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    • 专利摘要:
    catalytic article, emission treatment system, and method for preparing a catalytic article catalysts and catalytic articles for treating exhaust gas streams are described. in one or more embodiments, a catalyst system includes a first zone for oxidizing nitrogen oxides by selective catalytic reduction, a second zone for oxidizing ammonia, and a third zone for oxidizing carbon monoxide and hydrocarbons. methods and systems for treating the exhaust gas flow are also presented. methods for making and using these catalysts and catalytic articles are also described.
    公开号:BR112012028320B1
    申请号:R112012028320-0
    申请日:2011-05-04
    公开日:2021-07-20
    发明作者:Matthew T. Caudle；Martin Dieterle；Sanath V. Kumar；Kenneth E. Voss；Samuel R. Boorse
    申请人:Basf Corporation；
    IPC主号:
    专利说明:

    TECHNICAL FIELD
    [01] The invention relates to catalysts, methods for their manufacture and methods of treating emissions in an exhaust stream. BACKGROUND
    [02] Diesel engine exhaust is a heterogeneous mixture that contains particulate emissions such as soot and gaseous emissions such as carbon monoxide, unburned or partially burned hydrocarbons and nitrogen oxides (collectively referred to as NOx), but also materials condensed phase (liquids and solids) that constitute the so-called particulate or particulate materials. Catalyst compositions, often arranged on one or more monolithic substrates, are placed in engine exhaust systems to convert certain or all of these exhaust components into innocuous compounds. For example, diesel exhaust systems can contain one or more of a diesel oxidation catalyst, a soot filter and a catalyst for NOx reduction.
    [03] Oxidation catalysts containing daplatinum group metals, base metals and combinations thereof are known to facilitate diesel engine exhaust treatment by promoting the conversion of gaseous pollutants from both HC and CO and some proportion of the material particles by oxidizing these pollutants to carbon dioxide and water. Such catalysts were generally contained in units called diesel oxidation catalysts (“DOC”), which are placed in the exhaust of diesel engines to treat the exhaust before relieving it to the atmosphere. Such catalysts are also contained in units called catalyzed soot filters which simultaneously trap particulate material and oxidize HC, CO and particulate materials. In addition to converting gaseous HC, CO and particulate material, oxidation catalysts containing platinum group metals (which are typically dispersed on a refractory oxide support) promote the oxidation of nitric oxide (NO) to NO2.
    [04] Selective Ammonia Catalytic Reduction (SCR) is a NOx reduction technology that will be used to meet stringent NOx emission targets in lean-mix and diesel engines. In the ammonia SCR process, NOx (usually consisting of NO + NO2) is reacted with ammonia (or an ammonia precursor such as urea) to form dinitrogen (N2) over a catalyst typically composed of base metals. This technology is capable of NOx conversions greater than 90% over a typical diesel cranking cycle, and as such represents one of the best approaches to achieving aggressive NOx abatement goals.
    [05] A characteristic feature of some ammonia SCR catalyst materials is a propensity to retain considerable amounts of ammonia at acidic Br0nsted and Lewis sites on the catalyst surface during low temperature portions of a typical drive cycle. A subsequent increase in exhaust temperature can cause ammonia to desorb from the ammonia SCR catalyst surface and exit the vehicle tailpipe. Overdosing ammonia to increase the NOx conversion rate is another potential scenario where ammonia can exit the ammonia SCR catalyst.
    [06] The ammonia that escapes from the ammonia SCR catalyst presents several problems. The odor threshold for NH3 is 20 ppm in air. Throat and eye irritation is noticeable above 100 ppm, skin irritation occurs above 400 ppm, and IDLH is 500 ppm in air. NH3 is caustic, especially in its aqueous form. Condensation of NH3 and water in cooler regions of the exhaust line downstream of the exhaust catalysts will provide a corrosive mixture.
    [07] Therefore, it is desirable to eliminate the ammonia before it can pass into the exhaust pipe. A selective ammonia oxidation catalyst (AMOx) is employed for this purpose, with the aim of converting excess ammonia into N2. It would be desirable to provide a catalyst for selective ammonia oxidation that is capable of converting ammonia over a wide range of temperatures where ammonia exhaust occurs in the vehicle's drive cycle, and can produce minimal nitrogen oxide by-products. The AMOX catalyst must also produce minimal N2O, which is a potent greenhouse gas. SUMMARY
    [08] Aspects of the invention include catalytic articles, catalyst systems and methods for treating an exhaust gas stream, and methods of preparing catalytic articles for treating such gas. A first aspect concerns a catalytic article for treating an exhaust gas stream containing particulate material, hydrocarbons, CO and ammonia. In a first embodiment, the article comprises a substrate having an inlet end and an outlet end defining an axial length of a first catalyst coating including a platinum group metal, the first catalyst coating extending from the outlet end towards the inlet end over less than the full axial length of the substrate; and a second catalyst coating including a catalyst for selective catalytic reduction (SCR) of nitrogen oxides, the second catalyst coating extending from the inlet end towards the outlet end over less than the total axial length of the substrate and overlaying a portion of the first catalyst coating. In a second embodiment, the substrate is a through-flow substrate having a plurality of longitudinally extending passages formed by longitudinally extending walls limiting and defining the passages. In a third embodiment, the substrate is a wall flow filter having gas permeable walls formed in a plurality of axially extending channels, each channel having a buffered end with any pair of adjacent channels buffered on opposite ends thereof.
    [09] In a fourth embodiment, the first through third embodiments can be modified so that at least a portion of the platinum group metal is on a particulate refractory metal oxide support. In a fifth embodiment, the first through fourth embodiments can be modified so that the platinum group metal is platinum. In a sixth embodiment, the first through fifth embodiments can be modified so that the first catalyst coating and second catalyst coating overlap to form three zones, a first zone to remove NOx by selective catalytic reduction, a second zone to oxidize ammonia, and a third zone to oxidize carbon monoxide and hydrocarbons. In a seventh modality, the first through sixth modality can be modified so that each of the three zones individually occupies in the range of approximately 10 to approximately 80% of the axial length of the substrate. In an eighth modality, the first through seventh modality can be modified so that the platinum group metal is directly supported on the substrate walls.
    [10] Another aspect of the invention relates to an emissions treatment system. In a ninth modality, the system comprises a diesel engine that emits an exhaust stream including particulate material, NOx and carbon monoxide; and a catalytic article according to the first to eighth modalities. For example, the catalytic article may include a first substrate having an inlet end and an outlet end defining an axial length positioned downstream of and in flow communication with the diesel engine, the substrate having a first catalyst coating including a platinum group metal, the first catalyst coating extending from the exit end towards the entry end over less than the full axial length of the substrate, and a second catalyst coating including a selective catalytic reduction (SCR) catalyst ) of oxides of nitrogen, the second catalyst coating extending from the inlet end towards the outlet end over less than the full axial length of the substrate and overlapping a portion of the first catalyst coating layer. In one or more embodiments of the system, the first substrate is selected from the group consisting of a wall-flow substrate and a through-flow substrate.
    [11] In a tenth modality, the ninth modality can be modified so that there is an upstream substrate coated with a catalyst for selective catalytic reduction of nitrogen oxides arranged in flow communication with the exhaust stream and between the diesel engine and the first substrate. In an eleventh embodiment, the tenth embodiment is modified so that the upstream substrate comprises an alveolar through-flow substrate. In a twelfth embodiment, the tenth embodiment is modified so that the upstream substrate comprises a wall flow filter substrate having gas permeable walls formed in a plurality of axially extending channels, each channel having a buffered end with any pair. of adjacent channels plugged at opposite ends thereof.
    [12] In a thirteenth embodiment, the tenth embodiment is modified so that there is a wall flow filter substrate having gas permeable walls formed in a plurality of axially extending channels, each channel having a buffered end with any pair of channels adjacent buffers at opposite ends thereof coated with a CO or hydrocarbon oxidation catalyst disposed in flow communication with the exhaust stream and between the diesel engine and the porous substrate.
    [13] Another aspect of the invention relates to a method of preparing a catalytic article. In the fourteenth embodiment a catalytic article according to the first through eighth embodiments is prepared according to a method comprising directly coating a substantially unsupported first platinum group metal onto porous walls of a honeycomb substrate; drying and calcining the coated substrate to fix the substantially unsupported first platinum group metal onto the substrate; slurry coating a portion of the porous walls with a reactive coating layer containing a catalyst for selective catalytic reduction (SCR) of nitrogen oxides; and drying and calcining the coated substrate to fix the reactive coating layer onto the substrate.
    [14] In a fifteenth embodiment, a method of preparing a catalytic article having an inlet end and an outlet end for treating an exhaust stream containing NOx is provided. In the fifteenth embodiment, a catalytic article according to the first through eighth embodiments is prepared according to a method using a method comprising slurry coating a first reactive coating layer containing a platinum group metal adjacent to the porous walls of the exit end of a honeycomb substrate; slurry coat the porous walls with a second reactive coating layer containing a catalyst for selective catalytic reduction (SCR) of nitrogen oxides, the second reactive coating layer extending from the inlet end and at least partially overlapping the first layer reactive coating; and drying and calcining the coated substrate to fix the reactive coating layers onto the substrate to provide a first zone for decreasing selective catalytic reduction of ammonia, a second zone for oxidizing ammonia, and a third zone for oxidizing carbon monoxide and hydrocarbons.
    [15] In a sixteenth embodiment, a method of preparing a catalytic article having an inlet end and an outlet end for treating an exhaust stream containing NOx is provided. In the fifteenth embodiment, a catalytic article according to the first through eighth embodiments is prepared according to a method comprising coating an exit portion of the substrate with a first catalyst coating containing a platinum group metal effective to catalyze oxidation of carbon monoxide in the exhaust stream, the first catalyst coating layer extending from the output end of the substrate towards the input end over less than the full axial length; drying and calcining the coated substrate to fix the first catalyst coating on the exit portion of the substrate; coating an inlet portion of the substrate with a second catalyst coating containing a selective catalytic reduction (SCR) catalyst effective to reduce NOx in the exhaust stream, the second catalyst coating extending from the inlet end of the substrate towards the end of exiting over less than the full axial length and overlapping a portion of the first catalyst coating layer; and drying and calcining the coated substrate to affix the second catalyst coating onto the input portion of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS
    [16] The following drawings illustrate embodiments of the invention. It should be understood that the figures are not intended to be to scale and that certain features such as monolith channels may be increased in size to show features in accordance with embodiments of the invention.
    [17] Figure 1 shows a schematic diagram of a monolith-catalyst and the reactive coating geometry in an individual monolith channel after coating with a first and second catalyst.
    [18] Figure 2 is a schematic view illustrating the conversion of NH3 to N2 and CO, HC to CO2 in a catalyst system according to one or more modalities.
    [19] Figure 3 shows a schematic diagram of a catalytic monolith and the reactive coating geometry in an individual monolith channel after coating the entire substrate of Figure 1; and
    [20] Figure 4 is a schematic diagram of an engine emission treatment system, according to an embodiment of the present invention. DETAILED DESCRIPTION
    [21] Before describing various exemplary embodiments of the invention, it should be understood that the invention is not limited to the construction details or process steps set out in the following description. The invention is capable of other embodiments and of being practiced or carried out in various ways.
    [22] As used in this specification and the appended claims, the singular forms “a”, “an” and “o, a” include plural referents unless the context clearly indicates otherwise. Thus, for example, reference to "a catalyst" includes a mixture of two or more catalysts, and the like. As used herein, the term "decrease" means decrease in amount and "decrease" means a decrease in amount, caused by any means. Where they appear here, the terms "exhaust stream" and "engine exhaust stream" refer to engine output effluent as well as effluent downstream of one or more other catalyst system components including, but not limited to, a catalyst of diesel oxidation and/or soot filter.
    [23] One aspect of the invention relates to a catalyst. According to one or more embodiments, the catalyst can be disposed on a monolithic substrate as a reactive coating layer. As used here and as described in Heck, Ronald, and Robert Farrauto, Catalytic air pollution control, New York; Wiley-Interscience, 2002, p. 18-19, a reactive coating layer includes a compositionally distinct layer of material disposed on the surface of the monolithic substrate or an underlying reactive coating layer. A catalyst can contain one or more reactive coating layers, and each reactive coating layer can have unique chemical catalytic functions.
    [24] In one or more modalities, bifunctional catalysts are provided. According to one aspect of the invention, a bifunctional catalyst is provided which comprises a modular catalyst system with physically separate compositions for the SCR function and the NH3 oxidation function. According to one or more embodiments, such modular catalyst systems allow greater flexibility to independently tune the kinetics of the two functions. By doing this, the physical structure of the catalyst can be used to control the sequence of chemical catalytic events, increase the conversion of NOx and NH3 and increase selectivity to N2. Catalyst compositions for the SCR function and NH3 oxidation function may reside in distinct reactive coating layers on the substrate or, alternatively, compositions for the SCR and NH3 oxidation functions may reside in distinct longitudinal zones on the substrate.
    [25] The term “SCR function” will be used here to refer to a chemical process described by Eq. 1 stoichiometric: 4 NOX 4* 4 NH3 + (3-2x) 02 -» 4 N2 + 6 H20More generally, it will refer to any chemical process in which NOx and NH3 are combined to preferably produce N2. The term “SCR composition” refers to a material composition effective to catalyze the SCR function. The term "NH3 oxidation function" will be used here to refer to a chemical process described by equation 2: More generally, it will refer to a process in which NH3 is reacted with oxygen to produce NO, NO2, N2O, or preferably N2. The term "NH3 oxidation composition" refers to a material composition effective to catalyze the oxidation function of NH3.
    [26] Referring to Figure 1, one or more embodiments of the invention are directed to catalytic articles 10 for treating an exhaust gas stream containing particulate matter, hydrocarbons, CO and ammonia. Catalytic articles comprise a substrate 12, often referred to as a vehicle or vehicle substrate. Substrate 12 has an inlet end 22 and an outlet end 24 defining an axial length L. Substrate 12 generally has a plurality of channels 14, of which only one is shown for clarity. A first catalyst coating 16 on the substrate includes a platinum group metal. The first catalyst coating 16 extends from the output end 24 of the substrate 12 towards the input end 22 over less than the total axial length L of the substrate 12. A second catalyst coating 18 includes a catalyst for selective catalytic reduction (SCR) of nitrogen oxides. The second catalyst coating 18 extends from the inlet end 22 of the substrate 12 towards the outlet end 24 over less than the total axial length L of the substrate 12. The second catalyst coating 18 overlays 20 a portion of the first coating. of catalyst 16.
    [27] The platinum group metal of some modalities is one or more of platinum, palladium, rhodium, ruthenium, osmium, and iridium. In detailed embodiments, the platinum group metal is one or more of palladium, platinum and combinations thereof. In specific embodiments, the platinum group metal includes platinum, alone or in combination with other platinum group metals.
    [28] According to detailed embodiments, at least a portion of the platinum group metal is supported on a particulate refractory oxide support. In some specific embodiments, the platinum group metal is directly supported on the substrate walls. As used in this specification and the appended claims, the term “directly supported on the substrate wall” means that the metal is not in a particulate support, such as by solution impregnation. Additionally, the term "substantially unsupported" means that the metal is directly supported on the substrate wall. For example, the metal is coated onto the substrate without an intervening particulate refractory oxide support.
    [29] In detailed embodiments, the first decatalyst coating and the second catalyst coating overlap to form three zones 16, 18, and 20. As shown in Figure 2, the first zone 18 removes NOx by selective catalytic reduction. Second zone 20 oxidizes ammonia and third zone 16 oxidizes carbon monoxide and hydrocarbons. To allow for the oxidation of CO and HC, the third zone must be accessible to CO and HC to allow for inflammation and oxidation.
    [30] In detailed modalities, each of the three zones individually occupies the range of approximately 10 to approximately 80% of the axial length of the substrate. In specific modalities, each of the three zones occupies 1/3 of the axial length of the substrate. The substrate
    [31] According to one or more embodiments, the substrate for the catalyst can be any of those materials typically used to prepare automotive catalysts and will typically comprise a metal ceramic or metal honeycomb structure. Any suitable substrate may be employed, as a monolithic through-flow substrate and having a plurality of thin, parallel gas stream passages extending from an inlet to an outlet face of the substrate, such that passages are open for current. of fluid. The passages, which are essentially straight paths from their fluid inlet to their fluid outlet, are defined by walls in which the catalytic material is coated as a "reactive coating" so that the gases flowing through the passages count the catalytic material. Monolithic substrate current passages are thin-walled channels that can be of any suitable cross-sectional shape such as trapezoidal, rectangular, square, sinusoidal, hexagonal, oval, circular, etc. such structures can contain from approximately 60 to approximately 1200 or more gas inlet openings (ie, “cells”) per square inch of cross section (cpsi) (1 square inch = 6.45 cm2). A representative commercially available through-flow substrate is Corning 400/6 cordierite material, which is constructed of cordierite and has 400 cpsi (1 square inch = 6.45 cm2) and 6 mil wall thickness. However, it will be understood that the invention is not limited to a specific substrate type, material or geometry.
    [32] Ceramic substrates can be made from any suitable refractory material, eg cordierite, cordierite-α alumina, silicon nitride, zirconium mullite, spodumene, alumina-silica magnesia, zirconium silicate, silimanite, magnesium silicates, zirconium, petalilta, α alumina, aluminosilicates and the like.
    [33] Substrates useful for catalysts according to one or more embodiments of the present invention may also be metallic in nature and be composed of one or more metals or metal alloys. Exemplary metallic supports include heat resistant metals and metal alloys such as titanium and stainless steel as well as other alloys in which iron is a substantial or major component. Such alloys may contain one or more of nickel, chromium and/or aluminium, and the total amount of these metals may comprise at least 15% by weight of the alloy, for example 10-25% by weight of chromium, 3-8% by weight aluminum weight and up to 20% nickel weight. Alloys may also contain small or residual amounts of one or more other metals such as manganese, copper, vanadium, titanium and the like. Metallic substrates can be used in various formats such as corrugated sheet or monolithic form. A representative commercially available metal substrate is manufactured by Emitec. However, it will be understood that the invention is not limited to a specific type of substrate, material or geometry. The surface of metal substrates can be oxidized at elevated temperatures, for example 1000°C and higher, to form an oxide layer on the substrate surface, improving the corrosion resistance of the alloy. Such high temperature induced oxidation can also increase the adhesion of the refractory metal oxide support and catalytic promoting metal components to the substrate.
    [34] Wall flow substrates useful for supporting SCR catalyst compositions in accordance with embodiments of the invention have a plurality of substantially parallel, thin gas stream passages extending along the longitudinal axis of the substrate. Typically, each pass is blocked at one end of the substrate body, with alternate passes blocked at opposite end faces. Such monolithic carriers can contain up to approximately 700 or more current passages (or “cells”) per square inch of cross section, although a much smaller number may be used. For example, the carrier may have approximately 7 to 600, more commonly approximately 100 to 400, cells per square inch (“cpsi” (1 square inch = 6.45 cm2)). Cells can have cross sections that are rectangular, square, circular, oval, triangular, hexagonal, or are of other polygonal shapes. Wall flux substrates typically have a wall thickness between 0.002 and 0.1 inch. Suitable wall flux substrates have wall thicknesses between 0.002 and 0.015 inches.
    [35] Suitable wall flow filter substrates are composed of ceramic-like materials such as cordierite, alpha-alumina, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silica-magnesia or zirconium silicate, or porous refractory metal. Wall flux substrates can also be formed from ceramic fiber composite materials. Suitable wall flux substrates are formed from cordierite and silicon carbide. Such materials are able to withstand the particularly high ambient temperatures encountered in the treatment of exhaust streams. The wall flow filter can be coated with SCR catalyst for its entire axial length, or a portion of the full axial length of the filter in a zone coated configuration.
    [36] Suitable wall flow substrates for use in the inventive system include thin porous wall metal combs (monoliths) through which the fluid stream passes without causing an excessive increase in back pressure or pressure across the article. Typically, the presence of a clean wall flow article will create a 1-inch backpressure of water column at 10 psig (68.9 kPa). In one embodiment, ceramic wall flow substrates used in the system are formed from a material having a porosity of at least 40% or 45% (eg, 40% to 80%) having an average pore size of at least 5 microns (for example, 5 to 30 microns). In specific embodiments, such materials have a porosity of at least 50% (eg, 50% to 80%). The porosity of the material that forms the walls can be defined by wall density versus the theoretical density of the material. In specific embodiments, the substrates have a porosity of at least 55% and have an average pore size of at least 10 microns. When substrates with these porosities and these average pore sizes are coated with the techniques described below, suitable levels of SCR catalyst compositions can be loaded onto the substrates to obtain excellent NOx conversion efficiency. These substrates are still able to retain characteristics of adequate exhaust current, i.e. acceptable back pressures, despite the SCR catalyst load. US Patent 4,329,162 is incorporated herein by reference with respect to the disclosure of suitable wall flux substrates. Substrate 12 can also be a high efficiency filter that removes at least approximately 70% of the particulate material in the gas stream.
    [37] Typical wall flow filters in commercial use are typically formed with lower wall porosities, eg approximately 35% to 50%, than the wall flow filters used in the invention. In general, the pore size distribution of commercial wall flow filters is typically very broad with an average pore size of less than 17 microns. SCR composition
    [38] According to one or more embodiments of the invention, a component effective to catalyze the SCR function (referred to herein as an "SCR component") is used in a reactive coating as part of a NOx reduction catalyst composition. Typically, the SCR component is part of a composition that includes other components in a reactive coating. However, in one or more embodiments the NOx reduction catalyst composition can include only the SCR component.
    [39] In some embodiments, the invention utilizes an SCR component that includes an inorganic microporous structure or molecular sieve onto which a metal from one of the periodic table groups VB, VIB, VIIB, VIIIB, IB, or IIB has been deposited onto extra sites. -structure on the outer surface or in the channels, cavities, or cages of molecular sieves. Metals can be in one of several forms, including, but not limited to, zerovalent metal atoms or clusters, isolated cations, mononuclear or polynuclear oxications, or as extended metal oxides. In specific embodiments, metals include iron, copper and mixtures or combinations thereof.
    [40] In certain embodiments, the SCR component contains in the range of approximately 0.10% and approximately 10% by weight of a metal group VB, VIB, VIIB, VIIIB, IB or IIB located at extrastructural sites on the outer surface or in the channels , cavities, or molecular sieve cages. In preferred embodiments, the extrastructure metal is present in an amount ranging from approximately 0.2% to approximately 5% by weight.
    [41] The microporous inorganic structure may consist of a microporous luminosilicate or zeolite having any of the scaffold structures listed in the DATABASE OF ZEOLITE STRUCTURES published by the International Zeolite Association (IZA). Frame structures include, but are not limited to, those of types CHA, FAU, BEA, MFI, MOR. Non-limiting examples of zeolites having such structures include chabazite, faujasite, zeolite Y, ultra-stable zeolite Y, beta zeolite, mordenite, silicalite, zeolite X and ZSM-5. Some embodiments utilize aluminosilicate zeolites which have a silica/alumina molar ratio (defined as SiO2/Al2O3 and abbreviated as SAR) of at least about 5, preferably at least about 20, with useful ranges of about 10 to 200.
    [42] In a specific embodiment, the SCR component includes an aluminosilicate molecular sieve having a CHA crystal structure type, a SAR greater than approximately 15, and copper content exceeding approximately 0.2% by weight. In a more specific embodiment, the SAR is at least about 10, and copper content from about 0.2% by weight to about 5% by weight. Zeolites having the CHA structure include, but are not limited to, natural chabazite, SSZ-13, LZ-218, Linde D, Linde R, Phi, ZK-14, and ZYT-16. Other suitable zeolites are also described in US patent 7,601,662 entitled "Cooper CHA zeolite catalysts", the entire contents of which are incorporated herein by reference.
    [43] According to one or more embodiments of the invention, SCR compositions that include non-zeolytic molecular sieves are provided. As used herein, the terminology "non-zeolitic molecular sieve" refers to corner-sharing tetrahedral structures where at least a portion of the tetrahedral sites is occupied by an element other than silicon or aluminum. Non-limiting examples of such molecular sieves include metal aluminophosphates and aluminophosphates, where metal could include silicon, copper, zinc or other suitable metals. Such modalities can include a non-zeolitic molecular sieve having a type of crystal structure selected from CHA, FAU, MFI, MOR and BEA.
    [44] Non-zeolytic compositions can be used in SCR components in accordance with embodiments of the present invention. Specific non-limiting examples include silicoaluminophosphates SAPO-34, SAPO-37, SAPO-44. The synthetic form synthesis of SAPO-34 is described in US Patent 7,264,789, which is hereby incorporated by reference. A method of making yet another synthetic non-zeolytic molecular sieve having chabazite structure, SAPO-44, is described in US patent 6,162,415, which is hereby incorporated by reference.
    [45] SCR compositions consisting of vanadium supported on a refractory metal oxide such as alumina, silica, zirconia, titania, ceria and combinations thereof are also well known and widely used commercially in mobile applications. Typical compositions are described in US Patents 4,010,238 and 4,085,193, the entire contents of which are incorporated herein by reference. Compositions used commercially, especially in mobile applications, comprise TiO2 in which WO3 and V2O5 have been dispersed in concentrations ranging from 5 to 20% by weight and 0.5 to 6% by weight, respectively. These catalysts can contain other inorganic materials such as SiO2 and ZrO2 acting as binders and promoters. NH3 Oxidation Composition
    [46] According to one or more embodiments of the invention, a composition effective to catalyze the NH3 oxidation function (referred to herein as an "NH3 oxidation component") is used in a NOx reduction catalyst. The ammonia contained in an exhaust gas stream is reacted with oxygen over the oxidation component of NH3 to form N2 according to equation 1.
    [47] According to one or more embodiments, the NH3 deoxidizing component can be a supported precious metal component that is effective in removing ammonia from the exhaust gas stream. In one or more embodiments, the precious metal component includes ruthenium, rhodium, iridium, palladium, platinum, silver or gold. In specific embodiments, the precious metal component includes physical mixtures and atomic and chemical doped combinations of ruthenium, rhodium, iridium, palladium, platinum, silver and gold. In a more specific embodiment, the precious metal component includes platinum. In an even more specific embodiment, platinum is present in an amount in the range of approximately 0.008% to approximately 2% by weight (metal), based on Pt bearing load.
    [48] In one or more embodiments, the precious metal component is deposited on a high surface area refractory metal oxide support. Examples of suitable high surface area refractory metal oxides include, but are not limited to, alumina, silica, titania, ceria and zirconia, as well as physical mixtures, chemical combinations and/or atomically doped combinations thereof. In specific embodiments, the refractory metal oxide can contain a mixed oxide such as silica-alumina, amorphous or crystalline aluminosilicates, alumina-zirconia, alumina-lanthanum, alumina-chromium, alumina-barium, alumina-ceria and the like. An exemplary refractory metal oxide comprises high surface area y-alumina having a specific surface area of approximately 50 to approximately 300 m 2 /g.
    [49] As otherwise mentioned herein, the NH3 deoxidation component may include a zeolitic or non-zeolitic molecular sieve, which may have any of the scaffold structures listed in the DATABASE OF ZEOLITE STRUCTURES, published by the International Zeolite Association (IZA). Frame structures include but are not limited to those of types CHA, FAU, BEA, MFI and MOR. In one embodiment, a molecular sieve component can be physically mixed with an oxide-supported platinum component. In an alternative embodiment, platinum can be distributed on the outer surface or in the channels, cavities, or cages of the molecular sieve.
    [50] The NH3 oxidizing composition may contain an active component for the ammonia SCR function. The SCR component can consist of any of the SCR components described in the previous section. In one embodiment, the NH3 oxidation component includes a physical mixture of an oxide-supported platinum component and an SCR component. In an alternative embodiment, platinum can be distributed on the outer surface or in the channels, cavities or cages of the SCR component. In one or more embodiments, the catalytic article includes two layers for oxidizing NH3, a first layer including a platinum group metal component; for example Pt, and a second layer including a molecular sieve, for example a zeolite. Reactive coating layers
    [51] According to one or more embodiments, the deSCR component and the NH3 oxidation component can be applied in reactive coating layers, which are coated onto and adhered to the substrate.
    [52] For example, a reactive coating layer of a composition containing an NH3 oxidation component can be formed by preparing a mixture or a solution of a platinum precursor in an appropriate solvent, eg, water. Generally, from the point of view of economics and environmental aspects, aqueous solutions of soluble compounds or platinum complexes are preferred. Typically, the platinum precursor is used in the form of a compound or complex to obtain dispersion of the platinum precursor on the support. For purposes of the present invention, the term "platinum precursor" means any compound, complex, or the like which, upon calcination or the initial phase of use thereof, decomposes or otherwise converts into a catalytically active form. Suitable platinum complexes or compounds include, but are not limited to, platinum chlorides (eg, [PtCl4]2-, [PtCl6]2-) salts, platinum hydroxides (eg, [Pt(OH) salts 6]2-), platinum amines (for example, [Pt(NH3)4]2+, [Pt(NH3)4]4+ salts, platinum hydrates (for example, [Pt(OH2) salts 4]2+), platinum bis(acetyl acetonates), and mixed compounds or complexes (eg, [Pt(NH3)2(Cl)2]). A representative commercially available platinum source is 99% ammonium hexachloroplatinate from Strem Chemicals, Inc., which may contain residues of other precious metals. However, it will be understood that this invention is not limited to platinum precursors of a specific type, composition or purity. A mixture or solution of the platinum precursor is added to the support by one of several chemical means. These include impregnation of a platinum precursor solution onto the support, which may be followed by a fixation step incorporating an acid component (eg acetic acid) or a basic component (eg ammonium hydroxide). This wet solid can be chemically reduced or calcined or used as is. Alternatively, the support can be suspended in an appropriate vehicle (eg water) and reacted with the platinum precursor in solution. This last mentioned method is more typical when the support is a zeolite, and it is desired to fix the platinum precursor to ion exchange sites in the zeolite scaffold. Additional processing steps may include fixation by an acid component (eg acetic acid) or a basic component (eg ammonium hydroxide), chemical reduction or calcination.
    [53] In one or more embodiments utilizing reactive coating layers of an SCR composition, the layer may contain a zeolitic or non-zeolitic molecular sieve in which a metal of one of the groups VB, VIB, VIIB, VIIB, IB or IIB has been distributed of the periodic table. An exemplary metal in this series is copper. Exemplary molecular sieves include, but are not limited to zeolites having one of the following crystal structures CHA, BEA, FAU, MOR and MFI. An appropriate method for distributing the metal into the zeolite is to first prepare a mixture or a solution of the metal precursor in an appropriate solvent, eg, water. Generally from the point of view of economics and environmental aspects, aqueous solutions of soluble compounds or metal complexes are preferred. For purposes of the present invention, the term "metal precursor" means any compound, complex or the like that can be dispersed on the zeolite support to provide a catalytically active metal component. For exemplary group IB metal copper, suitable complexes or compounds include, but are not limited to anhydrous and hydrated copper sulfate, copper nitrate, copper acetate, copper acetylacetonate, copper oxide, copper hydroxide, and salts of copper amines (for example, [Cu(NH3)4]2+). A representative commercially available copper source is 97% copper acetate from Strem Chemicals, Inc., which may contain residues of other metals, particularly iron and nickel. However, it will be understood that the present invention is not limited to metal precursors of a specific type, composition or purity. Molecular sieve can be added to the metal component solution to form a suspension. This suspension can be allowed to react so that the copper component is distributed in the zeolite. This can result in copper being distributed in the pore channels as well as the outer surface of the molecular sieve. Copper can be distributed as copper(II) ions, copper(I) ions, or as copper oxide. After the copper is distributed on the molecular sieve, solids can be separated from the liquid phase of the suspension, washed and dried. The resulting copper-containing molecular sieve can also be calcined to fix the copper.
    [54] To apply a reactive coating layer according to one or more embodiments of the invention, finely divided particles of a catalyst, consisting of the SCR component, the NH3 oxidation component or a mixture thereof, are suspended in an appropriate vehicle , for example, water, to form a slurry. Other promoters and/or stabilizers and/or surfactants can be added to the slurry as mixtures or solutions in water or a water miscible vehicle. In one or more embodiments, the slurry is ground to result in substantially all solids having particle sizes less than approximately 10 microns, i.e., in the range of approximately 0.1 to 8 microns, in an average diameter. Crushing can be carried out in a ball mill, continuous Eiger mill, or other similar equipment. In one or more embodiments, the slurry or suspension has a pH of from about 2 to less than about 7. The pH of the slurry can be adjusted if necessary by adding a suitable amount of an inorganic or organic acid to the slurry. The solids content of the slurry can be, for example, approximately 20-60% by weight, and more particularly approximately 35-45% by weight. The substrate may then be dipped into the slurry, or the slurry may otherwise be coated onto the substrate such that a desired charge of the catalyst layer will be deposited on the substrate. Thereafter, the coated substrate is dried at approximately 100°C and calcined by heating, for example, at 300 to 650°C for approximately 1 to approximately 3 hours. Drying and calcining are typically done in air. The coating, drying and calcining processes can be repeated if necessary to obtain the final desired gravimetric amount of catalyst reactive coating layer on the support. In some cases, complete removal of liquid and other volatile components may not occur until the catalyst is put into use and subjected to the elevated temperatures encountered during operation.
    [55] After calcination, the catalyst reactive coating load can be determined by calculating the difference in coated and uncoated weights of the substrate. As will be apparent to those of skill in the art, catalyst loading can be modified by changing coating slurry solids content and slurry viscosity. Alternatively, repeated dips of the substrate into the coating slurry may be conducted, followed by removal of excess slurry as described above. Method of preparing a catalyst
    [56] As shown in Figure 3, a catalyst or catalytic article according to one or more embodiments of the present invention can be prepared in a two-step process. In the first step, a carrier substrate 12 which, in specific modalities, is an alveolar substrate with porous walls and containing channels 14 of dimensions in the range of approximately 100 channels/in2 (6.45 cm2) and 1000 channels/in2 (6.45 cm2), is directly coated with a platinum group metal. For ease of illustration, only a single channel 14 is shown. In detailed embodiments, the platinum group metal is coated without an intermediate particulate refractory oxide support. For ease of illustration, this is shown as the first catalyst coating 16. The coated substrate 12 is dried and calcined to fix the substantially unsupported platinum group metal onto the substrate 12. A portion of the porous walls of the substrate 12 is then slurry coated with a reactive coating layer of the second catalyst coating 18 containing a catalyst for selective catalytic reduction of nitrogen oxides. Substrate 12 is dried and calcined to fix the reactive coating layer of second catalyst coating 18 onto substrate 12.
    [57] In detailed embodiments, the second decatalyst coating 18 is formed in a zone between an inlet end 22 and an outlet end 24 of substrate 12 to provide three zones, a first zone to decrease selective catalytic reduction of ammonia, a second zone to oxidize ammonia and a third zone to oxidize carbon monoxide. in specific embodiments, substrate 12 comprises a wall flow filter having gas permeable walls formed in a plurality of axially extending channels, each channel having a buffered end with any pair of adjacent channels buffered on opposite ends thereof.
    [58] Additional embodiments of the invention are directed to methods of preparing a catalytic article having an inlet end 22 and an outlet end 24 for treating an exhaust stream containing NOx. A first reactive coating layer 16 is slurry coated over the walls of honeycomb substrate 12 adjacent to exit end 24 of substrate 12. In detailed embodiments, first reactive coating layer 16 comprises a platinum group metal. The porous walls of substrate 12 are then slurry coated with a second reactive coating layer 18 containing a catalyst for selective catalytic reduction (SCR) of nitrogen oxides. The second reactive coating layer 18 extends from the inlet end 22 and at least partially overlaps the first reactive coating layer 16. The coated substrate 12 is dried and calcined to fix the reactive coating layers 16, 18 onto the substrate 12. This provides a first zone to lower ammonia through selective catalytic reduction, a second zone to oxidize ammonia and a third zone to oxidize carbon monoxide and hydrocarbons. In detailed embodiments, substrate 12 comprises a through-flow substrate.
    [59] In one or more specific embodiments, substrate 12 comprises a wall flow substrate filter having gas permeable walls formed in a plurality of axially extending channels, each channel having a buffered end with any pair of adjacent end buffered channels opposites of the same.
    [60] Additional embodiments of the invention are directed to methods of preparing a catalyst for treating an exhaust stream containing particulate material, NOx and carbon monoxide. substrate 12 includes an inlet end 22 and an outlet end 24 defining an axial length L. an outlet portion of substrate 12 is coated with a first catalyst coating 16 containing a platinum group metal effective to catalyze the oxidation of carbon monoxide in the exhaust stream. The first catalyst coating layer 16 extends from the exit end 24 of the substrate 12 towards the inlet end 22 over less than the full axial length L. The coated substrate 12 is dried and calcined to secure the first coating of catalyst. catalyst 16 over the exit portion of substrate 12. An inlet portion of substrate 12 is coated with a second catalyst coating 18 containing a selective catalytic reduction (SCR) catalyst effective to reduce NOx in the exhaust stream. The second catalyst coating 18 extends from the inlet end 22 of the substrate 12 towards the outlet end 24 over less than the full axial length L and overlaps a portion of the first catalyst coating layer 16. The coated substrate 12 is dried and calcined to affix the second catalyst coating 18 onto the substrate inlet portion 12. Method for treating emissions
    [61] Another aspect of the present invention includes a method of treating emissions produced in the exhaust gas stream of an engine. The exhaust gas stream can include one or more of NOx, CO, hydrocarbons and ammonia. In one or more embodiments, the method includes injecting ammonia or an ammonia precursor into an exhaust gas stream and then passing the exhaust gas stream first through the upstream SCR zone described here to remove NOx by the SCR function. In such embodiments, the exhaust gas stream is then passed through an AMOx zone of intermediate stream to remove ammonia by the NH3 oxidation function. The intermediate stream catalyst zone can also be followed by a downstream zone that oxidizes one or more of CO and hydrocarbons.
    [62] In one embodiment, the upstream SCR zone, the intermediate current AMOX zone, and the downstream DOC zone are arranged on a single catalyst substrate. The SCR zone can be present in the range of approximately 50% to approximately 90% of the length of the substrate or in the range of approximately 20% to approximately 90% of the length of the substrate, and consists only of the SCR component. The AMOx zone comprises in the range of approximately 5% to approximately 50% of the length of the substrate, and includes a base layer containing the NH3 oxidation component and a cover layer containing the SCR component. The downstream DOC zone comprises in the range of approximately 5% to approximately 50% of the length of the substrate, and includes an oxidation component.
    [63] In an alternative embodiment of the method, the upstream SCR zone is disposed on a carrier substrate, and the downstream AMOx zone is disposed on a separate carrier substrate. In this modality, the AMOx zone is set up as an independent AMOx as described above. The volume of the downstream independent AMOx catalyst is in the range of approximately 10% to approximately 100% of the volume of the upstream SCR catalyst, and consists of a base layer containing the NH3 oxidation component and a cover layer containing the SCR component .
    [64] In the two modalities above, the AMOx zone includes two distinct layers functionally and in composition mode. The base layer includes a supported precious metal component and functions to oxidize ammonia according to equation 2. Ammonia molecules that are desorbed from an SCR catalyst under conditions where they cannot be readily consumed by a NOx molecule (for example , under a thermal desorption event) move down the channel 14 while colliding with the reactive coating layer 18 in the upstream zone, comprising an SCR catalyst. The molecule can diffuse into and out of reactive coating layer 18, but is not otherwise converted by the catalyst until it enters the downstream zone and contacts base layer 16, which contains a composition that includes an oxidation component of NH3. In base layer 16, ammonia is initially converted to NOx which subsequently can diffuse to cover layer 18. In cover layer containing an SCR catalyst composition, NO can react with NH3 to form N2, thereby increasing the net selectivity for N2.
    [65] Placing the supported precious metal in the lower reactive coating layer beneath the SCR component in the cover layer limits NO to being generated in the base layer only. This has the effect of increasing the average NO residence life in the catalyst reactive coating layers. As the residence time of NO is increased, NO has a higher probability of colliding with an ammonia molecule in the SCR reactive coating layer and producing N2 which is ultimately released from the catalyst.
    [66] In use, the SCR zone 18 upstream of the catalyst is primarily responsible for removing NOx emissions from wear by selective catalytic reduction reaction of ammonia. The downstream AMOx zone is primarily responsible for the ammonia oxidation function. As discussed elsewhere here, the downstream zone 20, having an upper layer of SCR composition will have SCR activity and may function further in NOx abatement. In this way, the AMOx zone can contribute to pure NOx removal. Furthermore, at elevated temperatures, some SCR compositions, particularly copper-based SCR catalysts, can also have appreciable ammonia oxidizing activity even in the absence of a precious metal component. Furthermore, copper-based SCR catalyst compositions can convert NH3 to N2 with high selectivity at temperatures above 350°C. In one or more modalities, the SCR zone can thus contribute to excess ammonia depletion. Emission treatment system
    [67] One aspect of the invention is directed to emission treatment systems for treating exhaust gases emitted by a diesel engine. Figure 4 shows one or more embodiments of the emission treatment system 40 including a diesel engine 41 which emits an exhaust stream including particulate material, NOx and carbon monoxide. a first substrate 45 has an entry end and an exit end defining an axial length. The first substrate 45 is positioned downstream of and in flow communication with the diesel engine 41. The first substrate 45 has a first catalyst coating including a platinum group metal, the first catalyst coating extending from the end of exit toward the inlet end over less than the full axial length of the substrate, and a second catalyst coating including a catalyst for selective catalytic reduction (SCR) of nitrogen oxides, the second catalyst coating extending from the end of inlet towards the outlet end over less than the full axial length of the substrate and overlapping a portion of the first catalyst coating layer. In detailed embodiments, the first substrate 45 is selected from the group consisting of a wall-flow substrate and a through-flow substrate. In specific embodiments, at least a portion of the platinum group metal is on the refractory metal oxide support. In additional specific embodiments, the platinum group metal is platinum.
    [68] In one or more embodiments, there is an upstream substrate coated with a catalyst for selective catalytic reduction of nitrogen oxides. The upstream substrate 43 is in flow communication with the exhaust stream from the diesel engine 41 and disposed between the diesel engine 41 and the first substrate 45. In detailed embodiments, the upstream substrate 43 comprises a flux substrate alveolar through. In specific embodiments, the upstream substrate 43 comprises a wall flow filter substrate having gas permeable walls formed in a plurality of axially extending channels, each channel having a buffered end with any pair of adjacent channels buffered on opposite ends thereof. .
    [69] In some specific embodiments, the first catalyst and the second catalyst overlap to form three zones. A first zone depletes nitrogen oxides by selective catalytic reduction, a second zone oxidizes ammonia and a third zone oxidizes carbon monoxide and hydrocarbons, and the platinum group metal is directly supported on substrate walls in the first zone and third zone.
    [70] According to one or more detailed embodiments, the first substrate comprises an alveolar flow-through substrate and the first catalyst and second catalyst overlap to form three zones. The first zone decreases nitrogen oxides by selective catalytic reduction, the second zone oxidizes ammonia and the third zone oxidizes carbon monoxide and hydrocarbons. At least a portion of the platinum group metal is on a particulate oxide refractory support.
    [71] In some specific embodiments, the first substrate is a wall flow filter substrate having gas permeable walls formed in a plurality of axially extended channels. Each channel has a plugged end with any pair of adjacent channels plugged into opposite ends thereof.
    [72] In one or more embodiments, there is a wall-flow filter substrate having gas permeable walls formed in a plurality of axially extended channels in flow communication with and disposed between the diesel engine 41 and the first substrate 45. Each The wall flow filter substrate channel 43 has a buffered end with any pair of adjacent channels buffered on opposite ends thereof coated with a CO or hydrocarbon oxidation catalyst.
    [73] Reference throughout this descriptive report to “a modality”, “certain modalities”, “one or more modalities” or “a modality” means that at least a specific aspect, structure, material or characteristic described with respect to the modality is included. in an embodiment of the invention. Thus, the emergence of phrases such as "in one or more modalities", "in certain modalities", "in a modality" or "in a modality" in several places throughout this descriptive report are not necessarily referring to the same modality of invention. In addition, specific features, structures, materials or features may be combined in any appropriate way in one or more modalities.
    [74] Although the invention has been described herein with reference to specific embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Accordingly, the present invention is intended to include modifications and variations that fall within the scope of the appended claims and their equivalents.
    权利要求:
    Claims (21)
    [0001]
    1. A catalytic article for treating an exhaust gas stream containing particulate matter, hydrocarbons, CO, and ammonia, wherein the catalytic article comprises: a first substrate having an inlet end and an outlet end defining an axial length; catalyst coating including a platinum group metal, the first catalyst coating extending from the exit end toward the entry end through less than the full axial length of the first substrate; and a second catalyst coating including a catalyst for selective catalytic reduction (SCR) of nitrogen oxides, the second catalyst coating extending from the inlet end towards the outlet end through less than the full axial length of the first substrate and overlapping a portion of the first catalyst coating, characterized in that the first catalyst coating and the second catalyst coating overlap to form three zones, a first zone to remove NOx by selective catalytic reduction, a second zone to oxidize ammonia, and a third zone to oxidize carbon monoxide and hydrocarbons.
    [0002]
    2. Catalytic article according to claim 1, characterized in that the first substrate is a flow-through substrate having a plurality of longitudinally extending passages formed by longitudinally extending walls delimiting and defining said passages.
    [0003]
    3. Catalytic article according to claim 1, characterized in that the first substrate is a wall flow filter having gas permeable walls formed in a plurality of axially extending channels, each channel having a buffered end with any pair of adjacent buffered channels at opposite ends thereof.
    [0004]
    4. Catalytic article according to any one of claims 1 to 3, characterized in that at least a portion of the platinum group metal is on a particulate refractory metal oxide support.
    [0005]
    5. Catalytic article according to any one of claims 1 to 4, characterized in that the platinum group metal is platinum.
    [0006]
    6. Catalytic article according to any one of claims 1 to 5, characterized in that the platinum group metal is directly supported on the walls of the first substrate.
    [0007]
    7. Catalytic article according to any one of claims 1 to 6, characterized in that each of the three zones individually occupies in the range of 10% to 80% of the axial length of the first substrate.
    [0008]
    8. Catalytic article according to any one of claims 1 to 7, characterized in that the second catalyst coating comprises a microporous inorganic structure comprising a microporous aluminosilicate, on which a metal selected from copper and iron was deposited.
    [0009]
    9. Catalytic article according to any one of claims 1 to 7, characterized in that the second catalyst coating comprises a non-zeolitic molecular sieve selected from metal aluminophosphates and aluminophosphates, wherein the metal comprises silicon, copper, or zinc , on which a metal selected from iron and copper was deposited.
    [0010]
    10. Emission treatment system, characterized in that it comprises: a diesel engine emitting an exhaust stream including particulate matter, NOx and carbon monoxide; and a catalyst article as defined in any one of claims 1 to 9.
    [0011]
    11. Emission treatment system according to claim 10, characterized in that there is an upstream substrate coated with a catalyst for selective catalytic reduction of nitrogen oxides arranged in flow communication with the exhaust stream and between the engine diesel and the first substrate.
    [0012]
    12. Emission treatment system according to claim 11, characterized in that the upstream substrate comprises an alveolar through-flow substrate.
    [0013]
    13. An emission treatment system according to claim 11, characterized in that the upstream substrate comprises a wall flow filter substrate having gas permeable walls formed in a plurality of axially extending channels, each channel having a plugged end with any pair of adjacent channels plugged at opposite ends thereof.
    [0014]
    14. An emission treatment system according to any one of claims 10 to 12, characterized in that there is a wall flow filter substrate having gas permeable walls formed in a plurality of axially extending channels, each channel having one end capped with any pair of adjacent channels capped at opposite ends thereof coated with a hydrocarbon or CO oxidation catalyst disposed in flow communication with the exhaust stream and between the diesel engine and the first substrate.
    [0015]
    15. Emission treatment system according to claim 10, characterized in that the first substrate is a wall-flow substrate or a through-flow substrate.
    [0016]
    16. Emission treatment system according to claim 10 or 15, characterized in that the first substrate is positioned downstream of and in flow communication with the diesel engine.
    [0017]
    17. Emission treatment system according to any one of claims 10 to 14, characterized in that the microporous aluminosilicate is a zeolite.
    [0018]
    18. Emission treatment system according to claim 17, characterized in that the zeolite has a frame structure selected from CHA, FAU, BEA, MFI, and MOR.
    [0019]
    19. A method for preparing a catalytic article as defined in any one of claims 1 to 9, characterized in that it comprises: directly coating a substantially unsupported first platinum group metal on the porous walls of an alveolar substrate; drying and calcining the coated substrate for fixing the substantially unsupported first platinum group metal on the coated substrate; slurry coating a portion of the porous walls with a reactive coating layer containing a catalyst for selective catalytic reduction (SCR) of nitrogen oxides; Dry and calcine the coated substrate to fix the reactive coating layer on the coated substrate.
    [0020]
    20. A method for preparing a catalytic article having an inlet end and an outlet end as defined in any one of claims 1 to 9, characterized in that the method comprises: coating with slurry a first reactive coating layer containing a platinum group metal adjacent to the porous walls of the exit end of an alveolar substrate; slurry the porous walls with a second reactive coating layer containing a catalyst for selective catalytic reduction (SCR) of nitrogen oxides, the second reactive coating layer extending from the inlet end and at least partially overlapping the first reactive coating layer; Drying and calcining the coated substrate to fix the first and second reactive coating layers on the coated substrate to provide a first zone for decreasing selective catalytic reduction of ammonia, a second zone for oxidizing ammonia, and a third zone for oxidizing carbon monoxide and hydrocarbons.
    [0021]
    21. A method for preparing a catalytic article as defined in any one of claims 1 to 9, the substrate including an inlet end and an outlet end defining an axial length, characterized in that it comprises: coating an outlet portion of the first substrate with a first catalyst coating containing a platinum group metal effective to catalyze the oxidation of carbon monoxide in an exhaust stream, the first catalyst coating layer extending from the output end of the first substrate toward the input end less than full axial length; air and calcine the coated substrate to affix the first catalyst coating to the output portion of the first substrate; coat an input portion of the first substrate with a second catalyst coating containing a selective catalytic reduction (SCR) catalyst effective to reduce NOx by an exhaust stream, the second catalyst coating extending from the inlet end of the first substrate toward the outlet end through less than the full axial length and overlapping a portion of the first catalyst coating layer; Drying and calcining the coated substrate to affix the second catalyst coating to the inlet portion of the coated substrate.
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    同族专利:
    公开号 | 公开日
    WO2011140251A3|2012-03-29|
    JP6254844B2|2017-12-27|
    JP6259484B2|2018-01-10|
    ZA201209014B|2014-03-26|
    EP3674524A1|2020-07-01|
    EP2567081A2|2013-03-13|
    CN102985655A|2013-03-20|
    ES2820459T3|2021-04-21|
    MY179455A|2020-11-06|
    US20110271664A1|2011-11-10|
    KR101867259B1|2018-06-12|
    CA2798332C|2018-05-29|
    KR20130098880A|2013-09-05|
    US8293182B2|2012-10-23|
    WO2011140251A2|2011-11-10|
    JP2013525109A|2013-06-20|
    EP2567081B1|2020-07-08|
    EP2567081A4|2015-05-27|
    CA2798332A1|2011-11-10|
    MX2012012829A|2013-01-28|
    JP2016193429A|2016-11-17|
    KR20180016638A|2018-02-14|
    CN102985655B|2016-01-20|
    PL2567081T3|2021-01-11|
    BR112012028320A2|2017-07-18|
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    法律状态:
    2018-12-26| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-11-05| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-10-06| B07A| Application suspended after technical examination (opinion) [chapter 7.1 patent gazette]|
    2021-02-23| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|
    2021-06-08| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-07-20| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 04/05/2011, OBSERVADAS AS CONDICOES LEGAIS. PATENTE CONCEDIDA CONFORME ADI 5.529/DF, QUE DETERMINA A ALTERACAO DO PRAZO DE CONCESSAO. |
    优先权:
    申请号 | 申请日 | 专利标题
    US12/774,469|US8293182B2|2010-05-05|2010-05-05|Integrated SCR and AMOx catalyst systems|
    US12/774,469|2010-05-05|
    PCT/US2011/035234|WO2011140251A2|2010-05-05|2011-05-04|Integrated scr and amox catalyst systems|
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