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, 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 washcoatings 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 the exhaust gas with the disclosed exhaust gas treatment system.

Description

[0001] Disclosed herein is an exhaust treatment system comprising a combustion engine and a selective catalytic reduction article located downstream of the combustion engine; wherein the exhaust treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, the exhaust 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. Also disclosed is a method for exhaust treatment comprising contacting the exhaust with the disclosed exhaust treatment system.

[0002] Internal combustion engines, such as, for example, diesel engines, have an exhaust gas stream that contains pollutants, such as, for example, particulate matter, nitrogen oxides, unburned hydrocarbons, and / or carbon monoxide.

[0003] Exhaust treatment systems and catalytic articles are exemplary means for reducing pollution from internal combustion engines. For example, some exhaust treatment systems include a diesel oxidation catalyst upstream of a selective catalytic reduction catalyst. An exemplary diesel oxidation catalyst can be used to reduce pollutants such as, for example, unburned hydrocarbons and / or carbon monoxide. An exemplary selective catalytic reduction catalyst can be used to reduce, for example, nitrogen oxides (NO x ). However, effective reduction of pollutants may be difficult to achieve in practice. For example, there may be trade-offs between the reduction of various pollutants, there may be trade-offs between the reduction of pollutants under different operating conditions of the combustion engine, and / or there may be trade-offs between the performance of various catalytic products within the exhaust 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 have enhanced pollution reduction. In addition, there is a need for catalytic articles, such as selective catalytic reduction articles, that can enhance the performance of downstream catalytic articles within an exhaust gas treatment system. For example, there is a need for catalytic articles that can selectively reduce NO with low N2O output. x Selective catalytic reduction products.

[0005] Disclosed herein is an exhaust treatment system comprising a combustion engine and a selective catalytic reduction article located downstream of the combustion engine; wherein the exhaust treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, the exhaust 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.

[0006] In some embodiments, the exhaust 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 in the range of 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 wt % to 10 wt % alumina, based on the total weight of the one or more washcoats.

[0009] In some embodiments, the one or more washcoats include 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 molar ratio of copper to alumina in the range of 0.05 to 0.25.

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

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

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

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

[0015] In some embodiments, 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.

[0016] In some embodiments, 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.

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

[0018] Also disclosed is a method for exhaust gas treatment, the method comprising contacting the exhaust gas with the disclosed exhaust gas treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A An exemplary embodiment of NO is shown. x Conversion rate.

[0020] Figure 1B The N2O selectivity of exemplary embodiments is shown.

[0021] Figure 2A An exemplary embodiment of NO is shown. x Conversion rate.

[0022] Figure 2B The N2O selectivity of exemplary embodiments is shown.

[0023] Figure 2C The N2O selectivity of exemplary embodiments is shown.

[0024] Figure 3A An exemplary embodiment of NO is shown. x Conversion rate.

[0025] Figure 3B The N2O selectivity of exemplary embodiments is shown.

[0026] Figure 4 An exemplary embodiment of hydrocarbon masking is shown.

[0027] definition :

[0028] As used herein, unless otherwise specified, "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. Therefore, the terms "a" (or "an"), "one or more" and "at least one" are used interchangeably herein.

[0029] As used herein, the term "material" refers to elements, components, and / or substances that make up something or can be made into something.

[0030] As used herein, the term "about" refers to a range of ±5% of the stated quantity. For example, "about 100" refers to a number within the range of 95 to 105, including, for example, 95, 100, and 105. Unless otherwise specified, all numbers are assumed to be modified with "about".

[0031] As used herein, the term "platinum group metals" (abbreviated as "PGM") refers to ruthenium, rhodium, palladium, osmium, iridium, platinum, and combinations thereof.

[0032] As used herein, a "catalyzed soot filter" includes a filter for trapping soot particles from exhaust gas and a catalyst composition for oxidizing the trapped soot particles.

[0033] As used herein, "loading" of a material (such as, for example, a washcoat or metal) on a substrate refers to the dry mass of the material coated on the substrate per unit volume of the substrate. For example, 1 g / in 3 The washcoat loading of 1 g / ft3 is 1 g of total dry mass of washcoat per cubic inch of substrate. 3 The platinum group metal loading of means that the total mass of platinum group metals per cubic foot of substrate is 1 gram. The loading of material may be local to a subvolume of the substrate. Such loadings are reported as the total dry mass of material applied to the substrate subvolume per unit volume of the substrate subvolume. For example, a substrate may have a first region of volume X cubic inches, the first region having a total dry washcoat mass of Ag deposited thereon, and a second region of volume Y cubic inches, the first region having a total dry washcoat mass of Bg deposited thereon. In this example, the first region has (A / X) g / in 3 The second zone has a washcoat loading of (B / Y) g / in 3 of carrier coating loading.

[0034] As used herein, the term "diesel oxidation catalyst" refers to a catalyst comprising a platinum group metal that is capable of oxidizing carbon monoxide, NO2, and hydrocarbons when in contact with exhaust gas from a diesel engine.

[0035] As used herein, the term "NO x ” refers to nitrogen oxides and mixtures thereof. Exemplary nitrogen oxides include, but are not limited to, NO, N2O, NO2, and N2O2.

[0036] As used herein, the term "selective catalytic reduction catalyst" refers to a catalyst that is capable of selectively reducing NO to x Catalyst for reduction to N2 and water.

[0037] As used herein, "particle size DX" (where X is a number in the range of 0 to 100) refers to the particle size at which about X% of the particles have a smaller particle size. For example, "particle size D90" refers to the particle size at which about 90% of the particles have a smaller particle size.

[0038] As used herein, the term "washcoat" refers to a coating that is applied to a substrate.

[0039] As used herein, a second entity is "downstream" of a first entity if the two entities are in fluid communication and a fluid (such as exhaust) flows from the first entity to the second entity; one or more additional entities may or may not be in fluid communication between the first and second entities.

[0040] As used herein, a first entity is located "upstream" from a second entity if the second entity is located downstream from the first entity.

[0041] 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. According to this classification, zeolite framework types are assigned three letter codes and are described in Atlas of Zeolite Framework Types, 5th Edition, Elsevier, London, England (2001).

[0042] As used herein, a "small pore zeolite" is a zeolite having an 8-membered ring pore opening and a pore size 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.

[0043] As used herein, a region on a substrate may or may not at least partially overlap with another region on the substrate.

[0044] As used herein, a layer on a substrate may or may not at least partially overlap with another layer on the substrate.

[0045] Exhaust gas treatment system :

[0046] Without being bound by theory, it is believed that hot exhaust gases from the engine heat the downstream catalytic components. As the downstream components heat up, it is believed that they are exposed to different gas temperatures, different gas compositions, and the catalytic components heat up 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 of 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 catalytic soot filter may not be suitable for exhaust gas treatment when in a close-coupled position immediately downstream of the engine.

[0047] For example, the exhaust catalyst system may be heated by the hot exhaust gases from the engine, so the upstream catalyst may be heated faster than the downstream catalyst. In some heavy-duty diesel exhaust systems, a selective catalytic reduction (SCR) catalyst is placed downstream of the DOC (diesel oxidation catalyst) and CSF (catalyzed 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 and may result in a significant proportion of NOx during cold start x Without wishing to be bound by theory, it is believed that when the SCR catalyst is positioned directly at the exhaust of the engine (i.e., a close-coupled position), the SCR catalyst can be quickly heated to its operating temperature. In this position, it is believed that the SCR catalyst can be heated more quickly and NO x The transformation can start earlier.

[0048] However, it is believed that a close-coupled SCR (cc-SCR) catalyst may be exposed to an environment that is different from that of a downstream location. For example, hydrocarbons from the engine exhaust will flow directly through the cc-SCR and may cause hydrocarbon poisoning. Similarly, SO2 that may be present in the engine exhaust can cause severe deactivation of the SCR catalyst. In some exhaust treatment systems, a sulfur-poisoned SCR catalyst may be regenerated at high temperatures (such as 550°C), which may be accomplished during regeneration of the soot filter when the SCR catalyst is placed downstream of the CSF. However, achieving such high temperatures in a close-coupled position may be challenging. Therefore, it may be beneficial for the cc-SCR to have a lower desulfurization temperature (such as 450°C. In addition, it may be beneficial for the SCR catalyst to have a low selectivity for undesirable greenhouse gases (such as N2O) to meet stringent emissions regulations such as Euro 7.

[0049] Some SCR catalysts can be used in heavy-duty diesel exhaust systems, such as Cu small holes or V2O5 / TiO2. Although some V2O5-based SCRs may have low N2O selectivity and sulfur poisoning resistance, their NO xThe reducing activity can be reduced by hydrocarbon masking. In addition, the volatility of V2O5 may limit its application.

[0050] Disclosed herein is an exhaust treatment system comprising a combustion engine and a selective catalytic reduction article located downstream of the combustion engine; wherein the exhaust treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, the exhaust 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.

[0051] In some embodiments, the exhaust treatment system does not have a catalytic article in fluid communication between the combustion engine and the selective catalytic reduction article.

[0052] In some embodiments, the exhaust treatment system further includes a diesel oxidation catalyst located downstream of the selective catalytic reduction article.

[0053] In some embodiments, the exhaust treatment system further includes a catalyzed soot filter positioned downstream of the selective catalytic reduction article.

[0054] Catalytic products :

[0055] A selective catalytic reduction article comprising a copper-containing small pore zeolite having a silica to alumina molar ratio in the range of 5 to less than 30 is disclosed.

[0056] 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.

[0057] In some embodiments, the copper-containing small pore zeolite has 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. Based on the total weight of the copper-containing small pore zeolite, the copper-containing small pore zeolite has a copper amount in the range of 0.1 wt % CuO to 3 wt % CuO. In some embodiments, based on the total weight of the copper-containing small pore zeolite, the copper-containing small pore zeolite has a copper amount in the range of 1.5 wt % CuO to 3 wt % CuO.

[0058] In some embodiments, the copper-containing small pore zeolite has a silica to alumina molar ratio in the range of 10 to 20 and has a copper amount 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 has a copper amount 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.

[0059] In some embodiments, the one or more washcoats further comprise 1 wt % to 10 wt % alumina, based on the total weight of the one or more washcoats.

[0060] In some embodiments, the one or more washcoats include less than 1 wt % alumina, based on the total weight of the one or more washcoats.

[0061] In some embodiments, the copper-containing small pore zeolite has a molar ratio of copper to alumina in the range of 0.05 to 0.25.

[0062] In some embodiments, the one or more washcoats contain less than 0.5 wt. % vanadium, based on the total weight of the one or more washcoats.

[0063] In some embodiments, a selective catalytic reduction article includes a flow-through substrate.

[0064] In some embodiments, the selective catalytic reduction article comprises catalytic particles having a D90 particle size in the range of 3 μm to 11 μm as measured with a Sympatec particle size analyzer.

[0065] In some embodiments, 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. 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 in total, based on the total weight of the selective catalytic reduction article.

[0066] In some embodiments, 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. In some embodiments, the selective catalytic reduction article comprises less than 0.1 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.

[0067] 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.

[0068] In some embodiments, a catalytic article comprises: a substrate having a length and including an inlet end and an outlet end, 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 molar ratio of silica to alumina in a range of 5 to less than 30.

[0069] In some embodiments, the washcoat has a 3 Up to 5g / in 3 In some embodiments, the carrier coating has a loading in the range of 0.5 g / in 3 Up to 5g / in 3 load within the range.

[0070] Base :

[0071] In some embodiments, one or more washcoats are disposed on one or more substrates to form, for example, a catalytic article. In some embodiments, the one or more substrates are three-dimensional and have 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.

[0072] In some embodiments, the one or more substrates are ceramic substrates. In some embodiments, the ceramic substrates are made of any suitable refractory material, for example, cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesium, zirconium silicate, sillimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicate, etc.

[0073] In some embodiments, these substrates include one or more metals or metal alloys. In some embodiments, the metal substrate may include any metal substrate, such as those with openings or "punching holes" in the channel wall. In some embodiments, these metal substrates can be used in various shapes, such as pellets, compressed metal fibers, corrugated sheets or integral foams. In some embodiments, the metal substrate includes a heat-resistant alkali metal alloy, particularly those metal substrates in which iron is a basic or main component. Such alloys may contain one or more of nickel, chromium and aluminum, and the total amount of these metals may account for at least about 15 weight % (weight percentage) of the alloy based on the weight of the substrate in each case, for example, about 10 weight % to about 25 weight % of chromium, about 1 weight % to about 8 weight % of aluminum and about 0 weight % to about 20 weight % of nickel. In some embodiments, the metal substrate includes those metal substrates with straight channels; those metal substrates with protruding blades along the axial channel to interrupt the gas flow and open the gas flow between the channels; and those metal substrates with blades and holes to enhance the gas transmission between the channels so as to allow radial gas transmission throughout the entire body.

[0074] In some embodiments, any suitable substrate may be used, such as a monolithic substrate of the type having thin, parallel gas flow channels extending therethrough from an inlet face of the substrate to an outlet face, such that the channels are open to fluid flow therethrough (a "flow-through substrate"). In some embodiments, the substrate has a plurality of thin, substantially parallel gas flow channels extending along the longitudinal axis of the substrate, wherein, for example, each channel is blocked at one end of the substrate body, while alternating channels are blocked at the opposite end face (a "wall flow filter").

[0075] In some embodiments, the substrate comprises a honeycomb substrate or a flow-through substrate in the form of a wall-flow filter. In some embodiments, the substrate is a wall-flow filter. In some embodiments, the substrate is a flow-through substrate.

[0076] 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 thin, parallel gas flow channels extending from the inlet end of the substrate to the outlet end, so that the channels are open to fluid flow. In some embodiments, the channel as a path from the inlet to the outlet has a wall, and the coating is disposed on or in the wall so that the gas flowing through the channel contacts the coated material. In some embodiments, the flow channel of the flow-through substrate is a thin-walled channel, which may have any suitable cross-sectional shape and size, such as a trapezoid, rectangle, square, sinusoidal, hexagonal, elliptical, circular, etc. As described above, the flow-through substrate may be ceramic or metallic.

[0077] Exemplary flow-through substrate volumes are not particularly limited. In some embodiments, the flow-through substrate has a volume of about 50 in. 3 About 1200in 3 of volume, a pore density (entrance opening) of about 60 pores per square inch (cpsi) to about 500 cpsi or up to about 900 cpsi (e.g., about 200 cpsi to about 400 cpsi), and a wall thickness of about 50 microns to about 200 microns or about 400 microns.

[0078] In some embodiments, the substrate is a wall-flow filter having a plurality of fine channels extending along the longitudinal axis of the substrate. In some embodiments, each channel is blocked at one end of the substrate body, and the alternating channels are blocked at the opposite end faces. In some embodiments, the monolithic wall-flow filter substrate may contain up to about 900 or more flow channels (or "holes") per square inch of cross section, although fewer flow channels may be used. For example, the substrate may have about 7 holes per square inch to 600 holes per square inch, such as about 100 holes per square inch to 400 holes per square inch ("cpsi"). In some embodiments, the hole has a cross section of a rectangular, square, circular, oval, triangular, hexagonal or other polygonal shape. In some embodiments, the wall-flow filter substrate is ceramic or metallic as described above.

[0079] Exemplary wall-flow filter article substrate volumes are not particularly limited. In some embodiments, the wall-flow filter article substrate has, for example, about 50 cm 3 , about 100 inches 3 、About 200in 3 、About 300in 3 、About 400in 3 、About 500in 3 、About 600in 3 、About 700in 3 、About 800in 3 、About 900in 3 or about 1000in 3 To about 1500in 3 、About 2000in 3 、About 2500in 3 、About 3000in 3 、About 3500in 3 、About 4000in 3 、About 4500in 3 or about 5000in 3In some embodiments, the wall flow filter substrate has a wall thickness of about 50 microns to about 500 microns, such as about 50 microns to about 450 microns or about 150 microns to about 400 microns.

[0080] In some embodiments, the wall of the wall flow filter has a standard porosity or a high porosity. In some embodiments, the wall of the 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 microns before the functional coating is provided. For example, in some embodiments, the wall flow filter product substrate has a porosity of ≥40%, ≥50%, ≥60%, ≥65% or ≥70%. In some embodiments, before the catalytic coating is provided, the wall flow filter product 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 microns or about 20 microns to about 30 microns or about 40 microns. The terms "wall porosity" and "substrate porosity" mean the same thing and are used interchangeably in this article. Porosity is the ratio of the void volume (or pore volume) divided by the total volume of the substrate material. Pore size and pore size distribution can be determined by, for example, Hg porosimetry measurement.

[0081] Carrier coating :

[0082] In some embodiments, the slurry is coated on the substrate using washcoat techniques known in the art. Washcoats are described, for example, in Heck, Ronald and Farrauto, Robert, Catalytic Air Pollution Control, New York: Wiley-Interscience, 2002, pp. 18-19, as a layer of a material of different composition disposed on the surface of a monolithic substrate or a washcoat layer below. In some embodiments, the substrate contains one or more washcoat layers, and each washcoat layer may have a different composition.

[0083] In some embodiments, the substrate is dipped into the slurry one or more times or otherwise coated with the slurry, e.g., sprayed. In some embodiments, the coated substrate is dried at elevated temperature (e.g., 100° C. to 150° C.) in static air or under an air stream or air jet for about 2 minutes to about 3 hours, and then calcined by heating (e.g., 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 is substantially free of solvent.

[0084] In some embodiments, after calcination, the washcoat loading can be determined by calculating the difference in the coated and uncoated weights of the substrate. It will be apparent to one skilled in the art that the washcoat loading can be varied by changing the slurry rheology, solids content, or number of coating runs. In some embodiments, the coating / drying / calcining process is repeated as needed to build the coating to the desired loading level or thickness.

[0085] In some embodiments, the composition is applied as a single layer or multiple layers. In some embodiments, the layer resulting from repeated wash coating of the same material to establish loading levels is a single layer. In some embodiments, the composition can be zone coated, meaning that a single substrate can be coated with different catalyst compositions in different zones along the axial gas effluent flow path.

[0086] In some embodiments, the composition is mixed with water to form a slurry for coating the substrate. In some embodiments, the slurry also includes an inorganic binder, an associative thickener, or a surfactant (e.g., one or more anionic, cationic, nonionic, or amphoteric surfactants). The order of addition can be varied; in some embodiments, all components are simply combined together to form a slurry, and in some embodiments, certain components are combined and then the remaining components are combined with them. In some embodiments, the pH of the slurry can be adjusted to, for example, an acidic pH of about 3 to about 5.

[0087] In some embodiments, the slurry is ground. In some embodiments, the grinding is done in a ball mill, a continuous mill or other similar equipment, and the solid content of the slurry can be, for example, about 20% to about 60% by weight, about 30% to about 40% by weight. In some embodiments, the slurry after grinding is characterized by a D90 particle size of about 10 microns to about 50 microns (e.g., about 10 microns to about 20 microns).

[0088] In some embodiments, the first washcoat and the second washcoat are in a layered relationship. In some embodiments, the first washcoat and the second washcoat are in a layered relationship, and the first washcoat is layered on top of the second washcoat, which is layered directly on the substrate. In some embodiments, the first washcoat and the second washcoat are in a layered relationship, and the second washcoat is layered on top of the first washcoat, which is layered directly on the substrate.

[0089] In some embodiments, the first washcoat and the second washcoat are in a zoned relationship. In some embodiments, the first washcoat is in the upstream zone and the second washcoat is in the downstream zone. In some embodiments, the first washcoat is applied on x% of the axial length of the substrate; wherein x is in the range of greater than 0% to less than 100% from the inlet face of the coated structure. In some embodiments, the second washcoat is applied on y% of the axial length of the substrate; wherein y is in the range of greater than 0% to 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%.

[0090] In some embodiments, the first and second washcoats are in a zoned and layered relationship, wherein a portion of the first washcoat overlaps a portion of the second washcoat. In some embodiments, the first washcoat is applied directly or indirectly over x% of the axial length of the substrate; wherein x is in the range of greater than 0% to less than 100% from the inlet face of the coated structure. In some embodiments, the second washcoat is applied directly or indirectly over y% of the axial length of the substrate; wherein y is in the range of greater than 0% to 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 overlaps a portion of the second washcoat 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.

[0091] In some embodiments, a second washcoat is at least partially layered on top of the first washcoat, and the second washcoat comprises Pt, Mn, Zr, and optionally Pd.

[0092] Catalytic soot filters :

[0093] Catalyzed soot filters provide an exemplary means for trapping and oxidizing soot particles entrained in an engine exhaust gas stream. A non-limiting exemplary catalyzed soot filter comprises a catalyst composition comprising a platinum group metal, wherein the catalyst composition is deposited on a wall-flow substrate filter. A non-limiting exemplary catalyzed soot filter is disclosed in International Application No. PCT / US2004 / 024864, filed on July 30, 2004; International Application No. PCT / US2006 / 043574, filed on November 8, 2006; International Application No. PCT / US2007 / 086095, filed on November 30, 2007; International Application No. PCT / US2016 / 024889, filed on March 30, 2016; and International Application No. PCT / US2011 / 061681, filed on November 21, 2011; the disclosure of each of these documents is incorporated herein by reference in its entirety.

[0094] Diesel Oxidation Catalyst

[0095] Diesel oxidation catalysts provide an exemplary means for oxidizing carbon monoxide and hydrocarbons when in contact with exhaust gas from a diesel engine. Non-limiting exemplary diesel oxidation catalysts are disclosed in International Application No. PCT / US2010 / 021105 filed on January 15, 2010; International Application No. PCT / US2010 / 030226 filed on April 7, 2010; International Application No. PCT / EP2013 / 073495 filed on November 11, 2013; International Application No. PCT / US2012 / 067208 filed on November 30, 2012; U.S. Pat. No. 7,875,597; No. 73; International Application No. PCT / US2021 / 071898 filed on October 15, 2021; International Application No. PCT / IB2019 / 054454 filed on May 29, 2019; International Application No. PCT / IB2017 / 053514 filed on June 13, 2017; and International Application No. PCT / US2014 / 070356 filed on December 15, 2014; the disclosure of each of these documents is incorporated herein by reference in its entirety.

[0096] Methods of treating waste gas :

[0097] Disclosed are methods for exhaust gas treatment, the methods comprising contacting the exhaust gas with an exhaust gas treatment system disclosed herein.

[0098] Non-limiting exemplary embodiments :

[0099] Without limitation, some embodiments of the present disclosure include:

[0100] 1. An exhaust treatment system, the exhaust treatment system comprising: a combustion engine, and a selective catalytic reduction article located downstream of the combustion engine; wherein: the exhaust treatment system does not have a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, the exhaust 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 has one or more washcoats comprising a copper-containing small pore zeolite, the copper-containing small pore zeolite having a silica to alumina molar ratio in the range of 5 to less than 30, the copper-containing small pore zeolite having 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 the copper-containing small pore zeolite having a copper to alumina molar ratio in the range of 0.05 to 0.25.

[0101] 2. The exhaust treatment system of embodiment 1, wherein the exhaust treatment system does not have a catalytic article in fluid communication between the combustion engine and the selective catalytic reduction article.

[0102] 3. An exhaust gas treatment system according to 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.

[0103] 4. The exhaust gas treatment system of any one of embodiments 1 to 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.

[0104] 5. The exhaust treatment system of any one of embodiments 1 to 3, wherein the one or more washcoats comprise less than 1 wt% alumina, based on the total weight of the one or more washcoats.

[0105] 6. The exhaust gas treatment system according to any one of embodiments 1 to 5, wherein the copper-containing small-pore zeolite has a chabazite framework structure.

[0106] 7. The exhaust treatment system of any one of embodiments 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.

[0107] 8. The exhaust treatment system of any one of embodiments 1 to 7, wherein the selective catalytic reduction article comprises a flow-through substrate.

[0108] 9. The exhaust treatment system of any one of embodiments 1 to 8, further comprising a diesel oxidation catalyst located downstream of the selective catalytic reduction article.

[0109] 10. The exhaust treatment system of any one of embodiments 1 to 9, further comprising a catalyzed soot filter located downstream of the selective catalytic reduction article.

[0110] 11. The exhaust treatment system of any one of embodiments 1 to 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.

[0111] 12. The exhaust treatment system of any one of embodiments 1 to 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.

[0112] 13. The exhaust gas treatment system according to any one of embodiments 1 to 11, wherein the copper-containing small pore zeolite comprises less than 1 wt% in total of all metals other than copper, silicon, and aluminum, based on the total weight of the copper-containing small pore zeolite.

[0113] 14. A method for exhaust gas treatment, the method comprising: contacting the exhaust gas with the exhaust gas treatment system according to any one of embodiments 1 to 10. Example

[0114] The following examples are intended to be illustrative, and are not meant to limit the scope of the present disclosure in any way.

[0115] Example 1 A catalytic preparation comprising Cu / SSZ-13 (SAR=17, CuO%=1.75%) was prepared.

[0116] 93.3 parts by weight of SSZ-13 in hydrocarbon form, 1.7 parts by weight of CuO and 5.0 parts by weight of zirconium acetate calculated as ZrO2 were mixed into deionized water to form a slurry. The slurry was ground to a D of between 6 μm and 9 μm. 90 The particle size was measured with a Sympatec particle size analyzer. The slurry was mixed at room temperature for 20 hours to exchange the copper ions into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a pore density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcining at 550°C. The washcoat loading was 2.75 g / in 3 .

[0117] Figure 1A The NO of Example 1 after hydrothermal aging as described below is shown. x conversion rate, and Figure 1B Its N2O selectivity is shown.

[0118] Example 2 A catalytic preparation comprising Cu / SSZ-13 (SAR=17, CuO%=2.0%) was prepared.

[0119] 93.1 parts by weight of SSZ-13 in hydrocarbon form, 1.9 parts by weight of CuO and 5.0 parts by weight of zirconium acetate calculated as ZrO2 were mixed into deionized water to form a slurry. The slurry was ground to a D of between 6 μm and 9 μm. 90 The particle size was measured with a Sympatec particle size analyzer. The slurry was mixed at room temperature for 20 hours to exchange the copper ions into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a pore density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcining at 550°C. The washcoat loading was 2.75 g / in 3 .

[0120] Figure 1A The NO of Example 2 after hydrothermal aging as described below is shown. x conversion rate, and Figure 1B Its N2O selectivity is shown.

[0121] Figure 2A and Figure 2B No x The conversion and N2O selectivity were compared with Comparative Examples 1 and 2 as described below.

[0122] FIG. 3 shows the NO of Example 2 after hydrothermal aging and before sulfation, after sulfation, and after desulfurization as described below. x Conversion (3A) and N2O selectivity (3B).

[0123] Example 3 A catalytic preparation comprising Cu / SSZ-13 (SAR=17, CuO%=2.25%) was prepared.

[0124] 92.9 parts by weight of SSZ-13 in hydrocarbon form, 2.1 parts by weight of CuO and 5.0 parts by weight of zirconium acetate calculated as ZrO2 were mixed into deionized water to form a slurry. The slurry was ground to a D of between 6 μm and 9 μm. 90The particle size was measured with a Sympatec particle size analyzer. The slurry was mixed at room temperature for 20 hours to exchange the copper ions into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a pore density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcining at 550°C. The washcoat loading was 2.75 g / in 3 .

[0125] Figure 1A The NO of Example 3 after hydrothermal aging as described below is shown. x conversion rate, and Figure 1B Its N2O selectivity is shown.

[0126] Example 4 A catalytic preparation comprising Cu / SSZ-13 (SAR=17, CuO%=2.5%) was prepared.

[0127] 92.6 parts by weight of SSZ-13 in hydrocarbon form, 2.4 parts by weight of CuO and 5.0 parts by weight of zirconium acetate calculated as ZrO2 were mixed into deionized water to form a slurry. The slurry was ground to a D of between 6 μm and 9 μm. 90 The particle size was measured with a Sympatec particle size analyzer. The slurry was mixed at room temperature for 20 hours to exchange the copper ions into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a pore density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcining at 550°C. The washcoat loading was 2.75 g / in 3 .

[0128] Figure 1A The NO of Example 4 after hydrothermal aging as described below is shown. x conversion rate, and Figure 1B Its N2O selectivity is shown.

[0129] Example 5 Preparation of a catalytic product containing Cu / SSZ-13 (SAR=17, CuO%=2.0%)

[0130] 88.7 parts by weight of SSZ-13 in hydrocarbon form, 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 ZrO2 were mixed into deionized water to form a slurry. The slurry was ground to a D of between 6 μm and 9 μm. 90The particle size was measured with a Sympatec particle size analyzer. The slurry was mixed at room temperature for 20 hours to exchange the copper ions into the zeolite framework. The final slurry was coated onto a flow-through cordierite monolith substrate with a pore density of 400 cpsi and a wall thickness of 4 mils, followed by drying at 130°C and calcining at 550°C. The washcoat loading was 2.9 g / in 3 .

[0131] FIG. 3 shows the NO of Example 5 after hydrothermal aging and before sulfation, after sulfation, and after desulfurization as described below. x Conversion (3A) and N2O selectivity (3B).

[0132] Figure 4 The hydrocarbon masking effects of Example 5 and Comparative Example 2 were compared, as discussed below.

[0133] Comparative Example 1 Preparation of a catalytic product comprising Cu / SSZ-13 (SAR=30, CuO%=2.4 wt%)

[0134] 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 into deionized water in a weight ratio of 95:5 to form a slurry. The slurry was then ground to a D of between 7 μm and 10 μm. 90 Particle size, as measured with a Sympatec particle size analyzer. The milled slurry was coated onto a flow-through cordierite monolith substrate having a pore density of 600 cpsi and a wall thickness of 3 mils, followed by drying at 130°C and calcining at 450°C. The washcoat loading was 2.5 g / in 3 .

[0135] Comparative Example 2 Preparation of catalytic articles comprising V2O5.

[0136] An amount of TiO2 that had been pre-doped with SbO3 (6%) and V2O5 (4%) was combined with DI-H2O and a polymer-based dispersant so that the solid content after mixing was 53%; the amount of polymer dispersant was 3% of the final target carrier coating loading of the catalyst. The pH was set to 7 to 7.5 using ammonium hydroxide solution. A colloidal silica binder was then added so that 5% of the final carrier coating loading consisted of silica binder. Under high shear mixing or grinding, the particle size D90 was in the range of 1 μm to 8 μm. The slurry was coated onto a flow-through cordierite monolithic substrate with a pore density of 300 cpsi, then dried at 110°C to 120°C and calcined at 450°C. The carrier coating loading was 4.0 g / in 3 .

[0137] Sulfurization and desulfurization

[0138] Sulfidation: A gas stream containing 35 ppmv SO2, 10 vol% O2, 8 vol% CO2, 7 vol% H2O and the balance N2 based on the volume of the SCR catalyst was heated at 60,000 hr. -1 The gas flow was continued for a period of time to produce an S exposure of 10 g / L based on the volume of the SCR to provide a sulfided SCR catalyst.

[0139] Desulfurization: A gas stream containing 1000 ppmv NO, 1050 ppmv NH3, 10 vol% O2, 7 vol% H2O, 8 vol% CO2 and the balance N2 was heated to 60,000 h. -1 The sulfurized SCR catalyst was passed at a space velocity of 450° C. for 30 minutes to provide a desulfurized SCR catalyst.

[0140] Testing of NOx conversion and N2O selectivity

[0141] The NOx conversion was tested under pseudo-steady-state conditions using a flow reactor with a gas flow of 1000 ppmv NO, 1050 ppmv NH3, 10 vol% O2, 7 vol% H2O, 8 vol% CO2 and the balance N2 at a space velocity of 60,000 h -1 NOx conversion is reported in mol% and is measured as NO and NO2. NOx conversion is calculated according to the following formula:

[0142]

[0143] The N2O selectivity was calculated according to the following formula:

[0144]

[0145] Test procedures for HC masking

[0146] For this test, a 1" diameter and 3" long core was installed into the reactor. The feed gas was adjusted so that the space velocity based on the core volume was 60 k / h. The feed gas stream had constant concentrations of NH3=550 ppm, NO=500 ppm, O2=10%, H2O=5%, and N2 as the remaining component. The temperature of the inlet of the catalyst was adjusted to 300°C and maintained at this condition for most 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 metered as a liquid into the preheated (230°C) high-pressure gas stream by a mass flow controller. Upon impacting 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 approximately close to 230°C. Upon leaving the second evaporation chamber, the diesel fuel should be completely evaporated and directed to combine with the primary gas feed stream. Using the described procedure, 1000 ppm C1 diesel was injected into the catalyst for 1 hour while maintaining all other conditions and gas composition. An FTIR located downstream of the catalyst monitors the NOx concentration.

[0147] Figure 1A The NO of Example 1, Example 2, Example 3 and Example 4 are shown. x conversion rate, and Figure 1B Its N2O selectivity is shown. The sample was tested after hydrothermal aging at 550°C for 200 hours under a gas flow of 10 vol% H2O, 10 vol% O2 and the balance N2 at a flow rate of 20 liters per minute.

[0148] As the Cu / Al ratio increases 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 increases and the N2O selectivity also increases.

[0149] Comparative Example 1, despite its low CuO content (2.4%), surprisingly has higher N2O selectivity than 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).

[0150] FIG. 2 shows the NO of Example 2 and Comparative Examples 1 and 2. x Conversion and N2O selectivity. The samples were tested after hydrothermal aging at 550°C for 100 hours at a flow rate of 20 liters per minute under a gas flow of 10 vol% H2O, 10 vol% O2 and the balance N2. Example 2 showed similar NO conversion as Comparative Example 1. xconversion, but surprisingly with lower N2O selectivity. In some embodiments, low N2O selectivity is an important feature of SCR catalysts used in close-coupled locations in order to meet stringent N2O regulation targets.

[0151] Example 2 NO x The conversion is similar to Comparative Example 2 at low temperatures and surprisingly higher at high temperatures. At high temperatures, the N2O selectivity of Example 2 is surprisingly lower than that of Comparative Example 2. Example 5 contains 4.8% dispersed boehmite alumina, while Example 2 does not. Without being bound by theory, it is believed that the addition of alumina improves the catalyst's tolerance to sulfur poisoning.

[0152] FIG. 3 shows the NO2 content of Example 2 and Example 5 before sulfation, after sulfation and after desulfurization. x Conversion and N2O selectivity. The samples were tested after hydrothermal aging at 550°C for 200 hours under a gas flow of 10 vol% H2O, 10 vol% O2 and the balance N2 at a flow rate of 20 liters per minute. Example 5 shows higher NO conversion than Example 2 after sulfation and after desulfurization. x Conversion rate: Example 2 and Example 5 have similar N2O selectivity.

[0153] The hydrocarbon resistance of Example 5 and Comparative Example 2 is shown in Figure 4 Examples 1 to 5 have similar NOx conversion rates in the presence of hydrocarbons as compared to the absence of hydrocarbons.

[0154] 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 provides a reduced NO selectivity at a close-coupled position. 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 can improve the distribution of bound copper to sites having one framework aluminum atom or sites having two framework aluminum atoms. It is believed that the catalytic activity of copper bound to one framework aluminum atom is 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 can reduce NO selectivity relative to a small pore zeolite that does not have a low copper to alumina molar ratio and a low silica to alumina ratio.

[0155] Claims or specific embodiments that include "or" or "and / or" between at least one member of the group are considered satisfied if one, more than one, or all of the group members are present in, used in, or otherwise related to a given product or method, unless indicated to the contrary or otherwise obvious from the context. The present disclosure includes embodiments in which exactly one member of the group is present in, used in, or otherwise related to a given product or method. The present disclosure includes embodiments in which more than one or all of the group members are present in, used in, or otherwise related to a given product or method.

[0156] In addition, the present disclosure encompasses all variations, combinations and arrangements, wherein at least one limitation, element, clause and descriptive term from at least one of the listed claims is introduced into another claim. For example, any claim subordinate to another claim can be modified to include at least one limitation found in any other claim subordinate to the same basic claim. In the case where an element exists in a list (such as, for example, in Markush (Markush) group format), each subgroup of the element is also disclosed, and any element can be removed from the group. It should be understood that, in general, in the case where the present disclosure or the various aspects of the present disclosure are referred to as including specific elements and / or features, the embodiments of the present disclosure or the various aspects of the present disclosure are made up of or substantially made up of such elements and / or features. For simplicity, these embodiments are not specifically described herein. When a range is given, endpoints are also included. In addition, unless otherwise stated or clearly seen from the context and the understanding of those of ordinary skill in the art, otherwise in different embodiments of the present disclosure, the value expressed as a range can be assumed to be any specific value or sub-range within the range, unless the context clearly indicates otherwise.

[0157] 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. Such equivalents are intended to be encompassed by the following claims.

Claims

1. An exhaust gas treatment system, comprising: Combustion engines, and a selective catalytic reduction article located downstream of said combustion engine; in: the exhaust treatment system being free of a diesel oxidation catalyst in fluid communication between the combustion engine and the selective catalytic reduction article, the exhaust treatment system being free of a catalyzed soot filter in fluid communication between the combustion engine and the selective catalytic reduction article, 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, The copper-containing small pore zeolite has 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 The copper-containing small pore zeolite has a molar ratio of copper to alumina in the range of 0.05 to 0.

25.

2. The exhaust treatment system of claim 1, wherein the exhaust treatment system is free of a catalytic article in fluid communication between the combustion engine and the selective catalytic reduction article.

3. The exhaust gas treatment system of claim 1 or 2, wherein the copper-containing small pore zeolite has a framework structure selected from the group consisting of 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 treatment system of any one of claims 1 to 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 treatment system of any one of claims 1 to 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 according to claim 1 , wherein the copper-containing small-pore zeolite has a chabazite framework structure.

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

9. The exhaust treatment system of any one of claims 1 to 8, further comprising a diesel oxidation catalyst located downstream of the selective catalytic reduction article.

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

11. The exhaust treatment system of any one of claims 1 to 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 treatment system of any one of claims 1 to 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 treatment system of any one of claims 1 to 11, wherein the copper-containing small pore zeolite comprises less than 1 wt% in total 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 waste gas treatment, the method comprising: The exhaust gas is contacted with an exhaust gas treatment system according to any one of claims 1 to 10.

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