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WO2007104382A1 - Catalyseur pour la purification de gaz d'echappement constitue d'une pluralite de catalyseurs individuels - Google Patents

Catalyseur pour la purification de gaz d'echappement constitue d'une pluralite de catalyseurs individuels Download PDF

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Publication number
WO2007104382A1
WO2007104382A1 PCT/EP2007/000735 EP2007000735W WO2007104382A1 WO 2007104382 A1 WO2007104382 A1 WO 2007104382A1 EP 2007000735 W EP2007000735 W EP 2007000735W WO 2007104382 A1 WO2007104382 A1 WO 2007104382A1
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Prior art keywords
catalyst
reduction
oxidation
reducing agent
reduction catalyst
Prior art date
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Ceased
Application number
PCT/EP2007/000735
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German (de)
English (en)
Inventor
Lothar Hofmann
Jörg Münch
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Johnson Matthey Catalysts Germany GmbH
Original Assignee
Argillon GmbH
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Application filed by Argillon GmbH filed Critical Argillon GmbH
Priority to EP07703095A priority Critical patent/EP1993709A1/fr
Publication of WO2007104382A1 publication Critical patent/WO2007104382A1/fr
Anticipated expiration legal-status Critical
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/19—Catalysts containing parts with different compositions
    • 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
    • B01D53/9431—Processes characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/648—Vanadium, niobium or tantalum or polonium
    • B01J23/6482—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
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/652—Chromium, molybdenum or tungsten
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0242—Coating followed by impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0244—Coatings comprising several layers
    • 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
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features having two or more separate purifying devices arranged in series
    • F01N13/0097—Exhaust or silencing apparatus characterised by constructional features having two or more separate purifying devices arranged in series the purifying devices are arranged in a single housing
    • 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
    • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
    • F01N3/106—Auxiliary oxidation catalysts
    • 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]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • 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
    • B01D2255/20769—Molybdenum
    • 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
    • B01D2255/20776—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
    • F01N2340/00—Dimensional characteristics of the exhaust system, e.g. length, diameter or volume of the exhaust apparatus; Spatial arrangements of exhaust apparatuses
    • 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
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • 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
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • 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 invention relates to a catalyst for purifying oxygen-containing exhaust gases of an incinerator, in particular an internal combustion engine operated with excess air, comprising a reduction catalyst for the selective catalytic reduction of nitrogen oxides contained in the exhaust gas by means of a reducing agent and an oxidation catalyst downstream of the reduction catalyst for the oxidation of the reducing agent wherein the oxidation catalyst is applied to the reduction catalyst via a downstream region which is 1-19% of the total catalyst volume.
  • Such a catalyst is known from EP 1 264 628 A1 and is used to purify the oxygen-containing exhaust gases of a combustion plant by means of selective catalytic reduction of nitrogen oxides, without the reductant used being released into the environment.
  • the reduction catalyst hereby reduces by means of a reducing agent, such as e.g. Ammonia, in the presence of oxygen nitrogen oxides to molecular nitrogen and water.
  • a reducing agent such as e.g. Ammonia
  • This method of selective catalytic reduction is also known by the abbreviation SCR method.
  • a reductant-donating substance e.g. Urea, which liberates ammonia in the exhaust gas added.
  • the delivery of the added reducing agent to the environment must be kept as low as possible, for example, to avoid odor nuisance. For this reason, in the applied SCR method, a substoichiometric metering of the reducing agent takes place with respect to the actual or the expected nitrogen oxide content of the exhaust gas. Although this reliably prevents a reduction agent emission, the reduction catalyst does not have the maximum possible, but a smaller amount of nitrogen oxides eliminated. As a consequence, the reduction catalyst must be designed to be sufficiently large and the control of the reducing agent metering work exactly to achieve a significant reduction of nitrogen oxides, in particular during transient engine operation, as is usual in a motor vehicle.
  • a catalyst of the type mentioned circumvents this problem by the downstream of the reduction catalyst an oxidation catalyst for the oxidation of the reducing agent is applied.
  • this oxidation catalyst in the presence of oxygen, the reducing agent, in particular ammonia, into harmless compounds, in particular molecular nitrogen and water, oxidized.
  • the reduction catalyst produced in one piece according to EP 0 410 440 B1 is coated downstream with the oxidation catalyst, the coated area making up 20-50% of the total catalyst volume.
  • the upstream reduction catalyst can now be used effectively.
  • the reducing agent can be metered in stoichiometrically or superstoichiometrically in order to achieve maximum degradation of the nitrogen oxides.
  • such a catalyst has undesirable side reactions. So again nitrogen oxides can be formed. Also, for example, ammonia can be converted to nitrous oxide or ammonium nitrate in the presence of excess air. Optionally, hydrocarbons present in the exhaust may react to harmful nitro compounds.
  • the oxidation catalyst is applied to a honeycomb-shaped reduction catalyst over a downstream length of 1 to 20% of the total length.
  • the object of the invention is to provide a catalyst of the type mentioned above, which allows avoiding a reducing agent slip and undesirable side reactions as high as possible degree of conversion of nitrogen oxides, and is as versatile as possible.
  • This object is achieved according to the invention for a catalyst according to the preamble of claim 1 in that the reduction catalyst is composed of a number of individual catalysts, wherein the oxidation catalyst is applied to the last individual catalyst (s) on the outflow side.
  • such a catalyst already allows a stoichiometric or superstoichiometric metered addition of the reducing agent, so that the reduction catalyst converts a maximum possible amount of nitrogen oxides, without causing a reduction agent slip.
  • a volume of 1% provided with the oxidation catalyst is sufficient. If a volume of the entire catalyst of more than 19% is provided with the oxidation catalyst, then the mentioned undesired side reactions occur increasingly.
  • nitrogen oxides are formed again on the oxidation catalyst in the interaction of nitrogen, oxygen and unreacted reducing agent. A volume of oxidation catalyst which exceeds 19% thus does not serve to degrade the reducing agent, but undesirable reactions are then catalysed at free adsorption sites.
  • the specified catalyst can be produced inexpensively, since no two separate catalysts for reduction or for oxidation must be made.
  • For the preparation of the reduction catalyst is prepared in a conventional manner. Subsequently, the composition of the catalytically active surface is changed downstream of this reduction catalyst to create the oxidation catalytic converter. This can be done, for example, by re-coating or by introducing compounds or elements catalyzing the oxidation of the reducing agent. Alternatively, it would also be conceivable to replace the existing catalytically active surface in terms of reduction.
  • the catalyst is included in the - A -
  • the reduction catalytic converter is composed of a number of individual catalytic converters, wherein the oxidation catalytic converter is applied to the last single catalytic converter or catalytic converters on the outflow side.
  • the desired length of the reduction catalyst can be set in a modular manner via the number of individual catalysts.
  • the desired downstream of the entire catalyst volume outflow area, which acts as an oxidation catalyst, may extend over several of the individual catalysts downstream.
  • the reduction catalyst or catalysts may be formed as a supported catalyst having an SCR-active coating, and then the oxidation catalyst is applied.
  • the catalytically active coating is applied to a usually plate-shaped carrier material. The coated carrier plates are then stacked to form the catalyst, wherein for the flowing exhaust gas flow channels are formed by introduced into the substrate corrugations and / or waves.
  • the reduction catalyst is formed as an SCR active Vollextrudat, whereupon the oxidation catalyst is applied.
  • the bulk extrudate consists of a ceramic mass which is produced and extruded as a slurry of metal oxides, in particular titanium dioxide. The shaped body thus produced is then dried and calcined to ceramic.
  • the bulk extrudate comprises a series of continuous pores through which the exhaust gas flows and contacts the surface of the catalyst.
  • the catalytically active material which may in particular have the same composition as the mass of the bulk extrudate, is applied to the support material in the supported catalyst. This can be done by applying or dipping the substrate. A layer of an aluminum oxide can also be applied between the SCR-active material and the carrier material.
  • a zeolite as material containing the catalytically active further components.
  • the oxidation catalyst is applied to the reduction catalyst as an impregnation or impregnation.
  • the later acting as an oxidation catalyst part of the reduction catalyst is immersed, for example, in a solution containing an oxidation catalyzing substances or their reactive precursors. These substances precipitate on the open surface of the catalytically active material of the reduction catalyst or penetrate into the volume of the material.
  • the impregnated material of the reduction catalyst is then converted to the catalytically active material of the oxidation catalyst.
  • the catalytically active material of the reduction catalyst which is used both as Besen ichtung for the support material of the plate catalyst and as a material of the bulk extrudate, advantageously comprises predominantly titanium dioxide and as additives vanadium, molybdenum, tungsten and / or their oxides.
  • titanium dioxide is used in the anatase structure. Such a titanium dioxide may be prepared, for example, by flame hydrolysis or by precipitation.
  • the catalytically active material of the oxidation catalyst preferably also comprises predominantly titanium dioxide and, as additives, platinum, rhodium and / or palladium.
  • the noble metals can be introduced by impregnation of the catalytically active material of the reduction catalyst with an aqueous solution of hexachloroplatinic acid, palladium chloride and / or rhodium chloride.
  • a ⁇ -aluminum oxide with additions of cerium oxide and zirconium oxide can be applied to the catalytically active material of the reduction catalyst as the oxidation coating.
  • the noble metals are then introduced into the alumina.
  • a cordierite ie, a magnesium-aluminum silicate
  • the ⁇ -aluminum oxide can also be applied as a coating on the plate catalyst and be impregnated with the corresponding substances to form the catalytically active material of the reduction catalyst.
  • FIG. 1 schematically shows a reduction catalyst with downstream oxidation catalyst
  • FIG. 2 shows a multi-part reduction catalytic converter with a downstream oxidation catalyst, used for the exhaust gas treatment of an internal combustion engine.
  • the catalyst 1 shows schematically a catalyst 1 designed as a vol-extruded honeycomb body, as it could be used as the last single catalyst downstream.
  • the catalyst 1 comprises a reduction catalyst 2 and a downstream oxidation catalyst 3.
  • the material used for the honeycomb body of the catalyst 1 is a titanium dioxide ceramic which comprises catalytically active additives vanadium and molybdenum and tungsten compounds.
  • the downstream applied oxidation catalyst 3 is prepared by impregnation of the reduction catalyst 2 with platinum.
  • the illustrated catalyst 1 is flowed through by the exhaust gas of an incinerator 5 in the illustrated arrow direction.
  • the exhaust gas 5 contains on the inlet side nitrogen oxides and oxygen and as additionally introduced reducing agent ammonia.
  • ammonia is added slightly more than stoichiometrically.
  • At the reduction catalyst 2 are in the exhaust 5 contained nitrogen oxides with ammonia in the presence of oxygen to form molecular nitrogen and water. Excess ammonia then flows through the downstream deposited oxidation catalyst 3. There, ammonia is oxidized with oxygen to molecular nitrogen and water. An ammonia slip into the environment is certainly avoided.
  • the volume fraction of the oxidation catalyst 3 in the total volume of the catalyst 1 is 18%. This ensures that the residual ammonia is oxidized to nitrogen, with undesirable side reactions, such as the formation of nitrous oxide or of new nitrogen oxides are avoided.
  • an emission control system 6 for a diesel engine 8 is shown as an internal combustion engine.
  • the diesel engine 8 works more than stoichiometrically, so that the resulting exhaust gas 6 contains oxygen.
  • the exhaust gas 6 flows via an exhaust manifold 10 into an exhaust pipe 12, is then passed through a catalytic converter 1, and cleans out via the exhaust 14 into the environment.
  • the arranged in the exhaust pipe 12 catalyst 1 is composed of a total of four individual modules. Each of these individual modules is formed as a bulk extrudate of titanium dioxide ceramic and SCR-active by additions of vanadium pentoxide, tungsten trioxide and molybdenum trioxide.
  • the three individual catalytic converters 15 arranged on the inflow side are manufactured entirely as reduction catalysts.
  • the last single catalyst 16 on the outflow side is manufactured as a reduction catalyst whose last third is active by impregnating the SCR-active material with platinum and palladium as the oxidation catalyst.
  • the volume fraction of the oxidation catalyst 3 to the total catalyst volume is 10%.
  • the exhaust gas 5 is supplied before reaching the catalyst 1 as a reducing agent ammonia.
  • an aqueous urea solution is stored in a reservoir 18, which is fed via a feed line 19 to the exhaust pipe 12.
  • Control valve 20 is adapted to be metered amount of aqueous urea solution of the nitrogen oxide concentration generated by the diesel engine 8.
  • a control unit accesses an implemented characteristic curve which predicts a nitrogen oxide concentration on the basis of current engine codes.
  • urea is pyrolyzed or hydrolyzed in ammonia.
  • ammonia added in approximately stoichiometric amounts in accordance with the nitrogen oxide concentration is reacted with the nitrogen oxides to form molecular nitrogen and water at the reduction catalyst 2 formed from the individual catalysts 15 and 16. Due to a low catalyst temperature or due to adsorption or desorption effects excess ammonia is then oxidized to the oxidation catalyst 3.
  • the purified by nitrogen oxides under optimal utilization of the reduction catalyst 2 exhaust gas 5 finally flows through the exhaust 14 into the environment.
  • the 10% by volume of the catalyst 1, which is used as the oxidation catalyst 2 is sufficient to safely prevent ammonia slip. Undesirable side reactions due to oxidative processes are certainly avoided due to the short oxidation range.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Toxicology (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Catalysts (AREA)

Abstract

L'invention concerne un catalyseur (1) destiné à la purification de gaz d'échappement (5) contenant de l'oxygène d'un dispositif de combustion, notamment un moteur à combustion fonctionnant avec un excès d'air, ledit catalyseur comprenant un catalyseur de réduction (2) pour la réduction catalytique sélective des oxydes d'azote contenus dans le gaz d'échappement (5) au moyen d'un réducteur et un catalyseur d'oxydation (3), disposé en aval par rapport au catalyseur de réduction (2), pour l'oxydation du réducteur. Il est ainsi prévu que le catalyseur d'oxydation (3) soit disposé dans une zone en aval par rapport au catalyseur de réduction (2), ladite zone représentant de 1 à 19 % du volume catalytique total. Le catalyseur de réduction (2) est constitué d'une pluralité de catalyseurs individuels (15, 16), le catalyseur d'oxydation (3) étant disposé en aval du ou des derniers catalyseurs individuels. Le catalyseur (1) permet, par des utilisations multiples, d'obtenir un degré de transformation élevé des oxydes d'azote, tout en évitant une fuite de réducteur, ainsi que des réactions secondaires indésirables.
PCT/EP2007/000735 2006-03-11 2007-01-29 Catalyseur pour la purification de gaz d'echappement constitue d'une pluralite de catalyseurs individuels Ceased WO2007104382A1 (fr)

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DE102006011411A DE102006011411B3 (de) 2006-03-11 2006-03-11 Katalysator
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GB2493987A (en) * 2011-08-26 2013-02-27 Jc Bamford Excavators Ltd An engine system
WO2015130212A1 (fr) * 2014-02-28 2015-09-03 Scania Cv Ab Système de traitement de gaz d'échappement et procédé de traitement d'un flux d'échappement
WO2015128247A1 (fr) * 2014-02-28 2015-09-03 Haldor Topsøe A/S Procédé de nettoyage de gaz d'échappement d'un moteur à allumage par compression
US10344647B2 (en) 2015-08-27 2019-07-09 Scania Cv Ab Method and system for a first and a second supply of additive to an exhaust gas stream from an internal combustion engine
US10495569B2 (en) 2015-06-05 2019-12-03 Scania Cv Ab Method and a system for determining a composition of a gas mix in a vehicle
US10724460B2 (en) 2015-08-27 2020-07-28 Scania Cv Ab Method and system for treatment of an exhaust gas stream
US10807041B2 (en) 2015-08-27 2020-10-20 Scania Cv Ab Exhaust treatment system and method for treatment of an exhaust gas stream
US10837338B2 (en) 2015-08-27 2020-11-17 Scania Cv Ab Method and exhaust treatment system for treatment of an exhaust gas stream
US10920632B2 (en) 2015-08-27 2021-02-16 Scania Cv Ab Method and exhaust treatment system for treatment of an exhaust gas stream
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EP2607641A1 (fr) 2011-12-19 2013-06-26 Mtu Friedrichshafen Gmbh Dispositif de mélange pour l'introduction d'un agent de réduction dans un flux de gaz d'échappement avec des éléments en forme d'aube
EP2792864A1 (fr) 2013-04-17 2014-10-22 ROTH-TECHNIK AUSTRIA Gesellschaft m.b.H. Dispositif de traitement des gaz d'échappement pour un flux de gaz d'échappement d'un moteur à combustion interne
DE102016004333A1 (de) 2016-04-13 2017-10-19 Roth Technik Austria Gesellschaft Mit Beschränkter Haftung Abgasnachbehandlungsvorrichtung mit Katalysator und Mischvorrichtung

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US9410459B2 (en) 2011-08-26 2016-08-09 J.C. Bamford Excavators Limited Engine system
GB2493987B (en) * 2011-08-26 2014-03-19 Jc Bamford Excavators Ltd An engine system
GB2493987A (en) * 2011-08-26 2013-02-27 Jc Bamford Excavators Ltd An engine system
US10273852B2 (en) 2014-02-28 2019-04-30 Scania Cv Ab Exhaust treatment system and method for treatment of an exhaust stream
US10273850B2 (en) 2014-02-28 2019-04-30 Scania Cv Ab Method and system for controlling nitrogen oxide emissions from a combustion engine
WO2015130215A1 (fr) * 2014-02-28 2015-09-03 Scania Cv Ab Système de traitement de gaz d'échappement et procédé de traitement d'un flux d'échappement
CN106062333A (zh) * 2014-02-28 2016-10-26 托普索公司 用于清洁来自压燃式发动机的废气的方法
US10054023B2 (en) 2014-02-28 2018-08-21 Scania Cv Ab Exhaust treatment system and method for treatment of an exhaust stream
US10260391B2 (en) 2014-02-28 2019-04-16 Scania Cv Ab Exhaust treatment system and method for treatment of an exhaust stream
US10260392B2 (en) 2014-02-28 2019-04-16 Scania Cv Ab Method and system for controlling nitrogen oxide emissions from a combustion engine
US10267198B2 (en) 2014-02-28 2019-04-23 Scania Cv Ab Device and method for impacting the amount of nitrogen oxides in exhaust gases from an internal combustion engine
US10267197B2 (en) 2014-02-28 2019-04-23 Scania Cv Ab System and method for purification of an exhaust stream by use of two reduction catalysts
WO2015130212A1 (fr) * 2014-02-28 2015-09-03 Scania Cv Ab Système de traitement de gaz d'échappement et procédé de traitement d'un flux d'échappement
US10273851B2 (en) 2014-02-28 2019-04-30 Scania Cv Ab Exhaust treatment system and method for treatment of an exhaust stream
WO2015128247A1 (fr) * 2014-02-28 2015-09-03 Haldor Topsøe A/S Procédé de nettoyage de gaz d'échappement d'un moteur à allumage par compression
CN106062333B (zh) * 2014-02-28 2021-11-09 优米科尔股份公司及两合公司 用于清洁来自压燃式发动机的废气的方法
US10364724B2 (en) 2014-02-28 2019-07-30 Scania Cv Ab Device and method comprising double reducing devices and a catalytically coated particle filter for treatment of an exhaust stream
US10399036B2 (en) 2014-02-28 2019-09-03 Umicore Ag & Co. Kg Method for the cleaning of exhaust gas from a compression ignition engine
US10626769B2 (en) 2014-02-28 2020-04-21 Scania Cv Ab Exhaust treatment system and method for treatment of an exhaust stream
US10495569B2 (en) 2015-06-05 2019-12-03 Scania Cv Ab Method and a system for determining a composition of a gas mix in a vehicle
US10724460B2 (en) 2015-08-27 2020-07-28 Scania Cv Ab Method and system for treatment of an exhaust gas stream
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US10344647B2 (en) 2015-08-27 2019-07-09 Scania Cv Ab Method and system for a first and a second supply of additive to an exhaust gas stream from an internal combustion engine

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Publication number Publication date
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DE102006011411B3 (de) 2007-11-29
DE202006020151U1 (de) 2007-11-29

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