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EP1998875A2 - Catalyseur d'oxydation - Google Patents

Catalyseur d'oxydation

Info

Publication number
EP1998875A2
EP1998875A2 EP07723517A EP07723517A EP1998875A2 EP 1998875 A2 EP1998875 A2 EP 1998875A2 EP 07723517 A EP07723517 A EP 07723517A EP 07723517 A EP07723517 A EP 07723517A EP 1998875 A2 EP1998875 A2 EP 1998875A2
Authority
EP
European Patent Office
Prior art keywords
oxide
zeolite
platinum
catalyst
catalyst according
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.)
Withdrawn
Application number
EP07723517A
Other languages
German (de)
English (en)
Inventor
Wolfgang Strehlau
Olga Gerlach
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.)
HTE GmbH
Original Assignee
HTE GmbH
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 HTE GmbH filed Critical HTE GmbH
Publication of EP1998875A2 publication Critical patent/EP1998875A2/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific 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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/064—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing iron group metals, noble metals or copper
    • B01J29/068—Noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1023—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20738—Iron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/012—Diesel engines and lean burn gasoline engines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to a catalyst for the simultaneous removal of carbon monoxide and hydrocarbons from oxygen-rich exhaust gases, for example from the exhaust gases of diesel engines, lean gasoline engines and stationary sources.
  • the catalyst contains a composition comprising platinum, palladium, tin oxide, zeolite and carrier oxide.
  • the catalyst contains doping elements in the form of gallium, indium or iron oxide.
  • the invention also relates to a process for the preparation of the catalyst and a process for exhaust gas purification using the catalyst.
  • the catalyst has a high conversion performance for carbon monoxide and hydrocarbons and high thermal stability.
  • the main pollutants from the exhaust gas of diesel engines are carbon monoxide (CO), unburned hydrocarbons (HC), such as paraffins, olefins, aldehydes, aromatics, as well as nitrogen oxides (NO x ), sulfur dioxide (SO 2 ) and soot particles containing the carbon both as a solid and in the form of the so-called "volatile organic fraction" (VOF)
  • CO carbon monoxide
  • HC unburned hydrocarbons
  • NO x nitrogen oxides
  • SO 2 sulfur dioxide
  • the diesel exhaust gas also contains oxygen in a concentration which, depending on the operating point, is between approximately 1.5 and 15%.
  • the pollutants that are emitted from lean gasoline engines consist essentially of CO, HC, NO x and SO 2 .
  • the oxygen is in stoichiometric excess over CO and HC.
  • Industrial and commercial flue gases may also contain unburned hydrocarbons and carbon monoxide.
  • oxygen-rich exhaust gas is understood to mean an exhaust gas in which the oxygen is present in a stoichiometric excess over the oxidizable pollutants such as CO and HC.
  • oxidation catalysts are used. They have the task of removing carbon monoxide and hydrocarbons by oxidation, which ideally produces water and carbon dioxide. In addition, soot can be removed by oxidation, which also forms water and carbon dioxide.
  • the catalysts used industrially usually contain platinum as an active component.
  • platinum-containing oxidation catalysts for exhaust gases from diesel passenger cars are therefore usually equipped with very high platinum contents. They typically range from 2.1 to 4.6 g / L (60-130 g / ft 3). For example, up to 9 grams of platinum are used in a 2 liter catalyst.
  • the use of high amounts of platinum is an important cost factor in the exhaust aftertreatment of diesel vehicles. A reduction of the platinum content in the catalyst is of great economic interest.
  • platinum catalysts are also loaded with palladium, in particular in applications for exhaust gas purification of direct injection (“DI"). Diesel engines platinum-palladium ratios of 2: 1 or 3: 1 can be adjusted. Such catalysts are less expensive and more thermally stable, but the addition of palladium to platinum can result in a decrease in the fresh state of the catalyst.
  • One of the objects of the invention was to develop catalysts which have very good performance properties in the removal of pollutants from oxygen-rich exhaust gases, in particular lean internal combustion engines and stationary sources. At the same time, a cost effective manufacturing process for the catalysts should be developed.
  • a catalyst which is characterized in that it contains a composition comprising platinum, palladium, tin oxide, an aluminum-containing carrier oxide and zeolite.
  • carrier oxide preferably means an oxide which is thermally stable and has a high surface area.
  • carrier oxide also includes a mixture of at least two different carrier oxides.
  • titanium oxide includes all possible oxides and suboxides as well as all possible hydroxides and carbonates.
  • palladium includes both the element and compounds thereof, for example, oxides and suboxides.
  • One or more zeolites can be used in each case.
  • Preferred carrier oxides are oxides having a BET surface area of greater than 50 m 2 / g. Particular preference is given to oxides having a BET surface area in the range from 60 to 200 m 2 / g.
  • carrier oxides are used which, even after high temperature loading, have a high BET surface area. Also preferred is a carrier oxide having a low tendency to bind sulfur oxides (SO x ).
  • the carrier oxide used is aluminum-containing materials.
  • An aluminum-containing carrier oxide is to be understood as meaning a carrier oxide which comprises in particular aluminum oxide, silicon / aluminum mixed oxide, titanium / aluminum oxide, zirconium / aluminum oxide, aluminosilicate, kaolin, modified kaolin or mixtures thereof.
  • aluminas doped with silica, zirconia or titania may also be used.
  • Zeolites are known compounds and are sometimes commercially available.
  • modification here includes the zeolite type and the specific chemical composition, eg. As the Si / Al ratio.
  • the zeolite is preferably in the so-called H-form. Also particularly suitable are hydrothermal-stable zeolites having a Si / Al ratio> 8, with higher Si / Al ratios being preferred.
  • zeolite types Y zeolite, DAY zeolite (dealuminated Y), USY (Ultra Stabilized Y), ZSM-5, ZSM-II, ZSM-20, silicalite, ferrierite, mordenite and ⁇ -zeolite are particularly suitable.
  • the zeolites can also be hydrothermally treated.
  • zeolites it is also possible to use several zeolites. These then differ preferably in that they have different pore radii or different Si / Al ratios or different pore radii and different Si / Al ratios. Depending on the requirement profile of the catalyst, ie the exhaust gas temperatures and concentrations of carbon monoxide and hydrocarbons occurring under real conditions, it may be useful to dope the catalyst with the oxides of gallium, indium or iron.
  • the oxides of gallium, indium and iron are understood to mean all oxides, suboxides, sulfates and cationic forms of gallium, indium and iron.
  • the oxides of gallium, indium and iron are also referred to below as doping elements.
  • the particularly high activity and stability of the catalyst is caused by the special properties of the composition of platinum, palladium, tin oxide, carrier oxide, zeolite and possibly the doping elements.
  • the mixture of at least two different zeolite types is preferred.
  • the tin oxide deposited on the carrier oxide has an X-ray-amorphous or a nanoparticulate form.
  • the tin oxide particles have particle sizes of about 0.5 to 10 nm.
  • X-ray amorphous is intended to mean that no evaluable reflections characteristic of a substance are obtained by means of X-ray wide-angle diffraction This statement applies at least to the experimental conditions disclosed in the experimental section.
  • particle sizes can be determined from X-ray diffractograms using the Scherrer equation:
  • D is the thickness of a crystallite
  • ⁇ is the wavelength of the X-ray used
  • B is the half-width of the respective reflection
  • B is the position of the fresh catalysts, ie calcined at 500 ° C., according to the Scherrer method
  • X-ray amorphous can be used.
  • the sizes of corresponding tin oxide particles remain in the nanoparticulate dimension, that is, at sizes of a few nm to a maximum of 100 nm, depending on the temperatures to which the catalyst is exposed. This emphasizes the very good durability of the catalysts of the invention.
  • the catalyst contains, for example, mixtures of at least two platinum, palladium and tin oxide-containing carrier oxides, each having different concentrations of the tin oxide and / or the palladium or the platinum.
  • the catalyst to be applied to a honeycomb-shaped carrier body is produced by the gradient coating or zone coating method. In gradient coating, a gradient of platinum and palladium is adjusted over the length of the honeycomb body. In this way, a higher concentration of noble metal is provided at the point of entry of the exhaust gas of the internal combustion engine into the catalyst, which, depending on the application, can lead to a better utilization of the noble metal.
  • the catalyst is preferably used for the application as powder, granules, extrudate, shaped article or coated honeycomb body.
  • the catalyst is present as a coated shaped body, preferably as a coated honeycomb body, wherein it is structured in the form of a double layer.
  • the catalyst is present as a coated molded body, wherein a layer of the composition consisting of platinum, palladium, tin oxide, carrier oxide and zeolite is applied to the shaped body.
  • this layer may contain oxides of gallium, indium and iron as doping elements.
  • the catalyst preferably has a structure in which channels formed by macropores coexist with meso- and / or micropores.
  • the catalyst is prepared by a process characterized in that it comprises steps (i) and (ii): (i) contacting a tin compound, a palladium compound, a platinum compound, a carrier oxide and a zeolite and optionally a compound of gallium, indium or iron, (ii) calcination of the composition formed in (i).
  • the catalyst precursor is converted by a thermal treatment in the catalytically active form.
  • platinum, platinum, and tin compound are meant all compounds which can be suspended in a liquid medium and / or which are completely or at least partially soluble in this medium.
  • compound of gallium, indium and iron is meant all compounds which can be suspended in a liquid medium and / or which are completely or at least partially soluble in that medium.
  • platinum, palladium, tin compounds and optionally compounds of gallium, indium and iron are used, which are completely or at least partially soluble in the liquid medium.
  • the liquid medium is water.
  • salts of palladium, platinum, tin and optionally gallium, indium and iron are used.
  • Salts are, for example, the salts of inorganic and organic acids, such as chlorides, bromides, cyanides, nitrates, oxalates, acetates or tartrates.
  • a tin compound is preferably used in water dissolved or suspended tin oxalate, wherein the solubility can be further increased by the addition of acids, such as nitric acid.
  • the compounds of platinum and palladium are to be applied to the carrier oxide together with the tin compounds present in acidic solutions, the use of platinum and palladium nitrates is particularly advantageous.
  • the compounds of gallium, indium and iron are to be applied to the carrier oxide together with the tin compounds present in acidic solutions, their use in the form of nitrates is particularly advantageous.
  • a process is preferably used in which the compounds of platinum, palladium, tin and optionally of gallium, indium and ice are brought into contact with the carrier oxide by means of an aqueous medium.
  • Contacting of step (i) means that compounds of tin, of platinum, of palladium, of zeolite and optionally of the compounds of gallium, indium and iron in suspended or preferably dissolved form either be applied simultaneously, in blends or sequentially to the common carrier oxide.
  • the compounds of tin may first be applied to the carrier oxide, while the compounds of palladium and platinum are brought into contact with the carrier oxide in a subsequent step. It is particularly economical to submit all compounds in a common solution and then bring them in contact with the carrier oxide in the form of a co-impregnation.
  • the compounds applied to the carrier oxide are converted by a thermal treatment into their catalytically active form.
  • the method also includes the step (ii):
  • the calcining step is carried out at a temperature of preferably 200 to 1000 ° C, more preferably 300 ° C to 900 ° C, especially 400 to 800 ° C.
  • Calcination also increases the mechanical strength of the catalyst.
  • the calcination can be carried out, for example, in dry or moist air, in nitrogen, forming gas or steam.
  • all known methods can be used for the loading of the carrier oxide by contacting with the dissolved platinum compounds, palladium compounds, compounds of tin and optionally the compounds of gallium, indium and ice, and for drying and calcination.
  • washcoat comprising carrier oxide and zeolite
  • the compounds of tin, platinum and palladium are impregnated or a powder process is selected in which the compounds of the platinum, palladium, tin and optionally of gallium, indium and iron is first applied to the mixture of carrier oxide and zeolite and this is then processed into a washcoat.
  • the powder process allows greater flexibility in the preparation of the catalysts, since the aforementioned compounds can for example be impregnated exclusively on the carrier oxide, while the zeolite is added to the carrier oxide at a later date and thus does not come into contact with the aforementioned compounds , It is also possible to impregnate carrier oxide and zeolite separately with the abovementioned compounds so as to represent different concentrations of platinum, palladium, tin oxide and the doping elements on the carrier oxide and the zeolite.
  • the step (i) thus comprises contacting a tin compound, a palladium compound, a platinum compound, a zeolite and optionally a compound of gallium, indium or iron with a carrier oxide, or contacting a tin compound, a palladium compound, a platinum compound and optionally one Combining gallium, indium or iron with a carrier oxide, drying and calcining, then contacting the calcined composition with a zeolite.
  • the catalyst is represented as honeycomb technology, it is advisable first to load the corresponding honeycomb substrate by immersion in a suspension of ground zeolite and carrier oxide with zeolite / carrier oxide and, after drying the substrate so loaded, according to step (i). with the compounds of platinum, palladium, tin and possibly gallium, indium and iron in contact. This is the simplest and most cost effective method of producing the catalyst as honeycomb technology.
  • the preparation of the catalyst can also be carried out by other known methods, for example by extrusion or extrusion.
  • the catalyst according to the invention after the preparation is preferably in the form of a powder, granules, extrudate or as a shaped body, for example as a coated honeycomb body.
  • the percentages by weight in each case relate to the elemental masses of the platinum, palladium, the tin and the doping elements.
  • the weights are based on the respective oxidic compounds.
  • Typical palladium levels of the catalyst of the present invention are 0.35 g / L - 0.59 g / L (15-60 g / ft 3 ) while that of the platinum is 1.06 to 1.59 g / L (30 g / ft 3 - 45 g / ft 3 ).
  • the units "g / L" or "g / ft 3 " relate, as is familiar to those skilled in the supported catalysts on the elemental mass noble metal in relation to the carrier volume, for example to the volume of a honeycomb carrier body.
  • the total amount of tin is 0.1 - 7 wt .-% (calculated as element) based on the carrier oxide. In this case, a total amount of 0.5 to less than 3 wt .-% is particularly preferred.
  • the total amount of doping elements is 0.01 - 5 wt .-% (calculated as element) based on the carrier oxide, wherein a total amount of 0.1 - 3 wt .-% is preferred.
  • the total amount of palladium (calculated as element) based on the carrier oxide is preferably 0.2-5 wt .-%. More preferred is a total amount of 0.4-2 wt%.
  • the total amount of platinum (calculated as element) based on the carrier oxide is preferably 0.2-5 wt .-%. More preferred is a total amount of 0.4-2 wt%.
  • the weight ratio of tin to the total weight of palladium and platinum is preferably in a range of 0.5: 1 to 3: 1.
  • the optimum ratio of the total mass platinum and palladium to tin depends strongly on the mass ratio of platinum to palladium. For example, with a platinum / palladium mass ratio of 2.7: 1, a significant improvement in the performance characteristics of the corresponding catalysts is already observed by the addition of a small amount of tin. In this case, a mass ratio of tin to the total amount of palladium and platinum in a range of 0.2: 1 to 2.5: 1 proves to be particularly favorable. Increasing the amount of tin beyond the 2.5: 1 ratio does not result in any further improvement in the performance of the catalysts.
  • the platinum / palladium mass ratio is reduced to, for example, 0.33: 1, an increase in the mass ratio of tin to the total mass of platinum and palladium may be expedient. In this case, a range of 0.6: 1 to 3: 1 proves to be particularly favorable. With a further reduction of the platinum / palladium mass ratio, mass ratios of tin to the total mass of platinum and palladium can prove to be advantageous up to 7: 1.
  • the total amount of zeolite based on the carrier oxide is preferably 3-60% by weight. More preferably, a total amount of zeolite is in a range of 8-50 wt%. Particularly preferred is a range of 10 to 35 wt .-%.
  • aluminum oxides are used with BET surface areas of 60 to 200 m 2 / g.
  • the zeolite used is preferably a silicon-rich zeolite of the beta type ( ⁇ -zeolite).
  • the catalyst contains a further zeolite in the form of a silicon-rich ZSM-5.
  • zeolite beta and ZSM-5 are each in the H form.
  • this does not exclude that during steps (i) “contacting” and (ii) "calcination” to some extent a so-called ion exchange takes place, in which the proton of the zeolite is replaced by the platinum, palladium, tin oxide or possibly by the oxides of gallium, indium and iron.
  • the catalysts of the invention also show a very good sulfur tolerance, which is superior to that of the tin-free Pt / Pd catalysts.
  • the invention also relates in particular to the use of the catalyst for the removal of pollutants from exhaust gases of lean internal combustion engines and exhaust.
  • Another subject of the invention is thus also the use of the catalyst for the removal of pollutants from lean internal combustion engines and venting by oxidation, wherein the pollutants carbon monoxide and carbon hydrogens which are oxidized to water on the catalyst.
  • exhaust gases contain soot, they are also oxidized, preferably simultaneously with carbon monoxide and hydrocarbons.
  • the present invention also relates to a method for exhaust gas purification of lean internal combustion engines and venting using the catalyst disclosed above.
  • the process of the exhaust gas purification is performed such that the exhaust gas purification comprises the simultaneous oxidation of hydrocarbons and carbon monoxide as well as the removal of soot by oxidation.
  • the method for removing pollutants from exhaust gases of lean internal combustion engines is characterized in that it comprises the step (i): (i) contacting an exhaust gas stream of lean internal combustion engines with the catalyst.
  • This process is further characterized in that carbon monoxide and hydrocarbons are oxidized to produce carbon dioxide and water.
  • the process is also characterized in that carbon black particles are simultaneously removed by oxidation.
  • the pictures show:
  • Fig. 1 Activity measurement: conversions of CO and HC of a commercial "Pt only" reference catalyst according to Comparative Example 3 (VB03) as a function of temperature The catalyst was previously aged for 5 hours hydrothermally at 800 0 C and then for about 20 hours in a cyclical. Operation preconditioned between 140 and 400 ° C ..
  • Fig. 2 Activity measurement conversions of CO and HC of a tin-free platinum-palladium reference catalyst according to Comparative Example 2 (VBOl) as a function of temperature.
  • the catalyst was previously hydrothermally aged at 800 ° C for 5 hours.
  • Fig. 3 Activity measurement: conversions of CO and HC of a tin-free platinum-palladium reference catalyst according to Comparative Example 2 (VBOl) as a function of temperature. The catalyst was previously hydrated for 5 hours.
  • the temperature is plotted in degrees Celsius (° C) on the x-axis, and the conversion on the y-axis is divided by 100.
  • honeycomb-shaped catalysts had a diameter of 2.54 cm and a length of 2.54 cm.
  • VBOl Tin-free platinum-palladium catalyst with 1.59 g / L platinum and 0.59 g / L palladium.
  • VB02 Tin-free platinum-palladium catalyst with 1.06 g / L platinum and 0.35 g / L palladium.
  • the determination of CO was carried out with ABB ND-IR analyzers (type "Advance Optima”)
  • the determination of the hydrocarbon was carried out with a FID from ABB (type “Advance Optima”).
  • the T 50 values were (temperature is reached at which 50% conversion) of CO oxidation as well as the integral HC reduction from 123 to 250 ° C, which is referred to as t Hci "used .
  • t Hci integral HC reduction
  • the hydrocarbons are first adsorbed only at the catalyst at lower temperatures and only oxidized to CO 2 and H 2 O at higher temperatures.
  • the term HC conversion thus includes the adsorption and oxidation of hydrocarbons.
  • Table 2 contains the integral HC conversion HCj nt determined over the temperature range of 130 to 250 ° C.
  • the hydrothermal aging was carried out in a muffle furnace at a temperature of 800 ° C in an air stream containing 10% water. The catalysts were held at this temperature for 5 hours and then cooled to room temperature.
  • cyclic preconditioning the catalytic converters are exposed to a simulated diesel exhaust gas that corresponds to the exhaust gas composition of the activity measurements.
  • the catalyst is heated at a heating rate of 2 ° C / minute from 140 0 C to 400 0 C, cooled at a cooling rate of about 2 0 C minute to 140 ° C, then again heats up, etc.
  • the total duration of this Konditionierzy- Vietnamese s is 20 hours.
  • Cyclic preconditioning is used to simulate catalyst aging at low and medium exhaust gas temperatures. Unlike hydrothermal aging, the catalyst is exposed to high CO, NO x and HC emissions.
  • the catalysts of the examples below use a washcoat / honeycomb technology in which a honeycomb-shaped carrier was loaded with washcoat. Subsequently, the compounds of tin, platinum, palladium and optionally gallium and iron were impregnated together.
  • the supports were cordierite at 400 cpsi (channels per square inch) and manufactured by NGK.
  • the resulting coating suspension had a solids content of 20% by weight. This coating suspension showed very good adhesion properties and was used without the addition of further binders
  • the catalyst support used was a honeycomb cordierite core of 400 cpsi (channels per square inch) from NGK, which had been previously cut to a dimension of 1 inch diameter and 2 inches in length.
  • the drill core was coated with the alumina / zeolite washcoat by repeated immersion in the coating suspension, after each dip.
  • the channels of the Bohrkems were blown out to remove excess suspension.
  • the core was dried in a stream of air and finally calcined for 15 minutes in a stream of air at 500 ° C.
  • the washcoat loading was 120 g / L. This loading represents the solid fraction of the washcoat after calcination applied to the shaped body.
  • the tin and precious metals were applied to the washcoated core by impregnation with an aqueous solution containing tin oxalate, platinum nitrate, palladium nitrate and nitric acid.
  • an aqueous solution containing tin oxalate, platinum nitrate, palladium nitrate and nitric acid was added 216.8 ⁇ l of an aqueous, nitric acid-containing, 1.0 molar tin oxalate solution containing 209.7 ⁇ l of a 1.0 molar platinum nitrate solution and 142.7 ⁇ l of a 1.0 molar palladium nitrate Mixed solution and diluted with 9 ml of water.
  • the resulting solution was applied to the washcoat coated core in two steps.
  • the thus impregnated drill core was then dried in a stream of air and calcined for 15 minutes at 300 ° C in an air stream.
  • the catalyst was calcined for 2 hours at 700 ° C in a muffle furnace under air (referred to as "fresh").
  • the final catalyst contained 96 g / L Puralox SCFa 140, 12 g / L Zeocat PZ-2 / 100H, 12 g / L CP 7104, 1.0 g / L tin, 1.59 g / L platinum and 0.59 g / L palladium.
  • the catalysts were prepared analogously to Example B12, the loadings being varied with platinum, palladium and tin. Furthermore, in example B04, iron was used as the doping element, which was added in the form of the nitrate of the nitric acid solution of tin oxalate, platinum nitrate, and palladium nitrate impregnating solution.
  • compositions of the catalysts according to Example B02 to B04 are reproduced on a weight basis in the unit g / L, these statements being based on the oxide form of the carrier oxide and of the zeolite and on the elementary form of the platinum, palladium, tin and Refer to iron.
  • the catalysts were prepared analogously to Example B12, using a mechanical mixture of silica-doped aluminum oxide (Siralox 5/170) from Sasol and the zeolites for the washcoat. In this case, and the loading amounts of platinum, palladium and tin were varied. Furthermore, the catalysts of Examples B06 and B07 additionally contained gallium as doping elements, which was added in the form of the nitrate of the nitric acid solution consisting of tin oxalate, platinum nitrate, and palladium nitrate.
  • compositions of the catalysts according to Example B05 to B07 are reproduced on a weight basis in the unit g / L, these details being based on the oxide form of the carrier oxide and of the zeolite and on the elemental form of the platinum, palladium, tin and Refer to gallium.
  • Table 1 Composition of the catalysts according to Examples B01 to B07 and Comparative Examples VBO1 and VB02.
  • Table 3 Results of the catalytic tests of the integral HC reduction in the temperature range between 130 and 250 ° C on the catalysts after the different aging.

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Abstract

L'invention concerne un catalyseur caractérisé en ce qu'il contient une composition comprenant du palladium, du platine, de l'oxyde d'étain, un oxyde de support, et de la zéolithe. Eventuellement, le catalyseur peut être doté d'oxyde de gallium, d'indium ou de fer. L'invention concerne, de plus, un procédé de production dudit catalyseur, son utilisation dans l'élimination de substances nocives provenant de moteurs à combustion interne à fonctionnement en mélange pauvre et des effluents gazeux, ainsi qu'un procédé d'élimination des substances nocives des gaz d'échappements provenant de moteurs à combustion interne à fonctionnement en mélange pauvre, lors de l'utilisation du catalyseur dans l'oxydation du monoxyde de carbone et d'hydrocarbures, des particules de suies étant éliminées simultanément par oxydation.
EP07723517A 2006-03-22 2007-03-22 Catalyseur d'oxydation Withdrawn EP1998875A2 (fr)

Applications Claiming Priority (2)

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DE102006013234A DE102006013234A1 (de) 2006-03-22 2006-03-22 Oxidationskatalysator
PCT/EP2007/002566 WO2007107371A2 (fr) 2006-03-22 2007-03-22 Catalyseur d'oxydation

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RU2489206C2 (ru) * 2008-06-19 2013-08-10 Умикоре Аг Унд Ко. Кг Катализатор окисления для оснащенных дизельным двигателем транспортных средств для перевозки пассажиров, грузов и для нетранспортных работ
NL2001788C2 (nl) * 2008-07-11 2010-01-12 Stichting Energie Werkwijze voor de decompositie van N2O, katalysator daarvoor en bereiding van deze katalysator.
US8211821B2 (en) * 2010-02-01 2012-07-03 Celanese International Corporation Processes for making tin-containing catalysts
US8846988B2 (en) 2010-07-09 2014-09-30 Celanese International Corporation Liquid esterification for the production of alcohols
US9120077B2 (en) * 2010-10-01 2015-09-01 Basf Corporation Surface-coated zeolite materials for diesel oxidation applications
US9000233B2 (en) 2011-04-26 2015-04-07 Celanese International Corporation Process to recover alcohol with secondary reactors for hydrolysis of acetal
US8907141B2 (en) 2011-04-26 2014-12-09 Celanese International Corporation Process to recover alcohol with secondary reactors for esterification of acid
US20120308439A1 (en) * 2011-06-01 2012-12-06 Johnson Matthey Public Limited Company Cold start catalyst and its use in exhaust systems
US9024086B2 (en) 2012-01-06 2015-05-05 Celanese International Corporation Hydrogenation catalysts with acidic sites
WO2013103396A1 (fr) * 2012-01-06 2013-07-11 Celanese International Corporation Procédés de fabrication de catalyseurs avec des précurseurs d'oxalate
US8980789B2 (en) 2012-01-06 2015-03-17 Celanese International Corporation Modified catalyst supports
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US8980209B2 (en) 2012-12-12 2015-03-17 Basf Corporation Catalyst compositions, catalytic articles, systems and processes using protected molecular sieves
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WO2007107371A3 (fr) 2007-11-08
DE102006013234A1 (de) 2007-11-29

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