Cu-zeolite selective catalytic reduction catalyst and method for exhaust gas treatment

Abstract

Disclosed herein is an exhaust gas treatment system comprising a combustion engine and a selective catalytic reduction article downstream of the combustion engine, wherein the exhaust gas treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, wherein the exhaust gas treatment system does not have a catalyzed soot filter in fluid communication between the combustion engine and the selective catalytic reduction article, and wherein the selective catalytic reduction article has one or more washcoats comprising a copper-containing small pore zeolite having a silica-to-alumina molar ratio in the range of from 5 to less than 30. Also disclosed is a method for exhaust gas treatment comprising contacting exhaust gas with the disclosed exhaust gas treatment system.

Description

[Technical Field]

[0001] Disclosed herein is an exhaust gas treatment system comprising a combustion engine and a selective catalytic reduction article downstream of the combustion engine, wherein the exhaust gas treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, wherein the exhaust gas treatment system does not have a catalyzed soot filter in fluid communication between the combustion engine and the selective catalytic reduction article, and wherein the selective catalytic reduction article has one or more washcoats comprising a copper-containing small pore zeolite having a silica-to-alumina molar ratio in the range of from 5 to less than 30. Also disclosed is a method for exhaust gas treatment comprising contacting exhaust gas with the disclosed exhaust gas treatment system.

[0002] For example, an internal combustion engine, such as a diesel engine, has an exhaust gas stream that includes pollutants such as, for example, particulate matter, oxides of nitrogen, unburned hydrocarbons, and / or carbon monoxide.

[0003] Exhaust gas treatment systems and catalyst articles are exemplary means for abating pollution from internal combustion engines. For example, some exhaust gas treatment systems include a diesel oxidation catalyst upstream of a selective catalytic reduction catalyst. Exemplary diesel oxidation catalysts are useful for abating pollutants such as, for example, unburned hydrocarbons and / or carbon monoxide. Exemplary selective catalytic reduction catalysts are useful for abating pollutants such as, for example, nitrogen oxide (NO x ), but effective pollutant abatement can be difficult to achieve in practice. For example, there may be trade-offs between the abatement of various pollutants, between the abatement of pollutants across different operating conditions of the combustion engine, and / or between the performance of various catalyst articles within the exhaust gas treatment system.

[0004] Therefore, there is a need for improved catalytic articles, exhaust gas treatment systems, and methods for treating exhaust gas streams. For example, there is a need for catalytic articles, such as selective catalytic reduction articles, that provide enhanced pollution abatement. Furthermore, there is a need for catalytic articles, such as selective catalytic reduction articles, that can enhance the performance of downstream catalytic articles in exhaust gas treatment systems. For example, there is a need for catalytic articles, such as selective catalytic reduction articles, that can enhance the performance of downstream catalytic articles in exhaust gas treatment systems. For example, there is a need for catalytic articles, such as selective catalytic reduction articles, that can enhance the performance of downstream catalytic articles in exhaust gas treatment systems with low NO output. x There is a need for a selective catalytic reduction article that can selectively reduce

[0005] Disclosed herein is an exhaust gas treatment system comprising a combustion engine and a selective catalytic reduction article downstream of the combustion engine, wherein the exhaust gas treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, the exhaust gas treatment system does not have a catalyzed soot filter in fluid communication between the combustion engine and the selective catalytic reduction article, and the selective catalytic reduction article has one or more washcoats comprising a copper-containing small pore zeolite having a silica-to-alumina molar ratio in the range of from 5 to less than 30.

[0006] In some embodiments, the exhaust gas treatment system does not have a catalytic article in fluid communication between the combustion engine and the selective catalytic reduction article.

[0007] In some embodiments, the copper-containing small pore zeolite has an amount of copper ranging from 0.1 wt. % CuO to 3 wt. % CuO, based on the total weight of the copper-containing small pore zeolite.

[0008] In some embodiments, the one or more washcoats further comprise 1% to 10% by weight of alumina, based on the total weight of the one or more washcoats.

[0009] In some embodiments, the one or more washcoats comprise less than 1 wt. % alumina, based on the total weight of the one or more washcoats.

[0010] In some embodiments, the copper-containing small pore zeolite has a copper to alumina molar ratio in the range of 0.05 to 0.25.

[0011] In some embodiments, the one or more washcoats comprise less than 0.5 wt. % vanadium, based on the total weight of the one or more washcoats.

[0012] In some embodiments, the selective catalytic reduction article comprises a flow-through substrate.

[0013] In some embodiments, the exhaust gas treatment system further comprises a diesel oxidation catalyst downstream of the selective catalytic reduction article.

[0014] In some embodiments, the exhaust gas treatment system further comprises a catalyzed soot filter downstream of the selective catalytic reduction article.

[0015] In some embodiments, the selective catalytic reduction article comprises less than 1 wt. % total of all metals other than copper, aluminum, magnesium, iron, and zirconium, based on the total weight of the selective catalytic reduction article.

[0016] In some embodiments, the selective catalytic reduction article comprises less than 1 wt. % of all elements other than copper, silicon, aluminum, oxygen, magnesium, iron, hydrogen, and zirconium, in total, based on the total weight of the selective catalytic reduction article.

[0017] In some embodiments, the copper-containing small pore zeolite comprises less than 1 wt. % of all metals other than copper, silicon, and aluminum combined, based on the total weight of the copper-containing small pore zeolite.

[0018] A similarly disclosed method for treating exhaust gases comprising contacting the exhaust gases with the disclosed exhaust gas treatment system. [Brief explanation of the drawings]

[0019] [Figure 1A]1 depicts NOx conversion for an exemplary embodiment. [Figure 1B] 1 depicts N2O selectivity for an exemplary embodiment. [Figure 2A] 1 depicts NOx conversion for an exemplary embodiment. [Figure 2B] 1 depicts N2O selectivity for an exemplary embodiment. [Figure 2C] 1 depicts N2O selectivity for an exemplary embodiment. [Figure 3A] 1 depicts NOx conversion for an exemplary embodiment. [Figure 3B] 1 depicts N2O selectivity for an exemplary embodiment. [Figure 4] 1 depicts hydrocarbon masking of an exemplary embodiment;

[0020] Definition: As used herein, "a" or "an" entity refers to one or more of that entity; for example, "a compound" refers to one or more compounds or at least one compound, unless otherwise specified. Thus, the terms "a" (or "an"), "one or more," and "at least one" are used interchangeably herein.

[0021] As used herein, the term "material" refers to elements, components, and / or substances that make up or can make something.

[0022] As used herein, the term "about" refers to a range of ±5% of the stated number. For example, "about 100" refers to a number in the range of 95 to 105, inclusive of 95, 100, and 105. Unless otherwise specified, all numbers are considered to be modified by "about."

[0023] As used herein, the term "platinum group metals," abbreviated as "PGM," refers to ruthenium, rhodium, palladium, osmium, iridium, platinum, and combinations thereof.

[0024] As used herein, a "catalyzed soot filter" includes a filter for trapping soot particles from exhaust gases and a catalyst composition for oxidizing the trapped soot particles.

[0025] As used herein, the "loading" of a material, such as a washcoat or metal, on a substrate refers to the dry mass of material coated on the substrate per unit volume of the substrate. For example, 1 g / in on the substrate. 3 A washcoat loading of 1 g / ft 3 means that the total dry mass of washcoat is 1 gram per cubic inch of substrate. 3 A platinum group metal loading of 1 g / in 3 means a total mass of platinum group metal of 1 gram per cubic foot of substrate. Material loading may also be local to a subvolume of the substrate. Such loading is reported as the dry mass of material coated on a subvolume of the substrate per unit volume of the subvolume of the substrate. For example, a substrate may have a first zone of X cubic inches volume onto which a total dry washcoat mass of Ag is deposited, and a second zone of Y cubic inches volume onto which a total dry washcoat mass of Bg is deposited. In this example, the first zone has a volume of (A / X) g / in 3 . 3 and the second zone has a washcoat dosage of (B / Y) g / in 3 has a washcoat loading of

[0026] As used herein, the term "diesel oxidation catalyst" refers to a catalyst containing a platinum group metal that is capable of oxidizing carbon monoxide, NO2, and hydrocarbons when contacted with exhaust from a diesel engine.

[0027] As used herein, "NO x The term "nitrogen oxides" refers to nitrogen oxides and mixtures thereof. Exemplary nitrogen oxides include, but are not limited to, NO, N2O, NO2, and N2O2.

[0028] As used herein, the term "selective catalytic reduction catalyst" refers to a catalyst that converts NO, optionally in the presence of a reducing agent such as NH x This refers to a catalyst that can selectively reduce N2 and water.

[0029] As used herein, "particle size DX" (where X is a number ranging from 0 to 100) refers to the particle size below which approximately X% of the particles have a particle size. For example, "particle size D90" refers to the particle size below which approximately 90% of the particles have a particle size.

[0030] As used herein, the term "washcoat" refers to a coating applied to a substrate.

[0031] As used herein, when two entities are in fluid communication and a fluid, such as exhaust gas, flows from the first entity to the second entity, the second entity is "downstream" of the first entity, and there may or may not be one or more additional entities in fluid communication between the first and second entities.

[0032] As used herein, a first entity is "upstream" of a second entity if the second entity is downstream of the first entity.

[0033] As used herein, zeolite framework types are classified by the Structure Commission of the International Zeolite Association according to the rules of the IUPAC Commission on Zeolite Nomenclature, in which zeolite framework types are assigned three-letter codes and are described in Atlas of Zeolite Framework Types, 5th edition, Elsevier, London, England (2001).

[0034] As used herein, a "small pore zeolite" is a zeolite having an 8-ring pore opening and a pore diameter of less than 5 angstroms. Some exemplary small pore zeolites have a framework structure selected from AEI, AFT, AFV, AFX, AVL, CHA, DDR, EAB, EEI, ERI, IFY, IRN, KFI, LEV, LTA, LTN, MER, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations thereof.

[0035] As used herein, a zone on a substrate may or may not at least partially overlap another zone on the substrate.

[0036] As used herein, a layer on a substrate may or may not at least partially overlap another layer on the substrate.

[0037] Exhaust Gas Treatment System: Without being bound by theory, it is believed that the hot exhaust gases coming from the engine heat the downstream catalytic components. As the downstream components heat up, they are exposed to different gas temperatures and compositions, and the catalytic components heat at different rates depending on their positioning downstream of the engine. Therefore, it is believed that exhaust gas treatment may depend on both the positioning of the catalytic components downstream from the engine and the composition of the catalytic components. For example, without being bound by theory, it is believed that a selective catalytic reduction article that is suitable for exhaust gas treatment when positioned downstream of, for example, a diesel oxidation catalyst and / or a catalyzed soot filter may not be suitable for exhaust gas treatment when in a close-coupled position immediately downstream of the engine.

[0038] For example, exhaust catalyst systems may be heated by the hot exhaust gases coming from the engine, and therefore, the upstream catalyst may heat up faster than the downstream catalyst. In some heavy-duty diesel exhaust systems, a selective catalytic reduction (SCR) catalyst is located downstream of the DOC (diesel oxidation catalyst) and CSF (catalytic soot filter). In such systems, it may take some time for the SCR catalyst to reach its minimum operating temperature. During this heating period, NO x Emissions can occur and a significant proportion of NO x Without being bound by theory, it is believed that the SCR catalyst may heat up to its operating temperature more quickly if it is positioned directly in the engine exhaust (i.e., a close-coupled location). In this location, the SCR catalyst may heat up more quickly, resulting in NO emissions. x It is thought that the conversion of

[0039] However, close-coupled SCR (cc-SCR) catalysts may be exposed to a different environment than downstream locations. For example, hydrocarbons from the engine exhaust may flow directly through the cc-SCR, causing hydrocarbon poisoning. Similarly, SO2, which may be present in the engine exhaust, may cause severe deactivation of the SCR catalyst. In some exhaust gas treatment systems, sulfur-poisoned SCR catalysts can be regenerated at high temperatures, such as 550°C, which can be achieved during soot filter regeneration when the SCR catalyst is located downstream of the CSF. However, achieving such high temperatures in close-coupled locations can be difficult. Therefore, it may be beneficial for cc-SCRs to have a lower desulfation temperature, such as 450°C. Additionally, to meet stringent emissions regulations such as Euro 7, it may be beneficial for SCR catalysts to have low selectivity for undesirable greenhouse gases, such as NO.

[0040] Some SCR catalysts, for example, in heavy-duty diesel exhaust systems, may use Cu-small pore or V2O5 / TiO2. Some V2O5-based SCRs may have low N2O selectivity and sulfur poisoning resistance, but their NO x The reduction activity may be reduced by hydrocarbon masking. Additionally, the volatility of V2O5 may limit its applications.

[0041] Disclosed herein is an exhaust gas treatment system comprising a combustion engine and a selective catalytic reduction article downstream of the combustion engine, wherein the exhaust gas treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, the exhaust gas treatment system does not have a catalyzed soot filter in fluid communication between the combustion engine and the selective catalytic reduction article, and the selective catalytic reduction article has one or more washcoats comprising a copper-containing small pore zeolite having a silica-to-alumina molar ratio in the range of from 5 to less than 30.

[0042] In some embodiments, the exhaust gas treatment system does not have a catalytic article in fluid communication between the combustion engine and the selective catalytic reduction article.

[0043] In some embodiments, the exhaust gas treatment system further comprises a diesel oxidation catalyst downstream of the selective catalytic reduction article.

[0044] In some embodiments, the exhaust gas treatment system further comprises a catalyzed soot filter downstream of the selective catalytic reduction article.

[0045] Catalyst article: A selective catalytic reduction article is disclosed that includes a copper-containing small pore zeolite having a silica to alumina molar ratio in the range of 5 to less than 30.

[0046] In some embodiments, the copper-containing small pore zeolite has a silica to alumina molar ratio in the range of 10 to 28. In some embodiments, the copper-containing small pore zeolite has a silica to alumina molar ratio in the range of 10 to 25. In some embodiments, the copper-containing small pore zeolite has a silica to alumina molar ratio in the range of 10 to 20. In some embodiments, the copper-containing small pore zeolite has a silica to alumina molar ratio in the range of 15 to 20.

[0047] In some embodiments, the copper-containing small pore zeolite has a copper amount ranging from 0.1 wt% CuO to 3 wt% CuO, based on the total weight of the copper-containing small pore zeolite. The copper-containing small pore zeolite has a copper amount ranging from 0.1 wt% CuO to 3 wt% CuO, based on the total weight of the copper-containing small pore zeolite. In some embodiments, the copper-containing small pore zeolite has a copper amount ranging from 1.5 wt% CuO to 3 wt% CuO, based on the total weight of the copper-containing small pore zeolite.

[0048] In some embodiments, the copper-containing small pore zeolite has a silica-to-alumina molar ratio in the range of 10 to 20 and an amount of copper in the range of 1.5 wt.% CuO to 3 wt.% CuO, based on the total weight of the copper-containing small pore zeolite. In some embodiments, the copper-containing small pore zeolite has a silica-to-alumina molar ratio in the range of 15 to 20 and an amount of copper in the range of 1.75 wt.% CuO to 2.5 wt.% CuO, based on the total weight of the copper-containing small pore zeolite.

[0049] In some embodiments, the one or more washcoats further comprise 1% to 10% by weight of alumina, based on the total weight of the one or more washcoats.

[0050] In some embodiments, the one or more washcoats comprise less than 1 wt. % alumina, based on the total weight of the one or more washcoats.

[0051] In some embodiments, the copper-containing small pore zeolite has a copper to alumina molar ratio in the range of 0.05 to 0.25.

[0052] In some embodiments, the one or more washcoats comprise less than 0.5 wt. % vanadium, based on the total weight of the one or more washcoats.

[0053] In some embodiments, the selective catalytic reduction article comprises a flow-through substrate.

[0054] In some embodiments, the selective catalytic reduction article comprises catalyst particles having a D90 particle size in the range of 3 μm to 11 μm as measured by a Sympatec particle size analyzer.

[0055] In some embodiments, the selective catalytic reduction article comprises less than 1 wt.% of all metals other than copper, aluminum, magnesium, iron, and zirconium, based on the total weight of the selective catalytic reduction article. In some embodiments, the selective catalytic reduction article comprises less than 0.1 wt.% of all metals other than copper, aluminum, magnesium, iron, and zirconium, based on the total weight of the selective catalytic reduction article.

[0056] In some embodiments, the selective catalytic reduction article comprises less than 1 wt.% of all elements other than copper, silicon, aluminum, oxygen, magnesium, iron, hydrogen, and zirconium, based on the total weight of the selective catalytic reduction article. In some embodiments, the selective catalytic reduction article comprises less than 0.1 wt.% of all elements other than copper, silicon, aluminum, oxygen, magnesium, iron, hydrogen, and zirconium, based on the total weight of the selective catalytic reduction article.

[0057] In some embodiments, the copper-containing small pore zeolite comprises less than 1 wt.% of all metals other than copper, silicon, and aluminum, based on the total weight of the copper-containing small pore zeolite. In some embodiments, the copper-containing small pore zeolite comprises less than 0.1 wt.% of all metals other than copper, silicon, and aluminum, based on the total weight of the copper-containing small pore zeolite.

[0058] In some embodiments, a catalyst article comprises a substrate having a length and including an inlet end and an outlet end, and one or more washcoats deposited thereon, wherein at least one of the one or more washcoats comprises a copper-containing small pore zeolite having a silica to alumina molar ratio in the range of from 5 to less than 30.

[0059] In some embodiments, the washcoat has a coating density of 1 g / in 3 ~5g / in 3 In some embodiments, the washcoat has a loading in the range of 0.5 g / in 3 ~5g / in 3 The input range is:

[0060] Base material: In some embodiments, one or more washcoats are disposed on one or more substrates, for example, to form a catalyst article. In some embodiments, the one or more substrates are three-dimensional, having a length, a diameter, and a volume. In some embodiments, the one or more substrates are cylindrical. In some embodiments, the one or more substrates are not cylindrical. In some embodiments, the one or more substrates have an axial length from an inlet end to an outlet end.

[0061] In some embodiments, one or more substrates are ceramic substrates. In some embodiments, the ceramic substrate is made of any suitable refractory material, such as cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon-mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicate, and the like.

[0062] In some embodiments, the substrate comprises one or more metals or metal alloys. In some embodiments, the metal substrate can include any metal substrate, such as those with openings or "punch-outs" in the channel walls. In some embodiments, the metal substrate can be used in various shapes, such as pellets, compressed metal fibers, corrugated sheets, or monolithic foams. In some embodiments, the metal substrate comprises a heat-resistant base metal alloy, particularly one in which iron is a substantial or major component. Such alloys may contain one or more of nickel, chromium, and aluminum, the sum of which metals may comprise at least about 15% by weight (weight percent) of the alloy, e.g., about 10% to about 25% by weight chromium, about 1% to about 8% by weight aluminum, and about 0% to about 20% by weight nickel, in each case based on the weight of the substrate. In some embodiments, metal substrates include those with straight channels, those with blades that protrude along the axial channels to disrupt the gas flow and open gas flow communication between the channels, and those with blades and holes to enhance gas transport between the channels to allow radial gas transport throughout the monolith.

[0063] In some embodiments, any suitable substrate may be used, such as a monolithic substrate of the type having fine, parallel gas flow passages extending from an inlet face to an outlet face of the substrate such that the passages are open to fluid flow therethrough (a "flow-through substrate"). In some embodiments, the substrate has a plurality of fine, substantially parallel gas flow passages extending along the longitudinal axis of the substrate, where, for example, each passage is blocked at one end of the substrate body and alternating passages are blocked at opposing end faces (a "wall-flow filter").

[0064] In some embodiments, the substrate comprises a honeycomb substrate in the form of a wall-flow filter or a flow-through substrate. In some embodiments, the substrate is a wall-flow filter. In some embodiments, the substrate is a flow-through substrate.

[0065] In some embodiments, the substrate is a flow-through substrate (e.g., a monolithic substrate, including a flow-through honeycomb monolithic substrate). In some embodiments, the flow-through substrate has fine parallel gas flow passages extending from the inlet end to the outlet end of the substrate such that the flow passages are open to fluid flow. In some embodiments, the passages, which are the path from the inlet to the outlet, have walls with a coating disposed thereon or therein such that gas flowing through the passage contacts the coated material. In some embodiments, the flow passages of the flow-through substrate are thin-walled channels, which can be of any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, oval, circular, etc. Flow-through substrates can be ceramic or metallic, as described above.

[0066] The volume of an exemplary flow-through substrate is not particularly limited. In some embodiments, the flow-through substrate is about 50 in 3 ~About 1200in 3a volume of about 60 cells per square inch (cpsi) to about 500 cpsi or up to about 900 cpsi, e.g., a cell density (inlet opening) of about 200 to about 400 cpsi, and a wall thickness of about 50 micrometers to about 200 micrometers or about 400 micrometers.

[0067] In some embodiments, the substrate is a wall-flow filter having a plurality of fine passages extending along the longitudinal axis of the substrate. In some embodiments, each passage is blocked at one end of the substrate body, with alternating passages being blocked at the opposing end faces. In some embodiments, a monolithic wall-flow filter substrate may contain up to about 900 or more passages (or "cells") per square inch of cross section, although fewer passages may be used. For example, the substrate may have about 7-600, e.g., about 100-400, cells per square inch ("cpsi"). In some embodiments, the cells have a rectangular, square, circular, oval, triangular, hexagonal, or other polygonal cross section. In some embodiments, the wall-flow filter substrate is ceramic or metallic, as described above.

[0068] The volume of an exemplary wall-flow filter article substrate is not particularly limited. In some embodiments, the wall-flow filter article substrate may be, for example, about 50 cm 3 , about 100in 3 , approximately 200in 3 , about 300in 3 , approximately 400 in 3 , approximately 500in 3 , approximately 600in 3 , approximately 700 in 3 , approximately 800 in 3 , approximately 900in 3 , or about 1000 in 3 From about 1500 in 3 , approximately 2000 in 3 , about 2500in 3 , about 3000in 3 , about 3500in 3 , approximately 4000in 3 , approximately 4500 in3 , or about 5000 in 3 In some embodiments, the wall-flow filter substrate has a wall thickness of from about 50 micrometers to about 500 micrometers, e.g., from about 50 micrometers to about 450 micrometers or from about 150 micrometers to about 400 micrometers.

[0069] In some embodiments, the wall of a wall-flow filter has a normal porosity or a high porosity. In some embodiments, the wall of a wall-flow filter has a wall porosity of at least about 40% or at least about 50% and an average pore size of at least about 10 micrometers before the application of a functional coating. For example, in some embodiments, the wall-flow filter article substrate has a porosity of ≥ 40%, ≥ 50%, ≥ 60%, ≥ 65%, or ≥ 70%. In some embodiments, the wall-flow filter article substrate has a wall porosity of about 50%, about 60%, about 65%, or about 70% to about 75% and an average pore size of about 10 micrometers or about 20 micrometers to about 30 micrometers or about 40 micrometers before the application of a catalytic coating. The terms "wall porosity" and "substrate porosity" mean the same thing and are used interchangeably herein. Porosity is the ratio of the void volume (or pore volume) divided by the total volume of the substrate material. The pore size and pore size distribution can be determined, for example, by Hg porosimetry measurements.

[0070] Wash Coat: In some embodiments, the slurry is coated onto the substrate using washcoat techniques known in the art. A washcoat is as described, for example, in Heck, Ronald and Farrauto, Robert, Catalytic Air Pollution Control, New York: Wiley-Interscience, 2002, pp. 18-19, as a compositionally distinct layer of material disposed on the surface of a monolithic substrate or an underlying washcoat layer. In some embodiments, the substrate contains one or more washcoat layers, and each washcoat layer may have a different composition.

[0071] In some embodiments, the substrate is dipped into or otherwise coated, e.g., sprayed, with the slurry one or more times. In some embodiments, the coated substrate is dried at an elevated temperature (e.g., 100°C to 150°C) in still air or under a flow or air jet for about 2 minutes to about 3 hours, and then calcined, for example, by heating at 400°C to 600°C for about 10 minutes to about 3 hours. In some embodiments, after drying and calcining, the final washcoat coating layer is essentially solvent-free.

[0072] In some embodiments, after calcination, the washcoat loading can be determined by calculating the difference between the coated and uncoated weight of the substrate. As will be apparent to one skilled in the art, the washcoat loading can be altered by varying the rheology, solids content, or number of coating runs of the slurry. In some embodiments, the coating / drying / calcining process is repeated as necessary to build up a coating of the desired loading level or thickness.

[0073] In some embodiments, the composition is applied as a single layer or in multiple layers. In some embodiments, a layer obtained by repeatedly washcoating the same material to increase loading levels is a single layer. In some embodiments, the composition may be zone coated, meaning that a single substrate may be coated with different catalyst compositions in different regions along the axial gas effluent flow path.

[0074] In some embodiments, the composition is mixed with water to form a slurry for coating a substrate. In some embodiments, the slurry further comprises an inorganic binder, an associative thickener, or a surfactant (e.g., one or more anionic, cationic, nonionic, or amphoteric surfactants). The order of addition may be varied; in some embodiments, all components are simply combined together to form the slurry; in some embodiments, certain components are combined and then the remaining components are combined with them. In some embodiments, the pH of the slurry may be adjusted to an acidic pH, for example, from about 3 to about 5.

[0075] In some embodiments, the slurry is milled. In some embodiments, milling is performed in a ball mill, continuous mill, or other similar equipment, and the solids content of the slurry can be, for example, about 20% to about 60% by weight, or about 30% to about 40% by weight. In some embodiments, the milled slurry is characterized by a D90 particle size of about 10 micrometers to about 50 micrometers (e.g., about 10 micrometers to about 20 micrometers).

[0076] In some embodiments, the first and second washcoats are in a layered relationship. In some embodiments, the first and second washcoats are in a layered relationship, with the first washcoat stacked on top of the second washcoat, which is stacked directly on the substrate. In some embodiments, the first and second washcoats are in a layered relationship, with the second washcoat stacked on top of the first washcoat, which is stacked directly on the substrate.

[0077] In some embodiments, the first and second washcoats are in a zonal relationship. In some embodiments, the first washcoat is in an upstream zone and the second washcoat is in a downstream zone. In some embodiments, the first washcoat is coated over x% of the axial length of the substrate, where x is greater than 0% and less than 100% from the inlet face of the coated structure. In some embodiments, the second washcoat is coated over y% of the axial length of the substrate, where y is greater than 0% and less than 100% from the outlet face of the coated structure. In some embodiments, x% is 10% and y% is 90%. In some embodiments, x% is 20% and y% is 80%. In some embodiments, x% is 30% and y% is 70%. In some embodiments, x% is 40% and y% is 60%. In some embodiments, x% is 50% and y% is 50%. In some embodiments, x% is 60% and y% is 40%. In some embodiments, x% is 70% and y% is 30%. In some embodiments, x% is 80% and y% is 20%. In some embodiments, x% is 90% and y% is 10%.

[0078] In some embodiments, the first and second washcoats are in a zonal and layered relationship, with a portion of the first washcoat overlapping a portion of the second washcoat. In some embodiments, the first washcoat is coated, directly or indirectly, over x% of the axial length of the substrate, where x is greater than 0% and less than 100% from the inlet face of the coated structure. In some embodiments, the second washcoat is coated, directly or indirectly, over y% of the axial length of the substrate, where y is greater than 0% and less than 100% from the outlet face of the coated structure. In some embodiments, x%+y% is in the range of 100% to 180%. In some embodiments, x%+y% is in the range of 100% to 150%. In some embodiments, x%+y% is in the range of 100% to 120%. In some embodiments, x%+y% is in the range of 100% to 110%. In some embodiments, x%+y% is in the range of 100% to 105%. In some embodiments, a portion of the first washcoat and a portion of the second washcoat overlap such that x%+y% is greater than 100%. In some embodiments, the first washcoat overlaps the second washcoat. In some embodiments, the second washcoat overlaps the first washcoat.

[0079] In some embodiments, a second washcoat is at least partially stacked on top of the first washcoat, the second washcoat comprising Pt, Mn, Zr, and optionally Pd.

[0080] Catalyzed soot filters: Catalyzed soot filters provide an exemplary means for capturing and oxidizing soot particles entrained in an engine exhaust stream. A non-limiting exemplary catalyzed soot filter includes a catalyst composition including a platinum group metal, the catalyst composition being deposited on a wall-flow substrate filter. Non-limiting exemplary catalyzed soot filters are disclosed in International Application No. PCT / US2004 / 024864, filed July 30, 2004, International Application No. PCT / US2006 / 043574, filed November 8, 2006, International Application No. PCT / US2007 / 086095, filed November 30, 2007, International Application No. PCT / US2016 / 024889, filed March 30, 2016, and International Application No. PCT / US2011 / 061681, filed November 21, 2011, the disclosures of each of which are incorporated herein by reference in their entirety.

[0081] Diesel Oxidation Catalyst Diesel oxidation catalysts provide an exemplary means for oxidizing carbon monoxide and hydrocarbons when contacted with exhaust from a diesel engine. Non-limiting exemplary diesel oxidation catalysts are described in International Application No. PCT / US2010 / 021105, filed January 15, 2010, International Application No. PCT / US2010 / 030226, filed April 7, 2010, International Application No. PCT / EP2013 / 073495, filed November 11, 2013, International Application No. PCT / US2012 / 067208, filed November 30, 2012, U.S. Patent No. 7,875,573, U.S. Patent No. 2 ... and PCT / US2014 / 070356, filed December 15, 2014, the disclosures of each of which are incorporated herein by reference in their entirety.

[0082] How to treat exhaust gases: A method for exhaust gas treatment is disclosed that includes contacting the exhaust gas with the exhaust gas treatment system disclosed herein.

[0083] Non-limiting exemplary embodiments: Without limitation, some embodiments of the present disclosure include: 1. An exhaust gas treatment system comprising a combustion engine and a selective catalytic reduction article downstream of the combustion engine, wherein the exhaust gas treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, and the exhaust gas treatment system does not have a catalyzed soot filter in fluid communication between the combustion engine and the selective catalytic reduction article, and the selective catalytic reduction article has one or more washcoats comprising a copper-containing small pore zeolite having a silica to alumina molar ratio in the range of 5 to less than 30, wherein the copper-containing small pore zeolite has an amount of copper in the range of 0.1 wt. % CuO to 3 wt. % CuO, based on the total weight of the copper-containing small pore zeolite, and wherein the copper-containing small pore zeolite has a copper to alumina molar ratio in the range of 0.05 to 0.25. 2. The exhaust gas treatment system of embodiment 1, wherein the exhaust gas treatment system does not have a catalyst article in fluid communication between the combustion engine and the selective catalytic reduction article. 3. The exhaust gas treatment system of embodiment 1 or 2, wherein the copper-containing small pore zeolite has a framework structure selected from AEI, AFT, AFV, AFX, AVL, CHA, DDR, EAB, EEI, ERI, IFY, IRN, KFI, LEV, LTA, LTN, MER, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations thereof. 4. The exhaust gas treatment system of any one of embodiments 1-3, wherein the one or more washcoats further comprise 1 wt. % to 10 wt. % alumina, based on the total weight of the one or more washcoats. 5. The exhaust gas treatment system of any one of embodiments 1-3, wherein the one or more washcoats comprise less than 1 wt. % alumina, based on the total weight of the one or more washcoats. 6. The exhaust gas treatment system of any one of embodiments 1 to 5, wherein the copper-containing small pore zeolite has a chabazite framework structure. 7. The exhaust gas treatment system of any one of embodiments 1-6, wherein the one or more washcoats comprise less than 0.5 wt. % vanadium, based on the total weight of the one or more washcoats. 8. The exhaust gas treatment system of any one of embodiments 1-7, wherein the selective catalytic reduction article comprises a flow-through substrate. 9. The exhaust gas treatment system of any one of embodiments 1-8, further comprising a diesel oxidation catalyst downstream of the selective catalytic reduction article. 10. The exhaust gas treatment system of any one of embodiments 1-9, further comprising a catalyzed soot filter downstream of the selective catalytic reduction article. 11. The exhaust gas treatment system of any one of embodiments 1-10, wherein the selective catalytic reduction article comprises less than 1 wt. % in total of all metals other than copper, aluminum, magnesium, iron, and zirconium, based on the total weight of the selective catalytic reduction article. 12. The exhaust gas treatment system of any one of embodiments 1-11, wherein the selective catalytic reduction article comprises less than 1 wt. % in total of all elements other than copper, silicon, aluminum, oxygen, magnesium, iron, hydrogen, and zirconium, based on the total weight of the selective catalytic reduction article. 13. The exhaust gas treatment system of any one of embodiments 1-11, wherein the copper-containing small pore zeolite comprises less than 1 wt. % of all metals other than copper, silicon, and aluminum, combined, based on the total weight of the copper-containing small pore zeolite. 14. A method for exhaust gas treatment, comprising contacting exhaust gas with the exhaust gas treatment system of any one of embodiments 1-10. [Example]

[0084] The following examples are intended to be illustrative and are not meant to limit the scope of the present disclosure in any way.

[0085] Example 1 Preparation of a catalyst article containing Cu / SSZ-13 (SAR=17, CuO%=1.75%). 93.3 parts by weight of the hydrogen form of SSZ-13, 1.7 parts by weight of CuO, and 5.0 parts by weight of zirconium acetate, calculated as ZrO2, were mixed in deionized water to form a slurry. The slurry had a D of 6 μm to 9 μm as measured by a Sympatec particle size analyzer. 90 The slurry was milled to a particle size of 1.5g / in. The slurry was mixed at room temperature for 20 hours to allow the copper ions to exchange into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a cell density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcination at 550°C. The washcoat loading was 2.75g / in. 3 It was.

[0086] Figure 1A shows the NO x FIG. 1B depicts the conversion and FIG. 1B depicts the N2O selectivity for Example 1 after hydrothermal aging, described below.

[0087] Example 2 Preparation of a catalyst article containing Cu / SSZ-13 (SAR=17, CuO%=2.0%). 93.1 parts by weight of the hydrogen form of SSZ-13, 1.9 parts by weight of CuO, and 5.0 parts by weight of zirconium acetate, calculated as ZrO, were mixed in deionized water to form a slurry. The slurry had a D of 6 μm to 9 μm as measured by a Sympatec particle size analyzer. 90 The slurry was milled to a particle size of 1.5g / in. The slurry was mixed at room temperature for 20 hours to allow the copper ions to exchange into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a cell density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcination at 550°C. The washcoat loading was 2.75g / in. 3 It was.

[0088] Figure 1A shows the NO x FIG. 1B depicts the conversion and FIG. 1B depicts the N2O selectivity for Example 2 after hydrothermal aging, described below.

[0089] 2A and 2B are NO x Conversion and N2O selectivity are compared with Comparative Examples 1 and 2 described below.

[0090] FIG. 3 shows the NO content of Example 2 after hydrothermal aging, and before, after, and after desulfation, as described below. x Conversion (3A) and N2O selectivity (3B) are shown.

[0091] Example 3 Preparation of a catalyst article containing Cu / SSZ-13 (SAR=17, CuO%=2.25%). 92.9 parts by weight of the hydrogen form of SSZ-13, 2.1 parts by weight of CuO, and 5.0 parts by weight of zirconium acetate, calculated as ZrO2, were mixed in deionized water to form a slurry. The slurry had a D of 6 μm to 9 μm as measured by a Sympatec particle size analyzer. 90 The slurry was milled to a particle size of 1.5g / in. The slurry was mixed at room temperature for 20 hours to allow the copper ions to exchange into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a cell density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcination at 550°C. The washcoat loading was 2.75g / in. 3 It was.

[0092] Figure 1A shows the NO x FIG. 1B depicts the conversion and FIG. 1B depicts the N2O selectivity for Example 3 after hydrothermal aging, described below.

[0093] Example 4 Preparation of a catalyst article containing Cu / SSZ-13 (SAR=17, CuO%=2.5%). 92.6 parts by weight of the hydrogen form of SSZ-13, 2.4 parts by weight of CuO, and 5.0 parts by weight of zirconium acetate, calculated as ZrO2, were mixed in deionized water to form a slurry. The slurry had a D of 6 μm to 9 μm as measured by a Sympatec particle size analyzer. 90The slurry was milled to a particle size of 1.5g / in. The slurry was mixed at room temperature for 20 hours to allow the copper ions to exchange into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a cell density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcination at 550°C. The washcoat loading was 2.75g / in. 3 It was.

[0094] Figure 1A shows the NO x 1A depicts the conversion and FIG. 1B depicts the N2O selectivity for Example 4 after hydrothermal aging, described below.

[0095] Example 5 Preparation of a catalyst article containing Cu / SSZ-13 (SAR=17, CuO%=2.0%) 88.7 parts by weight of the hydrogen form of SSZ-13, 1.8 parts by weight of CuO, 4.8 parts by weight of dispersible boehmite alumina, and 4.8 parts by weight of zirconium acetate, calculated as ZrO, were mixed in deionized water to form a slurry. The slurry had a D of 6-9 μm as measured by a Sympatec particle size analyzer. 90 The slurry was milled to a particle size of 1.0 g / in. The slurry was mixed at room temperature for 20 hours to allow the copper ions to exchange into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a cell density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcination at 550°C. The washcoat loading was 2.9 g / in. 3 It was.

[0096] FIG. 3 shows the NO content of Example 5 after hydrothermal aging, and before, after, and after desulfation, as described below. x Conversion (3A) and N2O selectivity (3B) are shown.

[0097] FIG. 4 compares the hydrocarbon masking effectiveness for Example 5 and Comparative Example 2, as described below.

[0098] Comparative Example 1 Preparation of a catalyst article containing Cu / SSZ-13 (SAR=30, CuO%=2.4 wt%) 95 parts by weight of Cu / SSZ-13 containing 2.4% CuO and 5 parts by weight of zirconium acetate, calculated as ZrO2, were mixed in a 95:5 weight ratio in deionized water to form a slurry. The slurry was then measured with a Sympatec particle size analyzer to have a D of 7-10 μm. 90 The milled slurry was coated onto a flow-through cordierite monolith substrate with a cell density of 600 cpsi and a wall thickness of 3 mils, followed by drying at 130°C and calcination at 450°C. The washcoat loading was 2.5 g / in 3 It was.

[0099] Comparative Example 2 Preparation of a catalyst article containing V2O5. A quantity of TiO2 pre-doped with SbO3 (6%) and V2O5 (4%) was combined with DI-H2O and a polymeric dispersant to achieve a solids content of 53% after mixing. The amount of polymeric dispersant was 3% of the final target washcoat loading of the catalyst. The pH was set to 7-7.5 using ammonium hydroxide solution. A colloidal silica binder was then added such that 5% of the final washcoat loading consisted of silica binder. The particle size D90 ranged from 1 μm to 8 μm using high-shear mixing or milling. The slurry was coated onto a flow-through cordierite monolith substrate with a cell density of 300 cpsi, followed by drying at 110-120 °C and calcination at 450 °C. The washcoat loading was 4.0 g / in 3 is.

[0100] Sulfurization and desulfurization Sulfidation: A gas stream containing 35 ppmv SO, 10% by volume O, 8% by volume CO, 7% by volume H, O, and the balance N was subjected to a 60,000-hour test based on the volume of the SCR catalyst. -1 The gas was passed through the SCR catalyst at a space velocity of 100° C. The inlet temperature of the SCR catalyst was maintained at 300° C. The gas flow was continued for a period of time to provide an S exposure of 10 g / L based on the volume of the SCR to provide a sulfided SCR catalyst.

[0101] Desulfurization: A gas stream containing 1000 ppmv NO, 1050 ppmv NH, 10% by volume O, 7% by volume H2O, 8% by volume CO, and the balance N2 was desulfurized at a space velocity of 60,000 h -1 , and passed through the sulfided SCR catalyst at 450°C for 30 minutes to provide a desulfurized SCR catalyst.

[0102] NOx conversion and N2O selectivity tests A gas flow of 1000 ppmv NO, 1050 ppmv NH, 10% by volume O, 7% by volume H, O, 8% by volume CO, and the balance N was used for 60,000 h. -1 NOx conversion was tested using a flow reactor under pseudo-steady-state conditions at a space velocity of 0.05 MPa. NOx conversion is reported as mole % and is measured as NO and NO2. NOx conversion was calculated according to the following equation:

[0103]

number

[0104] The N2O selectivity was calculated according to the following formula:

[0105]

number

[0106] Testing Protocol for HC Masking For this test, a core with a diameter of 1 inch and a length of 3 inches was installed in the reactor. The feed gas was adjusted to a space velocity of 60 kJ / h based on the core volume. The feed gas stream had constant concentrations of NH3 = 550 ppm, NO = 500 ppm, O2 = 10%, HO = 5%, and the remainder N2. The catalyst inlet temperature was adjusted to 300 °C and maintained at this condition for the majority of the test. The catalyst was allowed to equilibrate for 20 minutes. At this point, 1000 ppm of C1 diesel was added to the gas stream. The diesel was injected as a liquid into the preheated (230 °C) high-pressure gas stream via a mass flow controller. Upon impact with the gas stream, the liquid diesel was atomized and flowed into two evaporation chambers oriented in series with each other. The evaporation chambers were insulated to maintain a temperature near 230 °C. Upon exiting the second evaporation chamber, the diesel fuel was to be fully evaporated and sent to merge with the primary gas feed stream. Using this described procedure, 1000 ppm C1 diesel was injected over the catalyst for 1 hour while maintaining all other conditions and gas composition. An FTIR downstream of the catalyst monitors the NOx concentration.

[0107] FIG. 1A shows the NO of Examples 1, 2, 3, and 4. x Figure 1B shows the conversion and Figure 1B shows the N2O selectivity for Examples 1, 2, 3, and 4. The samples were tested after hydrothermal aging at 550 °C for 200 hours using a gas flow of 10 vol% H2O, 10 vol% O2, and balance N2 at a flow rate of 20 liters / min.

[0108] With increasing Cu / Al ratio from 0.127 (1.75% CuO) to 0.146 (2.0% CuO), 0.164 (2.25% CuO), and 0.183 (2.5% CuO), NO x The conversion rate increased and the N2O selectivity also increased.

[0109] Although the CuO content in Comparative Example 1 is low (2.4%), its NO selectivity is surprisingly higher than that in Examples 1 to 5. Without being bound by theory, it is believed that this difference may be due to the Cu / Al ratio (0.29).

[0110] FIG. 2 shows the NO of Example 2 and Comparative Examples 1 and 2. x Conversion and N2O selectivity are shown. Samples were tested after hydrothermal aging at 550°C for 100 hours using a gas flow of 10% by volume H2O, 10% by volume O2, and balance N2 at a flow rate of 20 liters / min. Example 2 was the same as Comparative Example 1. x conversion, but surprisingly with lower N2O selectivity. In some embodiments, low N2O selectivity is an important feature for SCR catalysts used in a closed coupled position to meet stringent N2O regulatory targets.

[0111] Example 2 No. x Conversion was similar to Comparative Example 2 at low temperatures and surprisingly higher at high temperatures. The N2O selectivity of Example 2 was surprisingly lower than that of Comparative Example 2 at high temperatures. Example 5 contained 4.8% dispersible boehmite alumina, while Example 2 did not. Without being bound by theory, it is believed that the addition of alumina improved the catalyst's resistance to sulfur poisoning.

[0112] FIG. 3 shows the NO concentrations of Examples 2 and 5 before sulfation, after sulfation, and after desulfation. x Conversion and N2O selectivity are shown. Samples were tested after hydrothermal aging at 550°C for 200 hours using a gas flow of 10% by volume H2O, 10% by volume O2, and balance N2 at a flow rate of 20 liters / min. Example 5 produced higher NO2O after sulfation and desulfation than Example 2. x Conversions are shown. Examples 2 and 5 had similar N2O selectivities.

[0113] The hydrocarbon tolerance of Example 5 and Comparative Example 2 is shown in Figure 4. Examples 1-5 had similar NOx conversion in the presence of hydrocarbons compared to the absence of hydrocarbons.

[0114] Without being bound by theory, it is believed that the combination of a small pore zeolite having a silica-to-alumina ratio in the range of 5 to less than 30, a copper amount in the range of 0.1 wt.% CuO to 3 wt.% CuO, based on the total weight of the copper-containing small pore zeolite, and a copper-to-alumina molar ratio in the range of 0.05 to 0.25 results in reduced NO selectivity at tightly bound sites. For example, it is believed that a small pore zeolite having a low copper-to-alumina molar ratio and a low silica-to-alumina ratio may have improved distribution of copper bound to either sites with one framework aluminum atom or sites with two framework aluminum atoms. The catalytic activity of copper bound to one framework aluminum atom is believed to be different from the catalytic activity of copper bound to two framework aluminum atoms. Therefore, it is believed that a small pore zeolite having a low copper-to-alumina molar ratio and a low silica-to-alumina ratio may reduce NO selectivity compared to a small pore zeolite without a low copper-to-alumina molar ratio and a low silica-to-alumina ratio.

[0115] Unless indicated to the contrary or otherwise clear from context, a claim or specification condition containing "or" or "and / or" between at least one member of a group is considered satisfied when one, more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process. The disclosure includes embodiments in which exactly one group member is present in, employed in, or otherwise relevant to a given product or process. The disclosure includes embodiments in which more than one or all of the group members are present in, employed in, or otherwise relevant to a given product or process.

[0116] Furthermore, the present disclosure encompasses all variations, combinations, and permutations in which at least one limitation, element, clause, or descriptive term from at least one of the enumerated claims is introduced into another claim. For example, any claim dependent on another claim can be amended to include at least one limitation found in any other claim dependent on the same independent claim. When elements are presented as lists, such as in Markush group format, each subgroup of elements is also disclosed, and any element can be removed from the group. In general, when the present disclosure or aspects of the present disclosure are referred to as including particular elements and / or features, it should be understood that embodiments of the present disclosure or aspects of the present disclosure consist of or consist essentially of such elements and / or features. For the sake of brevity, these embodiments have not been specifically described in this language herein. When ranges are given, endpoints are included. Furthermore, unless otherwise indicated or otherwise apparent from the context and the understanding of one of ordinary skill in the art, values ​​expressed as ranges can assume any specific value or subrange within the stated range in different embodiments of the present disclosure, unless the context clearly dictates otherwise.

[0117] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the disclosure described herein which equivalents are intended to be encompassed by the following claims.

Claims

1. A combustion engine, a selective catalytic reduction article downstream of the combustion engine, the exhaust gas treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article; the exhaust gas treatment system does not have a catalyzed soot filter in fluid communication between the combustion engine and the selective catalytic reduction article; the selective catalytic reduction article having one or more washcoats comprising a copper-containing small pore zeolite having a silica to alumina molar ratio in the range of from 5 to less than 30; the copper-containing small pore zeolite having an amount of copper ranging from 0.1 wt. % CuO to 3 wt. % CuO, based on the total weight of the copper-containing small pore zeolite; The exhaust gas treatment system wherein the copper-containing small pore zeolite has a copper to alumina molar ratio in the range of 0.05 to 0.

25.

2. 10. The exhaust gas treatment system of claim 1, wherein the exhaust gas treatment system does not have a catalyst article in fluid communication between the combustion engine and the selective catalytic reduction article.

3. 3. The exhaust gas treatment system of claim 1 or 2, wherein the copper-containing small pore zeolite has a framework structure selected from AEI, AFT, AFV, AFX, AVL, CHA, DDR, EAB, EEI, ERI, IFY, IRN, KFI, LEV, LTA, LTN, MER, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations thereof.

4. 4. The exhaust gas treatment system of claim 1, wherein the one or more washcoats further comprise from 1 wt % to 10 wt % alumina, based on the total weight of the one or more washcoats.

5. 4. The exhaust gas treatment system of claim 1, wherein the one or more washcoats comprise less than 1 wt. % alumina, based on the total weight of the one or more washcoats.

6. 6. The exhaust gas treatment system of claim 1, wherein the copper-containing small pore zeolite has a chabazite framework structure.

7. 7. The exhaust gas treatment system of any one of claims 1 to 6, wherein the one or more washcoats comprise less than 0.5 wt. % vanadium, based on the total weight of the one or more washcoats.

8. The exhaust gas treatment system of any one of claims 1 to 7, wherein the selective catalytic reduction article comprises a flow-through substrate.

9. 9. The exhaust gas treatment system of claim 1, further comprising a diesel oxidation catalyst downstream of the selective catalytic reduction article.

10. The exhaust gas treatment system of any one of claims 1 to 9, further comprising a catalyzed soot filter downstream of the selective catalytic reduction article.

11. 11. The exhaust gas treatment system of claim 1, wherein the selective catalytic reduction article comprises less than 1 wt. % of all metals other than copper, aluminum, magnesium, iron, and zirconium in total, based on the total weight of the selective catalytic reduction article.

12. 12. The exhaust gas treatment system of claim 1, wherein the selective catalytic reduction article comprises less than 1 wt. % of all elements other than copper, silicon, aluminum, oxygen, magnesium, iron, hydrogen, and zirconium, based on the total weight of the selective catalytic reduction article.

13. 12. The exhaust gas treatment system of claim 1, wherein the copper-containing small pore zeolite comprises less than 1 wt. % of all metals other than copper, silicon, and aluminum, based on the total weight of the copper-containing small pore zeolite.

14. A method for treating exhaust gases comprising contacting the exhaust gases with the exhaust gas treatment system of any one of claims 1 to 10.

Images