EP1137486A2 - Element catalyseur et procede de decomposition d'oxyde d'azote - Google Patents

Element catalyseur et procede de decomposition d'oxyde d'azote

Info

Publication number
EP1137486A2
EP1137486A2 EP99963228A EP99963228A EP1137486A2 EP 1137486 A2 EP1137486 A2 EP 1137486A2 EP 99963228 A EP99963228 A EP 99963228A EP 99963228 A EP99963228 A EP 99963228A EP 1137486 A2 EP1137486 A2 EP 1137486A2
Authority
EP
European Patent Office
Prior art keywords
catalyst body
zeolite
nitrogen oxides
gas stream
reducing agent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99963228A
Other languages
German (de)
English (en)
Inventor
Stefan Fischer
Frank Witzel
Günther PAJONK
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP1137486A2 publication Critical patent/EP1137486A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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 ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • 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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
    • B01J29/16—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J29/166—Y-type faujasite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/48—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing arsenic, antimony, bismuth, vanadium, niobium tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/78—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J29/7815—Zeolite Beta
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • 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
    • B01D2255/20738—Iron
    • 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
    • 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
    • B01D2255/92—Dimensions
    • B01D2255/9205—Porosity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9207—Specific surface
    • 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
    • F01N2510/063—Surface coverings for exhaust purification, e.g. catalytic reaction zeolites
    • 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 body for breaking down nitrogen oxides in the presence of a reducing agent, with an active composition which comprises a zeolite and titanium dioxide.
  • the invention further relates to a process for the decomposition of nitrogen oxides in a gas stream, a gas stream containing nitrogen oxides being passed over the catalyst body.
  • the nitrogen oxides on the catalyst body are converted to molecular nitrogen and water using the reducing agent, even in the presence of oxygen, in accordance with the selective catalytic reduction process.
  • a catalyst body of the type mentioned is known from GB 2 193 655 A.
  • the active composition of the catalyst body specified there comprises a titanium dioxide with a low specific surface area and a zeolite containing copper obtained by ion exchange.
  • the zeolite has an average pore diameter of 10 ⁇ or less and a molar ratio of silicon oxide to aluminum oxide of 10 or more.
  • the stated catalyst body should have a high mechanical strength and a good resistance of its catalytic activity to volatile catalyst poisons such as arsenic, selenium or tellurium. Mordenite, ZSM-5 and Fer ⁇ erit are given as preferred zeolites.
  • EP 0 393 917 A2 discloses a catalyst body for breaking down nitrogen oxides, the active composition of which comprises a zeolite which contains copper and / or iron after ion exchange.
  • the zeolite has a molar ratio of silicon oxide to aluminum oxide of at least 10 and a pore structure, channels m in all three spatial directions having a diameter of at least 7 A.
  • the catalyst body is to decompose the nitrogen oxides in a temperature range from 250 to 600 ° C.
  • USY (Ultra Stabilized Y), Beta and ZSM-20 are stated as preferred zeolites.
  • a catalyst body for the degradation of nitrogen oxides is known, the active composition of which comprises a zeolite.
  • the zeolite is impregnated with cerium oxide or iron oxide.
  • the catalyst body is suitable for breaking down the nitrogen oxides according to the selective catalytic reduction process in a temperature range from 500 to
  • the specified catalyst body has a high resistance to sulfurous components contained in the exhaust gas.
  • a zeolite of the ZSM-5 type is specified as the preferred zeolite, the molar ratio of silicon oxide to aluminum oxide being 20 or more.
  • the object of the invention is to provide a catalyst body which, even in a temperature range from 400 to 750 ° C., is still suitable for breaking down nitrogen oxides in the presence of a reducing agent.
  • the catalyst body should have both a sufficient mechanical and a sufficient catalytic stability.
  • the first-mentioned object is achieved according to the invention by a catalyst body having an active composition which comprises a zeolite and titanium dioxide in that the zeolite is an acidic zeolite exchanged with hydrogen ion.
  • An acidic zeolite exchanged for hydrogen ion is understood to mean a zeolite in which the exchangeable cations are predominantly exchanged for hydrogen ions. This can be done, for example, by thermal reaction of ammonium (NH 4 + ) ions contained in synthetic zeolites, by hydrogen ion exchange or by hydrolysis of a zeolite containing multiply charged cations during dehydrogenation.
  • NH 4 + ammonium
  • the zeolite of the active composition is exchanged for metal cations, i.e. that the exchangeable cations of the zeolite are replaced by metal cations, e.g. of copper or iron.
  • a zeolite is also understood to mean a framework aluminosilicate, the ratio of the oxygen atoms to the sum of the aluminum and silicon atoms being 2: 1.
  • the framework or the framework structure By exchanging some silicon atoms of oxidation level IV with aluminum atoms of oxidation level III, the framework or the framework structure as a whole receives a negative charge. This negative charge is compensated for by cations in the structure. These cations are so-called interchangeable cations, which can easily be replaced by other cations, in particular metal cations, by ion exchange.
  • a zeolite is further characterized by the fact that the framework structure has continuous pores with a characteristic pore size having.
  • Zeolites are classified according to the molar ratio of - silicon oxide to aluminum oxide or according to the framework structure which is characteristic of this ratio. For the classification, reference is made to the article “Chemical Nominal and Formulation of Compositions of Synthetic and Natural Zeolites” by RM Barrer, Pure Appl. Che. 51 (1979), pages 1091 to 1100.
  • a natural zeolite is, for example, mordenite or chabazite.
  • Synthetic zeolites are, for example, A, X and Y zeolites, which are synthetic forms of mordenite, a ZSM-5 (brand name of a synthetic zeolite manufactured by Mobil Oil Company Ltd.), a USY (Ultra Stabilized Y) or a Beta -Zeolite.
  • the structure of the mordenite, the ZSM-5 and the Y zeolite will be discussed further on
  • a catalyst body with an active composition which contains titanium dioxide and a hydrogen ion-exchanged acidic zeolite is suitable up to temperatures of 750 ° C. for a catalytic reduction of the nitrogen oxides according to the SCR process.
  • Such a catalyst body is namely on the one hand catalytically active up to these high temperatures and on the other hand also has the necessary temperature stability.
  • the catalyst body has a high stability to moisture and a high resistance to sulfur-containing components in an exhaust gas to be treated.
  • the catalyst body opens up the possibility of reducing nitrogen oxides in the exhaust gases of an internal combustion engine or a gas turbine, it being possible for very high temperatures of the exhaust gas to occur without additional measures being taken Lowering the temperature to protect the catalyst body "must be taken.
  • the active composition of the catalyst body has 40 to 60% by weight of zeolite. With this composition, particularly good temperature stability and particularly low deactivation of the catalytic activity at high temperatures are achieved.
  • the catalyst body has a high catalytic activity with regard to the reduction of nitrogen oxides according to the SCR process, i.e. to break down nitrogen oxides in the presence of a reducing agent.
  • the active component comprises 8 to 12% by weight of tungsten trioxide.
  • a USY, a beta or a ZSM-5 zeolite is used as the zeolite.
  • Such a zeolite is particularly well suited for the desired catalytic use due to its framework structure.
  • the active mass has a BET surface area of 30 to 150 m 2 / g and a pore volume, measured by the mercury penetration method, of 100 to 1000 ml / g.
  • the active composition of the catalyst body can be produced as follows in a manner known per se.
  • the individual components or their components are mixed, ground and / or kneaded Precursor compounds (for the metal oxides specified, for example, water-soluble salts) and, if appropriate, with the addition of customary ceramic auxiliaries and fillers and / or glass fibers, a starting material.
  • the starting mass is then either further processed into full extrudates or applied as a coating to a ceramic or metallic carrier in honeycomb or plate form. Then the starting mass is dried at a temperature of 20 to 100 ° C. After the drying process, the starting mass is calcined to the active mass by calcining at temperatures between 400 and 700 ° C.
  • the calcined active composition can be pre-aged after the calcining process by a final heat treatment at a temperature higher than the calcining temperature.
  • a temperature is selected which is approximately 50 ° C. above the later maximum operating temperature of the catalyst body.
  • the final heat treatment is carried out over a period of 20 to 80 hours.
  • the catalyst body has an improved temperature resistance.
  • the object with regard to a process for the decomposition of nitrogen oxides in a gas stream is achieved according to the invention in that a gas stream containing nitrogen oxides is passed over the specified catalyst body in the presence of a reducing agent, the nitrogen oxides being converted to nitrogen and water.
  • ammonia or an aqueous urea solution is added to the gas stream as a reducing agent.
  • the gas stream is advantageously passed over the catalyst body at a temperature of 250 to 750 ° C. Within this specified temperature range there is a effective conversion of nitrogen oxides to nitrogen and water instead. A deactivation of the active mass of the catalyst body is not to be expected.
  • FIG. 1 shows a honeycomb-shaped catalyst body in an exhaust gas cleaning system of a diesel engine
  • Figure 1 shows an exhaust gas purification system for the catalytic removal of nitrogen oxides according to the SCR method from the exhaust gas of a diesel engine 1 not shown.
  • the exhaust gas of the diesel engine 1 flows as a gas stream 2 through an exhaust pipe 3 and a catalyst body 4 arranged in the exhaust pipe 3
  • Catalyst body 4 is designed as a honeycomb body through which flow can pass and has a number of parallel channels 5 through which flow can pass. After flowing through the catalyst body 4, the gas stream 2 freed from the nitrogen oxides is released into the environment via an outlet 6.
  • the catalyst body 4 is produced as a full extrudate from the active composition.
  • the active composition comprises 50% by weight of ZSM-5 zeolite and 50% by weight of an active component which 90% by weight of titanium dioxide and 10% by weight of tungsten trioxide. The proportions by weight of the usual auxiliaries and fillers are not included.
  • the catalyst body 4 was produced by mixing a titanium dioxide / tungsten oxide coprecipitate with an acidic, hydrogen ion-exchanged ZSM-5 zeolite.
  • a zeolite is available as a so-called ZSM-5 zeolite m H form from Alsi-Penta.
  • a kneadable mass is produced from the mixture, and this is further processed by extrusion to form the honeycomb body.
  • the honeycomb body is dried at 80 ° C and finally calcined at a temperature of 600 ° C.
  • an introduction device 7 for a reducing agent is arranged on the exhaust line 3 m in the flow direction in front of the catalyst body 4.
  • the introduction device 7 in this case comprises a reducing agent container 8 with a reducing agent line 9 connected to the exhaust line 3.
  • an aqueous urea solution 11 by means of a Compressor 12 introduced via the controllable valve 13, depending on requirements, the exhaust line 3.
  • the hot gas stream 2 is
  • Example A The high-temperature activity and high-temperature stability of the catalyst body according to the invention are demonstrated below using exemplary embodiments.
  • Example A The high-temperature activity and high-temperature stability of the catalyst body according to the invention are demonstrated below using exemplary embodiments.
  • a titanium dioxide / tungsten trioxide coprecipitate composed of 90% by weight of titanium dioxide and 10% by weight of tungsten trioxide is mixed with a ZSM-5 zeolite of the H form with the addition of customary ceramic auxiliaries and fillers, mixed and added processed from water to a so-called slip, ie a liquid ceramic mass.
  • the slip is then applied as a coating to a honeycomb-shaped carrier made of cordierite (a magnesium-alumino-silicate with the composition Mg 2 Al 4 Si5 ⁇ i8 with a rhombic-halohedral structure). With an inflow area of 150 x 150 mm 2, the cordierite carrier has 2 1225 continuous channels.
  • the coated cordierite support is further processed into the catalyst body with the active composition applied thereon.
  • the proportions of the starting materials are chosen so that the active composition of the finished catalyst body has equal proportions of the active component, including titanium dioxide and tungsten trioxide, and of the zeolite.
  • Example B In the same way as in Example A, a coated cordierite carrier is produced in such a way that the active composition of the finished catalyst body has a weight ratio of the active component, comprising titanium dioxide and tungsten trioxide, to the zeolite of 75 to 25.
  • the active component comprising titanium dioxide and tungsten trioxide
  • Example A a coated cordierite support is produced in such a way that the active composition of the finished catalyst body has a weight ratio of the active component, comprising titanium dioxide and tungsten trioxide, to the zeolite of 25 to 75.
  • Example D the active component, comprising titanium dioxide and tungsten trioxide, to the zeolite of 25 to 75.
  • the coprecipitate of titanium dioxide and tungsten trioxide given in Example A is mixed with a ZSM-5 zeolite in H form with the addition of ceramic auxiliaries and fillers, ground and processed to a kneadable, plastic mass with the addition of water.
  • the kneadable mass is then extruded into a honeycomb-shaped catalyst body.
  • the honeycomb-shaped catalyst body produced as a full extrudate again has 1225 parallel flow channels with an inflow area of 150 x 150 mm 2 .
  • the catalyst body is dried at 90 ° C and then calcined at 600 ° C. This final process gives the catalyst body its catalytic activity.
  • honeycomb-shaped catalyst body produced as a full extrudate according to Example D is subjected to a constant temperature load of 700 ° C. for a period of 500 hours.
  • a model exhaust gas is passed over the catalyst body according to Examples A to E at a space velocity of 15500 / h.
  • the model exhaust gas is nitrogen and comprises 200 ppm nitrogen monoxide NO, 200 ppm ammonia NH 3 as a reducing agent, 11% by volume oxygen 0 2 and 10% by volume water H 2 0.
  • the catalytic conversion of nitrogen monoxide NO to molecular nitrogen N is successively carried out on the catalyst body 2 measured.
  • the content of nitrogen monoxide NO before and after the catalyst body and the content of nitrogen N 2 after the catalyst body in the model exhaust gas are measured.
  • FIG. 2 shows the measured dependency of the NO / N 2 conversion in percent on the temperature of the model exhaust gas for the catalyst bodies according to Examples A, B and C.
  • FIG. 3 shows the dependence of the measured NO / N 2 conversion in percent on the temperature for the catalyst body according to Examples D and E.
  • the catalyst bodies according to Examples A, B and C show a catalytic conversion of between 40 and 60% in the range of high temperatures between 450 and 650 ° C. This means that between 40 and 60% of the NO contained in the model exhaust gas was converted to N 2 .
  • the catalyst body according to Example A shows a catalytic conversion of 50% and above over the entire temperature range from 450 to 650 ° C. The measured conversion of the catalyst body according to Example C even increases with higher temperatures.
  • the temperature resistance of the catalyst body is clear from Figure 3.
  • the model exhaust gas indicated is also passed over the catalyst bodies according to Examples D and E.
  • the catalytic conversion of nitrogen monoxide NO to molecular nitrogen N 2 is determined in succession.
  • the measured NO / N 2 conversion in percent as a function of the temperature is shown in FIG. 3. It can clearly be seen that the catalyst body according to Example E, which was exposed to a high temperature load, also experienced only a loss of its high catalytic activity of about 10% even after this load.

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

Abstract

Selon l'invention, un flux de gaz (2) contenant des oxydes d'azote est acheminé, en présence d'un agent réducteur, à un élément catalyseur (4) comportant une matière active qui contient une zéolithe et du dioxyde de titane. La zéolithe est constituée par une zéolithe acide, dont les cations ont été remplacés essentiellement par des ions hydrogène. Même à des températures supérieures à 450 °C, les oxydes d'azote présents dans le flux de gaz sont convertis efficacement en azote et en eau.
EP99963228A 1998-11-25 1999-11-12 Element catalyseur et procede de decomposition d'oxyde d'azote Withdrawn EP1137486A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19854502A DE19854502A1 (de) 1998-11-25 1998-11-25 Katalysatorkörper und Verfahren zum Abbau von Stickoxiden
DE19854502 1998-11-25
PCT/DE1999/003615 WO2000030746A2 (fr) 1998-11-25 1999-11-12 Element catalyseur et procede de decomposition d'oxyde d'azote

Publications (1)

Publication Number Publication Date
EP1137486A2 true EP1137486A2 (fr) 2001-10-04

Family

ID=7889053

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JP (1) JP2002530190A (fr)
KR (1) KR20010080539A (fr)
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NO (1) NO20012588L (fr)
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JP2002530190A (ja) 2002-09-17
NO20012588D0 (no) 2001-05-25
NO20012588L (no) 2001-07-24
TW546165B (en) 2003-08-11
US20020004446A1 (en) 2002-01-10
WO2000030746A3 (fr) 2000-08-10
WO2000030746A2 (fr) 2000-06-02
DE19854502A1 (de) 2000-05-31
US6569394B2 (en) 2003-05-27
KR20010080539A (ko) 2001-08-22

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