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WO2025087895A1 - Utilisation de mailles en métal noble pour l'oxydation de l'ammoniac - Google Patents

Utilisation de mailles en métal noble pour l'oxydation de l'ammoniac Download PDF

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Publication number
WO2025087895A1
WO2025087895A1 PCT/EP2024/079811 EP2024079811W WO2025087895A1 WO 2025087895 A1 WO2025087895 A1 WO 2025087895A1 EP 2024079811 W EP2024079811 W EP 2024079811W WO 2025087895 A1 WO2025087895 A1 WO 2025087895A1
Authority
WO
WIPO (PCT)
Prior art keywords
meshes
nets
precious metal
use according
wires
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2024/079811
Other languages
German (de)
English (en)
Inventor
Dirk Born
Dieter Prasch
Sait OEZTAS
Artur WISER
Marco Schoepp
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Umicore AG and Co KG
Original Assignee
Umicore AG and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Umicore AG and Co KG filed Critical Umicore AG and Co KG
Publication of WO2025087895A1 publication Critical patent/WO2025087895A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/24—Nitric oxide (NO)
    • C01B21/26—Preparation by catalytic or non-catalytic oxidation of ammonia
    • C01B21/265—Preparation by catalytic or non-catalytic oxidation of ammonia characterised by the catalyst
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/42—Platinum
    • 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
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/58—Fabrics or filaments
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/24—Nitric oxide (NO)
    • C01B21/26—Preparation by catalytic or non-catalytic oxidation of ammonia
    • C01B21/267—Means for preventing deterioration or loss of catalyst or for recovering lost catalyst
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/38—Nitric acid

Definitions

  • the present invention relates to the use of certain precious metal meshes in the oxidation of ammonia to nitrogen oxides.
  • the precious metal meshes used are characterized by a specific mesh density.
  • the precious metal meshes are advantageously used in high-pressure systems.
  • noble metal catalysts in the form of gas-permeable spatial structures on or in which the reaction takes place.
  • Meshes in the form of woven fabrics (DE4028916C2), knitted fabrics (DE4300791A1; EP606535A1), or knitted fabrics (EP364153B1, DE4206199C1) made of fine precious metal wires have been widely used for some time.
  • the catalyst meshes are typically arranged in a flow reactor in a plane perpendicular to the flow direction of the gas mixture. Conical arrangements are also known. It is advisable to arrange several meshes one behind the other and combine them into a mesh stack.
  • reaction gas or fresh gas (ammonia-air mixture with an ammonia content of 9 - 13 vol.%) flows through the mesh stack under atmospheric or elevated pressure, with the ignition of the gas mixture taking place in the inlet area and the combustion reaction to nitrogen monoxide (NO) and water covering the entire reaction zone:
  • the NO2 in turn reacts with water in a downstream absorption to form nitric acid, which is used in fertilizer production, for example:
  • Precious metal wires made of platinum, rhodium, or alloys of these metals with other precious or base metals are used to manufacture the precious metal meshes.
  • Typical alloys are platinum-rhodium or platinum-palladium-rhodium alloys containing 88 to 98 wt.% platinum. Platinum is required to achieve the highest possible ammonia conversion. Rhodium improves the selectivity to NO, thereby reducing nitrous oxide emissions, and increases the mechanical strength of the meshes (G. R. Maxwell: "Synthetic Nitrogen Products - A Practical Guide to the Products and Processes", Springer Science + Business Media, Inc. 2005, page 220). Palladium, in turn, is used to reduce precious metal loss by forming more stable alloys and, depending on current precious metal prices, to reduce precious metal costs by replacing less platinum.
  • US5266293A describes a knitted precious metal fabric in which the precious metal is selected from platinum group metals, gold, silver, and alloys thereof.
  • the aforementioned DE4206199C1 relates to a process for producing gas-permeable nets made of precious metals for the catalytic oxidation of ammonia.
  • Precious metal nets obtained by knitting wires are used, whereby the wires consist of platinum-rhodium alloys with 4 to 12 wt.% rhodium or wires of platinum-palladium-rhodium alloys with 4 to 12 wt.% palladium and rhodium.
  • the diameters of the wires range from 50 to 120 ⁇ m. They can preferably be produced on flat knitting machines, with the pitch (spacing of the needles on the flat knitting machine) being between 3.63 mm and 1.81 mm and the mesh length between 2 and 6 mm. Multi-layer nets can also be advantageously used for the oxidation reaction under consideration (EP680787A1).
  • WO2004096702A2 proposes a process for ammonia oxidation in which different chemical compositions of the precious metal meshes within the mesh stack are intended to lead to lower nitrous oxide production.
  • mesh stacks are used in which the meshes facing the fresh gas contain a platinum alloy richer in rhodium than the meshes facing the exhaust gas.
  • the aforementioned EP364153B1 describes knitted precious metal nets for ammonia oxidation. These can have mesh sizes of 10–30 meshes per inch. Mesh sizes of 19 meshes per inch were achieved using circular knitting machines. However, for the tests in so-called high-pressure systems, nets with a mesh size of 10x12 meshes per inch were used.
  • N2O nitrous oxide
  • the mesh density is at least 16, preferably up to 18 meshes/inch, which can further improve conversion due to the higher catalytically active surface area and further reduce selectivity to N2O.
  • the risk of wire breakage during the knitting process increases due to the tight bending radius, or the risk of needle heads breaking off because their material thickness can no longer meet the required specifications.
  • the stitch density refers to the number of stitches per length within a row of stitches.
  • the unit commonly used is [stitches/inch]. In this text, this always refers to the number of stitches per length within a row of stitches. This number is equivalent to the number of needles in a knitting machine, provided each of these needles is actually involved in the knitting process.
  • Knitted precious metal nets have several advantages over woven precious metal nets, which is why they are preferred in industrial applications today. On the one hand, knitting technology offers the possibility of a high degree of flexibility with regard to knitting patterns, wire thicknesses used and resulting surface weight. On the other hand, precious metal knits can be produced more economically, as knitting technology requires shorter setup times than weaving technology. This results in a significantly reduced precious metal binding during production.
  • precious metal nets of any length can be produced on flat knitting machines.
  • the number of stitches in ammonia production was typically 12 stitches/inch (e.g. DE4206199C1).
  • the precious metal net according to the invention is preferably produced on a flat knitting machine.
  • the advantage of the flat knitting machine is the short setup time and the associated flexibility with regard to wire thickness, alloy and knit structure.
  • the use of the flat knitting machine is recognizable in the end product due to the stitch shape.
  • the precious metal meshes used for the present ammonia oxidation are well known to those skilled in the art. Generally, gold, silver, and the platinum group metals (Ru, Rh, Pd, Os, Ir, Pt) are considered precious metals in this context.
  • the present meshes comprise platinum and rhodium. It has proven advantageous to use an alloy of these two metals.
  • one or more wires made of a precious metal alloy comprising platinum and rhodium are used, wherein the alloy preferably comprises 80 to 98% by weight platinum and 2 to 20% by weight rhodium, more preferably 90 to 98% by weight platinum and 2 to 10% by weight rhodium.
  • the alloy is further preferably selected from the group consisting of PtRh5, PtRh8, PtRhIO, PtRh5Pd5, PtRh3, PtRh2, PtRh3.5Pd21.5, and PtRh3.5Pd80.
  • the numbers in the formula indicate the respective weight percentage of the component preceding the number. If there is no number following a precious metal element, the proportion of this precious metal is the remainder of the composition.
  • the wires of the meshes used here have a specific thickness. Firstly, they must not be too thin, as they would otherwise tear easily; secondly, they should not be too thick, as otherwise the ratio of surface area to the amount of precious metal becomes too unfavorable for the catalytic reaction. It has proven advantageous for the mesh wires used to have a thickness of > 60 pm and ⁇ 125 pm, more preferably 70-100 pm, and most preferably 70-90 pm.
  • high-pressure systems for ammonia oxidation are understood to mean systems that operate at a pressure of 700-1500 kPa, preferably 700-1300 kPa, and most preferably 700-1000 kPa.
  • Medium-pressure systems are characterized by a pressure of less than 700 kPa. High-pressure systems have the advantage over medium-pressure systems that they require lower investment costs while maintaining the same production capacity.
  • Flat knitting machines are preferably used for knitting precious metal nets (DE4206199C1).
  • the flat knitting machine preferably has a front and a rear needle bed into which the latch needles are installed.
  • the latch needles move through different positions depending on the machine's programming. The programming therefore determines the structure of the knitted fabric.
  • a special feature of the flat knitting machine compared to other fabric-forming machines is that knitted fabrics can be formed synchronously on both the front and rear needle beds, independently of each other (single-bedded fabric). If these two knitted fabrics are knitted together using pile threads during the knitting process, the newly created knitted fabric is a double-bedded fabric.
  • spacer knits double-bedded fabric
  • the thread alternately forms stitches or tucks at the front and back (EP1358010B2).
  • the knitted fabric is knitted downwards between the two needle beds. This is particularly preferred if the precious metal nets are knitted in two layers.
  • three-dimensional meshes preferably consist of two mesh layers, with the meshes of the individual layers connected by one or more pile threads.
  • the use of three-dimensional precious metal meshes allows the reaction zone to be enlarged.
  • a two-layer net can be knitted, with the net layers being joined at only one or both edges. If the net is joined at one edge, the resulting net can be unfolded. This creates a single-layer net twice as large in a single knitting process. Two-layer nets joined at both edges can form tubes. These are easier to manufacture than nets joined at one edge. Therefore, it may be advantageous for the present application to use nets joined at one or both edges and/or between them by connecting stitches.
  • a mesh stack contains 5-35, more preferably 7-30, and most preferably 8-20 precious metal meshes in a packed state. Additional auxiliary meshes, such as separation and getter meshes, are also used (see explanation below).
  • the individual precious metal meshes within the mesh stack have a certain structure.
  • a different sequence of precious metal meshes with different compositions can be used along the gas flow direction.
  • the meshes facing the fresh gas have a more rhodium-rich composition than the meshes on the side facing the exhaust gas.
  • the meshes facing the fresh gas have an alloy of, for example, PtRh8, whereas the meshes facing the exhaust gas have a composition of, for example, PtRh5.
  • mesh stack it may be useful for the mesh stack to use meshes that are 10% - 50%, preferably 30% - 40% richer in rhodium and 90% - 50%, preferably 70% - 60% poorer in rhodium. It is still preferred to place 6 precious metal nets with the lower-rhodium alloy and up to 6 nets, preferably 2-4, with the higher-rhodium alloy in the net stack. More preferably, 4 higher-rhodium and 4 lower-rhodium nets are installed.
  • Nets with the following compositions have proven particularly effective: PtRh1-10Pd20-90, more preferably PtRh2-7Pd40-85, and very preferably PtRh3-5Pd50-85.
  • PtRh1-10Pd20-90 Preferably, 2-10 of these nets are used in the net stack, more preferably 3-8 and most preferably 4-6.
  • a different design of the precious metal nets in the net stack can also make sense with regard to the basis weight.
  • the basis weights (g/cm 2 ) of the meshes facing the fresh gas are greater than the basis weights of the meshes on the exhaust gas side.
  • the constellations of the precious metal meshes can preferably correspond to those just mentioned.
  • the basis weight of the first precious metal mesh facing the fresh gas is in this case in relation to the basis weight of the last precious metal mesh facing the exhaust gas in a ratio of 3 - 1, preferably 2.5 - 1 and very preferably 1.5 - 1. In areas where the Pt removal is increased, i.e.
  • One or more of the precious metal meshes can consist of a single wire.
  • the mesh(es) can also be constructed from wires consisting of multiple individual wires.
  • the wires of the precious metal mesh can, for example, be constructed as a sheathed wire and consist of a core and one or more sheathed wires arranged radially symmetrically one above the other from the core. Reference is made in this regard to the explanations in EP3900826A1.
  • the wire of the precious metal mesh(es) can consist of twisted individual wires. It is advantageous if the wires are constructed of twisted individual wires comprising an arrangement of n interwoven individual wires, where n is an integer with 2 ⁇ n ⁇ 8. Reference is made in this regard to the explanations in EP3523024A1.
  • the precious metal meshes are used in a mesh stack in the flow reactor.
  • the flow reactor is the reactor that ensures that the reaction gas is passed over the mesh stack installed within it.
  • One or more precious metal meshes are preferably followed by getter meshes and, if necessary, separation meshes.
  • Precious metal meshes are those meshes whose catalytic activity is used for the conversion of ammonia with oxygen.
  • Getter meshes are those meshes installed in the reaction gas flow downstream of the catalyst meshes to capture volatile platinum oxide for recycling by alloying with, for example, the palladium in the getter meshes, thus minimizing platinum loss. Volatile rhodium can also be captured to a certain extent in this way and subsequently recycled.
  • Separation meshes are preferably meshes made of, for example, high-temperature-resistant steel, which are installed between the precious metal meshes to prevent the precious metal meshes from sintering together.
  • Getter meshes for example, consist of an alloy comprising 90 to 98 wt% palladium and 2 to 10 wt% nickel. Other compositions have also been proposed (e.g., EP216493A1). Depending on requirements, support meshes made of high-temperature-resistant steel—so-called separation meshes—can be installed in or below the catalytic precious metal mesh stack or in or below the getter mesh stack to increase the long-term stability of the mesh stack.
  • This arrangement allows the mesh stack, if installed in a flow reactor with the fresh gas side as the inlet and the exhaust gas side as the outlet, to be used in such a way that the reaction gas first reacts on the precious metal meshes, and subsequently sublimed platinum is redeposited on the getter meshes.
  • This deposition can be further improved if the getter meshes also have 16 to 20 meshes/inch. Accordingly, when using a mesh stack for the oxidation of ammonia, it is preferred if one or more, preferably 2-4, meshes for the deposition of volatile platinum or rhodium are present downstream.
  • the temperature in the flow reactor after the mesh stack is controlled to a value between 800°C and 1300°C, preferably 850°C - 1200°C and particularly preferably 890°C - 1100°C.
  • Figure 7 Structure of a flow reactor for the oxidation of ammonia
  • Figure 8 Representation of a side view of a flat knitting machine for producing the

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Catalysts (AREA)

Abstract

La présente invention concerne l'utilisation de certaines mailles en métal noble dans l'oxydation de l'ammoniac en oxydes d'azote. Les mailles en métal noble utilisées sont caractérisées par une densité de maille spéciale. Les mailles en métal noble sont avantageusement utilisées dans des systèmes à haute pression.
PCT/EP2024/079811 2023-10-23 2024-10-22 Utilisation de mailles en métal noble pour l'oxydation de l'ammoniac Pending WO2025087895A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102023129020.7 2023-10-23
DE102023129020.7A DE102023129020A1 (de) 2023-10-23 2023-10-23 Verwendung von Edelmetallnetzen zur Oxidation von Ammoniak

Publications (1)

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WO2025087895A1 true WO2025087895A1 (fr) 2025-05-01

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PCT/EP2024/079811 Pending WO2025087895A1 (fr) 2023-10-23 2024-10-22 Utilisation de mailles en métal noble pour l'oxydation de l'ammoniac

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DE (1) DE102023129020A1 (fr)
WO (1) WO2025087895A1 (fr)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4412859A (en) * 1981-08-12 1983-11-01 Engelhard Corporation Method for recovering platinum in a nitric acid plant
EP0216493A1 (fr) 1985-08-19 1987-04-01 Engelhard Corporation Récupération de platine à l'aide de grilles résistant à la perforation
EP0364153B1 (fr) 1988-10-12 1992-03-04 Johnson Matthey Public Limited Company Tissu métallique
DE4206199C1 (fr) 1991-03-16 1992-11-12 Degussa Ag, 6000 Frankfurt, De
DE4028916C2 (de) 1990-09-12 1994-05-05 Heraeus Gmbh W C Aus Draht gewebtes Katalysator-Netz aus den Edelmetall-Legierungen Platin/Rhodium oder Platin/Rhodium/Palladium
EP0606535A1 (fr) 1993-01-14 1994-07-20 W.C. Heraeus GmbH Tricot de fils à base de métaux précieux et son procédé de fabrication
EP0680787A1 (fr) 1994-04-06 1995-11-08 Degussa Aktiengesellschaft Réseaux catalytiques pour réactions en phase gazeuse
DE4423714A1 (de) * 1994-07-08 1996-01-11 Heraeus Gmbh W C Gewirk aus edelmetallhaltigen Drähten und Verfahren für seine Herstellung
US5656567A (en) 1990-07-31 1997-08-12 Pgp Industries, Inc. Self-gettering catalysts
WO2004096702A2 (fr) 2003-04-29 2004-11-11 Johnson Matthey Plc Conception de charge de catalyseur amelioree
EP1358010B2 (fr) 2001-02-08 2008-07-23 Umicore AG & Co. KG Gazes catalytiques tridimensionnelles tricotees en deux couches

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3680015B1 (fr) * 2019-01-14 2024-03-06 Heraeus Precious Metals GmbH & Co. KG Système de catalyseur ainsi que procédé de combustion catalytique d'ammoniac en oxyde d'azote dans une installation moyenne pression

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4412859A (en) * 1981-08-12 1983-11-01 Engelhard Corporation Method for recovering platinum in a nitric acid plant
EP0216493A1 (fr) 1985-08-19 1987-04-01 Engelhard Corporation Récupération de platine à l'aide de grilles résistant à la perforation
EP0364153B1 (fr) 1988-10-12 1992-03-04 Johnson Matthey Public Limited Company Tissu métallique
US5266293A (en) 1988-10-12 1993-11-30 Johnson Matthey Public Limited Company Metal fabrics
US5656567A (en) 1990-07-31 1997-08-12 Pgp Industries, Inc. Self-gettering catalysts
DE4028916C2 (de) 1990-09-12 1994-05-05 Heraeus Gmbh W C Aus Draht gewebtes Katalysator-Netz aus den Edelmetall-Legierungen Platin/Rhodium oder Platin/Rhodium/Palladium
DE4206199C1 (fr) 1991-03-16 1992-11-12 Degussa Ag, 6000 Frankfurt, De
EP0606535A1 (fr) 1993-01-14 1994-07-20 W.C. Heraeus GmbH Tricot de fils à base de métaux précieux et son procédé de fabrication
EP0606535B1 (fr) * 1993-01-14 1995-05-17 W.C. Heraeus GmbH Tricot de fils à base de métaux précieux et son procédé de fabrication
DE4300791A1 (de) 1993-01-14 1994-07-21 Heraeus Gmbh W C Gewirk aus edelmetallhaltigen Drähten und Verfahren für seine Herstellung
EP0680787A1 (fr) 1994-04-06 1995-11-08 Degussa Aktiengesellschaft Réseaux catalytiques pour réactions en phase gazeuse
DE4423714A1 (de) * 1994-07-08 1996-01-11 Heraeus Gmbh W C Gewirk aus edelmetallhaltigen Drähten und Verfahren für seine Herstellung
EP1358010B2 (fr) 2001-02-08 2008-07-23 Umicore AG & Co. KG Gazes catalytiques tridimensionnelles tricotees en deux couches
WO2004096702A2 (fr) 2003-04-29 2004-11-11 Johnson Matthey Plc Conception de charge de catalyseur amelioree

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
"Optimizing catalyst pack design for ammonia oxidation", NITROGEN & METHANOL, no. 239, May 1999 (1999-05-01), pages 51ff
ANDREAS JESSPETER WASSERSCHEID: "Chemical Technology", 2013, WILEY-VCH VERLAG
G. R. MAXWELL: "Synthetic Nitrogen Products - A Practical Guide to the Products and Processes", 2005, SPRINGER SCIENCE + BUSINESS MEDIA, INC.
GIEREJ ET AL.: "Investigation of the degradation mechanism of catalytic wires during oxidation of ammonia process", APPLIED SURFACE SCIENCE, vol. 388, 2016, pages 670, XP029750094, DOI: 10.1016/j.apsusc.2016.05.071
R. KRÄHNERT: "Ph.D.-thesis", November 2005, TECHNISCHE UNIVERSITÄT BERLIN, article "Ammonia Oxidation over Polycrystalline Platinum: Surface Morphology and Kinetics at Atmospheric Pressure"

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