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WO2009103549A1 - Catalyseur à réduction catalytique sélective avec fonction de stockage d’ammoniac - Google Patents

Catalyseur à réduction catalytique sélective avec fonction de stockage d’ammoniac Download PDF

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Publication number
WO2009103549A1
WO2009103549A1 PCT/EP2009/001227 EP2009001227W WO2009103549A1 WO 2009103549 A1 WO2009103549 A1 WO 2009103549A1 EP 2009001227 W EP2009001227 W EP 2009001227W WO 2009103549 A1 WO2009103549 A1 WO 2009103549A1
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scr
zeolite
scr catalyst
catalyst according
active
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English (en)
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Martin Paulus
Arno Tissler
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Sued Chemie AG
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Sued Chemie AG
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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
    • 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
    • B01J29/061—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing metallic elements added to the zeolite
    • 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
    • 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
    • B01J29/80—Mixtures of different zeolites
    • 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
    • B01J37/0246—Coatings comprising a zeolite
    • 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
    • B01D2251/206—Ammonium compounds
    • 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
    • B01D2255/20746—Cobalt
    • 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
    • B01D2255/20761—Copper
    • 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
    • B01D2255/50—Zeolites
    • B01D2255/504—ZSM 5 zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/80—Type of catalytic reaction
    • B01D2255/808—Hydrolytic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/904—Multiple catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/911—NH3-storage component incorporated in the catalyst
    • 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
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • 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
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/7007—Zeolite Beta
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to an SCR catalyst which comprises an SCR-active component and an NH 3 storage component, wherein the NH 3 storage component is preferably a zeolite.
  • the invention further relates to the use of the SCR catalyst for reducing nitrogen oxides of mobile or stationary incinerators.
  • SCR Selective Catalytic Reduction
  • NO x nitrogen oxides
  • NH 3 ammonia
  • precursor compounds of ammonia are usually used, which are decomposed in the exhaust line of the vehicles with ammonia formation.
  • AdBlue® which is an approximately 32.5% eutectic solution of urea in water.
  • Other ammonia sources are, for example, ammonium carbamate, ammonium formate or urea pellets.
  • ammonia must first be formed from urea. This is done in two reaction steps, collectively referred to as a hydrolysis reaction. net. First, NH 3 and isocyanic acid are formed in a thermolysis reaction. Isocyanic acid is then reacted with water to form ammonia and carbon dioxide in the actual hydrolysis reaction.
  • NH 3 slip may occur.
  • the removal of the NH 3 can be achieved by an additional oxidation catalyst downstream of the SCR catalyst. This barrier catalyst oxidizes the possibly ammonia to N 2 and H 2 O. In addition, careful application of urea dosing is essential.
  • feed ratio ⁇ defined as the molar ratio of metered NH 3 to the NO x present in the exhaust gas.
  • the dosing strategy is of great importance in high NH 3 storage capacity catalysts because the NH 3 storage capability of prior art SCR catalysts typically decreases with increasing temperature.
  • catalysts based on titanium dioxide, vanadium pentoxide and tungsten oxide are predominantly used both in the power plant sector and in the automotive sector. Also, the use of SCR catalysts based on zeolites is known in the art.
  • the object of the present invention was thus to provide an improved SCR catalyst with respect to the SCR catalysts known from the prior art, which is also suitable for use in exhaust systems of internal combustion engines.
  • the presence of the NH 3 storage component does not require impregnation with a noble metal such as palladium, platinum, etc. on the SCR catalyst. It has also been shown that the existence of the Ammo niak storage component in the SCR catalyst, a further oxidation catalyst behind the SCR catalyst in an exhaust system is unnecessary.
  • This barrier catalyst hitherto used in the prior art for removing the NH 3 oxidizes the possibly occurring ammonia to N 2 and H 2 O. Due to the storage of the excess NH 3 , the barrier catalyst can thus surprisingly be dispensed with.
  • SCR catalysts comprising a NH 3 storage component with a zeolite containing SiO 2 and Al 2 O 3 in a specific specific ratio and which in a certain percentage based on the amount of the catalytically active composition in the SCR catalyst is present, have particularly advantageous properties. It has been found, in particular, that a zeolite comprising a very specific SiO 2 / Al 2 O 3 molar ratio and used in a certain percentage of the catalytically active composition in an SCR catalyst has an optimized absorption and desorption character - shows characteristic.
  • a SCR catalyst designed in this way already releases enough NH 3 during a cold start, so that the SCR-active constituent also has optimum NO x conversion rates in cold start behavior.
  • An additional effect here is that at fast Lastwech-, as they are common, for example in the automotive industry, an existing inert urea dosing is relieved, as can be compensated by optimized absorption and desorption the associated concentration peaks.
  • the present invention therefore relates, in a first aspect, to an SCR catalyst comprising a catalytically active composition comprising an SCR-active component and an a NH 3 storage component, wherein the SCR active component and the NH 3 storage component are different from each other, and wherein the NH 3 storage component comprises a zeolite having a Si0 2 / Al 2 ⁇ 3 molar ratio of 5: 1 to 150: 1 and the zeolite is contained in an amount of 2 to 30 wt .-% in the catalytically active composition.
  • the subject matter of the present invention also includes an exhaust gas purification system for the purification of diesel engine exhaust gases comprising a group of catalyst devices arranged one behind the other, consisting of an oxidation catalyst and an SCR catalyst according to the invention.
  • the present invention also relates to the use of the SCR catalyst according to the invention for reducing the nitrogen oxide emission of mobile or stationary combustion devices.
  • SCR active component refers to a material that catalyzes the aforementioned SCR reaction.
  • NH 3 storage component is understood as meaning a material which is capable of reversibly adsorbing NH 3. It is preferably a porous or particularly preferably a microsoporous material.
  • the storage component is a zeolite having a SiO 2 / Al 2 O 3 molar ratio of 5: 1 to 150: 1.
  • zeolite generally used in the definition of the International Mineralogical Association (DS Coombs et al., Can. Mineralogist, 35, 1997, 1571) is a crystalline substance. dance from the group of aluminum silicates with spatial network structure of the general formula
  • the zeolite structure contains voids and channels characteristic of each zeolite.
  • the zeolites are classified according to their topology into different structures (see above).
  • the zeolite framework contains open cavities in the form of channels and cages that are normally occupied by water molecules and extra framework cations that can be exchanged.
  • An aluminum atom has an excess negative charge which is compensated by these cations.
  • the interior of the pore system represents the catalytically active surface. The more aluminum and the less silicon a zeolite contains, the denser the negative charge in its lattice and the more polar its internal surface.
  • the pore size and structure are determined by the Si / Al ratio, which determines most of the catalytic character of a zeolite, in addition to the parameters in the preparation (use or type of template, pH, pressure, temperature, presence of seed crystals) , Due to the presence of z. B. 3-valent atoms (eg., Al or Ga), the zeolite receives a negative lattice charge in the form of so-called Anionstellen, in the vicinity of which are the corresponding cation positions. The negative charge is compensated by the incorporation of cations into the pores of the zeolite material.
  • the zeolites are distinguished mainly by the geometry of the cavities formed by the rigid network of SiO4 / AlO4 tetrahedra.
  • the entrances to the cavities are formed by 8, 10 or 12 "rings" (narrow, medium and large pore zeolites).
  • Certain zeolites show a uniform structure structure (eg ZSM-5 with MFI topology) with linear or zigzag running channels, in others close behind the pore openings larger cavities, eg. As in the Y and A zeolites, with the topologies FAU and LTA.
  • any zeolite in particular any 10 and 12 "ring" zeolite, which has a SiO 2 / Al 2 O 3 molar ratio of from 5: 1 to 150: 1, can be used in the context of the present invention the topologies AEL, BEA, CHA, EUO, FAO, FAU, FER, KFI, LTA, LTL, MAZ, MOR, MEL, MTW, LEV, OFF, TON and MFI
  • AEL, BEA, CHA, EUO, FAO, FAU, FER, KFI, LTA, LTL, MAZ, MOR, MEL, MTW, LEV, OFF, TON and MFI Very particular preference is given to zeolites of the topological structures FAU, MOR, BEA , MFI and MEL.
  • ⁇ , ⁇ and ⁇ positions which define the position of the exchange sites (also referred to as “interchangeable locations"). All of these three positions are accessible to reactants during the NH 3 -SCR reaction, especially when using MFI, BEA, FAU, MOR, MTW, and MEL zeolites.
  • MFI, BEA, FAU, MOR, MTW, and MEL zeolites Surprisingly, it has been found that the improvement in cold start emissions is dependent on the NH 3 storage capability of the SCR catalyst.
  • the NH 3 storage capacity depends on the (BrOnstedt) acidic surface centers of the zeolite preferably used according to the invention. Different zeolite types have different acid sites and thus different adsorption and desorption behaviors. Strongly acidic centers form stronger bonds to the adsorbed NH 3 molecules than weakly acidic centers.
  • the desorption temperature is significantly higher for a zeolite with predominantly strongly acidic centers than for weakly acidic centers.
  • the NH 3 storage function ie the amount of adsorbing NH 3 or of the NH 3 to be desorbed, can be adjusted in a targeted manner by suitably selecting the type of zeolite. Since the number of acidic centers can be influenced by the molar ratio of SiO 2 to Al 2 O 3 (the so-called "module"), the NH 3 storage capacity of an SCR catalyst can thus be precisely adjusted by varying this ratio.
  • the preferred SiO 2 / Al 2 O 3 modulus (molar ratio) is in the range from 5: 1 to 150: 1, more preferably in the range from 5: 1 to 50: 1 and most preferably in the range from 10: 1 to 30: 1st
  • the NH 3 storage zeolite is preferably present in an amount of from 2 to 30% by weight, more preferably in an amount of from 5 to 15% by weight, in the catalytically active composition.
  • the type of zeolite used is important since not all zeolites have an optimum NH 3 storage capacity. sen.
  • the zeolite is therefore preferably selected from the group comprising FAU (faujasite), MOR (mordenite), BEA (beta zeolite), MFI (Mobil Five, ZSM-5, Zeolite Secondary Mobile No. 5) and MEL, combinations of which above-mentioned zeolite can be used.
  • FAU farnesulite
  • MOR mordenite
  • BEA beta zeolite
  • MFI Mobil Five, ZSM-5, Zeolite Secondary Mobile No. 5
  • MEL MEL
  • the NH 3 storage zeolite is a metal-exchanged zeolite, for example an iron, copper or cobalt-exchanged zeolite.
  • the metal-exchanged zeolite is also selected from the group comprising FAU (faujasite), MOR (mordenite), BEA (beta zeolite), MFI (Mobil Five, ZSM-5, Zeolite Secondary Mobile No. 5) and MEL, including combinations said zeolites can be used.
  • the metal-exchanged zeolite is not an iron-exchanged zeolite in combination with a transition-metal-exchanged zeolite and / or in combination with a metal oxide-exchanged zeolite, wherein the transition metal oxide is selected from the group consisting of vanadium pentoxide, tungsten trioxide or titanium dioxide.
  • the metal content or the degree of exchange of a zeolite is decisively determined by the metal species present in the zeolite.
  • the zeolite can be doped with only a single metal or with different metals.
  • the preferred metals for exchange and doping are catalytically active metals such as Fe, Ce, Co, Ni, Ag, V, Rh, Pd, Pt, Ir. He- According to the invention, very particular preference is given to zeolites which contain iron, copper or cobalt species.
  • the production processes for metal-exchanged zeolites, for example via solid or liquid phase exchange, are known to the person skilled in the art.
  • the SCR catalyst also requires an SCR active component.
  • This may be, for example, a conventional vanadium / titanium / tungsten based component.
  • the vanadium / titanium / tungsten based component is an oxide coating that essentially contains TiO 2 in the anatase modification.
  • TiO 2 is stabilized by WO 3 in order to achieve an improvement in its thermal stability.
  • the proportion of WO 3 is typically about 10 wt .-%.
  • the actually active component forms the V 2 O 5 , which is typically present as a monolayer on the TiO 2 particles. It is also possible to add another NH 3 storage component, as will be suggested below.
  • An advantage of, for example, a vanadium based component as the SCR active component is the excellent low temperature activity of such a system.
  • the inventive combination of vanadium-based catalysts with zeolites can thus make use of the low-temperature activity of these catalysts and, at the same time, the NH 3 storage capacity of the zeolites, thus providing an SCR catalyst with excellent cold-start properties.
  • an SCR-active zeolite for example a metal-doped or exchanged zeolite, such as a Cu zeolite or Fe zeolite.
  • this provides many possible combinations for an SCR catalyst, which can be specifically adapted to the respective area of use.
  • an SCR-active zeolite which is active at low temperatures can be combined with an SCR-active zeolite which is active at higher temperatures and an NH 3 storage zeolite.
  • low temperatures are temperatures in the range below 280 ° C., preferably below 250 ° C.
  • high temperatures are understood to mean temperatures in the range of more than 350 ° C., preferably more than 400 ° C.
  • a corresponding example of such a combination is, for example, a mixture of a copper-exchanged zeolite such as Cu-ZSM-5 with a modulus of 150, which has a low-temperature, an iron-exchanged zeolite, such.
  • Catalyst in the form of an at least partially coating on a preferably monolithic carrier is present.
  • monolithic carriers are metallic or ceramic carriers, for example in honeycomb or foam form.
  • the NH 3 storage component is applied only on the inlet side and the SCR-active component only on the outlet side of such a coated monolithic carrier. It would also be possible for all of the components, such as the NH 3 storage component and the SCR active component (s), to be applied as a homogeneous coating to the entire surface of the monolith, thus greatly simplifying the preparation of such catalysts.
  • the application of the SCR catalyst is carried out according to methods known in the art, for example by applying a washcoat, by coating in an immersion bath or by spray coating.
  • the SCR catalyst according to the invention is outstandingly suitable for reducing nitrogen oxide emission from mobile or stationary combustion devices.
  • Mobile combustion devices in the context of this invention are, for example, internal combustion engines of motor vehicles, in particular diesel engines, power generators based on internal combustion engines, or other units based on internal combustion engines.
  • the stationary combustion facilities are usually power plants, combustion plants, waste incineration plants and also heating systems of private households.
  • the subject matter of the invention is also a method for reducing nitrogen oxide emissions in mobile or stationary incinerators, the method being characterized in that an exhaust gas stream is passed over an SCR catalyst according to the invention.
  • Fig. l the NH 3 storage capacity of zeolites as a function of the Si0 2 / Al 2 O 3 modulus
  • FIG. 1 shows the NH 3 storage capacity of zeolites as a function of the SiO 2 / Al 2 O 3 module.
  • the optimum modulus is in the range of 5 to 50, most preferably in the range of 10 to 30.
  • the selection of the module is also determined by the analysis of the later field of application and the conditions.
  • the range of application of the catalyst is determined by several factors Right. For example, the temperature range in operation varies considerably from car to truck. Typical work areas of internal combustion engines in trucks are between 180 and 430 0 C, and in the case of passenger cars temperatures of up to 600 0 C are often reached. Basically, the smaller the engines are (in terms of their cubic capacity), the more intensively a full-load operation occurs and thus the temperatures rise. Plays a role, whether installed in the exhaust system of the SCR catalyst before or after the diesel particulate filter (DPF), there can form high temperature peaks during the regeneration of the diesel particulate filter by burning off the collected PM in the filter above about 600 0 C.
  • DPF diesel particulate filter
  • the module not all areas of the module are accessible with any type of zeolite which can be used according to the invention.
  • a BEA zeolite only SiO 2 : Al 2 O 3 ratios of above 19 can be achieved. In order to achieve a certain storage capacity of NH3, therefore, in the case of using such zeolites, the amount must be increased.
  • the lower and upper limits for the SiO 2 : Al 2 O 3 ratios are as follows: FAU: 3 - 10, MOR: 10 - 400, BEA: 19 - 1000, MFI: 19-1000, MEL: 19-1000.
  • FIG. 2 shows the result of temperature-programmed desorption (TPD) of NH 3 in an iron-exchanged zeolite with the topology MFI and a SiO 2 / Al 2 O 3 modulus of 25.
  • TPD temperature-programmed desorption
  • the zeolite with the module according to the invention was saturated with NH 3 . That is, the maximum possible NH 3 concentration was adsorbed on the surface and then desorbed by increasing the temperature. The amount of NH 3 was detected by a mass spectrometer and simultaneously correlated with the discharge temperature. Thus, both the quantity and the temperature at which the desorption occurred could be determined what evidence was obtained to the strength of the bond between NH 3 and the zeolite.
  • test conditions were as follows:
  • the carrier structure used was a ceramic carrier from NGK with a honeycomb density of 400 cpsi.
  • Vanadyl oxalate solution and 80 g of distilled water mixed together.
  • the ZSM-5 zeolite had a modulus of 25.
  • the washcoat thus prepared was vibrated on the ceramic monolith with the volume of the washcoat equal to 50-120% of the carrier volume.
  • the monolith was emptied.
  • the washcoat residues on the outlet side of the monolith were sucked off.
  • the SCR catalyst thus obtained was then dried at 80 ° C. and calcined at about 500 ° C. for 5 hours.
  • Preparation of the catalyst 2 As the support structure, the same structure as in Example 1 was used. To prepare the washcoat, 90 g of TiO 2 powder, 10 g of WO 3 , 10 g of ZSM-5, 10 g of BEA, 20 g of SiO 2 sol, 15 g of TiO 2 sol, 20 ml of 10% aqueous vanadyl oxalate solution and 80 g of distilled water mixed together.
  • the ZSM-5 zeolite had a modulus of 25, the BEA zeolite a modulus of 150.
  • the washcoat thus prepared was applied to the monolith as in Example 1 and then calcined.
  • Example 1 As the support structure, the same structure as in Example 1 was used.
  • washcoat 110 g of TiO 2 powder, 10 g of WO 3 , 20 g of SiO 2 sol, 15 g of TiO 2 sol, 20 ml of 10% aqueous vanadyl oxalate solution and 80 g of distilled water were mixed together.
  • the washcoat so prepared was applied to the monolith as in Example 1 and calcined.
  • the cold start was simulated by a temperature increase from room temperature to 400 0 C with a heating rate of 50 K / min. Rapid change of throughput and temperature simulates a load change from full load to idle and vice versa.
  • the space velocity of 100,000 h "1 and the temperature of 400 0 C (full load) were changed to a space velocity of 30,000 h " 1 and a temperature of 180 0 C (idle).
  • the exhaust gas composition corresponded to a typical diesel car and a load change between full load and idle was simulated.
  • Both catalysts according to the invention showed a significant improvement with respect to the NO x conversion and a reduced NH 3 slip at the catalyst outlet.

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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)
  • Combustion & Propulsion (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
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  • Toxicology (AREA)
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  • General Engineering & Computer Science (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

L'invention concerne un catalyseur à réduction catalytique sélective comprenant : un support pouvant être traversé par un flux de gaz d'échappement; et une couche d'une composition à action catalytique qui est appliquée par endroits sur le support, sachant que les composants ayant une action de réduction catalytique sélective et les composants de stockage de NH3 sont différents entre eux. L'invention concerne en outre l'utilisation du catalyseur à réduction catalytique sélective selon l'invention pour réduire les oxydes d'azote de dispositifs de combustion mobiles ou stationnaires.
PCT/EP2009/001227 2008-02-21 2009-02-20 Catalyseur à réduction catalytique sélective avec fonction de stockage d’ammoniac Ceased WO2009103549A1 (fr)

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DE102008010330A DE102008010330A1 (de) 2008-02-21 2008-02-21 SCR-Katalysator mit Ammoniak-Speicherfunktion

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2130605A3 (fr) * 2008-05-20 2010-03-10 Ibiden Co., Ltd. Appareil de traitement des gaz d'échappement
EP2130604A3 (fr) * 2008-05-20 2010-03-10 Ibiden Co., Ltd. Structure en nid d'abeille
CN101791549A (zh) * 2010-03-30 2010-08-04 东南大学 超声混合沉淀法制备成型选择性催化还原脱硝催化剂的方法
EP2324915A1 (fr) * 2009-11-19 2011-05-25 Ibiden Co., Ltd. Structure en nid d'abeille et convertisseur de gaz d'échappement
WO2014128270A1 (fr) * 2013-02-25 2014-08-28 Umicore Ag & Co. Kg Catalyseur scr avec rendement en nox amélioré
US9512760B2 (en) 2014-12-15 2016-12-06 Caterpillar Inc. Aftertreatment system implementing low-temperature SCR
WO2018115045A1 (fr) 2016-12-20 2018-06-28 Umicore Ag & Co. Kg Dispositif de catalyseur pour réduction catalytique (scr) contenant de l'oxyde de vanadium et un tamis moléculaire renfermant du fer
WO2018115044A1 (fr) 2016-12-20 2018-06-28 Umicore Ag & Co. Kg Dispositif catalyseur rcs comprenant de l'oxyde de vanadium et un tamis moléculaire contenant du fer
CN110668463A (zh) * 2019-11-06 2020-01-10 中国天辰工程有限公司 一种含钛高硅铝比丝光沸石的制备方法

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WO2014173824A1 (fr) 2013-04-23 2014-10-30 Bayer Technology Services Gmbh Procédé de production de benzène à partir de méthane et de dioxyde de carbone
WO2014173791A1 (fr) 2013-04-23 2014-10-30 Bayer Technology Services Gmbh Procédé de production de benzène à partir de méthane et de dioxyde de carbone avec une cloison étanche aux fluides dans le réacteur
WO2014173813A2 (fr) 2013-04-23 2014-10-30 Bayer Technology Services Gmbh Catalyseur et procédé d'aromatisation directe du méthane

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DE102006031724B3 (de) * 2006-07-08 2008-04-30 Umicore Ag & Co. Kg Strukturierter SCR-Katalysator zur Reduktion von Stickoxiden im Abgas von Magermotoren unter Verwendung von Ammoniak als Reduktionsmittel

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EP0773057A1 (fr) * 1995-11-09 1997-05-14 Toyota Jidosha Kabushiki Kaisha Catalyseur pour la purification de gaz d'échappement
EP1222952A1 (fr) * 2001-01-11 2002-07-17 Delphi Technologies, Inc. Catalyseur NOx contenant d'alumina alcalino-terreux et de zéolite alcalino-terreux
DE102004058210A1 (de) * 2004-12-02 2006-06-14 Hte Ag The High Throughput Experimentation Company Katalysator zur Entfernung von Schadstoffen aus Abgasen von Verbrennungsmotoren
US20080286184A1 (en) * 2007-05-09 2008-11-20 N.E Chemcat Corporation Selective catalytic reduction type catalyst, and exhaust gas purification equipment and purifying process of exhaust gas using the same

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2130605A3 (fr) * 2008-05-20 2010-03-10 Ibiden Co., Ltd. Appareil de traitement des gaz d'échappement
EP2130604A3 (fr) * 2008-05-20 2010-03-10 Ibiden Co., Ltd. Structure en nid d'abeille
US8105544B2 (en) 2008-05-20 2012-01-31 Ibiden Co., Ltd. Exhaust gas treating apparatus
EP2324915A1 (fr) * 2009-11-19 2011-05-25 Ibiden Co., Ltd. Structure en nid d'abeille et convertisseur de gaz d'échappement
CN101791549A (zh) * 2010-03-30 2010-08-04 东南大学 超声混合沉淀法制备成型选择性催化还原脱硝催化剂的方法
CN101791549B (zh) * 2010-03-30 2012-09-05 东南大学 超声混合沉淀法制备成型选择性催化还原脱硝催化剂的方法
WO2014128270A1 (fr) * 2013-02-25 2014-08-28 Umicore Ag & Co. Kg Catalyseur scr avec rendement en nox amélioré
US9694320B2 (en) 2013-02-25 2017-07-04 Umicore Ag & Co. Kg SCR catalytic converter having improved NOx conversion
US9512760B2 (en) 2014-12-15 2016-12-06 Caterpillar Inc. Aftertreatment system implementing low-temperature SCR
WO2018115045A1 (fr) 2016-12-20 2018-06-28 Umicore Ag & Co. Kg Dispositif de catalyseur pour réduction catalytique (scr) contenant de l'oxyde de vanadium et un tamis moléculaire renfermant du fer
WO2018115044A1 (fr) 2016-12-20 2018-06-28 Umicore Ag & Co. Kg Dispositif catalyseur rcs comprenant de l'oxyde de vanadium et un tamis moléculaire contenant du fer
US11229901B2 (en) 2016-12-20 2022-01-25 Umicore Ag & Co. Kg SCR catalyst device containing vanadium oxide and molecular sieve containing iron
US11300029B2 (en) 2016-12-20 2022-04-12 Umicore Ag & Co, Kg SCR catalyst device containing vanadium oxide and molecular sieve containing iron
CN110668463A (zh) * 2019-11-06 2020-01-10 中国天辰工程有限公司 一种含钛高硅铝比丝光沸石的制备方法
CN110668463B (zh) * 2019-11-06 2021-04-02 中国天辰工程有限公司 一种含钛高硅铝比丝光沸石的制备方法

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