swept region of which one dimension is at least about 50% of the largest dimension of the at least one particle. 64. - A process for oxidizing a substrate that is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde, and formic acid, the process comprising: contacting the substrate with an oxidizing agent in the presence of an oxidation catalyst comprising a carbon support particulate, a first metal, and a noble metal, where the support has on its surface metal particles comprising the first metal and the noble metal, where the catalyst is characterized by chemisorber at least 975 μ? t ??? ße CO per gram of catalyst per gram of noble metal during Cycle 2 of the static chemosorption analysis of carbon monoxide as described in protocol A. 65. - A process for oxidizing a substrate that is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde, and formic acid, the process comprising: contacting the substrate with an oxidizing agent in the presence of an oxidation catalyst according to any of claims 1 to 58. 66. - A method for preparing a catalyst comprising a first metal, a second metal, and a porous support with a surface comprising pores whose nominal diameter is within a predefined range and pores whose nominal diameter is outside the predefined range, the method comprises: disposing a pore-blocking agent within the pores of the porous support having a nominal diameter within the predefined range, wherein the pore-blocking agent has at least one dimension relative to the pore openings whose The nominal diameter is within the predefined range such that the pore-blocking agent is preferably retained within said pores; contacting the support with a first metal deposition bath comprising an aqueous medium and ions of the first metal, thereby depositing the first metal on the surface of the porous support within the pores having a nominal diameter outside the predefined range to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support between the pores whose nominal diameter is outside the predefined range; and contacting the catalyst precursor structure with a second metal deposition bath comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure. 67. - A method for preparing a catalyst comprising a first metal, a second metal, and a porous support with a surface comprising pores whose nominal diameter is within a predefined range and pores whose nominal diameter is outside the predefined range, the The method comprises: contacting the support and a first metal deposition bath comprising an aqueous medium, ions of the first metal, and a coordinating agent that forms a coordination compound with the first metal having at least one greater dimension than the nominal diameter of the pores within the predefined interval, thereby depositing the first metal on the surface of the support of the interior of the pores with a nominal diameter outside the predefined range to form a precursor structure of the catalyst having one or more regions of the first metal deposited on the surface of the support; and contacting the catalyst precursor structure with a second metal deposition bath comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure. 68. - A method for preparing a catalyst comprising a first metal, a second metal, and a porous carbon support, the method comprising: contacting the porous carbon support with a first metal deposition bath comprising ions of the first metal , thereby depositing the first metal on the surface of the porous carbon support to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support, where the first metal has an electropositive character greater than the electropositivity of the second metal; contacting the catalyst precursor structure with a second metal deposition bath comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure by displacing the first metal from one or more of said regions; and heating the catalyst precursor structure with the first and second metals deposited on the surface of the catalyst precursor structure to a temperature of at least about 500 ° C in an environment not oxidant 69. - A method for preparing a catalyst comprising a first metal, a second metal, and a porous carbon support, the method comprising: contacting the porous carbon support with a first metal deposition bath comprising ions of the first metal , thereby depositing the first metal on the surface of the porous carbon support to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support, where the carbon support has a surface area of Langmuir of at least about 500 m2 / g and the first metal has an electropositive character greater than the electropositivity of the second metal; and contacting the catalyst precursor structure with a second metal deposition bath comprising ions of the second metal, thereby depositing the second metal on the surface of the catalyst precursor structure by displacing the first metal from one or more of said regions. 70. - The method according to any of claims 66 to 69, further characterized in that the first metal deposition bath and the support are contacted in the absence of an externally applied voltage. 71. - The method according to any of claims 66 to 70, further characterized in that the support comprises a support of porous carbon, a porous alloy containing metal, silicon dioxide, aluminum oxide, zirconium oxide, titanium oxide, or a combination thereof. 72. The method according to claim 70 or 71, further characterized in that the support is in the form of a porous carbon support with a Langmuir surface area of at least about 500 m2 / g, at least about 750 m2 / g, at least about 1000 m2 / g, or at least about 1250 m2 / g. 73. - The method according to claim 72, further characterized in that the support is in the form of a porous carbon support with a surface area of Langmuir of between about 500 m2 / g and about 2100 m2 / g, between about 750 m2 / g and approximately 1900 m2 / g, between approximately 1000 m2 / g and approximately 1700 m2 / g, or between approximately 1250 m / g and approximately 1500 m2 / g. 74. - The method according to any of claims 71 to 73, further characterized in that the support is in the form of a porous carbon support with a pore volume of at least about 0.1 ml / g, at least about 0.2 ml / g, or at least about 0.4 ml / g. 75. - The method according to any of claims 71 to 73, further characterized in that the support is in the form of a porous carbon support with a volume of pore between about 0.1 and about 2.5 ml / g, between about 0.2 and about 2.0 ml / g, or between about 0.4 and about 1.5 ml / g. 76. - The method according to any of claims 66 to 75, further characterized in that the electropositivity of the first metal is greater than the electropositivity of the second metal. 77. The method according to any of claims 66 to 76, further characterized in that the first metal is selected from the group consisting of vanadium, tungsten, molybdenum, gold, osmium, iridium, tantalum, palladium, ruthenium, antimony, bismuth, arsenic, mercury, silver, copper, titanium, tin, lead, germanium, zirconium, cerium, nickel, cobalt, iron, chromium, zinc, manganese, aluminum, beryllium, magnesium, lithium, barium, cesium, and combinations thereof. 78. - The method according to claim 77, further characterized in that the first metal is selected from the group consisting of copper, tin, nickel, cobalt, and combinations thereof. 79. - The method according to claim 77, further characterized in that the first metal is selected from the group consisting of cobalt, copper, iron, and combinations thereof. 80. - The method according to any of claims 66 to 79, further characterized in that the first metal deposition bath comprises a source of the first metal that is selected from the group consisting of a sulphate of a first metal, nitrate of a first metal, chloride of a first metal, tartrate of a first metal, phosphate of a first metal, and combinations thereof. 81. - The method according to claim 80, further characterized in that the source of the first metal is present in the deposition bath in a concentration of at least about 1 g / l, at least about 2.5 g / l, or at least about 4 g / l. 82. - The method according to claim 80, further characterized in that the source of the first metal is present in the deposition bath in a concentration of between about 1 and about 20 g / l, between about 2.5 and about 12.5 g / l, or between about 4 and about 10 g / l. 83. - The method according to any of claims 66 to 82, further characterized in that the first metal deposition bath comprises a reducing agent selected from the group consisting of sodium hypophosphite, formaldehyde, formic acid, formic acid salts , borohydride salts, substituted borohydride salts, sodium alkoxides, hydrazine, ethylene glycol, and combinations thereof. 84. - The method according to claim 83, further characterized in that the reducing agent comprises formaldehyde. 85. - The method set forth in claim 83, further characterized in that the reducing agent comprises borohydride of sodium. 86. - The method set forth in claim 83, further characterized in that the reducing agent comprises ethylene glycol. 87. - The method according to any of claims 83 to 86, further characterized in that the reducing agent is present in the first metal deposition bath in a concentration of at least about 1 g / l, at least about 2 g / l, or at least about 5 g / l. 88. - The method according to any of claims 83 to 86, further characterized in that the reducing agent is present in the first metal deposition bath in a concentration of between about 1 and about 20 g / l, between about 2 and about 15 g / l, or between approximately 5 and approximately 10 g / l. 89. - The method according to any of claims 83 to 88, further characterized in that the weight ratio of reducing agent to the first metal in the first metal deposition bath is at least about 0.5: 1, or at least about eleven. 90. - The method according to claim 89, further characterized in that the weight ratio of reducing agent to the first metal in the first metal deposition bath is between about 0.5: 1 and about 5: 1, between about 1: 1 and about 3: 1, or between about 1: 1 and about 2: 1. 91. - The method according to any of claims 66 to 90, further characterized in that the first metal deposition bath and the support are brought into contact at a temperature of between about 10 ° C and about 50 ° C, or between about 20 ° C and approximately 45 ° C. 92. The method according to any of claims 66 to 91, further characterized in that the first metal deposition bath is agitated during said contact between the first metal deposition bath and the support. 93. - The method according to any of claims 66 to 92, further characterized in that the support and the first metal deposition bath are brought into contact in the presence of a non-oxidizing environment. 94. - The method according to any of claims 66 to 93, further characterized in that the first metal deposition bath comprises an alkali hydroxide which is selected from the group consisting of sodium hydroxide, potassium hydroxide, and combinations thereof . 95. - The method according to any of claims 66 to 94, further characterized in that the first metal comprises copper. 96. - The method according to claim 95, further characterized in that the first metal deposition bath comprises a copper source which is selected from the group consisting of the salts nitrate copper, copper sulfate, copper chloride, copper acetate, copper oxalate, copper formate, and combinations thereof. 97. - The method according to claim 95 or 96, further characterized in that the copper is present in the first metal deposition bath in a concentration of at least about 0.25 g / l, at least about 1 g / l, at least about 2 g / l, or at least about 3 g / l. 98. - The method according to claim 95 or 96, further characterized in that the copper is present in the first metal deposition bath in a concentration of between about 0.25 and about 15 g / l, between about 1 and about 12 g / l. l, or between approximately 2 and approximately 10 g / l. 99. The method according to any of claims 66 to 98, further characterized in that the first metal deposition bath has a pH greater than about 8, greater than about 9, or greater than about 10. 100. - The method according to any of claims 66 to 98, further characterized in that the first metal deposition bath has a pH between about 8 and about 13, or between about 9 and about 12. 101. - The method of compliance with any of the claims 66 to 94, further characterized in that the first metal comprises iron. 102. - The method according to claim 101, further characterized in that the first metal deposition bath comprises an iron source which is selected from the group consisting of the salts nitrate, sulfate, chloride, acetate, oxalate, and formate, and combinations thereof. 103. The method set forth in claim 101 or 102, further characterized in that the iron is present in the deposition bath in a concentration of between about 2 and about 8 g / l, more preferably between about 3 and about 6 g / l. and, even more preferably, between about 4 and about 5 g / l. 104. - The method according to any of claims 66 to 103, further characterized in that the first metal deposition bath comprises a coordinating agent that forms a coordination compound with the first metal. 105. The method according to claim 104, further characterized in that the coordinating agent comprises a sugar, polyol, Rochelle salt, acid, amine, citrate, or a combination thereof. 106. - The method according to claim 104, further characterized in that the coordinating agent comprises a compound which is selected from the group consisting of sucrose, sorbitol, mannitol, xylitol, Rochelle salts (potassium and sodium tartrates), ethylenediaminetetraacetic acid (EDTA), N-hydroxyethylethylenediaminetetraacetic acid (HEDTA), nitrilotriacetic acid (NTA),? ,?,? ',?' - tetrakis (2-hydroxypropyl) ethylenediamine, and combinations thereof. 107. - The method according to any of claims 104 to 106, further characterized in that the coordinating agent is present in the first metal deposition bath in a concentration of at least about 10 g / l, at least about 20 g / l, or at least about 30 g / l. 108. - The method according to any of claims 104 to 106, further characterized in that the coordinating agent is present in the first metal deposition bath in a concentration of between about 10 g / l and about 115 g / l, between about 25 g / l and approximately 100 g / l, or between approximately 40 g / l and approximately 85 g / l. 109. - The method according to any of claims 66 to 108, further characterized in that the second metal is deposited on the surface of the catalyst precursor structure by displacement of ions of the first metal of the one or more regions of the first metal deposited in the surface of the support. 110. - The method according to any of claims 66 to 109, further characterized in that the structure Catalyst precursor is subjected to temperatures not higher than about 200 ° C, not higher than 150 ° C, or not higher than 120 ° C before contact with the second metal deposition bath. 111. - The method according to any of claims 66 to 110, further characterized in that the precursor structure of the catalyst and the second metal deposition bath are brought into contact at a temperature of at least about 5 ° C, at least about 10 ° C, or at least about 15 ° C. 112. - The method according to any of claims 66 to 111, further characterized in that the precursor structure of the catalyst and the second metal deposition bath are brought into contact at a temperature between about 10 ° C and about 60 ° C, between about 20 ° C and about 50 ° C, or between about 25 ° C and about 45 ° C. 113. - The method according to any of claims 66 to 112, further characterized in that the second metal deposition bath has a pH lower than the pH of the first metal deposition bath. 114. - The method according to any of claims 66 to 113, further characterized in that the second metal deposition bath has a pH of between about 1 and about 12, between about 1.5 and about 10, between about 2 and about 7, between approximately 3 and about 5, between about 4 and about 9, or between about 5 and about 8. 115. - The method according to any of claims 66-114, further characterized in that the second metal is selected from the group consisting of vanadium, tungsten, molybdenum, gold, osmium, iridium, tantalum, palladium, ruthenium, antimony, bismuth, arsenic, mercury, silver, copper, titanium, tin, lead, germanium, zirconium, cerium, nickel, cobalt, iron, chromium, zinc, manganese, aluminum, beryllium, magnesium, lithium, barium, cesium, and combinations thereof. 116. - The method according to any of claims 66 to 115, further characterized in that the second metal is a noble metal that is selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, silver, osmium, gold, and combinations thereof. 117 -. 117. The method according to claim 115, further characterized in that the second metal deposition bath comprises two noble metals. 118. - The method according to claim 115, further characterized in that the second metal deposition bath comprises platinum and palladium or platinum and gold. 119. - The method according to any of claims 115 to 118, further characterized in that the second metal deposition comprises a source of noble metal that provides ions of noble metal with an oxidation state of +2. 120. - The method according to claim 115, further characterized in that the noble metal comprises platinum. 121. - The method according to claim 120, further wherein the second metal deposition bath comprises a source of platinum selected from the group consisting of H2PtCI4, H2PtCI6, K2PtCI4, Na2PtCI4, and combinations thereof. 122. The method according to claim 120, further characterized in that the second metal deposition bath comprises a platinum source that supplies platinum ions with an oxidation state of +2. 123. - The method according to any of claims 66 to 122, further characterized in that the molar ratio between the ions of the first metal of the first metal deposition bath and the ions of the second metal in the second metal deposition bath is at least about 1, at least about 2, at least about 3, or at least about 5. 124. - The method according to any of claims 66 to 122, further characterized in that the molar ratio between the ions of the first metal of the first metal deposition bath and the ions of the second metal in the second noble metal deposition bath is between approximately 1 and approximately 20, between approximately 2 and about 15, between about 3 and about 10, or between about 5 and about 7.5. 125. - The method according to any of claims 66 to 124, further characterized in that the contact between the precursor structure of the catalyst and the second metal deposition bath provides a precursor structure of the catalyst with the second metal deposited on the surface of the or more regions of the first metal deposited on the surface of the support. 126. - The method according to any of claims 66 to 125, further characterized in that the proportion in atoms of the first metal to the second metal of the catalyst precursor structure impregnated with the first and second metals is at least about 1.5, at least about 2, at least about 3, at least about 4, or at least about 5. 127. - The method according to any of claims 66 to 125, further characterized in that the proportion in atoms of the first metal to the second metal of the catalyst precursor structure impregnated with the first and second metals is between about 1.5 and about 10, between about 2 and about 8, between about 3 and about 6, or between about 4 and about 5. 128. - The method of compliance with any of the claims 66 to 127, further characterized in that the second metal is deposited on the surface of the catalyst precursor structure in the form of a layer of atoms of the second metal with a thickness of not more than about 5 atoms of the second metal, not greater than about 4 atoms of the second metal, no greater than about 3 atoms of the second metal, no greater than about 2 atoms of the second metal, or no greater than about 1 atom of the second metal. 129. - The method according to any of claims 66 to 128, further characterized in that it further comprises heating the surface of the catalyst precursor structure with the first and second metals deposited thereon to a temperature of at least about 500 ° C, at least about 600 ° C, at least about 700 ° C, at least about 800 ° C, at least about 850 ° C, at least about 900 ° C, or at least about 950 ° C in a non-oxidizing environment. 130. - The method according to any of claims 66 to 128, further characterized in that it further comprises heating the surface of the precursor structure of the catalyst impregnated with the first and the second metal to a temperature of between about 500 ° C and about 1200 ° C. , between approximately 600 ° C and approximately 1200 ° C, between approximately 700 ° C and about 1200 ° C, between about 8 ° C and about 1200 ° C, between about 850 ° C and about 1200 ° C, between about 900 ° C and about 1200 ° C, between about 900 ° C and about 100 ° C, or between about 925 ° C and about 975 ° C in a non-oxidizing environment. 131. - The method according to any of claims 66 to 128, further characterized in that the first metal is iron and the second metal is platinum, wherein the process further comprises heating the catalyst precursor structure to a temperature of between about 400 ° C and about 750 ° C, or between about 500 ° C and about 650 ° C. 132. - A method for preparing a catalyst comprising a first metal, a noble metal, and a porous support, the method comprising: contacting the support and a first metal deposition bath comprising an aqueous medium, ions of the first metal and a coordinating agent that forms a coordination compound with the first metal, thereby depositing the first metal on the surface of the support to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support, where the first metal has an electropositive character greater than the electropositivity of the noble metal; and contacting the catalyst precursor structure with a noble metal deposition bath comprising ions of the noble metal, thereby depositing the noble metal on the surface of the parent structure of the catalyst. catalyst by displacement of the first metal from one or more of said regions. 133. - A method for preparing a catalyst comprising a first metal, a noble metal, and a porous support with a surface comprising pores whose nominal diameter is within a predefined range and pores whose nominal diameter is outside the predefined range, the The method comprises: contacting the support and a first metal deposition bath comprising an aqueous medium, ions of the first metal and a coordinating agent which forms a coordination compound with the first metal having at least one dimension greater than the nominal diameter of the pores within the predefined range, thereby depositing the first metal on the support surface of the interior of the pores with a nominal diameter outside the predefined range to form a catalyst precursor structure having one or more regions of the first deposited on the surface of the support, and contact the precursor structure of the catalyst with a noble metal deposition bath comprising ions of the noble metal, thereby depositing the noble metal on the surface of the catalyst precursor structure. 134. - A method for preparing a catalyst comprising a first metal, a noble metal, and a porous support, the method comprising: contacting the support with a first metal deposition bath comprising an aqueous medium and ions of the first metal, depositing from that the first metal on the surface of the support to form a catalyst precursor structure having one or more regions of the first metal deposited on the surface of the support, wherein the first metal has an electropositive character greater than the electropositivity of the noble metal; and contacting the catalyst precursor structure with a noble metal deposition bath comprising ions of the noble metal, thereby depositing the noble metal on the surface of the catalyst precursor structure by displacing the first metal from one or more of said regions, wherein substantially all the noble metal is deposited by said displacement; or the noble metal ions consist essentially of noble metal ions with an oxidation number 2. 135. - A method for preparing a catalyst comprising a first metal, a noble metal, and a porous support, the method comprising: contacting the support with a first metal deposition bath comprising an aqueous medium, ions of the first metal, and a pore-blocking agent, thereby providing the pore-blocking agent within the pores of the substrate with a nominal diameter within a predefined range, wherein the pore blocking agent has at least one dimension relative to the pore opening of the predefined range which is sufficient for the pore-blocking agent to be preferably retained within said pores, and to deposit the first metal on the surface of the support within pores with a nominal diameter outside the predefined range, thereby forming a precursor structure of the catalyst having one or more regions of the first metal deposited on the surface of the support, where the first metal has an electropositive character greater than the electropositivity of the noble metal; and contacting the catalyst precursor structure with a noble metal deposition bath comprising ions of the noble metal, thereby depositing the noble metal on the surface of the catalyst precursor structure by displacing the first metal from one or more of the regions. 136. - The method according to any of claims 132 to 135, further characterized in that the first metal deposition bath and the support are contacted in the absence of an externally applied voltage. 137. - The method according to any of claims 132 to 136, further characterized in that the support comprises a support of porous carbon, a porous alloy containing metal, silicon dioxide, aluminum oxide, zirconium oxide, titanium oxide, or a combination of them. 138. - The method according to claim 136 or 137, further characterized in that the support is in the form of a porous carbon support with a surface area of Langmuir of at least about 500 m2 / g, at least about 750 m2 / g, at least about 1000 m2 / g, or at least about 1250 m2 / g. 139. - The method according to claim 138, further characterized in that the support is in the form of a porous carbon support with a Langmuir surface area of between about 500 m2 / g and about 2100 m2 / g, between about 750 m2 / g and about 1900 m2 / g, between about 1000 m2 / g and approximately 1700 m2 / g, or between approximately 1250 m2 / g and approximately 1500 m2 / g. 140. - The method according to any of claims 137 to 139, further characterized in that the support is in the form of a porous carbon support with a pore volume of at least about 0.1 ml / g, at least about 0.2 ml / g, or at least about 0.4 ml / g. 141. - The method according to any of claims 137 to 139, further characterized in that the support is in the form of a porous carbon support with a pore volume of between about 0.1 and about 2.5 ml / g, between about 0.2 and about 2.0 ml / g, or between about 0.4 and about 1.5 ml / g. 142. The method according to any of claims 132 to 141, further characterized in that the electropositivity of the first metal is greater than the electropositivity of the noble metal. 143. - The method according to any of claims 132 to 142, further characterized in that the first metal is selected from the group consisting of vanadium, tungsten, molybdenum, gold, osmium, iridium, tantalum, palladium, ruthenium, antimony, bismuth, arsenic, mercury, silver, copper, titanium, tin, lead, germanium, zirconium, cerium, nickel, cobalt, iron, chromium, zinc, manganese, aluminum, beryllium, magnesium, lithium, barium, cesium, and combinations thereof. 144. - The method according to claim 143, further characterized in that the first metal is selected from the group consisting of copper, tin, nickel, cobalt, and combinations thereof. 145. - The method according to claim 143, further characterized in that the first metal is selected from the group consisting of cobalt, copper, iron, and combinations thereof. 146. - The method according to any of claims 132 to 145, further characterized in that the first metal deposition bath comprises a source of the first metal that is selected from the group consisting of a sulphate of a first metal, nitrate of a first metal, chloride of a first metal, tartrate of a first metal, phosphate of a first metal, and combinations thereof. 147. - The method according to claim 146, further characterized in that the source of the first metal is present in the deposition bath at a concentration of at least about 1 g / l, at least about 2.5 g / l, or at least about 4 g / l. 148. - The method according to claim 146, further characterized in that the source of the first metal is present in the deposition bath in a concentration of between about 1 and about 20 g / l, between about 2.5 and about 12.5 g / l, or between about 4 and about 10 g / l. 149. - The method according to any of claims 132 to 148, further characterized in that the first metal deposition bath comprises a reducing agent selected from the group consisting of sodium hypophosphite, formaldehyde, formic acid, formic acid salts , borohydride salts, substituted borohydride salts, sodium alkoxides, hydrazine, and combinations thereof. 150. - The method according to claim 149, further characterized in that the reducing agent comprises formaldehyde. 151. - The method according to claim 149 or 150, further characterized in that the reducing agent is present in the first metal deposition bath in a concentration of at least about 1 g / l, at least about 2 g / l. , or at least about 5 g / l. 152. The method according to claim 149 or 150, further characterized in that the reducing agent is present in the first metal deposition bath in a concentration of between about 1 and about 20 g / l, between about 2 and about 15 g / l, or between approximately 5 and approximately 10 g / i- 153. - The method according to any of claims 149 to 152, further characterized in that the weight ratio of reducing agent to the first metal in the first metal deposition bath is at least about 0.5: 1, or at least about eleven. 154. The method according to any of claims 149 to 152, further characterized in that the weight ratio of reducing agent to the first metal in the first metal deposition bath is between about 0.5: 1 and about 5: 1, between about 1: 1 and approximately 3: 1, or between approximately 1: 1 and approximately 2: 1. 155. - The method according to any of claims 132 to 154, further characterized in that the first metal deposition bath and the support are brought into contact at a temperature of between about 10 ° C and about 50 ° C, or between about 20 ° C and approximately 45 ° C. 156. - The method according to any of claims 132 to 155, further characterized in that the first metal deposition bath is agitated during said contact between the first metal deposition bath and the support. 157. - The method according to any of claims 132 to 156, further characterized in that the support and the first metal deposition bath are brought into contact in the presence of a non-oxidizing environment. 158. The method according to any of claims 132 to 157, further characterized in that the first metal deposition bath comprises an alkali hydroxide which is selected from the group consisting of sodium hydroxide, potassium hydroxide, and combinations thereof . 159. - The method according to any of claims 132 to 158, further characterized in that the first metal comprises copper. 160. - The method according to claim 159, further characterized in that the first metal deposition bath comprises a copper source that is selected from the group consisting of the salts nitrate copper, copper sulfate, copper chloride, acetate copper, copper oxalate, copper formate, and combinations thereof. 161. - The method according to claim 159 or 160, further characterized in that the copper is present in the first metal deposition bath in a concentration of at least about 0.25 g / l, at least about 1 g / l, at least about 2 g / l, or at least about 3 g / l. 162. - The method according to claim 159 or 160, further characterized in that the copper is present in the first metal deposition bath in a concentration of between about 0.25 and about 15 g / l, between about 1 and about 12 g / l, or between approximately 2 and approximately 10 g / l. 163. - The method according to any of claims 132 to 162, further characterized in that the first metal deposition bath has a pH greater than about 8, greater than about 9, or greater than about 10. 164. - The method according to any of claims 132 to 162, further characterized in that the first metal deposition bath has a pH of between about 8 and about 13, between about 9 and about 12. 165. - The method according to any of claims 132 to 164, further characterized in that the first metal deposition bath comprises a coordinating agent that forms a coordination compound with the first metal. 166. - The method according to claim 165, further characterized in that the coordinating agent comprises a sugar, polyol, Rochelle salt, acid, amine, citrate, or a combination thereof. 167. - The method according to claim 165, further characterized in that the coordinating agent comprises a compound selected from the group consisting of sucrose, sorbitol, mannitol, xylitol, Rochelle salts (potassium and sodium tartrates), ethylenediaminetetraacetic acid ( EDTA), N-hydroxyethylenediaminetetraacetic acid (HEDTA), nitrilotriacetic acid (NTA),?,?,? ',?' - tetrakis (2- hydroxypropyl) ethylenediamine, and combinations thereof. 168. - The method according to any of claims 165 to 167, further characterized in that the coordinating agent is present in the first metal deposition bath in a concentration of at least about 10 g / l, at least about 20 g / l, or at least about 30 g / l. 169. - The method according to any of claims 165 to 167, further characterized in that the coordinating agent is present in the first metal deposition bath in a concentration of between about 10 g / l and about 115 g / l, between about 25 g / l and approximately 100 g / l, or between approximately 40 g / l and approximately 85 g / l. 170. - The method according to any of claims 132 to 169, further characterized in that the noble metal is deposited on the surface of the catalyst precursor structure by displacement of ions of the first metal of the one or more regions of the first metal deposited in the surface of the support. 171. - The method according to any of claims 132 to 170, further characterized in that the precursor structure of the catalyst is subjected to temperatures not higher than approximately 200 ° C, not higher than 150 ° C, or not higher than 120 ° C before contact with the noble metal deposition bath. 172. - The method of compliance with any of the claims 132 to 171, further characterized in that the catalyst precursor structure and the noble metal deposition bath are contacted at a temperature of at least about 5 ° C, at least about 10 ° C, or at least about 15 ° C. 173. - The method according to any of claims 132 to 172, further characterized in that the precursor structure of the catalyst and the noble metal deposition bath are brought into contact at a temperature of between about 10 ° C and about 60 ° C, between about 20 ° C and about 50 ° C, or between about 25 ° C and about 45 ° C. 174. The method according to any of claims 132 to 173, further characterized in that the noble metal deposition bath has a pH lower than the pH of the first metal deposition bath. 175. - The method according to any of claims 132 to 174, further characterized in that the noble metal deposition bath has a pH of between about 1 and about 12, between about 1.5 and about 10, between about 2 and about 7, between about 3 and about 5, between about 4 and about 9, or between about 5 and about 8. 176. - The method according to any of claims 132 to 175, further characterized in that the noble metal that it is selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, silver, osmium, gold, and combinations thereof. 177. - The method according to claim 176, further characterized in that the noble metal deposition bath comprises two noble metals. 178. - The method according to claim 176, further characterized in that the noble metal deposition bath comprises platinum and palladium or platinum and gold. 179. The method according to any of claims 176 to 178, further characterized in that the noble metal deposition comprises a source of noble metal that provides noble metal ions with an oxidation state of +2. 180. - The method according to claim 176, further characterized in that the noble metal comprises platinum. 181. The method according to claim 180, further characterized in that the noble metal deposition bath comprises a platinum source which is selected from the group consisting of H2PtCl4, H2PtCl6, I ^ PtCU, ^ PtCU, and combinations thereof . 182. The method according to claim 180, further characterized in that the noble metal deposition bath comprises a platinum source that provides platinum ions with an oxidation state of +2. 183. - The method according to any of claims 132 to 182, further characterized in that the molar ratio between the ions of the first metal of the first metal deposition bath and the noble metal ions of the noble metal deposition bath is therefore less about 1, at least about 2, at least about 3, or at least about 5. 184. - The method according to any of claims 132 to 182, further characterized in that the molar ratio between the ions of the first metal of the first metal deposition bath and the noble metal ions of the noble metal deposition bath is between about 1 and about 20, between about 2 and about 15, between about 3 and about 10, or between about 5 and about 7.5. 185. - The method according to any of claims 132 to 184, further characterized in that the contact between the catalyst precursor structure and the noble metal deposition bath provides a catalyst precursor structure with noble metal deposited on the surface of the one or more regions of the first metal deposited on the surface of the support. 186. - The method according to any of claims 132 to 185, further characterized in that the proportion in atoms between the first metal and the noble metal of the precursor structure of the catalyst impregnated with the first metal and the noble metal is therefore less about 1.5, at least about 2, at least about 3, at least about 4, or at least about 5. 187. - The method according to any of claims 132 to 185, further characterized in that the proportion in atoms between the first metal and the noble metal of the catalyst precursor structure impregnated with the first metal and the noble metal is between about 1.5 and about 10, between about 2 and about 8, between about 3 and about 6, or between about 4 and about 5. 188. - The method according to any of claims 132 to 187, further characterized in that the noble metal is deposited on the surface of the catalyst precursor structure in the form of a layer of noble metal atoms with a thickness not greater than about 5. atoms, no more than about 4 atoms of the second metal, no more than about 3 atoms of the second metal, or about 2 atoms, or 1 atom. 189. - The method according to any of claims 132 to 188, further characterized in that it further comprises heating the surface of the catalyst precursor structure with the first metal and the noble metal deposited thereon to a temperature of at least about 500 °. C, at least about 600 ° C, at least about 700 ° C, at least about 800 ° C, at least about 850 ° C, at least about 900 ° C, or at least about 950 ° C in a non-oxidizing environment. 190. - The method according to any of claims 132 to 188, further characterized in that it further comprises heating the surface of the precursor structure of the catalyst impregnated with the first metal and the noble metal up to a temperature between about 500 ° C and about 1200 °. C, between about 600 ° C and about 1200 ° C, between about 700 ° C and about 1200 ° C, between about 800 ° C and about 1200 ° C, between about 850 ° C and about 1200 ° C, between about 900 ° C C and about 1200 ° C, between about 900 ° C and about 100 ° C, or between about 925 ° C and about 975 ° C in a non-oxidizing environment. 191. - A method for preparing a catalyst comprising copper, platinum, and a porous carbon support, the method comprising: contacting the support with a copper deposition bath comprising copper ions and a coordinating agent in the absence of a voltage externally applied, thereby depositing copper on the surface of the porous carbon support to form a catalyst precursor structure with one or more regions of copper deposited on the surface of the support; and contacting the catalyst precursor structure and a platinum deposition bath comprising platinum ions, depositing in that way platinum on the surface of the catalyst precursor structure by copper displacement of one or more of said regions. 192. - A method for preparing a catalyst comprising copper, platinum, and a porous carbon support, the method comprising: contacting the support and a copper deposition bath comprising copper ions in the absence of an externally applied voltage, depositing thus copper on the surface of the carbon support to form a catalyst precursor structure with one or more copper regions deposited on the surface of the support, where the carbon support has a Langmuir surface area of at least about 500 m2 / g before the deposition of copper on it; and contacting the catalyst precursor structure and a platinum deposition bath comprising platinum ions, thereby depositing platinum on the surface of the catalyst precursor structure by displacement of copper from one or more of said regions. 193. - A method for preparing a catalyst comprising copper, platinum, and a porous carbon support, the method comprising: contacting the support and a copper deposition bath comprising copper ions in the absence of an externally applied voltage, depositing thereby copper on the surface of the carbon support to form a catalyst precursor structure with one or more regions of copper deposited on the surface of the support; contacting the catalyst precursor structure and a platinum deposition bath comprising platinum ions, thereby depositing platinum on the surface of the catalyst precursor structure by displacement of copper from one or more of said regions; and heating the surface of the catalyst precursor having platinum on the surface of the one or more copper regions to a temperature of at least about 500 ° C in a non-oxidizing environment. 194. - A process for oxidizing a substrate that is selected from the group consisting of N- (phosphonomethyl) iminodiacetic acid or a salt thereof, formaldehyde, and formic acid, the process comprising: contacting the substrate with an oxidizing agent in the presence of an oxidation catalyst prepared according to any of claims 66 to 193. 195. - The process according to any of claims 59 to 194, further characterized in that the substrate is N- (phosphonomethyl) iminodiacetic acid or a salt thereof. 196. - The process according to claim 195, further characterized in that said oxidation catalyst is effective to oxidize a by-product of formaldehyde and / or formic acid that is produced in the oxidation of N- (phosphonomethyl) iminodiacetic acid or a salt thereof. 197. - A method for treating a porous substrate for preparing a modified porous substrate with a smaller surface area that can be attributed to pores with a nominal diameter within a predefined range, the method comprising: arranging a pore-blocking agent within the interior of pores of the porous substrate with a nominal diameter within the predefined range, wherein the pore-blocking agent has at least one dimension relative to the opening of the pores with a nominal diameter within the predefined range that is sufficient for the blocking agent of pores is preferably retained within said pores. 198. - A method for treating a porous substrate with micropores and pores of larger diameter to prepare a modified porous substrate with a reduced micropore surface area, the method comprising: arranging a pore-blocking agent within the micropores of the porous substrate, wherein the agent The pore blocker has at least one dimension relative to the micropore openings such that the pore-blocking agent is preferably retained within said pores. 199. - A method for treating a porous substrate for preparing a modified porous substrate with a smaller surface area that can be attributed to pores with a nominal diameter within a predefined range, the method comprising: introducing a pore-blocking compound into the pores of the porous substrate, wherein the pore-blocking compound is susceptible to undergo a conformational change such that the pore-blocking compound is retained within the pores of the porous substrate with a diameter within the predefined range. 200. A method for treating a porous substrate with micropores and larger diameter pores to prepare a modified porous substrate with a reduced micropore surface area, the method comprises: pore-blocking compound inside the micropores of the porous substrate, wherein the pore-blocking compound is susceptible to undergo a conformational change such that the pore-blocking compound is retained within the micropores of the porous substrate. 201. A method for treating a porous substrate to prepare a modified porous substrate with a smaller surface area that can be attributed to pores with a nominal diameter within a predefined range, the method comprises: entering within the pores with a nominal diameter within from a predefined range, compounds capable of forming a pore-blocking compound having at least one dimension such that the pore-blocking compound is retained within the pores with a nominal diameter within a predefined range. 202. - A method for treating a porous substrate with micropores and pores of larger diameter to prepare a modified porous substrate with a reduced micropore surface area, the method comprising: introducing into the micropores of the substrate compounds capable of forming a pore-blocking compound that it has at least one dimension such that the pore-blocking compound is retained within the micropores. 203. - A method for treating a porous substrate with micropores and pores of larger diameter to prepare a modified porous substrate with a reduced micropore surface area, the method comprising: introducing a pore-blocking composition into the micropores of the porous substrate, wherein the composition pore blocker comprises a derivative substituted cyclohexane. 204. A method for preparing a catalyst comprising a metal on the surface of a porous substrate where the metal is preferably excluded from the pores of the porous substrate with a nominal diameter within a predefined range, the method comprising: (i) introducing one or more precursors of a pore-blocking compound within the pores of the porous substrate, where: at least one of the precursors of the pore-blocking compound is capable of undergoing a conformational change to form a pore-blocking compound that is retained in the interior of the pores of the porous substrate with a nominal diameter within the predefined range, or at least two precursors of the pore-blocking compound are capable of forming a pore-blocking compound having at least one dimension such that the pore-blocking compound remains retained within the pores of the porous substrate with a nominal diameter within a predefined range; (ii) preferably extract the pore-blocking compound from the pores of the porous substrate with a nominal diameter outside the predefined range for preparing a modified porous substrate with a smaller surface area that can be attributed to the pores with a nominal diameter within the predefined range; and (iii) contacting the surface of the modified porous substrate with a solution containing the metal. 205. - A porous substrate with a pore-blocking compound inside the pores of the porous substrate having a nominal diameter within a predefined range, the pore-blocking compound is retained within the pores with a nominal diameter within a predefined range because: the pore-blocking compound has at least one dimension greater than the pore openings with a nominal diameter within a predefined range, or the pore-blocking compound possesses a conformation that prevents the pore-blocking compound from leaving through pore openings with a nominal diameter within the predefined range. 206. - A porous substrate treated with a pore-blocking compound inside the micropores of the porous substrate, the surface area of the micropores of the treated substrate does not measure more than about 70% of the surface area of the micropores of the porous substrate before treatment . 207. - A porous substrate treated with a pore-blocking compound inside the micropores of the porous substrate, the pore-blocking compound is selected from the group consisting of the product of the condensation of a substituted cyclohexane derivative and a glycol, the product of the condensation of a di-substituted cyclohexane derivative and a glycol, and combinations thereof.
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Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102229621B (en) * 2011-05-07 2013-10-02 安徽国星生物化学有限公司 Method for preparing glyphosate by catalyzing and oxidizing glyphosine in the presence of ultraviolet light source
EP2771107A4 (en) * 2011-10-28 2015-09-02 Basf Se PROCESS FOR THE PREPARATION OF A SUPPORTED SILVER CATALYST
CN104437449A (en) * 2014-12-09 2015-03-25 黑龙江大学 Preparation method of black titanium dioxide visible light photocatalyst
CN107073448B (en) * 2015-08-14 2019-01-29 沙特基础工业全球技术公司 A method for the fabrication of metal clusters of desired dimensions using scanning tunneling microscopy tip-induced reactions
CN110339860B (en) * 2019-07-29 2022-03-01 湖北工程学院 Crosslinked norbornene copolymer composite carbon black three-dimensional network immobilized platinum nanocatalyst and its preparation method and application
JP7175857B2 (en) 2019-08-02 2022-11-21 日清紡ホールディングス株式会社 Metal-supported catalysts, battery electrodes and batteries
JP7130311B2 (en) 2019-08-02 2022-09-05 日清紡ホールディングス株式会社 Metal-supported catalysts, battery electrodes and batteries
JP7158350B2 (en) 2019-08-02 2022-10-21 日清紡ホールディングス株式会社 Metal-supported catalysts, battery electrodes and batteries
CN111054329A (en) * 2019-11-25 2020-04-24 广东工业大学 A kind of aluminum-supported precious metal monolithic catalyst and its preparation method and application
CN111430731A (en) * 2020-04-01 2020-07-17 安徽师范大学 Porous carbon-supported platinum material, preparation method and application thereof
CN112794508B (en) * 2021-01-05 2022-07-05 江山市双氧水有限公司 A kind of pretreatment method of producing hydrogen peroxide wastewater by anthraquinone method
CN113337719A (en) * 2021-06-07 2021-09-03 林西金易来砷业有限公司 Comprehensive utilization and harmless treatment process for arsenic-containing smoke dust
CN114177903B (en) * 2021-10-21 2025-06-06 江苏大学 A method for preparing microporous materials loaded with single-atom and diatomic catalysts
CN116272972B (en) * 2021-12-20 2025-05-27 中国石油化工股份有限公司 A dispersed catalyst for catalyzing methane to olefins, and its preparation method and application
CN114566661A (en) * 2022-03-09 2022-05-31 昆明理工大学 Preparation method of carbon material surface loaded with platinum-cobalt nanoparticles
CN114540889B (en) * 2022-03-25 2023-03-24 江阴纳力新材料科技有限公司 Copper plating additive, copper plating solution and application thereof
CN117065778B (en) * 2023-07-26 2025-06-27 浙江工业大学 A method for preparing a diatomic catalyst and a method for catalytic reforming of tar
CN117185909B (en) * 2023-08-30 2025-08-01 南京理工大学 Method for synthesizing 1, 2-diketone compound through surface coupling reaction
CN120115147B (en) * 2025-05-12 2025-07-29 中科鸿景(宁波)环保科技有限公司 High-activity platinum carbon catalyst, preparation method thereof and application thereof in formaldehyde catalytic purification

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1005249B (en) * 1985-04-01 1989-09-27 孟山都公司 Process for producing secondary or primary amines using pyrolyzed activated carbon catalyst
NZ265493A (en) * 1993-04-12 1996-10-28 Monsanto Co Preparation amino carboxylic acid salts from amino alcohols using an alkali metal hydroxide and a copper catalyst
US6417133B1 (en) * 1998-02-25 2002-07-09 Monsanto Technology Llc Deeply reduced oxidation catalyst and its use for catalyzing liquid phase oxidation reactions
JP2003518132A (en) * 1999-12-21 2003-06-03 モンサント テクノロジー エルエルシー Use of accelerators in combination with carbon-supported noble metal-containing catalysts in liquid phase oxidation reactions.
US8703639B2 (en) * 2004-09-15 2014-04-22 Monsanto Technology Llc Oxidation catalyst and its use for catalyzing liquid phase oxidation reactions
WO2008025750A1 (en) * 2006-08-30 2008-03-06 Umicore Ag & Co. Kg Core/shell-type catalyst particles and methods for their preparation

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