WO2025002948A1 - Catalyseurs scr pour réduction améliorée de nox - Google Patents

Catalyseurs scr pour réduction améliorée de nox Download PDF

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Publication number
WO2025002948A1
WO2025002948A1 PCT/EP2024/067120 EP2024067120W WO2025002948A1 WO 2025002948 A1 WO2025002948 A1 WO 2025002948A1 EP 2024067120 W EP2024067120 W EP 2024067120W WO 2025002948 A1 WO2025002948 A1 WO 2025002948A1
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Prior art keywords
scr
exhaust gas
combustion engines
manganese
catalyst
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PCT/EP2024/067120
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English (en)
Inventor
Fei WEN
Ruediger Hoyer
Mattia SIST
Leen VAN TENDELOO
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Umicore AG and Co KG
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Umicore AG and Co KG
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Priority to CN202480036534.1A priority Critical patent/CN121285423A/zh
Publication of WO2025002948A1 publication Critical patent/WO2025002948A1/fr
Anticipated expiration legal-status Critical
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    • 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
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
    • 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
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides 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
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • 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
    • B01J23/005—Spinels
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/32—Manganese, technetium or rhenium
    • B01J23/34—Manganese
    • 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
    • B01J35/19—Catalysts containing parts with different compositions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion
    • F01N3/206—Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • 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
    • B01D2255/20707—Titanium
    • 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
    • B01D2255/20723—Vanadium
    • 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
    • B01D2255/2073—Manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B01D2255/405—Spinels
    • 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
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/902—Multilayered catalyst
    • B01D2255/9022—Two layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/903—Multi-zoned catalysts
    • B01D2255/9032—Two zones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
    • 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
    • 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
    • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/20—Vanadium, niobium or tantalum
    • B01J23/22—Vanadium
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/24—Chromium, molybdenum or tungsten
    • B01J23/30—Tungsten
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2330/00—Structure of catalyst support or particle filter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2370/00—Selection of materials for exhaust purification
    • F01N2370/02—Selection of materials for exhaust purification used in catalytic reactors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2370/00—Selection of materials for exhaust purification
    • F01N2370/02—Selection of materials for exhaust purification used in catalytic reactors
    • F01N2370/04—Zeolitic material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • F01N2510/068—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings
    • F01N2510/0682—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings having a discontinuous, uneven or partially overlapping coating of catalytic material, e.g. higher amount of material upstream than downstream or vice versa
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • F01N2510/068—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings
    • F01N2510/0684—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings having more than one coating layer, e.g. multi-layered coatings
    • 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 catalytic devices for the selective catalytic reduction of nitrogen oxides from the exhaust gas of combustion engines.
  • the catalytic devices comprise a carrier substrate, a bottom layer and a top layer.
  • the bottom layer comprises a material zone comprising an SCR catalytically active composition consisting of one or more manganese-containing mixed oxides or a mixture of one or more manganese-con- taining mixed oxides and one or more metal-promoted small-pore zeolites.
  • the material zone in the bottom layer which comprises said SCR catalytically active composition, extends from the downstream end over 20 to 100% of the length of the carrier substrate.
  • the bottom layer additionally comprises a material zone which extends from the upstream end over 80 to 0% of the carrier substrate; said additional material zone comprising a vanadia-titania based SCR catalyst composition.
  • the bottom layer is directly affixed to the carrier substrate.
  • the top layer is affixed to the bottom layer and extends over the total length of the carrier substrate. It comprises a vanadia-titania based SCR catalyst composition.
  • the exhaust gas of combustion processes in particular that of diesel engines, but also that of direct-injection lean-mixture-operated gasoline engines, contains carbon monoxide (CO) and hydrocarbons (HC) resulting from incomplete combustion of the fuel.
  • the exhaust gas also contains particulate matter (PM) and nitrogen oxides (NO X ).
  • the exhaust gas of diesel engines contains, for example, up to 15 vol.-% oxygen.
  • oxidizable harmful gases CO and HC can be converted to harmless carbon dioxide (CO2) and water (H2O) by passing them over suitable oxidation catalytic converters and that particulates can be removed by passing the exhaust gas through a suitable particulate filter.
  • Nitrogen oxides may be converted on an SCR catalyst in the presence of oxygen to nitrogen and water by means of ammonia. “SCR” stands for “selective catalytic reduction”.
  • SCR stands for “selective catalytic reduction”.
  • a major driver for the recent and future development of catalysts are the increasingly stringent world-wide legislative emission levels for road (e.g. passenger cars, trucks) and non-road (e.g. ships, trains) applications.
  • the ammonia may be formed from an ammonia precursor compound by catalytic reactions within the exhaust gas.
  • ammonia precursor compounds are ammonium carbamate, ammonium formate and preferably urea.
  • ammonia is fed as a less hazardous urea solution, which is decomposed to ammonia in the catalytic unit, and can be filled and stored in the vehicle in a dedicated reservoir.
  • Nitric oxide (NO) is the main NO X compound produced in an engine.
  • the reduction of NO is referred to as the “standard” NH 3 -SCR reaction:
  • NO 2 is more reactive than NO.
  • the NH 3 -SCR reaction is easier, and the so-called “fast” NH 3 -SCR reaction can occur:
  • SCR catalysts are described extensively in literature as well. They are generally either so-called mixed oxide catalysts, or so-called zeolite catalysts.
  • Mixed oxide catalysts either comprise oxides of vanadium and titanium and optionally oxides of other metals like tungsten, molybdenum, antimony and cerium, or they are based on manganese-contain- ing mixed oxides or manganese of manganese oxide supported on metal oxides.
  • Zeolite catalysts comprise metal-promoted zeolites.
  • the SCR systems known in the prior art comprise SCR catalysts which effectively reduce nitrogen oxides NO X from exhaust gas flows of internal combustion engines during operation in normal to high temperature ranges, for example in temperature ranges between approximately 250°C and 450°C. However, during the cold start of an engine but also in low-load operation, the exhaust gas temperatures may fall to low temperature ranges between approximately 60°C and approximately 250°C. In such temperature ranges, conventional SCR catalysts, which are either based on oxides of vanadium and titanium or on metal-promoted zeolites, do not succeed in effectively reducing NO X from exhaust gas flows.
  • low- temperature SCR catalysts which can effectively reduce nitrogen oxides at low temperatures below a temperature threshold value of 100°C to 250°C, sometimes even at temperatures below 100°C.
  • SCR catalysts which contain manganese-containing mixed oxides or manganese or manganese oxide supported on metal oxides exhibit very high NO conversions even at low temperatures, sometimes even below 100°C.
  • a disadvantage of such manganese-containing SCR catalysts is that activity and selectivity are very poor at high temperatures, so that, for example, large amounts of N2O are formed. They also have a low stability to high aging temperatures and tend to be contaminated by SO X , wherein the possibilities for desulfurization are limited due to low aging stability.
  • WO 2017/168327 A1 addresses the problem of sulfur poisoning of metal-promoted zeolites.
  • the invention provides methods for low temperature desulfating sulfur-poisoned SCR catalysts, and emission control systems adapted to apply such desulfating methods, in order to regenerate catalytic NO X conversion activity.
  • the methods are adapted for treating an SCR catalyst to desorb sulfur from the surface of the SCR catalyst and increase NOx conversion activity of the SCR catalyst, the treating step including treating the SCR catalyst with a gaseous stream comprising a reductant for a first treatment time period and at a first treatment temperature, wherein the first treatment temperature is about 350°C or less, followed by a second treatment time period and a second treatment temperature higher than the first treatment temperature, wherein the molar ratio of reductant to NO X during the treating step is about 1.05:1 or higher.
  • the reductant can be ammonia or any precursor thereof.
  • WO 2019/115187 A1 discloses an exhaust-gas aftertreatment system for selective catalytic reduction with a plurality of SCR catalytic converters, which exhaust-gas aftertreatment system is able to reduce NO X in a large temperature range and can store SO X .
  • the invention further relates to a method for treating an exhaust gas flow, in which method the exhaustgas aftertreatment system according to the invention is used.
  • the system comprises a high- temperature SCR catalyst for temperature ranges between 250°C and 750°C and a low- temperature SCR catalyst arranged downstream thereof for temperature ranges between 60°C and less than 250°C.
  • the high-temperature SCR catalyst is designed to reduce NO X in exhaust gas that has a temperature above a temperature threshold value and to store SOx in the temperature range below the threshold value.
  • the low-temperature SCR catalyst reduces NO X in the temperature range below the threshold value. In each case, the exhaust gas flows through the high-temperature SCR catalyst.
  • An exhaust-gas bypass valve or flow control valve is arranged directly upstream of the low-temperature SCR catalyst. If the temperature of the exhaust gas is greater than or equal to the temperature threshold value, the exhaust gas is completely conducted past the low-temperature SCR catalyst.
  • the high-tem- perature SCR catalyst advantageously contains a molecular sieve as a catalytically active layer, and the catalytically active layer of the low-temperature SCR catalyst is preferably a manganese-containing mixed oxide.
  • WO 2022/174814 A1 relates to a SCR catalytic article, wherein the sulfurization and desulfurization are carried out in accordance with the processes as described in the specification, and to an exhaust treatment system comprising the same.
  • the invention also relates to a method for determining whether a metal-promoted small pore zeolite is resistant to irreversible sulfur poisoning and a method for evaluating whether a metal- promoted small pore zeolite is qualified for resistance to irreversible sulfur poisoning.
  • the background of this invention is that, in addition to the hydrothermal aging deactivation, another significant factor impacting the performance of the SCR catalytic articles is chemical poisoning such as sulfur poisoning.
  • Sulfur poisoning originates from the cumulative exposure of the catalyst to sulfur species in the fuel and fuel-derived sulfur-containing contaminants.
  • Sulfur content in diesel fuel has been significantly reduced in recent years, which may be even less than 15 ppm sulfur with the introduction of Ultra-Low Sulfur Diesel (ULSD) in North America for example.
  • ULSD Ultra-Low Sulfur Diesel
  • cumulative exposure of catalysts over their lifetime in heavy duty diesel engine exhaust treatment system may amount to kilograms of sulfur. The situation could be even worse for some off-road applications or in certain regions where high sulfur diesels (>350 ppm sulfur) are not uncommon.
  • SCR catalytic articles may be regenerated at high temperatures, which is commonly accomplished during the regeneration of the soot filter.
  • the NO X reduction activity of the SCR catalytic articles degraded by sulfur poisoning will be recovered significantly by the regeneration.
  • a proportion of NO X reduction activity loss cannot be remedied by the regeneration, resulting in permanent sulfur poisoning damage to the SCR catalyst activity, which is also known as irreversible sulfur poisoning.
  • WO 2022/174814 A1 provides a SCR catalytic article, comprising a substrate and thereon a copper-containing small pore zeolite, having a crystal structure characterized by a decrease of unit cell volume upon sulfurization and desulfurization of less than 10 A 3 as determined by an X-ray powder diffraction, wherein the sulfurization is carried out by passing a gas stream containing 35 ppmv SO2, 350 ppmv NO, 10 vol% O2, 10 vol% H2O and balanced N2 through a Pt-containing diesel oxidation catalyst (DOC) under an inlet temperature of 650 °C for partially oxidizing SO2 to provide a SO2 to SO3 ratio of 30 : 70 and then through the SCR catalytic article under an outlet temperature of 400°C, at a space velocity of 10,000 hr 1 based on the volume of the SCR catalytic article, for a period to provide 40 g/L of sulfur exposure based on the volume of the SCR catalytic article, wherein the S
  • US 2016/001228 A1 discloses an ammonia slip control catalyst having a layer containing perovskite and a separate layer containing an SCR catalyst.
  • the ammonia slip catalyst can have two stacked layers, with the top overlayer containing an SCR catalyst, and the bottom layer containing a perovskite.
  • the ammonia slip catalyst can alternatively be arranged in sequential layers, with the SCR catalyst being upstream in the flow of exhaust gas relative to the perovskite.
  • a system comprising the ammonia slip catalyst upstream of a PGM-containing ammonia oxidation catalyst and methods of using the system are also described. The system allows for high ammonia oxidation with good nitrogen selectivity.
  • the SCR catalyst comprises an oxide of a base metal, a molecular sieve, a metal-exchanged molecular sieve or a mixture thereof. If the SCR catalyst is an oxide of base metal, e.g. a vanadium- based SCR catalyst, it can be supported on a refractory metal oxide such as alumina, silica, zirconia, titania, ceria and combinations thereof.
  • the base metal is selected from the group consisting of cerium, chromium, cobalt, copper, iron, manganese, molybdenum, nickel, tungsten, vanadium and mixtures thereof.
  • the perovskite preferably has the formula ABO3, wherein A comprises at least one of calcium, barium, bismuth, cadmium, cerium, copper, lanthanum, lead, neodymium, nickel, strontium and yttrium; and B comprises at least one of aluminum, cerium, chromium, cobalt, iron, manganese, niobium, tin, titanium and zirconium.
  • the metal A in the perovskite is lanthanum.
  • US 2018/229224 A1 describes catalysts effective to abate NOx, hydrocarbons, and carbon monoxide from a gasoline engine exhaust gas.
  • Such catalysts include a substrate having a first and second material disposed thereon, the first material effective to catalyze selective catalytic reduction of nitrogen oxides in the presence of ammonia and the second material effective to abate hydrocarbons and carbon monoxide.
  • the first material comprises comprising a molecular sieve promoted with copper and/or iron in a low loading.
  • the second material comprises at least one base metal oxide on a support.
  • the base metal oxide is selected from vanadium, tungsten, titanium, copper, iron, cobalt, nickel, chromium, manganese, neodymium, barium, cerium, lanthanum, praseodymium, magnesium, calcium, zinc, niobium, zirconium, molybdenum, tin, tantalum, cerium, and strontium, or combinations thereof.
  • the metal oxide is an oxide of nickel, iron, manganese, cobalt, or copper.
  • the refractory metal oxide support is selected from activated alumina, bulk ceria, zirconia, alpha alumina, silica and titania.
  • the first and the second material are applied onto the catalyst substrate in the form of a first and a second layer.
  • the first and the second layer can be arranged in zones, wherein the first layer is disposed on the upstream end of the substrate, and the second layer is disposed on the downstream end, or vice versa.
  • either the first or the second layer can be disposed on the substrate, and the respective other layer at least partially overlies it.
  • CN 102 039 120 A discloses a cerium-containing nano MnTi composite oxide catalyst.
  • the catalyst is prepared from titanic acid butyl acetate, n-butyl alcohol, deionized water, glacial acetic acid, soluble salt of manganese and soluble salt of cerium which serve as raw materials by a sol-gel method, wherein the volume ratio of the titanic acid butyl acetate to the n-butyl alcohol to the deionized water to the glacial acetic acid is 1 :(2.0- 3.0):(0.2-0.4):(0.2-0.4); and the molar ratio of titanium contained in the titanic acid butyl acetate to cerium contained in the soluble salt of the cerium to manganese contained in the soluble salt of the manganese is 1 :(0.01-0.1):(0.1 -1).
  • the catalyst disclosed by the invention has high thermal stability, high activity and nanoscale particle size and can be applied to a low-temperature selective catalytic reduction (SCR) denitration reaction.
  • SCR selective catalytic reduction
  • the transformation rate of NO by using the catalyst is up to 100 percent.
  • the Examples shown in ON 102 039 120 A show MnCeTi ternary oxides with various molar ratios Mn:Ce:Ti. The molar ratios of cerium in these Examples range between 0.019 and 0.4.
  • ON 102 600 832 A discloses a combined catalyst for improving denitration performance and an application thereof.
  • industrial anatase crystal form TiC>2 is taken as a carrier.
  • X ⁇ Os-WOs/TiCh is applied onto the front section of the carrier substrate, and MnO x -CeO2/TiO2 is applied onto the back section of the carrier substrate.
  • “Front section” refers to a section where an air current main body is contacted firstly; the back section refers to a section where the air current main body is contacted secondly.
  • the mass ratio of the front section to the back section is 1 : 1-1 :3.
  • V2O5 accounts for 2-4 percent of the mass of the carrier TiO2; WO3 accounts for 8-10 percent of the mass of the carrier TiCh; Mn accounts for 10-20 percent of the mass of the carrier TiCh; CeC>2 accounts for 8-10 percent of the mass of the carrier TiO2; and MnO x is taken as the general name of MnC>2 and Mn2C>3.
  • V2O5 is 2% ⁇ 4%, WO3 is 8% to 10% of the mass of the carrier TiC>2, Mn is 10% to 20% of the mass of the carrier TiC>2, and CeC>2 is 8% to 10% of the mass of the carrier TiC>2.
  • TiC>2 serves as the carrier material, and therefore, it deals with a binary oxide MnO x -CeC>2 and not with a ternary oxide MnCeTiO x .
  • the amount of oxygen in the oxides is given as “x” because it can vary, depending on the oxidation state of manganese.
  • the combined catalyst can be applied to an integral catalyst for industrial application.
  • the combined catalyst has a wider active temperature window; particularly, the removing efficiency of NO X by NH3-SCR is greatly increased under the exhaust low-temperature wording condition of a diesel engine; and moreover, the same NO X removing efficiency as the conventional catalyst can be obtained at a medium-high temperature section.
  • EP 4 039 365 A1 relates to an SCR catalyst for removing nitrogen oxides (NO X ) from exhaust gas, comprising: 0.01-70 wt% of zeolite having an average pore size of 5 A or more; 25-90 wt% of titanium dioxide (TiCh); and 4-10 wt% of vanadium pentoxide (V2O5). Furthermore, the catalyst may comprise 0.01 to 15 wt.-% WO3.
  • the zeolite is preferably selected from zeolite-Y, ZSM-5 zeolite, AEL zeolite, AFI zeolite, AFO zeolite, AFR zeolite, BEA zeolite, HEU zeolite, MFI zeolite, MOR zeolite, MEL zeolite, and MTW zeolite.
  • the zeolite is not promoted with a metal component, for instance with a metal selected from iron, cobalt, nickel, copper, chromium, zinc or manganese, because said metals promote the reaction of SO2 to a sulfate, for instance ammonium sulfate (AS), ammonium bisulfate (ABS).
  • WO 2014/160289 A1 discloses SCR catalyst systems comprising a first SCR catalyst composition and a second SCR catalyst composition arranged in the system, the first SCR catalyst composition promoting higher N2 formation and lower N2O formation than the second SCR catalyst composition, and the second SCR catalyst composition having a different composition than the first SCR catalyst composition, the second SCR catalyst composition promoting lower N2 formation and higher N2O formation than the first SCR catalyst composition.
  • the first SCR catalyst composition preferably comprises a mixed oxide, which can be selected from Fe/titania (e.g. FeTiOa), Fe/alumina (e.g. FeAhCh), Mg/titania (e.g. MgTiCh), Mg/alumina (e.g. MgAhCh), Mn/alumina (e.g. MnAhCh), Mn/ti- tania (MnOx/TiCh), Cu/titania (e.g. CuTiOa), Ce/Zr (CeZrC>2), Ti/Zr (e.g. TiZrCh), vana- dia/titania (e.g. X ⁇ Os/TiCh) and mixtures thereof.
  • Fe/titania e.g. FeTiOa
  • FeAhCh FeAhCh
  • Mg/titania e.g. MgTiCh
  • Mg/alumina e.g. MgAhCh
  • the mixed oxide comprises vanadia/titania, which may optionally be stabilized with tungsten.
  • Vanadia concentrations of 1 to 10 wt.-% and tungsten concentrations of 0.1 to 10 wt.-% are preferred.
  • the second SCR catalyst composition preferably is a small-pore zeolite, more preferably CHA or AEI, and it is preferably promoted with a metal selected from Cu, Fe, Co, Ce and Ni. More preferably, the zeolite is promoted with 2 to 8 wt.-% of Cu.
  • the first and the second SCR catalyst compositions are arranged in zones on the substrate, with the mixed oxide SCR catalysts composition being arranged on the upstream end, and the zeolite SCR catalyst composition being arranged on the downstream end, of the carrier substrate.
  • the first zone covers 20 to 80% of the length L of the substrate, with the second zone covering the remainder of the length L of the substrate.
  • the first and the second SCR catalyst are arranged in layers, wherein the mixed oxide SCR catalyst, i.e. the first SCR catalyst, is present in the top layer, and the second SCR catalyst is present in the bottom layer.
  • the sulfur- tolerant vanadia/titania SCR catalyst composition shall protect the downstream sulfursensitive metal-promoted small-pore zeolite from sulfur poisoning.
  • the novel SCR catalytic devices show a good NO X removal over a wide temperature range, and also a low formation of N2O. Methods for making the novel SCR catalytic devices and uses thereof are also envisaged.
  • catalytic devices for the selective catalytic reduction of nitrogen oxides from the exhaust gas of combustion engines comprising a) a carrier substrate of length L, said length L extending from a face side A to a face side B, and b) a bottom layer comprising
  • the material zone D comprising a first SCR catalytically active composition and extending from face side B over a length L z which is 20 to 100% of the length L of the carrier substrate; wherein the first SCR catalytically active composition in said material zone D consist of one or more manganese-containing mixed oxides, or a mixture of one or more manganese-containing mixed oxides and one or more metal- promoted small-pore zeolites
  • a top layer affixed to the bottom layer said top layer comprising a material zone C comprising a second SCR catalytically active composition and extending from face side A to face side B of the carrier substrate; wherein the second SCR catalytically active composition in said material zone C consists of a V/TiC>2 SCR catalyst composition which comprises at least one oxide of vanadium supported on titanium dioxide, and wherein the second and the third SCR catalytically active composition are identical or different from one another.
  • the SCR catalysts with an improved low temperature performance and a good sulfur resistance are explained below, with the invention encompassing all the embodiments indicated below, both individually and in combination with one another.
  • SCR selective catalytic reduction of nitrogen oxides
  • a “catalytically active composition” is a substance or a mixture of substances which is capable to convert one or more components of an exhaust gas into one or more other components.
  • An example of such a catalytically active composition is, for instance, an oxidation catalyst composition which is capable of converting volatile organic compounds and carbon monoxide to carbon dioxide or ammonia to nitrogen oxides.
  • Another example of such a catalyst is, for example, a selective catalytic reduction catalyst (SCR) composition which is capable of converting nitrogen oxides to nitrogen and water.
  • SCR catalyst is a catalyst comprising a carrier substrate and a washcoat comprising an SCR catalytically active composition.
  • An ammonia slip catalyst (ASC) is a catalyst comprising a carrier substrate, a washcoat comprising an oxidation catalyst, and a washcoat comprising an SCR catalytically active composition.
  • a molecular sieve is a material with pores, i.e. with very small holes, of uniform size. These pore diameters are similar in size to small molecules, and thus large molecules cannot enter or be adsorbed, while smaller molecules can.
  • a molecular sieve is zeolitic. Zeolites are made of corner-sharing tetrahedral SiC>4 and AIO4 units. They are also called “silicoaluminates” or “aluminosilicates”. In the context of the present invention, these two terms are used synonymously.
  • non-zeolitic molecular sieve refers to corner-sharing tetrahedral frameworks wherein at least a portion of the tetrahedral sites are occupied by an element other than silicon or aluminum. If a portion, but not all silicon atoms are replaced by phosphorous atoms, it deals with so-called “silico aluminophosphates” or “SAPOs”. If all silicon atoms are replaced by phosphorous, it deals with aluminophosphates or “AlPOs”.
  • a “zeolite framework type”, also referred to as “framework type”, represents the cornersharing network of tetrahedrally coordinated atoms. It is common to classify zeolites according to their pore size which is defined by the ring size of the biggest pore aperture. Zeolites with a large pore size have a maximum ring size of 12 tetrahedral atoms, zeolites with a medium pore size have a maximum pore size of 10 and zeolites with a small pore size have a maximum pore size of 8 tetrahedral atoms.
  • Well-known small-pore zeolites belong in particular to the AEI, CHA (chabazite), ERI (erionite), LEV (levyne), AFX and KFI framework.
  • Examples having a large pore size are zeolites of the faujasite (FAU) framework type and zeolite Beta (BEA).
  • a ’’zeotype comprises any of a family of materials based on the structure of a specific zeolite.
  • a specific “zeotype” comprises, for instance, silicoaluminates, SAPOs and AlPOs that are based on the structure of a specific zeolite framework type.
  • chabazite (CHA) the silicoaluminates SSZ-13, Linde R and ZK-14, the sili- coaluminophosphate SAPO-34 and the aluminophosphate MeAIPO-47 all belong to the chabazite framework type.
  • silicoaluminates, silico aluminophosphates and aluminophosphates belong to the same zeotype.
  • ze- olitic and non-zeolitic molecular sieves belonging to the same zeotype are listed in the database of the International Zeolite Association (IZA). The skilled person can use this knowledge and the IZA database without departing from the scope of the claims.
  • the silica to alumina molar ratio (SiC ⁇ AhCh) of the zeolites is hereinafter referred to as the “SAR value”.
  • a “catalyst carrier substrate”, also just called a “carrier substrate” is a support to which the catalytically active composition is affixed and shapes the final catalyst.
  • the carrier substrate is thus a carrier for the catalytically active composition.
  • a “washcoat” as used in the present invention is an aqueous suspension of a catalytically active composition and optionally at least one binder and/or optionally at least one stabilizer. Materials which are suitable binders and stabilizers are, for example, aluminum oxide, titanium dioxide, silicon dioxide, zirconium dioxide, cerium dioxide, lanthanum oxide or mixtures thereof, for example mixtures of silica and alumina.
  • a washcoat that has been affixed to a catalyst carrier substrate is called a “coating”. It is also possible to affix two or more washcoats to the carrier substrate. The skilled person knows that affixing two or more washcoats onto one single carrier substrate is possible by “layering” or by “zoning”, and it is also possible to combine layering and zoning. In case of layering, the washcoats are affixed successively onto the carrier substrate, one above the other. The washcoat that is affixed first and thus in direct contact with the carrier substrate represents the “bottom layer”, and the washcoat that is affixed last is the “top layer”.
  • a first washcoat is affixed onto the carrier substrate from a first face side A of the carrier substrate towards the other face side B, but not over the entire length of the carrier substrate, but only to an endpoint which is between face sides A and B.
  • a second washcoat is affixed onto the carrier, starting from face side B until an endpoint between face sides B and A.
  • the endpoints of the first and the second washcoat need not be identical: if they are identical, then both washcoat zones are adjacent to one another. If, however, the endpoints of the two washcoat zones, which are both located between face sides A and B of the carrier substrate, are not identical, there can be a gap between the first and the second washcoat zone, or they can overlap.
  • layering and zoning can also be combined, if, for instance, one washcoat is applied over the entire length of the carrier substrate, and the other washcoat is only applied from one face side to an endpoint between both face sides.
  • the “washcoat loading” is the sum of a) the mass of the catalytically active composition per volume of the carrier substrate and b) the masses of the at least one binder and/or at least one stabilizer, if binders and/or stabilizers are present in the washcoat.
  • washcoats are prepared in the form of suspensions and dispersions.
  • Suspensions and dispersions are heterogeneous mixtures comprising solid particles and a solvent.
  • the solid particles do not dissolve, but get suspended throughout the bulk of the solvent, left floating around freely in the medium. If the solid particles have an average particle diameter of less than or equal to 1 pm, the mixture is called a dispersion; if the average particle diameter is larger than 1 pm, the mixture is called a suspension.
  • Washcoats in the sense of the present invention comprise a solvent, usually water, and suspended or dispersed particles represented by particles of one or more the catalytically active compositions, and optionally particles of at least one binder as described above. This mixture is often referred to as the “washcoat slurry”. The slurry is applied to the carrier substrate and subsequently dried to form the coating as described above.
  • washcoat suspension is used for mixtures of solvents, particles of one or more catalytically active compositions, and optionally particles of at least one binder, irrespective of the individual or average particle sizes. This means that in “washcoat suspensions” according to the present invention, the size of individual particles as well as the average particle size of the one or more catalytically active solid particles can be less than 1 pm, equal to 1 pm and/or larger than 1 pm.
  • mixture as used in the context of the present invention is a material made up of two of more different substances which are physically combined and in which each ingredient retains its own chemical properties and makeup. Despite the fact that there are no chemical changes to its constituents, the physical properties of a mixture, such as its melting point, may differ from those of the components.
  • mixed oxide refers to a substance that is composed of several oxides, i.e. whose crystal lattice consists of oxygen ions and the cations of more than one chemical element or cations of a single element in several states of oxidation. More specifically, the term refers to solid ionic compounds that contain the oxide anion O 2 ' and two or more metal cations.
  • a “manganese-containing mixed oxide” is a mixed oxide according to this definition wherein one of the metal cations is a manganese cation.
  • the manganese-containing mixed oxides used in the present invention are mixed oxides in the sense of this definition, because they contain cations of two or more different chemical elements.
  • a “mixture of oxides” is a physical mixture of two or more oxides, wherein each oxide has its own crystal lattice.
  • a physical mixture of MnC>2, CeC>2 and TiC>2, for example, is a mixture of three different oxides with three different crystal lattices, namely those of MnC>2, CeC>2 and TiC>2.
  • one group of the manganese-containing mixed oxides which can be used in the context of the present invention has the general formula Mn a CebTi c O x .
  • a, b and c represent the molar fractions of manganese, cerium and titanium, based on the total molar amount of manganese, cerium and titanium in the ternary oxide; and wherein a, b and c are, independently from one another, larger than zero and smaller than 1 ; and wherein a, b and c add up to 1 ; and wherein x is the molar amount of oxygen.
  • cations of manganese, cerium and titanium and anions of oxygen are present in one crystal lattice. The same applies, mutatis mutandis, for the other manganese-containing mixed oxides, which we be explained in more detail below.
  • These manganese- containing mixed oxides are also mixed oxides in the sense of the above definition, by contrast to a mixture of the oxides of the corresponding metals.
  • a “catalysed substrate monolith” is a carrier substrate comprising a catalytically active composition.
  • the carrier may be coated with a washcoat comprising the catalytically active composition, wherein the washcoat comprises a catalytically active composition and optionally at least one binder.
  • the catalytically active composition can be a component of the carrier substrate itself.
  • a “device” as used in the context of the present invention is a piece of equipment designed to serve a special purpose or perform a special function.
  • the catalytic devices according to the present invention serve the purpose and have the function to remove nitrogen oxides from the exhaust gas of combustion engines.
  • a “device” as used in the present invention may consist of one or more catalyst, also called “catalytic articles” or “bricks” as defined above.
  • Upstream and downstream are terms relative to the normal flow direction of the exhaust gas in the exhaust pipeline.
  • a “zone or catalyst 1 which is located upstream of a zone or catalyst 2” means that the zone or catalyst 1 is positioned closer to the source of the exhaust gas, i.e. closer to the motor, than the zone or catalyst 2.
  • the flow direction is from the source of the exhaust gas to the exhaust pipe. Accordingly, in this flow direction the exhaust gas enters each zone or catalyst at its inlet end, and it leaves each zone or catalyst at its outlet end.
  • nitrogen oxides encompasses nitrogen monoxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O).
  • NO X nitrogen monoxide
  • NO2O nitrogen dioxide
  • N2O nitrous oxide
  • NO X conversion means the percent conversion of NO X without taking N2O in the gas phase after the catalyst into account.
  • N2O selectivity means the percent conversion of NO X and NH3 in the gas feed into N2O.
  • the N2O selectivity can be calculated according to the equation
  • IX ⁇ Oin amount of N2O at the inlet end of a catalytic device
  • IXhOout amount of N2O at the outlet end of a catalytic device
  • N Hs.out amount of NH3 at the outlet end of a catalytic device
  • NO x ,in amount of NO X at the inlet end of a catalytic device
  • NO x ,out amount of NO X at the outlet end of a catalytic device
  • catalytic activity or just “activity” is the increase in rate of a chemical reaction caused by the presence of a catalytically active composition.
  • the SCR reaction requires a reductant to reduce nitrogen oxides to nitrogen and water.
  • a suitable reductant is ammonia
  • the SCR reaction in presence of ammonia is known as “NH3-SCR”.
  • the ammonia used as reducing agent may be made available by feeding liquid or gaseous ammonia or an ammonia precursor compound into the exhaust gas. If an ammonia precursor is used, it is thermolyzed and hydrolyzed to form ammonia. Examples of such ammonia precursors are ammonium carbamate, ammonium formate and preferably urea. Alternatively, the ammonia may be formed by catalytic reactions of the ammonia precursor within the exhaust gas.
  • the NO X conversion of an exhaust gas comprising NO X depends on several factors, for example on the chemical nature of the SCR catalytically active composition, the amount of the SCR catalytically active composition that is present in the catalytic device, the NO2 to NO X ratio of the exhaust gas, the temperature of the exhaust gas, and the presence and quantity of catalyst poisons.
  • SCR catalysts that show a good NOx conversion over a large temperature range, in particular at low temperatures, and that are, at the same time, sulfur-tolerant, i.e. which are not easily intoxicated or deactivated by sulfur components in the exhaust gas.
  • Well- known SCR catalytically active compositions are a) mixed oxides comprising oxides of vanadium and titanium, b) transition metal-promoted zeolites and c) ternary mixed oxides comprising manganese, cerium and titanium.
  • Mixed oxides comprising oxides of titanium and vanadium show a good NO X conversion at low temperatures, but their NO X conversion at high temperatures is not as good as that of transition metal-promoted zeolites.
  • mixed oxides comprising oxides of titanium and vanadium are largely sulfur-tolerant.
  • Transition-metal promoted zeolites show a good NO X conversion over a wide temperature range. They show the best NO X conversion at high temperatures of all three groups of SCR catalytically active compositions mentioned above. Transition metal-promoted zeolites are prone to sulfur intoxication and sulfur deactivation; but the intoxication and deactivation is partly reversible.
  • Ternary mixed oxides comprising manganese, cerium and titanium show the best low temperature NO X conversion, but they are very sensitive to sulfur intoxication and deactivation, and in their case, the intoxication and deactivation is not reversible.
  • the object of the present invention to provide SCR catalytic devices with an improved low temperature performance and, concomitantly, a good sulfur resistance is solved by combining mixed oxides comprising oxides of vanadium and titanium with ternary oxides comprising manganese, cerium and titanium, and optionally also with transition metal- promoted zeolites in such a way that good NO X conversion over the a broad temperature range, in particular at low temperatures, and at the same time high sulfur tolerance result.
  • the carrier substrates of the catalytic devices according to the present invention can be so-called honeycomb flow-through substrates and wall-flow filters as well as corrugated substrates, extruded substrates, wound or packed fiber filters, open cell foams and sintered metal filters.
  • the carrier substrate is a honeycomb flow- through substrate, a wall-flow filter or a corrugated substrate.
  • Flow-through substrates and wall-flow filters may consist of inert materials, such as silicon carbide, aluminum titanate and cordierite.
  • carrier substrates are well-known to the skilled person and available on the market.
  • Corrugated substrates are made of ceramic E-glass fiber paper or of metal or metal alloys. They are also well known to the skilled person and available on the market.
  • a bottom layer comprising a material zone D is affixed to the carrier substrate.
  • Said material zone D extends from face side B over a length L z which is 20 to 100% of the length L of the carrier substrate.
  • L z is 30 to 100%, more preferably 35 to 95% of the length L.
  • the first SCR catalytically active composition in said material zone D consists of one or more manganese-containing mixed oxides, or a mixture of one or more manganese- containing mixed oxides and one or more metal-promoted small-pore zeolites.
  • the first SCR catalytically active composition in said material zone D consists of one or more manganese-containing mixed oxides.
  • the manganese-containing mixed oxides can be selected from manganese cerium titanium oxides Mn a CebTi c O x .
  • a, b and c represent the molar fractions of manganese, cerium and titanium, based on the total molar amount of manganese, cerium and titanium in the ternary oxide; and wherein a, b and c are, independently from one another, larger than zero and smaller than 1 ; and wherein a, b and c add up to 1 ; and wherein x is the molar amount of oxygen.
  • a ranges from 0.05 to 0.50, preferably from 0.10 to 0.40, more preferably 0.12 to 0.35; b ranges from 0.05 to 0.50, preferably from 0.10 to 0.40, more preferably 0.12 to 0.3; and c ranges from 0.30 to 0.90, preferably from 0.35 to 0.80, more preferably 0.40 to 0.75, provided that a + b + c add up to 1 as described above; and x ranges from 1.5 to 2.
  • the molar ratios of manganese, cerium and titanium may vary, as will be explained in more detail below. Therefore, the molar ratios of Mn, Ce and Ti are indicated with a, b and c in the general formula. The molar ratio of oxygen is likewise indicated with x. The skilled person knows that the molar ratio of oxygen must be selected so that electrical neutrality of the ternary mixed oxide Mn a CebTi c O x is given.
  • the manganese-containing mixed oxides can furthermore be selected from compounds having the general formula MndMei-dO w , wherein d, 1-d and w represent the molar fractions of manganese, a metal Me and oxygen.
  • the metal Me is selected from the group consisting of Fe, Co, Ni, Cu, Zr, Nb, Mo, W, Ag, Sn, Ce, Pr, La, Nd, Ti, Al, Si and Y.
  • Me is particularly advantageously selected from Fe, Cu, Nb, Mo, W, Sn, Al, Si and Ti. More preferably, Me is selected from Fe, Cu, Nb, W, Al and Si.
  • d ranges from 0.02 to 0.98 and w ranges from 1.0 to 2.5.
  • the manganese-containing mixed oxides can furthermore be selected from compounds having the general formula Mn e CefMei- e .fO v , wherein e, f, 1-e-f- and v represent the molar fractions of manganese, cerium, the metal Me and oxygen.
  • the metal Me is selected from the group consisting of Fe, Co, Ni, Cu, Zr, Nb, Mo, W, Ag, Sn, Ce, Pr, La, Nd, Ti, Al, Si and Y.
  • Me is particularly advantageously selected from Fe, Cu, Nb, Mo, W, Sn, Al, Si and Ti. More preferably, Me is selected from Fe, Cu, Nb, W, Al and Si.
  • e ranges from 0.02 to 0.98
  • f ranges from 0.02 to 0.98
  • v ranges from 1.0 to 2.5.
  • the skilled person knows that the molar ratio of oxygen must be selected so that electrical neutrality of the ternary mixed oxide Mn e CefMei- e .fO v is given.
  • the manganese-containing mixed oxides can furthermore be selected from spinels having the general formula MnS2C>4 or SM ⁇ CL, wherein S is selected from Fe, Al, Cr, Co and Cu.
  • the first SCR catalytically active composition in material zone D consists of one manganese-containing mixed oxide
  • said manganese-containing mixed oxide can be selected from any of the compounds having the general formula Mn a CebTi c O x , MndMei-dO w , Mn e CefMei- e .fO v , MnS2C>4 or SM ⁇ CL as defined above.
  • the first SCR catalytically active composition in material zone D consists of two or more manganese-containing mixed oxides
  • said manganese-containing mixed oxides can be selected from any of the compounds having the general formula Mn a CebTi c O x , MndMei. dO w , Mn e CefMei- e .fO v , MnS2C>4 or SM ⁇ CL as defined above.
  • Mn a CebTi c O x MndMei. dO w , Mn e CefMei- e .fO v , MnS2C>4 or SM ⁇ CL as defined above.
  • said mixed oxides can be c) all selected from manganese-containing mixed oxides having the same general formula, but different molar ratios of the elements; or d) they can be selected from manganese-containing mixed oxides having all different structural formulas, or e) it can deal with a mixture of manganese-containing mixed oxides having the same general formula, but different molar ratios of the elements and manganese-containing mixed oxides having different structural formulas.
  • the first SCR catalytically active composition in said material zone D consists of a mixture of one or more manganese-containing mixed oxides and one or more metal-promoted small-pore zeolites.
  • the manganese- containing mixed oxides are selected from compounds having the general formula Mn a CebTi c O x , MndMei-dO w , Mn e CefMei- e .fO v , MnS2C>4 or SMn2O4 as defined above.
  • Suitable small-pore zeolites which have a maximum pore size of eight tetrahedral atoms as explained above, are, for instance, AGO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, BIK, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, ESV, ETL, GIS, GOO, IHW, ITE, ITW, LEV, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON and mixtures and intergrowths thereof.
  • the small-pore zeolites are chosen from AEI, AFT, AFX, CHA, DDR, ERI, ESV, ETL, KFI, LEV, UFI and mixtures and intergrowths thereof.
  • the zeolites are selected from AEI, CHA, AFX, LEV, ERI and mixtures and intergrowths that contain at least one of these framework types.
  • the zeolites are chosen from AEI and CHA and mixtures and intergrowths that contain at least one of these framework types.
  • the zeolite is AEI.
  • the zeolite is CHA.
  • An “intergrowth” of a zeolite comprises at least two different zeolite framework types or two different zeolite compositions of the same framework type.
  • overgrowth In an “overgrowth” zeolite, one framework structure grows on top of the other one.
  • overgrowth represents a species of “intergrowth”
  • intergrowth is the genus.
  • the small-pore zeolite has the CHA framework type
  • this comprises all zeotypes having the CHA framework type, provided that they are crystalline aluminosilicates.
  • Such zeotypes are, for example, SSZ-13, LZ-218, Linde D, Linde R, Phi, ZK-14, with SSZ-13 being preferred.
  • the small-pore zeolite has the AEI framework type
  • this comprises all zeotypes having the AEI framework type, provided that they are crystalline aluminosilicates.
  • Such zeotypes are, for instance, SSZ-39 and SIZ-8.
  • the small-pore zeolite has the AFX framework type
  • this comprises all zeotypes having the AFX framework type, provided that they are crystalline aluminosilicates.
  • Such a ze- otype is, for instance, SSZ-16.
  • the small-pore zeolite has the LEV framework type, this comprises all zeotypes having the LEV framework type, provided that they are crystalline aluminosilicates. Such zeotypes are, for instance, ZK-20, LZ-132 and Nu-3. If the small-pore zeolite has the ERI framework type, this comprises all zeotypes having the ERI framework type, provided that they are crystalline aluminosilicates. Such zeotypes are, for instance, LZ-220, UZM-12 and SSZ-98.
  • the small-pore zeolite has a molar ratio of silica-to-alumina (SAR) value of 5 to 50, preferably 6 to 40, more preferably 7 to 30.
  • SAR silica-to-alumina
  • the at least one small-pore zeolite is metal-promoted.
  • the small-pore zeolite is promoted with copper and optionally with one or two additional metals M1 and M2.
  • the copper to aluminum atomic ratio in these zeolites is between 0.12 and 0.55, and the copper content is between 2.0 and 6.5wt.-%, calculated as CuO and based on the total weight of the zeolite.
  • promoter metals M1 and M2 are, independently from one another, selected from magnesium, calcium, barium, strontium, yttrium, titanium, zirconium, niobium, manganese, iron, zinc, silver, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, provided that, if both M1 and M2 are present, they are different from one another.
  • copper is the only promoter metal, and the Cu:AI atomic ratio is between 0.12 and 0.55.
  • the M1 :Cu atomic ratio is in the range of 0.05 to 0.95
  • the (Cu + M1) : Al atomic ratio is in the range of 0.11 to 0.96.
  • the M1 :Cu ratio and the M2:Cu atomic ratio are both in the range of 0.05 to 0.95, and the (Cu + M1 + M2) : Al atomic ratio is in the range of 0.2 to 0.80, under the proviso that M1 and M2 are different from one another.
  • the copper content in all these embodiments is between 2.0 to 6.5 wt.-% calculated as CuO and based on the total weight of the zeolite.
  • the at least one small-pore zeolite is promoted with copper and a metal M1 which is manganese, but not with a metal M2.
  • the smallpore zeolite comprises 2.0 to 6.5 wt.-% copper, calculated as CuO and based on the total weight of the zeolite, and the Cu : Al molar ratio is between 0.12 to 0.40.
  • the (Cu + Mn) : Al molar ratio ranges between 0.11 and 0.96.
  • the preferred SAR value is between 7 and 30.
  • the small-pore zeolite preferably has a CHA framework type. More preferably, the zeolite has a CHA framework type and a SAR value of between 7 and 30.
  • the at least one small-pore zeolite is promoted with copper and two additional metals.
  • the small-pore zeolite comprises at least 2.0 wt.-% copper, calculated as CuO and based on the total weight of the zeolite, and the Cu : Al molar ratio is between 0.12 and 0.55.
  • the first additional metal M1 is manganese, and the Mn : Cu atomic ratio is between 0.05 and 0.95.
  • the second additional metal M2 is selected from magnesium, calcium, barium, strontium, yttrium, titanium, zirconium, niobium, iron, zinc, silver, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and mixtures thereof, and the M2:Cu atomic ratio is between 0.05 and 0.80.
  • the sum of the atomic ratios of the metals Cu, Mn and M2 to aluminum; (Cu + Mn + M2) : Al is between 0.20 and 0.80.
  • the at least one small-pore zeolite preferably has as framework type selected from AEI, CHA, AFX and LEV and a SAR value of 5 to 50, preferably 6 to 30, more preferably 7 to 25.
  • the small-pore zeolite has a CHA or AEI framework and is promoted with copper, manganese, and a metal M2 selected from Fe, and Sm.
  • the at least one small-pore zeolite is promoted with copper and two additional metals.
  • the small-pore zeolite comprises at least 2.0 wt.-% copper, calculated as CuO and based on the total weight of the zeolite, and the Cu : Al molar ratio is between 0.12 and 0.55.
  • the first additional metal M1 is selected from calcium, magnesium or strontium, wherein the M1 : Cu atomic ratio is between 0.10 and 0.92.
  • the second additional metal M2 is selected from magnesium, calcium, barium, strontium, yttrium, titanium, zirconium, niobium, iron, zinc, silver, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and mixtures thereof.
  • the M2 Cu atomic ratio is between 0.05 and 0.80; and M1 and M2 are different from one another.
  • the small-pore zeolite does not comprise manganese.
  • the sum of the atomic ratios of copper, metal M1 and metal M2 to aluminum, (Cu + M1 + M2) : Al, is between 0.20 and 0.80.
  • the small-pore zeolite preferably has as framework type selected from AEI, CHA, AFX and LEV and a SAR value of 5 to 50, preferably 6 to 30, more preferably 7 to 25. Most preferably, the small-pore zeolite has a CHA or AEI framework and is promoted with copper, a metal M1 which is calcium, and a metal M2 selected from Fe, and Sm.
  • the at least two metal-promoted small-pore zeolites can be selected from all embodiments described above.
  • only one metal promoted small pore zeolite selected form the zeolites promoted with copper only or with copper and a metal M1 , or with copper and metals M1 and M2, as described above, is used.
  • the SCR catalytically active composition in material zone D consists of a mixture of at least one manganese-containing mixed oxide and at least one metal-promoted small-pore zeolite
  • the weight ratio of at least one manganese-containing mixed oxide to the at least one metal-promoted small-pore zeolite is in the range of 0.1 to 99 wt.%, preferably 1 to 90 wt%.
  • Both the second and the third SCR catalytically active composition consist of a V/TiCh SCR catalyst composition which comprises at least one oxide of vanadium supported on titanium dioxide.
  • the second and the third SCR catalytically active composition are identical or different from one another.
  • Material zone C’ is also affixed to the carrier substrate.
  • a material zone C’ is not present, because material zone D extends over the entire length of the carrier substrate from face side A to face side B.
  • the second and third SCR catalytically active composition in said material zones C and C’ consist of at least one oxide of vanadium supported on titanium dioxide.
  • SCR catalyst compositions are known to the skilled person. They are based on titanium dioxide and oxides of vanadium, in particular vanadium pentoxide and vanadium dioxide.
  • the titanium dioxide can be selected from anatase, rutile, brookite, and mixtures thereof. Suitable titanium dioxides comprise at least 95 wt.-% of anatase, preferably at least 98 wt.-%, and even more preferably at least 99.5 wt.-%.
  • the remainder for adding up to 100 wt.-% is preferably represented by rutile and/or brookite, more preferably by rutile.
  • SCR catalyst compositions comprising at least one oxide of vanadium supported on titanium dioxide are hereinafter referred to as “V/TiC>2 catalyst compositions”.
  • the V/TiC>2 catalyst compositions may additionally contain other oxides, such as those of silicon, molybdenum, tungsten, antimony, niobium, tantalum, hafnium, zirconium, cerium and mixtures thereof.
  • the second and third V/TiC>2 SCR catalyst compositions comprise, independently from one another
  • V/TiC>2 catalyst at least one oxide of titanium in an amount that is measured so as to result in a total of 100 wt.-%, in each case based on the total weight of the V/TiC>2 catalyst and calculated as V2O5, WO3, SiC>2, MO2O3, Sb20s, Nb20s, ZrC>2, Ta20s, HfC>2, CeC>2 or TiC>2.
  • the above composition mandatorily contains oxides of vanadium and titanium, and optionally oxides of tungsten, silicon, molybdenum, antimony, niobium, zirconium, tantalum, hafnium, cerium or mixtures thereof in the amounts as given above.
  • the second and third V/TiCh SCR catalyst compositions contain, independently from one another,
  • At least one oxide of titanium in an amount that is measured so as to result in a total of 100 wt.-%, in each case based on the total weight of the V/TiCh catalyst and calculated as V2O5, WO3, Sb20s, ZrC>2, CeC>2 or TiC>2.
  • the V/TiC>2 catalyst of this embodiment does not contain any oxide of zirconium, based on the total weight of the V/TiCh catalyst composition and calculated as ZrC>2.
  • the second and third V/TiCh SCR catalyst compositions contain, independently from one another,
  • the V/TiCh catalyst of this embodiment contains at least one oxide each of vanadium, tungsten, antimony, cerium, silicon and titanium as listed above, but no oxides of molybdenum, niobium, zirconium, tantalum and/or hafnium.
  • the second and third V/TiCh catalyst compositions contain, independently from one another,
  • At least one oxide of titanium in an amount that is measured so as to result in a total of 100 wt.-%, in each case based on the total weight of the V/TiCh catalyst and calculated as V2O5, CeC>2, Nb20s, WO3, SiC>2, MoOs, Sb20s, ZrC>2, Ta2Os, HfC>2 or TiC>2.
  • the V/TiCh catalyst of this embodiment contains at least one oxide each cerium, niobium and titanium and at least one oxide of silicon and/or tungsten as listed above, but no oxides of molybdenum, antimony, zirconium, tantalum and/or hafnium.
  • the second and third V/TiCh SCR catalyst compositions contain, independently from one another,
  • V/TiC>2 catalyst composition wherein at least one oxide of silicon is present, said oxide can be present in the form of silica-doped titanium dioxide, or as a separate oxide of silicon, or a mixture of both.
  • the skilled person knows how to calculate the total amount of silica present in the V/TiC>2 catalyst composition.
  • the V/TiO2 catalyst compositions in the material zone C and C’ can be identical or different from one another. If they are different from one another, they differ from one another in that they either comprise oxides of different metals, and/or they comprise oxides of the same metal, but in different amounts.
  • one of these two catalyst compositions can comprise Sb20s, but no Nb20s, whereas the other one comprises Nb20s, but no Sb20s.
  • they can both comprise Sb 2 O 5 , but in different amounts.
  • catalyst compositions in material zones C and C’ are identical, this means that both compositions comprise the same oxides in identical amounts. In a preferred embodiment, the catalyst compositions in material zones C and C’ are identical.
  • the amount of the at least one oxide of vanadium in the V/TiC>2 SCR catalyst composition can be adjusted according to the intended NO X conversion at different temperatures: if a high NO X conversion at low temperatures, e.g. below 250°C, is needed, the amount of vanadium oxides should be rather high. A high amount of oxides of vanadium will, however, decrease the NO X conversion of the V/TiCh SCR catalyst compositions at high temperature, e.g. above 400 °C. By contrast, a rather low amount of oxides of vanadium will increase the NO X conversion at high temperatures, e.g. above 400°C, and at the same decrease the NO X conversion at low temperatures.
  • “High” and “low” amounts of oxides of vanadium refer to the lower and upper limits for these oxides as given above. In other words: the closer the amount of vanadium oxides is to the upper limits of the amounts given above, the better the NO X conversion at low temperatures, and vice versa.
  • the amounts of copper, manganese, titanium, vanadium, aluminum, silicon, magnesium, calcium, barium, strontium, molybdenum, antimony, niobium, zirconium, tantalum, hafnium, iron, zinc, silver, platinum, palladium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium can be measured by ICP-AES (inductively coupled plasma atomic emission spectroscopy), ICP-OES (inductively coupled plasma optical emission spectroscopy) or XRF (X-ray fluorescence spectroscopy).
  • ICP-AES inductively coupled plasma atomic emission spectroscopy
  • ICP-OES inductively coupled plasma optical emission spectroscopy
  • XRF
  • Energy-dispersive X-ray spectroscopy allows to analyze elements having an atomic number of 8 or larger, thus enable the measurement of the above- mentioned mentals and oxygen alike.
  • the skilled person knows how to perform such analyses and can apply this knowledge to the zeolites according to the present invention without departing from the scope of the claims.
  • vanadium, antimony and niobium can occur in the oxidation states III and V, and therefore, they can form the oxides V2O3, VO2, V2O5, Sb20a, Sb20s, Nb20a and Nb20s.
  • the skilled person can easily detect these oxides and convert the result for the oxide of a specific metal in one oxidation state to the corresponding value for the oxide of the same metal in a different oxidation state.
  • SAR values of zeolites can be determined by FTIR.
  • Metal to metal molar ratios for example copper to aluminum molar ratios or copper to manganese molar ratios in zeolites can be measured by ICP-OES. These methods are known to the skilled person and can be applied in the context of the present invention without departing from the scope of the claims.
  • the material zones C, D, and optionally C’ are affixed to the carrier substrate or to the bottom layer, respectively, in the form of washcoat suspensions using known wash-coating techniques.
  • the washcoat loading in the material zones C and, if present, C’ is, independently from one another, in the range of from 25 to 400 g/L, preferably 50 to 300 g/L. If material zone C’ is present, its washcoat loading is preferably identical to that of material zone C.
  • the washcoat loading in material zone D is in the range of from 50 to 300 g/L, preferably 70 to 250 g/L. This applies for embodiments wherein the first SCR catalytically active composition in material zone D consists of one or more manganese-containing mixed oxides as well as for embodiments wherein the first SCR catalytically active composition in material zone D consists of a mixture of one or more manganese-containing mixed oxides and one or more metal-promoted smallpore zeolites. In other embodiments of the present invention, the total washcoat loading of the material zones C, D and optionally C’ is in the range of from 75 to 450 g/L.
  • the washcoat loadings of material zones C and optionally C’ are identical and in the range of from 25 to 250 g/L each, the washcoat loading of material zone D is in the range of from 50 to 250 g/L, and the total washcoat loading of material zones C, D and optionally C’ is in the range of from 75 to 400 g/L.
  • the solid catalyst composition which is usually present in the form of a powder, is suspended in a liquid medium, preferably water, optionally together with binder(s) and/or stabilizer(s).
  • the washcoat suspension can then be affixed to the carrier substrate or onto the bottom layer.
  • the washcoat suspensions optionally also contain binders selected from TiC>2, SiC>2, AI2O3, ZrC>2, CeC>2, La2C>3 and combinations thereof.
  • the binder is present in an amount of 0 to 20 wt.-%, preferably in an amount of 0.1 to 20 wt.-%, more preferably 0.2 to 15 wt.-%, based on the total weight of the SCR catalytically active composition and the binder.
  • the washcoat suspension may furthermore optionally comprise an additive.
  • the additive may be present together with a binder, as mentioned above, or the washcoat suspension may comprise only a binder or only an additive.
  • Suitable additives are polysaccharides, linear or branched primary or secondary polyhydric alcohols, polyvinylalcohols, aminoalcohols, dialkyl sulfosuccinate salts, glycerol; linear or branched-chain poly-functionalized organic molecules having two or more carbon atoms in the chain, with up to about 12 carbon atoms (C n ; wherein 2 ⁇ n ⁇ 12); salts of basic quaternary amines, wherein one or more quaternary amine groups are attached to four carbon chains having length of C n , where 1 ⁇ n ⁇ 5 and wherein the cation is balanced as a salt using, but not limited to, one of the following anions: hydroxide, fluoride, chloride, bromide, iod
  • the additive is a polysaccharide selected from the group consisting of a galactomannan gum, xanthan gum, guar gum curdlan, Schizophyllan, Scleroglucan, Diutan gum, Welan gum, a starch, a cellulose or an alginate or is derived from a starch, a cellulose (i.e. cellulosic) or an alginate, and mixtures of thereof.
  • Cellulosic additives may be selected from the group consisting of carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose and ethyl hydroxyethyl cellulose.
  • the polysaccharide is selected from xanthan gum, guar gum or a mixture thereof. Even more preferably the additive is xanthan gum.
  • the additive is a dialkyl sulfosuccinate salt.
  • the dialkyl sulfosuccinate can optionally be admixed with a linear or branched primary or secondary polyhydric alcohol.
  • the washcoat suspension may furthermore additionally comprise pH modifiers, surfactants and/or antifoaming agents.
  • pH modifiers surfactants and/or antifoaming agents.
  • suitable pH modifiers, surfactants, antifoaming agents can apply them without departing from the scope of the claims.
  • the first, second and/or the third washcoat suspension comprises an additive
  • said additive is present in an amount of up to 20 wt.-%, preferably 3 to 15 wt.-%, more preferably 6 to 10 wt.-%, based on the total weight of the oxides, wherein the “total weight of the oxides” is the sum of weights of the metal oxides, zeolite (if present) and the binder. It will be understood that, if the washcoat suspension does not comprise a binder, the “total weight of the oxides” corresponds to the weight of metal oxides and the zeolite (if present).
  • the first, second and third washcoat suspensions contain the first, second and third SCR catalytically active compositions, respectively.
  • the washcoat suspensions for the material zones C, D and optionally C’ may, independently from one another, only contain the respective SCR catalyst composition, or the SCR catalyst composition and at least one binder, or the SCR catalyst composition and at least one additive, or the SCR catalyst composition and at least one binder and at least one additive, each together with at least one solvent, which is preferably water.
  • the washcoat suspension for material zone D comprises the at least one SCR catalytically active composition, at least one binder, and at least one additive, together with the at least one solvent.
  • the washcoat suspension for material zone D comprises the SCR catalytically active composition, at least one binder, and at least one solvent, but no additive.
  • the washcoat suspensions for material zones C and optionally C’ comprise the at least one V/TiC>2 SCR catalyst composition, at least one binder, and at least one additive, together with the at least one solvent.
  • the washcoat suspensions for material zones C and C’ comprise the at least one metal-promoted zeolite, at least one additive, and at least one solvent, but no binder.
  • the washcoat suspension for material zone D contains the respective SCR catalytically active composition, water and at least one binder, and the washcoat suspensions for material zones C and optionally C’ comprise the V/TiCh SCR catalyst composition, water and at least one additive.
  • the at least one binder and/or at least one additive in the washcoat suspensions for material zones C, D and optionally C’ can be identical or different from one another.
  • compositions of the washcoat suspensions for material zones C and C’ are identical. This means that the second washcoat suspension is used for affixing both material zones C and C’.
  • the one or more manganese-containing mixed oxide and, if present, the one or more metal-promoted small-pore zeolites, as well as the components of the V/TiC>2 SCR catalyst composition can optionally be milled.
  • Milling can take place before suspending the one or more manganese-containing mixed oxide and the one or more metal-promoted small-pore zeolite and/or the binder and/or the additive and/or pH modifiers and/or surfactants and/or antifoaming agents, or afterwards. Milling can, for example, be carried by circular milling in a bead mill, an agitator mill or an agitator bead mill.
  • Coating a carrier substrate is well known to the skilled person.
  • the carrier substrate is oriented such that the channels thereof are substantially vertical.
  • the washcoat suspension is brought into contact with the carrier substrate, either by a bottom-up or a top-down process.
  • the carrier substrate is dipped into the washcoat suspension, or the washcoat suspension is pumped into the carrier substrate from the lower end face of the substrate to the upper end face.
  • the washcoat suspension is poured or pumped onto the upper end face of the carrier substrate.
  • the application of the washcoat suspension can optionally be performed under vacuum or over-pressure.
  • excess washcoat suspension can optionally be removed by applying vacuum or overpressure.
  • the washcoated carrier substrate is dried and calcined.
  • the procedure described above is repeated to apply a second or further washcoats.
  • the carrier substrate which has been coated with the first washcoat can be turned 180 degrees so that the former lower end face becomes the new upper end face and vice versa prior to the application of the second or further washcoat.
  • the method for making the SCR catalytic devices comprises the following steps: a) orienting the carrier substrate such that the channels thereof are substantially vertical, b) pumping the first washcoat suspension into the carrier substrate from the lower end face over a length L z , c) sucking out excess first washcoat suspension from the lower end face, d) drying and calcining the washcoated carrier substrate obtained after step d), e) orienting the washcoated carrier substrate obtained after step d) such that the channels thereof are substantially vertical, f) pouring the second washcoat suspension onto the upper end face of the carrier substrate obtained after step e), g) applying vacuum at the lower end face of the carrier substrate and soaking the second washcoat suspension applied in step f) through the monolith, h) drying and calcining the washcoated carrier substrate obtained after step g).
  • Drying the monolith in steps d) and h) is preferably carried out at a temperature of between 100 and 150°C, preferably 110 to 130 °C.
  • Calcining the monolith in steps d) and h) is preferably carried out at a temperature of between 300 and 700°C.
  • the washcoat carrier substrate is oriented such that the channels thereof are substantially vertical. This can mean that the end face which has been the lower end face in step b) also becomes the lower end face in step e). Alternatively, the end face which has been the lower end face in step b) can become the upper end face in step e). This latter option is preferred in case the carrier substrate is a wall-flow filter.
  • the first washcoat can be poured onto the upper end face of the carrier substrate in step b), followed by sucking out excess washcoat in step c), if material zone D shall extend over the entire length L of the carrier substrate; and/or the second washcoat can be pumped into the carrier substrate from the lower end face in step f), followed by step g), which is applying vacuum at lower end face of the carrier substrate and soaking the second washcoat suspension applied in step f) through the monolith.
  • the method for making the SCR catalytic devices comprises the following steps: a) orienting the carrier substrate such that the channels thereof are substantially vertical, b) pumping the first washcoat suspension into the carrier substrate from the lower end face over a length L z , c) sucking out excess first washcoat suspension from the lower end face, d) drying and calcining the washcoated carrier substrate obtained after step d), e) orienting the carrier substrate such that the channels thereof are substantially vertical and so that the end face which has been the lower end face in step b) now represents the upper end face, f) pumping the third washcoat suspension into the carrier substrate from the lower end face over a length L y , g) sucking out excess third washcoat from the lower end face, h) drying and calcining the washcoated carrier substrate obtained after step g), i) orienting the washcoated carrier substrate obtained after step d) such that the channels thereof are substantially vertical, j) pouring the second washcoat suspension
  • step d), h) and I) Drying and calcining the monolith in steps d), h) and I) is carried out as described above. It will be understood by the skilled person that this embodiment is particularly suitable if a material zone C’ shall be present which is different from material zone C.
  • the first washcoat can be poured onto the upper end face of the carrier substrate in step b), followed by sucking out excess washcoat in step c), if material zone D shall extend over the entire length L of the carrier substrate; and/or the second washcoat can be pumped into the carrier substrate from the lower end face in step i), followed by step, k), which is applying vacuum at lower end face of the carrier substrate and soaking the second washcoat suspension applied in step i) through the monolith.
  • the washcoat suspension of the V/TiO2 SCR catalytically active does not comprise all the oxides of vanadium and, if desired, additionally tungsten, silicon, molybdenum, antimony, niobium, cerium, tantalum and/or hafnium as mentioned above.
  • oxides which have not been applied as components of the washcoat suspension can be applied in a subsequent step, for instance by impregnating the second washcoat with these oxides and/or with precursors thereof. Impregnation can be carried out, for example, by dipping the carrier substrates, which are washcoated with the second washcoat suspension, into an aqueous solution of the precursors of these oxides.
  • the carrier substrates may be catalytically active on their own, and they may further comprise catalytically active compositions, i.e. the first SCR catalytically active compositions as described above.
  • these carrier substrates comprise a matrix component. All inert materials which are otherwise used for the manufacturing of catalyst substrates may be used as matrix components in this context. It deals, for instance, with silicates, oxides, nitrides or carbides, with magnesium aluminum silicates being particularly preferred.
  • the first SCR catalytically active compositions themselves form part of the carrier substrate, for example as part of a flow-through substrate.
  • carrier substrates additionally comprise the matrix components described above.
  • Catalysed substrate monoliths comprising the SCR catalytically active compositions according to the present invention may be used as such in exhaust purification.
  • they may be coated with catalytically active compositions.
  • the second SCR catalytically active compositions mentioned above are suitable materials for said coatings.
  • catalytically active carrier materials are manufactured by mixing 10 to 95 wt.-% of at least one inert matrix component and 5 to 90 wt.-% of a catalytically active composition, followed by extruding the mixture according to well-known protocols.
  • inert materials that are usually used for the manufacture of catalyst substrates may be used as the matrix components in this embodiment.
  • Suitable inert matrix materials are, for example, silicates, oxides, nitrides and carbides, with magnesium aluminum silicates being particularly preferred.
  • Catalytically active carrier materials obtainable by such processes are known as “extruded catalysed substrate monoliths”.
  • an “extruded catalysed substrate monolith” is an extruded monolith wherein the catalytically active composition is a crystalline aluminosilicate zeolite having a maximum ring size of eight tetrahedral atoms, said zeolite comprising copper, manganese and a metal M as described above.
  • the application of the catalytically active components onto either the inert carrier substrate or onto a carrier substrate which is catalytically active on its own as well as the application of a catalytically active coating onto a carrier substrate, said carrier substrate comprising a catalyst according to the present invention can be carried out following manufacturing processes well known to the person skilled in the art, for instance by widely used dip coating, pump coating and suction coating, followed by subsequent thermal post-treatment (calcination).
  • the average pore sizes and the mean particle size of the catalytically active components according to the present invention may be adjusted to one another in a manner that the coating thus obtained is located onto the porous walls which form the channels of the wall-flow filter (on-wall coating).
  • the average pore sizes and the mean particle sizes are preferably adjusted to one another in a manner that the catalyst according to the present invention is located within the porous walls which form the channels of the wall-flow filter.
  • the inner surfaces of the pores are coated (in-wall coating).
  • the mean particle size of the catalysts according to the present invention has to be sufficiently small to be able to penetrate the pores of the wall-flow filter.
  • Wall-flow filters which are coated with an SCR catalytically active compositions are also known as “SDPF” (SCR on DPF, i.e. an SCR catalytically active composition coated onto a diesel particulate filter) or as “SCRF” (SCR on filter).
  • SDPF SCR on DPF
  • SCRF SCR on filter
  • the catalytic devices according to the present invention can be used in systems and methods for the removal of NO X from combustion exhaust gases.
  • the catalytic devices are applicable in exhaust purification systems of mobile and stationary combustion engines.
  • Mobile combustion engines are, for example, gasoline and diesel engines and also hydrogen internal combustion engines (H2 ICE).
  • H2 ICE hydrogen internal combustion engines
  • combustion processes usually take place under oxidizing conditions, and that either fuels comprises nitrogen or nitrogen compounds, which can be oxidized to NO X , and/or that the combustion takes place in the presence of air, wherein the oxygen which is present in the air acts as the oxidant, and at least a part of the nitrogen which is present in can be oxidized to NO X .
  • Mobile combustion engines can be engines for on-road and off-road applications, for example, gasoline and diesel engines and also hydrogen internal combustion engines for passenger cars, agricultural machinery like agricultural and forestry tractors and harvesting machines, construction wheel loaders, bulldozers, highway excavators, forklift trucks, road maintenance equipment, snow plows, ground support equipment in airports, aerial lifts and mobile cranes.
  • Stationary combustion engines are, for example, power stations, industrial heaters, cogeneration plants including wood-fired boilers, stationary diesel and gasoline engines, industrial and municipal waste incinerators, industrial drilling rigs, compressors, manufacturing plants for glass, steel and cement, manufacturing plants for nitrogen-containing fertilizers, nitric acid production plants (for example plants applying the Ostwald process) and ammonia burners for fueling gas turbines of nitric acid production.
  • the catalytic devices according to the present invention can be used in a process for the removal of NO X from automotive combustion exhaust gases, said exhaust gases deriving from diesel or gasoline engines.
  • the present invention encompasses ammonia slip catalysts (ASC).
  • ASC ammonia slip catalysts
  • An ASC is preferably located downstream of the SCR, because recognizable amounts of NH3 leave the SCR due to the dynamic driving conditions. Therefore, the conversion of excess ammonia which leaves the SCR is mandatory, since ammonia is also an emission regulated gas. Oxidation of ammonia leads to the formation of NO as main product, which would consequently contribute negatively to the total conversion of NO X of the whole exhaust system.
  • An ASC may thus be located downstream the SCR to mitigate the emission of additional NO.
  • the ASC catalyst combines the key NH3 oxidation function with an SCR function. Ammonia entering the ASC is partially oxidized to NO.
  • the freshly oxidized NO and NH3 inside the ASC, not yet oxidized, can consequently react to N2 following the usual SCR reaction schemes. In doing so, the ASC is capable of eliminating the traces of ammonia by converting them in a parallel mechanism to N2.
  • the SCR catalyst and the ASC catalyst may be present as two consecutive catalytic articles, or the SCR functionality and the ASC functionality may be present on one single catalytic article.
  • the upstream catalytic article is the SCR catalyst, i.e. a catalytic device for the selective catalytic reduction of nitrogen oxides according to the present invention
  • the downstream catalytic article is the ASC catalyst comprising a carrier substrate, a washcoat comprising an oxidation catalyst, and a washcoat comprising an SCR catalytically active composition.
  • the catalytic device for the selective catalytic reduction of nitrogen oxides according to the present invention represents the upstream zone of the carrier substrate, and the downstream zone of said carrier substrate contains a bottom layer with a washcoat comprising an oxidation catalyst and a top layer with a washcoat comprising an SCR catalytically active composition.
  • the SCR catalytically active composition of the ASC can be selected from manganese- containing mixed oxides, metal-promoted small-pore zeolites and V/TiC>2 SCR catalyst compositions according to the present invention, and mixtures thereof.
  • Platinum group metals are used as oxidation catalysts in an ASC.
  • the precious metal is a platinum group metal selected from ruthenium, rhodium, palladium, osmium, iridium, platinum and mixtures thereof.
  • the precious metal is chosen from palladium, platinum, rhodium and mixtures thereof, more preferably, the precious metal is platinum.
  • the platinum group metal is added in the form of a precursor salt to a washcoat slurry and applied to the carrier monolith.
  • the platinum group metal is present in a concentration of 0.01 to 10 wt.-%, preferably 0.05 to 5 wt.-%, even more preferably 0.1 to 3 wt.-%, calculated as the respective platinum group metal and based on the total weight of the washcoat loading.
  • the platinum group metal is platinum, and it is present in a concentration of 0.1 to 1 wt.-%, calculated as Pt and based on the total weight of washcoat loading.
  • the ASC catalyst is a catalysed substrate monolith, wherein the monolith is a flow-through monolith coated with a bottom layer comprising an oxidation catalyst and a top layer comprising manganese-containing mixed oxides, metal-promoted small-pore zeolites and V/TiC>2 SCR catalyst compositions according to the present invention, and mixtures thereof.
  • the present invention furthermore provides an emissions treatment system for the removal of NOx emissions from exhaust gases of internal combustion engines, and optionally also for the removal of particulate matter, the system comprising, in the following order, from upstream to downstream: a) means for injecting ammonia or an ammonia precursor solution into the exhaust gas stream, b) a catalytic device for the selective catalytic reduction of nitrogen oxides from the exhaust gas of combustion engines according to the present invention, wherein the carrier substrate is selected from honeycomb flow-through substrates, honeycomb wall-flow filters, corrugated substrates, wound or packed fiber filters, open cell foams, sintered metal filters and extruded catalysed substrate monoliths.
  • the carrier substrate is a flow- through monolith or a corrugated substrate
  • the corresponding catalysed substrate monolith will remove NO X emissions only. If, however, the carrier substrate is a wall-flow filter, the corresponding catalysed carrier substrate will also remove particulate matter.
  • Ammonia may be supplied in an appropriate form, for instance in the form of liquid ammonia or in the form of an aqueous solution of an ammonia precursor, and added to the exhaust gas stream as needed via means for injecting ammonia or an ammonia precursor.
  • Suitable ammonia precursors are, for instance urea, ammonium carbamate or ammonium formate.
  • the ammonia may be formed by catalytic reactions within the exhaust gas.
  • a widespread method is to carry along an aqueous urea solution and to and to dose it into the catalyst according to the present invention via an upstream injector and a dosing unit as required.
  • Means for injecting ammonia for example an upstream injector and a dosing unit, are well known to the skilled person and can be used in the present invention without departing from the scope of the claims.
  • an emissions treatment system for the removal of NOx emissions from exhaust gases of internal combustion engines, and optionally also for the removal of particulate matter may comprise additional catalytic articles, for instance a diesel oxidation catalyst (DOC), an ammonia slip catalyst (ASC), a catalysed or uncatalysed particulate filter, a passive NO X adsorber (PNA), and/or a lean NO X trap (LNT).
  • a catalysed particulate filter may be coated with a diesel oxidation catalyst, thus forming a “catalysed diesel particulate filter (CDPF), or it may be coated with an SCR catalytically active composition, thus forming an SDPF.
  • CDPF catalysed diesel particulate filter
  • the emissions treatment system comprising a catalytic device according to the present invention is arranged in a close-coupled position.
  • close-coupled refers to a position of a catalytic device in an engine’s exhaust gas treatment system which is less than 1 meter downstream of the engine’s exhaust gas manifold or turbocharger.
  • the emissions treatment system comprising a catalytic device according to the present invention furthermore comprises one or more particulate filters.
  • the “first” filter is the filter that is arranged closest to the engine.
  • the “second” filter if present, is located downstream of the first filter, either directly following the first filter, or in a position further downstream.
  • the catalytic device according to the present invention which is arranged in a close-coupled position, is arranged upstream of the first filter.
  • the catalytic device according to the present invention can be a honeycomb flow-through substrate, a honeycomb wall-flow filter, a corrugated substrate, a wound or packed fiber filter, an open cell foam or a sintered metal filter.
  • it is a honeycomb flow-through substrate, a wall-flow filter or a corrugated substrate. If the catalytic device according to the present invention is a honeycomb wall-flow filter, it deals with an SDPF.
  • the emissions treatment system is arranged in an underfloor position.
  • Underfloor catalyst members are also known in the prior art and are located downstream of any close-coupled and/or medium- coupled catalysts under the floor of the vehicle adjacent to or in combination with the vehicle's muffler.
  • the catalytic device according to the present invention is arranged downstream the first filter.
  • the substrates catalytic device according to the present invention are the same as those mentioned above for the close-coupled arrangement.
  • the emissions treatment system comprising a catalytic device according to the present invention is arranged upstream of the first particulate filter, but 1 meter or more downstream of the engine’s exhaust gas manifold or turbocharger.
  • the catalytic device according to the present invention preferably is the first brick downstream of the engine’s exhaust gas manifold or turbocharger.
  • the emissions treatment system comprising a catalytic device according to the present invention is arranged downstream of the first particulate filter.
  • the catalytic devices according to the present invention are the same as those mentioned above for the close- coupled arrangement and the underfloor arrangement.
  • face side A of the catalytic device according to the present invention is positioned upstream, and face side B is positioned downstream.
  • the present invention furthermore provides a method for the removal of NO X emissions from exhaust gases of internal combustion engines, and optionally also for the removal of particulate matter, the method comprising, in the following order, from upstream to downstream: a) injecting ammonia or an ammonia precursor solution into the exhaust gas stream, b) introducing the exhaust gas from step a) into a catalytic device for the removal of nitrogen oxides from the exhaust gas of combustion engines according to the present invention, and wherein the carrier substrate is selected from honeycomb flow-through substrates, honeycomb wall-flow filters, corrugated substrates, wound or packed fiber filters, open cell foams, sintered metal filters and extruded substrate monoliths.
  • the substrate monolith is selected from honeycomb flow-through substrates, wall-flow filters, and corrugated substrates. More preferably, the carrier substrate is a flow-through substrate or a corrugated substrate.
  • the carrier substrate used in step b) of the method above is a flow-through monolith or a corrugated substrate
  • the corresponding catalytic device will remove NO X emissions only. If, however, the carrier substrate used in step b) of the method above is a wall-flow filter, the corresponding catalysed carrier substrate will also remove particulate matter.
  • L L y + L z
  • FIG. 1 shows an embodiment of the present invention wherein S is the carrier substrate, C represents the top layer wherein the SCR catalytically active composition consists of a V/TiC>2 catalyst composition, and D represents the bottom layer wherein the SCR catalytically active composition consists of one or more manganese-containing mixed oxides, or a mixture of one or more manganese-containing mixed oxides and one or more metal-promoted small-pore zeolites. Both layers extend over the entire length of the substrate monolith from face side A to face side B.
  • Fig. 2 shows an embodiment of the present invention wherein S is the carrier substrate, C represents the top layer having a length L, wherein the SCR catalytically active composition consists of a V/TiCh catalyst composition; C’ represents the upstream bottom layer having a length L y , wherein the SCR catalytically active composition consists of a V/TiC>2 catalyst composition; and D represents the downstream bottom layer having a length L z and wherein the SCR catalytically active composition consists of one or more manganese-containing mixed oxides, or a mixture of one or more manganese-containing mixed oxides and one or more metal-promoted small-pore zeolites.
  • Fig. 3 shows the NO X conversion after sulfur deactivation of Comparative Example 1.
  • Fig. 4 shows the NO X conversion after sulfur deactivation of Comparative Example 2.
  • Fig. 5 shows the NO X conversion after sulfur deactivation of Comparative Example 3.
  • Fig. 6 shows the NO X conversion after sulfur deactivation of Comparative Example 4.
  • Fig. 7 shows the NO X conversion after sulfur deactivation of Comparative Example 5.
  • Fig. 8 shows the NO X conversion after sulfur deactivation of Example 1.
  • Fig. 9 shows the NO X conversion for Comparative Example 1 (“Cu-SCR”), Comparative Example 2 (“Mn-SCR”), Comparative Example 3 (“V-SCR”) and Example 1 (“Example”): White columns: NO X conversion without sulfur; black columns: NO X conversion after exposure to 2g S/L; hatched columns: NO X conversion after exposure to 2g S/L and subsequent desulfation at 400°C.
  • Fig. 10 shows the NO X conversion loss ((NO x % W ithout sulfur - NO x % W ith suifur)/NO x % W ithout sulfur) at 225°C after exposure to 2g S/L for Comparative Example 1 (“Cu-SCR”), Comparative Example 2 (“Mn-SCR”), Comparative Example 4 (“V-SCR as top layer for Cu-SCR”) and Examples 1, 2, 3 and 4. All examples showed less NO X conversion loss than the comparative examples after the same sulfur exposure.
  • a commercially available zeolite powder with the CHA framework structure, in H + -form, and with an SAR of 15.8 was used as base zeolite material.
  • 1.06 kg of the base zeolite was impregnated with an aqueous solution of Cu(NO 3 )2, which was dosed over 30 min while constantly mixing the powder in a closed stainless steel container.
  • the aqueous CU(NO 3 ) 2 solution was prepared from a mixture of 550 g water and 151.8 g CU(NO3)2' 3H2O, where the Cu-salt was fully dissolved before addition to the zeolite powder.
  • the Cu-loaded zeolite was dried for 8 h at 120°C and calcined at 600°C for 2 h.
  • a slurry consisting of H2O, AI2O3 as binder, and the Cu-loaded zeolite prepared from Comparative Example 1 was mixed and left for stirring overnight.
  • the commercial monolith carrier was submerged into the slurry, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 150 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • a slurry consisting of H2O and the Mn-based powder prepared from Comparative Example 2 was mixed and left for stirring overnight.
  • the commercial monolith carrier was submerged into the slurry, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 150 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • a commercially available titanium dioxide in the anatase form was dispersed in water and then vanadium dioxide (VO2), tungsten trioxide (WO3), cerium dioxide (CeCh) and antimony pentoxide (Sb20s) were added in amounts so as to result in a catalyst of the composition 87 wt% TiC>2, 5.0 % V2O5, 1 wt% WO3, 2 wt% CeC>2 and 5.0 wt% Sb20s.
  • the slurry was vigorously stirred and then milled in a commercially available agitator bead mill.
  • the commercial monolith carrier was submerged into the slurry, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 150 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • the catalyst was calcined at 580 °C for 2 hours
  • the catalyst from Comparative Example 1 was submerged into the slurry prepared in comparative example 3, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 65 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • the catalyst was calcined at 580 °C for 2 hours.
  • the catalyst from Comparative Example 1 was submerged into the slurry prepared in comparative example 3, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 100 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • the catalyst was calcined at 580 °C for 2 hours.
  • the catalyst from Comparative Example 2 was submerged into the slurry prepared in comparative example 3, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 150 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • the catalyst was calcined at 580 °C for 2 hours.
  • a slurry consisting of H2O, the Mn-based powder prepared from Example 2, and Cu/CHA from Comparative Example 1 were mixed and left for stirring overnight.
  • the weight ratio of Mn-based powder to Cu/CHA is 1 :1.
  • the commercial monolith carrier was submerged into the slurry, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 150 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • the prepared catalyst was submerged into the slurry prepared in comparative example
  • the catalyst was calcined at 580 °C for 2 hours.
  • a slurry consisting of H2O, the Mn-based powder prepared from Comparative Example 2, and Cu/CHA from Comparative Example 1 were mixed and left for stirring overnight.
  • the weight ratio of Mn-based powder to Cu/CHA is 3:7.
  • the commercial monolith carrier was submerged into the slurry and coated only 70% of the channel length from face B, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 150 g/L.
  • the substrate applied was commercially available with the dimensions 5.66” diameter and 3.0” length, and with channel dimensions 400 cpsi and wall thickness of 4 mil.
  • the prepared catalyst was submerged into the slurry prepared in comparative example 3, and subsequently dried by a flow of hot air. The process was repeated until reaching a loading of the dry coating of 150 g/L.
  • the catalyst was calcined at 580 °C for 2 hours.
  • the coated catalysts were measured after preparation in a model gas reactor for NOx for sulfur deactivation.
  • the NO X conversion of the catalysts was tested during sulfur exposure.
  • GHSV gas hourly space velocity
  • Example 1 showed almost no deactivation during sulfation and a much better sulfur resistance than Comparative Example 1 , 2, 4, and 5. Furthermore, the NO X conversion at 225°C of the current invention is higher than Comparative Example 3. After desulfation at 400°C, Comparative Example 1 could be recovered to certain extent, as shown in Figure 9, but it showed a still lower NO X conversion than the Example 1.

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Abstract

La présente invention divulgue des dispositifs catalytiques de réduction catalytique sélective d'oxydes d'azote de gaz d'échappement de moteurs à combustion, comprenant un substrat support de longueur L, une couche inférieure comprenant une zone D s'étendant d'un deuxième côté sur une longueur LZ et comprenant une première composition de SCR constituée d'un ou plusieurs oxydes mixtes contenant du manganèse, ou un mélange d'un ou plusieurs oxydes mixtes contenant du manganèse et d'une ou plusieurs zéolites à petits pores activées par un métal ; et une zone C' s'étendant à partir d'un premier côté sur une longueur LY = L - LZ et comprenant une troisième composition de SCR constituée d'une composition de catalyseur de SCR de V/TiO2qui comprend au moins un oxyde de vanadium, et une couche supérieure comprenant une zone de matériau C s'étendant sur le substrat support et comprenant une deuxième composition de SCR constituée d'une composition de catalyseur de SCR de V/TiO2 qui comprend au moins un oxyde de vanadium.
PCT/EP2024/067120 2023-06-30 2024-06-19 Catalyseurs scr pour réduction améliorée de nox Pending WO2025002948A1 (fr)

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