Exhaust gas treatment system for ammonia fuel vehicles

Abstract

The present disclosure relates to an emission treatment system for reducing NO in the exhaust stream of an ammonia fuel engine. The emission treatment system includes a selective catalytic reduction (SCR) catalyst disposed on a substrate in fluid communication with the exhaust stream, an oxidation catalyst disposed on a substrate positioned either upstream or downstream of the SCR catalyst and in fluid communication with the exhaust stream and the SCR catalyst, and optionally, one or more adsorption components disposed on a substrate positioned upstream and / or downstream of the SCR catalyst and in fluid communication with the exhaust stream and the SCR catalyst. The adsorption component is selected from a low-temperature NO x adsorber (LT-NA), a low-temperature ammonia adsorber (LT-AA), a low-temperature water vapor adsorber (LT-WA), and combinations thereof. The present disclosure further provides a method related to the treatment of exhaust gases. x The adsorption component is selected from a low-temperature NO x adsorber (LT-NA), a low-temperature ammonia adsorber (LT-AA), a low-temperature water vapor adsorber (LT-WA), and combinations thereof. The present disclosure further provides a method related to the treatment of exhaust gases.

Description

Technical Field

[0001] The present disclosure relates to compositions, components, emission treatment systems, and methods suitable for treating the exhaust gas stream of an ammonia-fueled internal combustion engine to reduce the emission of nitrogen oxides (NO x x).

[0002] Environmental regulations regarding the exhaust gases of internal combustion engines are becoming increasingly stringent worldwide in order to reduce greenhouse gas emissions such as CO2. More and more, vehicle manufacturers are focusing on engines that utilize fuels other than conventional hydrocarbon fuels. In recent years, electric vehicles and hydrogen vehicles have received attention, but the spread of these engine systems has not yet advanced. Both electric and hydrogen engine systems suffer from several drawbacks, including concerns about safety related to storing hydrogen under high pressure, the weight of the battery pack, and the fact that the electricity required for electric engines is often generated using fossil fuels.

[0003] One of the least invasive ways to achieve greenhouse gas reduction is to change the fuel from gasoline / diesel to ammonia, a non-hydrocarbon fuel. Ammonia is a liquid at room temperature, rapidly releases energy upon combustion, and is one of the few compounds that provides a high volumetric energy density.

[0004] Ammonia is composed of only hydrogen and nitrogen atoms. Thus, even when ammonia burns, it does not release carbon dioxide, carbon monoxide, or other greenhouse pollutants. The emissions from burned ammonia are typically nitrogen and water vapor. More specifically, the complete combustion of ammonia can be represented by the following equation: 4NH3 + 3O2 + heat → 2N2 + 6H2O. [ΔH° r = -1267.20 kJ / mol (or, when expressed per mole of NH3, -316.8 kJ / mol)]

[0005] However, some unburned NH3 and some trace amounts of overburn products can occur, for example, through the following reactions: 4NH3 + 5O2 → 4NO + 6H2O

[0006] Ammonia has a lower heating value (energy content) by about 20% than diesel on a volume basis, so more ammonia fuel is required to generate the same output as a diesel fuel vehicle. Therefore, it is highly desirable to provide, for example, an exhaust treatment system that provides effective NOx reduction for an engine fueled with ammonia.

[0007] The present disclosure relates to an exhaust treatment system and method for NO x reduction in the exhaust stream of an ammonia-fueled engine. In some embodiments, such a system can be effective not only in reducing NO x emissions associated with such an engine, but also in adsorbing certain gaseous components of the exhaust stream emitted by such an engine to enhance the effectiveness of the system. In some embodiments, the exhaust treatment system of the present disclosure can combine a selective catalytic reduction (SCR) catalyst with an oxidation catalyst positioned either upstream or downstream of the SCR catalyst. In other embodiments, the exhaust treatment system of the present disclosure can combine a selective catalytic reduction (SCR) catalyst and an oxidation catalyst with one or more adsorption components selected from a low-temperature NO x adsorber (LT-NA), a low-temperature ammonia adsorber (LT-AA), and a low-temperature water vapor adsorber (LT-WA). x Adsorber, LT-NA), a low-temperature ammonia adsorber (LT-AA), and a low-temperature water vapor adsorber (LT-WA).

[0008] The present disclosure includes, but is not limited to, the following embodiments.

[0009] Embodiment 1: An emission treatment system for reducing NOx in the exhaust stream of an ammonia-fueled engine, the emission treatment system comprising: A selective catalytic reduction (SCR) catalyst disposed on a substrate and in fluid communication with the exhaust stream of the ammonia-fueled engine; An oxidation catalyst disposed on a substrate positioned upstream and / or downstream of the SCR catalyst and in fluid communication with the exhaust stream and the SCR catalyst.

[0010] Embodiment 2: The emission treatment system according to Embodiment 1, wherein the oxidation catalyst comprises a refractory metal oxide support impregnated with a platinum group metal (PGM).

[0011] Embodiment 3: The emission treatment system according to Embodiment 2, wherein the PGM comprises platinum, palladium, rhodium, or a combination thereof.

[0012] Embodiment 4: The emission treatment system according to any one of Embodiments 2 to 3, wherein the oxidation catalyst further comprises a refractory metal oxide support impregnated with a non-PGM transition metal, an alkaline earth metal, or a combination thereof.

[0013] Embodiment 5: The emission treatment system according to Embodiment 4, wherein the non-PGM transition metal comprises manganese.

[0014] Embodiment 6: The emission treatment system according to any one of Embodiments 4 to 5, wherein the alkaline earth metal comprises barium.

[0015] Embodiment 7: The emission treatment system according to any one of Embodiments 1 to 6, wherein the oxidation catalyst is selected from a diesel oxidation catalyst (DOC) and a selective ammonia oxidation catalyst (AMOx).

[0016] Embodiment 8: The SCR catalyst is an exhaust gas treatment system according to any one of Embodiments 1 to 7, including a metal-promoted molecular sieve (molecular sieve), a vanadia-based composition, or a combination thereof.

[0017] Embodiment 9: The SCR catalyst is an exhaust gas treatment system according to any one of Embodiments 1 to 8, which is a copper-containing zeolite, an iron-containing zeolite, or a manganese-containing zeolite.

[0018] Embodiment 10: The zeolite has a framework type selected from LEV, CHA, AEI, MEI, FER, * BEA, FAU, or a combination thereof, and is an exhaust gas treatment system according to Embodiment 9.

[0019] Embodiment 11: The SCR catalyst and the oxidation catalyst are present in the form of an SCR / AMOx catalyst, and are an exhaust gas treatment system according to any one of Embodiments 1 to 10.

[0020] Embodiment 12: The exhaust gas treatment system according to any one of Embodiments 1 to 11 further includes one or more adsorption components selected from a low-temperature NO x adsorbent (LT-NA), a low-temperature ammonia adsorbent (LT-AA), a low-temperature water vapor adsorbent (LT-WA), or a combination thereof.

[0021] Embodiment 13: The one or more adsorption components are arranged in any order and combination, and are an exhaust gas treatment system according to Embodiment 12.

[0022] Embodiment 14: Each of the one or more adsorption components is disposed on a substrate, positioned upstream or downstream of the SCR catalyst, and in fluid communication with the exhaust gas stream and the SCR catalyst, and is an exhaust gas treatment system according to any one of Embodiments 12 to 13.

[0023] Embodiment 15: The emission treatment system according to any one of Embodiments 12 to 14, wherein each of the one or more adsorption components is arranged on the same substrate as a mixture, in a zoned configuration, or in a layered configuration.

[0024] Embodiment 16: The emission treatment system according to any one of Embodiments 12 to 15, wherein one or more of the SCR catalyst, the oxidation catalyst, and the one or more adsorption components are arranged on the same substrate as a mixture, in a zoned configuration, or in a layered configuration.

[0025] Embodiment 17: The emission treatment system according to any one of Embodiments 12 to 16, wherein the one or more adsorption components and the DOC are arranged on the same substrate as a mixture, in a zoned configuration, or in a layered configuration.

[0026] Embodiment 18: The emission treatment system according to any one of Embodiments 1 to 17, further comprising one or more additional SCR catalysts, one or more additional oxidation catalysts, or a combination thereof.

[0027] Embodiment 19: Starting from the emission treatment component closest to the engine in order, the following configurations: (a) Adsorption component(s), DOC, SCR catalyst, and AMOx, (b) SCR, adsorption component(s), DOC, and AMOx, (c) Adsorption component(s), SCR catalyst, DOC, SCR catalyst, and AMOx, (d) Adsorption component(s), SCR catalyst, and AMOx, (e) Adsorption component(s), DOC, and SCR catalyst, (f) SCR catalyst, AMOx, and adsorption component(s), (g) SCR catalyst and AMOx, (h) DOC and SCR catalyst, or (i) SCR catalyst, SCR catalyst, and AMOx, and including one of them, the emission treatment system according to Embodiment 18.

[0028] Embodiment 20: The exhaust gas treatment system according to any one of Embodiments 12 to 19, including a molecular sieve or a Metal Organic Framework (MOF) in which the LT-NA is present and at least one platinum group metal component is impregnated.

[0029] Embodiment 21: The exhaust gas treatment system according to any one of Embodiments 12 to 20, including a molecular sieve or a MOF in which the LT-AA is present.

[0030] Embodiment 22: The exhaust gas treatment system according to any one of Embodiments 12 to 21, including a molecular sieve, clay, activated carbon, activated alumina, silica, calcium sulfate, calcium chloride, MOF, or a combination thereof, in which the LT-WA is present.

[0031] Embodiment 23: One or more of the SCR catalyst, the one or more adsorption components, and the oxidation catalyst are disposed on a flow-through type substrate in the form of a honeycomb having a plurality of longitudinally extending gas flow paths extending from an inlet to an outlet, and / or one or more of the SCR catalyst, the one or more adsorption components, and the oxidation catalyst are disposed on a wall-flow type substrate having a flow-through type channel or optionally on a metal substrate, and a part of the exhaust gas is in fluid communication between the channels. The exhaust gas treatment system according to any one of Embodiments 12 to 22.

[0032] Embodiment 24: A method for reducing NOx in an exhaust gas stream from an ammonia fuel engine, the method including contacting the exhaust gas stream with the exhaust gas treatment system according to any one of Embodiments 1 to 23.

[0033] These and other features, aspects, and advantages of the present disclosure will become apparent from the following detailed description read in conjunction with the accompanying drawings, which are briefly described below. The present disclosure includes any combination of two, three, four, or more of the above-described embodiments, as well as any combination of two, three, four, or more features or elements described in the present disclosure, whether or not such features or elements are explicitly combined in the description of the embodiments herein. The present disclosure is intended to be read as a whole such that any separable feature or element is considered combinable in any of its various aspects and embodiments, unless the context otherwise clearly dictates.

Brief Description of the Drawings

[0034] To provide an understanding of the embodiments of the present disclosure, reference is made to the accompanying drawings, which show the components of exemplary embodiments of the present disclosure with reference numerals. The drawings are merely illustrative and are not to be construed as limiting the present disclosure. The disclosure described herein is shown in the accompanying drawings by way of example and not by way of limitation. For simplicity and clarity of explanation, the features shown in the drawings are not necessarily drawn to scale. Further, reference numerals are repeated between the drawings where appropriate to indicate corresponding or similar elements.

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0035] The present disclosure will now be described in more detail. However, the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those skilled in the art.

[0036] Definitions As used herein, the term "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.

[0037] Any range recited herein is inclusive. The term "about" is used throughout to account for and describe minor variations. For example, "about" may mean that a numerical value can be modified by up to ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, ±0.1%, or ±0.05%. A numerical value modified by the term "about" includes the specifically identified value. For example, "about 5.0" includes 5.0.

[0038] The term "abatement" means a reduction in amount caused by some means.

[0039] The term "adsorbent" refers to a material that adsorbs and / or absorbs a desired substance. An adsorbent may advantageously adsorb and / or absorb (store) a substance at one temperature and desorb (release) the substance at a higher temperature.

[0040] As used herein and in the claims, the term "ammonia-fueled engine" is an engine capable of converting ammonia into its final oxidation products, thereby releasing its latent heat energy (i.e., converting chemical energy into mechanical (work) energy). Thus, this engine can operate on any blended fuel such as gasoline and ammonia blended fuel as long as the fuel contains ammonia, or diesel containing ammonia, or a mixture of 10% alcohol (ethanol) and ammonia in gasoline, or a mixture of ammonia and any biofuel.

[0041] The term "associated" means, for example, "equipped with", "connected to" or "in communication with", e.g., "electrically connected" or "in fluid communication with" or connected to perform a function. The term "associated" may mean directly associated or indirectly associated, for example, via one or more other articles or elements.

[0042] The term "catalyst" refers to a material that promotes a chemical reaction. A catalyst includes a "catalytically active specie" and a "support" that supports the active specie. For example, zeolite may be a support for palladium active catalyst species. Similarly, refractory metal oxide particles may be a support for platinum group metal catalyst species. Catalytically active species are also called "promoters" because they promote chemical reactions.

[0043] As used herein, the term "catalytic article" means an article including a substrate having a catalyst coating composition.

[0044] The term "configured" as used in the description and claims is intended to be an open-ended term, similar to the terms "comprising" or "containing". The term "configured" does not mean excluding other possible articles or elements. The term "configured" may be equivalent to "adapted".

[0045] Generally, the term "effective" means, with respect to defined catalytic or storage / release activity, in weight or mole, for example, about 35% to 100% effective, for example, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95% effective.

[0046] The term "exhaust stream" or "exhaust gas stream" refers to any combination of flowing gases that may contain solid or liquid particulate matter. This stream contains gaseous components and may be, for example, the exhaust of a lean burn engine, which may contain certain non-gaseous components such as droplets, solid particles, etc. The exhaust gas stream of a combustion engine may further contain, for example, combustion products (CO2 and H2O), products of incomplete combustion (carbon monoxide (CO) and hydrocarbons), nitrogen oxides (NO x )), combustible and / or carbonaceous particulate matter (soot), and unreacted oxygen and nitrogen. In an ammonia fuel engine, the exhaust stream may, in certain embodiments, consist of nitrogen, water vapor, and a small amount of NOx. However, in a dual fuel system, although in smaller amounts compared to a conventional engine, some of the other materials described above may be present.

[0047] As used herein, the terms "upstream" and "downstream" refer to the relative direction due to the flow of engine exhaust gas from the engine towards the exhaust pipe, with the engine in the upstream position and the exhaust pipe and any pollution reduction articles such as filters and catalysts downstream of the engine. The inlet end of the substrate is synonymous with the "upstream" end or "front" end. The outlet end is synonymous with the "downstream" end or "rear" end. The upstream zone is upstream of the downstream zone. The upstream zone may be closer to the engine or manifold, and the downstream zone may be further away from the engine or manifold.

[0048] The term "in fluid communication" is used to refer to articles disposed on the same exhaust line, i.e., a common exhaust flow passes through articles that are in fluid communication with each other. Articles in fluid communication may be adjacent to each other within the exhaust line. Alternatively, articles in fluid communication may be separated by one or more articles, also referred to as "washcoated monoliths".

[0049] As used herein, "impregnated" or "impregnation" refers to the penetration of a catalyst material into the porous structure of a carrier material.

[0050] The terms "on", "over", and "overlapping" with respect to a coating layer may be used synonymously. The term "directly on" means in direct contact. The disclosed articles are referred to in certain embodiments as including one coating layer "on" a second coating layer, and such terms are intended to encompass embodiments having intervening layers where direct contact between the coating layers is not required, i.e., "on" is not equivalent to "directly on".

[0051] As used herein, the terms "nitrogen oxide" and "NO" x refer to nitrogen oxides such as NO, NO2, or N2O.

[0052] "Substantially free" means "little or no" or "no intentionally added", and allows for only trace amounts and / or inadvertent amounts. For example, in certain embodiments, "substantially free" means less than 2 weight percent (wt%), less than 1.5 wt%, less than 1.0 wt%, less than 0.5 wt%, less than 0.25 wt%, or less than 0.01 wt% based on the weight of the total composition shown.

[0053] As used herein, the term "washcoat" has its ordinary meaning in the art of a thin adhesive coating of a catalyst material or other material applied to a substrate material such as a honeycomb-shaped substrate that is porous enough to allow passage of the gas stream being treated. As used herein and as described in Heck, Ronald and Farrauto, Robert, Catalytic Air Pollution Control, New York: Wiley-Interscience, 2002, pp. 18-19, the washcoat layer includes layers of compositionally different materials disposed on the surface of a monolithic substrate or a washcoat layer thereunder. The substrate may contain one or more washcoat layers, and each washcoat layer may differ in some respect (e.g., may have different physical properties such as particle size or microcrystalline phase), and / or may have different chemical catalytic functions. The washcoat is formed, for example, by preparing a slurry containing a catalyst in a liquid at a predetermined solids content (e.g., 30-90 wt%), coating this on the substrate, and drying to provide the washcoat layer.

[0054] "Weight percent (wt%)" is based on the entire composition without any volatile substances, i.e., based on the dry solids, unless otherwise indicated. Unless otherwise indicated, all parts and percentages are by weight.

[0055] All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly precluded by the context. The use of any and all examples or exemplary terms (e.g., "such as") provided herein is merely intended to more deeply explain the materials and methods and does not impose a limitation on the scope unless otherwise claimed. No term in this specification should be construed as indicating any non-claimed element essential to the practice of the disclosed materials and methods. All U.S. patent applications, published pre-grant publications, and patents referenced herein are hereby incorporated by reference in their entirety.

[0056] Emission treatment system In a first aspect, the emissions treatment system may be adapted for use with an ammonia fuel internal combustion engine that includes a dual fuel system. Engine systems that combust ammonia are well known in the art and are shown, for example, in U.S. Pat. Nos. 8,464,515, 8,904,994, and 9,341,111, and U.S. Patent Application Publication Nos. 2011 / 0265463, 2011 / 0283684, and 2018 / 0100469, all of which are hereby incorporated by reference herein. Such an engine is similar to other types of combustion engines and may include an engine block, a cylinder block, one or more cylinder heads, one or more pistons, one or more combustion chambers, one or more spark plugs (e.g., plasma jet spark plugs) disposed on the upper surface of each combustion chamber, an intake valve, an intake port, an exhaust valve, and an exhaust port. Each intake port may be in fluid communication with an ammonia injector for injecting ammonia, and in a dual fuel system that is sometimes used to enhance the ignition characteristics of an ammonia fuel engine, the intake port may also be in fluid communication with a secondary combustible fuel such as a hydrocarbon fuel or hydrogen. In certain ammonia fuel engines, the exhaust from the combustion chamber containing ammonia passes through a reforming catalyst or a decomposition catalyst to produce hydrogen gas, which is then fed back to the intake port to improve the ignition characteristics of the engine. In certain embodiments, the ammonia fuel engine may utilize only ammonia as the combustion fuel. In other embodiments, the ammonia fuel engine is a dual fuel engine that utilizes ammonia and one or more additional combustion fuels (e.g., hydrogen or hydrocarbon fuel).

[0057] In certain embodiments, the emissions treatment system combines an SCR catalyst for reducing NOx in the exhaust stream with one or more adsorbents adapted to adsorb one or more of water, NOx, and NH3. The SCR catalyst is required to reduce NOx that may result from the combustion of ammonia under certain operating conditions. The exhaust treatment system further includes an oxidation catalyst. In some embodiments, the oxidation catalyst is an ammonia oxidation catalyst (AMOx) for oxidizing any residual ammonia in the exhaust stream (or trace amounts of CO or hydrocarbon fuel in a dual-fuel engine). In some embodiments, the oxidation catalyst is a diesel oxidation catalyst for oxidizing CO and / or hydrocarbon species from, for example, a dual-fuel engine to carbon dioxide and water vapor. In a single-fuel NH3 engine, a DOC catalyst may be incorporated into the emissions treatment system to oxidize trace hydrocarbon species, such as engine lubricants or feedstock impurities, that may be further included in the exhaust gas stream. In some embodiments, the emissions treatment system may include one or more oxidation catalysts, such as DOC and AMOx.

[0058] In certain embodiments, the water adsorbent is useful during low temperature (e.g., cold start) conditions to prevent water condensation within the emissions treatment system that could impair the catalyst function and / or impede NOx adsorption. In some embodiments, the water adsorbent is preferably located upstream of the NOx adsorbent to enhance the effectiveness of NOx adsorption. In certain embodiments, the NOx adsorbent and the NH3 adsorbent are useful during low temperature conditions to sequester NOx or NH3, respectively, until the exhaust temperature is high enough for effective SCR catalyst performance.

[0059] One exemplary emissions treatment system is shown in FIG. 3, which depicts a schematic of a non-limiting exhaust gas treatment system according to an exemplary embodiment of the present disclosure. As shown, the emissions treatment system 20 may include a plurality of components in series downstream of an engine 22, such as an ammonia-fueled engine. FIG. 3 illustrates five components 24, 26, 28, 30, 32 in series. However, the total number of components can be varied, and the five components are merely an example. Although FIG. 3 describes each component as a "catalyst component" for simplicity, not all components need to include a catalyst. For example, some components may consist of an adsorption composition.

[0060] Without limitation, Table 1 shows various exhaust gas treatment system configurations of one or more exemplary embodiments. It should be noted that each component is connected to the next component via an exhaust duct such that the engine is upstream of component A, upstream of component B, upstream of component C, upstream of component D, and upstream of component E (if present). References to components A-E in the table can be cross-referenced to the same names in FIG. 3.

[0061] As will be appreciated by those skilled in the art, Table 1 is a non-exhaustive list of configurations, and any one or more of components A, B, C, D, or E may be disposed on the same or different substrates, such as a particulate filter like a wall-flow type filter, or on a flow-through honeycomb type substrate. In some embodiments, each of the components of the engine exhaust system is on the same substrate. In some embodiments, two or more substrates may be used for the components of the engine exhaust system.

[0062] In one or more embodiments, the engine exhaust system includes one or more components attached at a location near the engine (close-coupled position, CC), and additional components are at a location under the vehicle body (underfloor position, UF). The reductant used herein for the SCR catalyst includes ammonia. Ammonia can be provided through a separate injection line upstream of the SCR catalyst, or ammonia can be provided through the release of stored ammonia in the LT-AA, or a combination of the above.

[0063] In one or more embodiments, the exhaust gas treatment system may further include an ammonia or ammonia precursor injection component disposed upstream of any SCR catalyst present in the system, for example. In Table 1, the adsorption component may include a lean NOx adsorber (LT-NA), a lean NH3 adsorber (LT-AA), a lean H2O (water vapor) adsorber (LT-WA), or a combination thereof. "SCR" refers to a selective catalytic reduction catalyst, DOC refers to a diesel oxidation catalyst, and "AMOx" refers to an ammonia oxidation catalyst, all of which are described in more detail below.

[0064]

Table 1

[0065] The adsorption components may be in any order and any combination. For example, the adsorption components of the exhaust treatment system of the present disclosure may be LT-AA, LT-WA, LT-NA, LT-AA and LT-WA, LT-AA and LT-NA, LT-WA and LT-NA, LT-WA, LT-NA and LT-AA, LT-NA, LT-WA and LT-AA, LT-WA, LT-A and LT-NA, LT-AA, LT-NA and LT-WA. In some embodiments, the adsorption components may be disposed on the same or different substrates. For example, the exhaust treatment system of the present disclosure may include LT-AA, LT-NA, and LT-WA on the same substrate, LT-NA and LT-WA disposed on the same substrate, LT-AA disposed on a different substrate, and LT-NA and LT-AA disposed on the same substrate.

[0066] SCR catalyst composition In certain embodiments, the SCR catalyst composition comprises a metal-promoted molecular sieve, a vanadia-based composition, or a combination thereof. In certain embodiments, the SCR catalyst composition comprises a metal-promoted (e.g., Cu-promoted, Fe-promoted, or Cu / Fe-promoted) molecular sieve. As used herein, the term "molecular sieve" refers to framework materials such as zeolites and other framework materials (e.g., isomorphously substituted materials), which may be used, for example, in particulate form in combination with one or more promoter metals as a catalyst. Molecular sieves generally include tetrahedral sites, have a substantially uniform pore distribution, and are materials based on an extensive three-dimensional network structure of oxygen ions with an average pore diameter of 20 Å or less. The pore size is defined by the ring size. As used herein, the term "zeolite" refers to a specific example of a molecular sieve that further includes silicon and aluminum atoms. According to one or more embodiments, defining molecular sieves by their structural type is intended to include both molecular sieves having that structural type and any and all isotype framework materials such as SAPO, AlPO, and MeAPO materials having the same structural type, as will be understood.

[0067] In some embodiments, reference to an aluminosilicate zeolite structure type limits the material to a molecular sieve that does not intentionally include phosphorus or other metals substituted in the framework. For clarity, as used herein, "aluminosilicate zeolite" excludes aluminophosphate materials such as SAPO, AlPO, and MeAPO materials, and the broader term "zeolite" is intended to include aluminosilicates and aluminophosphates. Zeolites are understood to be crystalline substances and aluminosilicates having an open three-dimensional framework structure composed of corner-sharing TO4 tetrahedra, where T is Al or Si. Zeolites generally have a silica / alumina (SAR) molar ratio of 2 or greater. The zeolites for use in the catalyst compositions of the present disclosure are not particularly limited with respect to the SAR value, although certain SAR values associated with the zeolites may, in some embodiments, affect the SCR performance of the catalyst composition in which it is incorporated (e.g., particularly after aging). In some embodiments, the SAR value of the zeolite is from about 5 to about 100 or from about 5 to about 50. In some embodiments, the SAR is from about 5 to about 20, and in other embodiments, the SAR is from about 20 to about 50.

[0068] The cations that balance the charge of the anionic framework are loosely associated with the framework oxygen, and the remaining pore volume may potentially be filled with water molecules. The non-framework cations are generally exchangeable, and the water molecules are removable. Zeolites can have a fairly uniform pore diameter in the range of about 3 angstroms to about 10 angstroms, depending on the type of zeolite and the type and amount of cations contained in the zeolite lattice.

[0069] Molecular sieves can be classified by the framework topology whose structure has been identified. For example, ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AWO, AWW, BCT, *Zeolites of any structural type, such as structural types including BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, SCO, CFI, SGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EMT, EON, EPI, ERI, ESV, ETR, EUO, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFR, IHW, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LAU, LEV, LIO, LIT, LOS, LOV, LTA, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, MSO, MTF, MTN, MTT, MTW, MWW, NAB, NAT, NES, NON, NPO, NSI, OBW, OFF, OSI, OSO, OWE, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SGT, SOD, SOS, SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET, VFI, VNI, VSV, WIE, WEN, YUG, ZON, or combinations thereof, etc., can be used. In certain embodiments, the structural type is 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. For example, existing twins of these materials, including but not limited to AEI-CHA, are also intended to be included herein. In certain embodiments, the zeolite of the SCR catalyst has a framework type selected from LEV, CHA, AEI, MEI, FER, or combinations thereof.

[0070] Zeolites are composed of secondary building units (SBUs) and composite building units (CBUs) and occur in many different framework structures. The secondary building units contain up to 16 tetrahedral atoms and are achiral. The composite building units do not necessarily have to be achiral and are not necessarily used to construct the entire framework. For example, a group of zeolites may have a single 4-ring (s4r) composite building unit in their framework structures. In a 4-membered ring, the "4" indicates the positions of the tetrahedral silicon and aluminum atoms, and the oxygen atoms are located between the tetrahedral atoms. Other composite building units include, for example, a single 6-ring (s6r) unit, a double 4-ring (d4r) unit, and a double 6-ring (d6r) unit. The d4r unit is generated by bonding two s4r units. The d6r unit is generated by bonding two s6r units. The d6r unit contains 12 tetrahedral atoms. Zeolite structure types having a d6r secondary building unit include AEI, AFT, AFX, CHA, EAB, EMT, ERI, FAU, GME, JSR, KFI, LEV, LTL, LTN, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC, WEN, and combinations thereof. In one or more embodiments of the present disclosure, the molecular sieve of the catalyst composition has a CHA structure type. In other embodiments, the molecular sieve has a CHA structure type and is selected from the group consisting of SSZ-13, SSZ-62, natural chabazite, zeolite K-G, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, ZYT-6, and combinations thereof.

[0071] In certain embodiments, the zeolite of the catalyst composition comprises small pore zeolites. Small pore zeolites contain channels defined by up to eight tetrahedral atoms. The phrase "8-ring" zeolite refers to zeolites having 8-ring pore openings, and in some cases, the "8-ring" zeolite may include double 6-ring secondary building units and may have a cage-like structure resulting from the bonding of double 6-ring structural units by 4-rings. Exemplary small pore zeolites include framework types ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, LEV, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON, and mixtures or twins thereof. For example, in certain embodiments, the zeolite comprises small pore zeolites having a framework type selected from CHA, LEV, AEI, AFT, AFX, ERI, SFW, KFI, DDR, ITE, and mixtures or twins thereof.

[0072] In certain embodiments, the zeolite of the disclosed catalyst composition comprises medium pore zeolites. Medium pore zeolites contain channels defined by 10-rings. Exemplary medium pore zeolites include framework types AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, WEN, and mixtures or twins thereof. For example, in certain embodiments, the zeolite comprises medium pore zeolites having a framework type selected from FER, MEL, MFI, STT, and mixtures or twins thereof.

[0073] In certain embodiments, the zeolite of the disclosed catalyst composition comprises a large pore zeolite. The large pore zeolite contains channels defined by 12-membered rings. Exemplary large pore zeolites include framework types AFI, AFR, AFS, AFY, ASV, ATO, ATS, * BEA, BEC, BOG, BPH, BSV, CAN, CON, CZP, DFO, EMT, EON, EZT, FAU, GME, GON, IFR, ISV, ITG, IWR, IWS, IWV, IWW, JSR, LTF, LTL, MAZ, MEI, MOR, MOZ, MSE, MTW, NPO, OFF, OHT, OSI, RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SFV, SOF, SOS, STO, SSF, SSY, USI, UWY, VET, and mixtures or intergrowths thereof. For example, in certain embodiments, the zeolite comprises * a large pore zeolite having a framework type selected from BEA, FAU, MOR, and mixtures or intergrowths thereof.

[0074] As referenced above in this specification, the disclosed catalyst compositions generally include a metal-promoted molecular sieve (e.g., zeolite). As used herein, "promoted" refers to a molecular sieve that includes one or more components that are intentionally added, as contrasted with including impurities that may be inherent to the molecular sieve. Thus, a promoter is a constituent that is intentionally added to enhance the activity of the catalyst as compared to a catalyst that does not have the intentionally added promoter. To promote the SCR of nitrogen oxides, in one or more embodiments, a suitable metal is exchanged into the molecular sieve. Copper can be a useful metal for exchange since it is involved in the conversion of nitrogen oxides. Thus, in some embodiments, catalyst compositions are provided that include a copper-promoted molecular sieve (e.g., zeolite), such as Cu-CHA. In other embodiments, catalyst compositions are provided that include an iron-promoted molecular sieve (e.g., zeolite), such as Fe-CHA. However, the present disclosure is not intended to be limited thereto, and catalyst compositions including other metal-promoted molecular sieves are also encompassed herein.

[0075] The promoter metal can generally be selected from the group consisting of alkali metals, alkaline earth metals, transition metals of groups IIIB, IVB, VB, VIB, VIIB, VIIIB, IB, and IIB, group IIIA elements, group IVA elements, lanthanides, actinides, and combinations thereof. In various embodiments, specific promoter metals that can be used to prepare metal-promoted molecular sieves include, but are not limited to, copper (Cu), cobalt (Co), nickel (Ni), lanthanum (La), manganese (Mn), iron (Fe), vanadium (V), silver (Ag), cerium (Ce), neodymium (Nd), praseodymium (Pr), titanium (Ti), chromium (Cr), zinc (Zn), tin (Sn), niobium (Nb), molybdenum (Mo), hafnium (Hf), yttrium (Y), tungsten (W), and combinations thereof. Combinations of such metals, for example, copper and iron, can be used to obtain mixed Cu-Fe-promoted molecular sieves, such as Cu-Fe-CHA. In certain embodiments, the promoter metal associated with the disclosed zeolite component comprises copper (e.g., as CuO), iron (e.g., as Fe2O3), or manganese (e.g., as MnO2).

[0076] The promoter metal content of the metal-promoted molecular sieve calculated as an oxide is, in one or more embodiments, at least about 0.1 wt% based on the total weight of the calcined molecular sieve (including the promoter), and is reported on a volatile-free basis. In some embodiments, the promoter metal of the zeolite component comprises Cu, and the Cu content calculated as CuO is, respectively, in the range of about 0.1 wt% to about 20 wt%, such as about 0.5 wt% to about 17 wt%, about 2 wt% to about 15 wt%, and about 2 wt% to about 10 wt% based on the total weight of the calcined molecular sieve reported on a volatile-free basis. In other embodiments, the promoter metal of the zeolite component comprises Fe, and the Fe content calculated as FeO is, respectively, in the range of about 0.1 wt% to about 20 wt%, such as about 0.5 wt% to about 17 wt%, about 2 wt% to about 15 wt%, and about 2 wt% to about 10 wt% based on the total weight of the calcined molecular sieve reported on a volatile-free basis. In some embodiments, the zeolite component (including the promoter metal) can be defined by the ratio of the promoter metal to the aluminum in the promoted zeolite. For example, in some embodiments, the molar ratio of promoter metal to aluminum is from about 0.1 to about 0.5 (e.g., the Cu / Al ratio is from about 0.1 to about 0.5).

[0077] In some embodiments, the SCR catalyst composition comprises one or more vanadium-containing components. Such compositions are referred to herein as "vanadia-based compositions." In such embodiments, vanadium can be in various forms including, but not limited to, free vanadium, vanadium ions, or vanadium oxides (vanadia) such as vanadium pentoxide (V2O5). As used herein, "vanadia" or "vanadium oxide" is intended to include any oxide of vanadium (e.g., vanadium pentoxide). In certain embodiments, the vanadia-based composition comprises a mixed oxide containing vanadia. The amount of vanadia in the mixed oxide can vary and in some embodiments is in the range of about 1 to about 10 weight percent based on the total weight of the mixed oxide. For example, the amount of vanadia can be at least 1 percent, at least 2 percent, at least 3 percent, at least 4 percent, at least 5 percent, or at least 6 percent, and the upper limit can be about 10 weight percent or 10 percent or less, 9 percent or less, 8 percent or less, 7 percent or less, 6 percent or less, 5 percent or less, or 4 percent or less, with the lower limit being about 1 weight percent.

[0078] Certain useful SCR compositions containing vanadium supported on refractory oxides such as alumina, silica, zirconia, titania, ceria, and combinations thereof are described in U.S. Patent No. 4,010,238 to Shiraishi et al., U.S. Patent No. 4,085,193 to Nakajima et al., and U.S. Patent Application Publication No. 2017 / 0341026 to Chen et al., which are hereby incorporated by reference in their entirety. In some embodiments, the upstream SCR catalyst composition comprises a mixed oxide comprising vanadia / titania (V2O5 / TiO2), for example, in the form of titania with vanadia dispersed therein. Vanadia / titania may optionally be activated or stabilized with tungsten (e.g., WO3) to provide, for example, V2O5 / TiO2 / WO3 in the form of titania with V2O5 and WO3 dispersed therein. It should be noted that in some embodiments, vanadia is not in the form of a true mixed metal oxide. Rather, the metal oxide constituents (e.g., titania and vanadia) may be present as discrete particles. The amount of tungsten in such embodiments can vary and can be, for example, in the range of about 0.5 to about 10 weight percent based on the total weight of the mixed oxide. For example, the amount of tungsten can be at least 0.5 percent, at least 1 percent, at least 2 percent, at least 3 percent, at least 4 percent, at least 5 percent, or at least 6 percent, and the upper limit can be about 10 weight percent, or 10 percent or less, 9 percent or less, 8 percent or less, 7 percent or less, 6 percent or less, 5 percent or less, or 4 percent or less, and the lower limit is about 0.5 weight percent.

[0079] Exemplary vanadium-based SCR catalyst compositions can include, but are not limited to, components including V2O5 / TiO2, V2O5 / WO3 / TiO2, V2O5 / WO3 / TiO2 / SiO2, or combinations thereof. Additional vanadium-based SCR catalyst compositions are described, for example, in U.S. Patent No. 4,782,039 to Lindsey, U.S. Patent No. 8,465,713 to Schermanz et al., and U.S. Patent No. 8,975,206 to Schermanz et al., which are hereby incorporated by reference in their entirety.

[0080] Certain vanadium-based SCR catalyst compositions can include other active components (e.g., other metal oxides). For example, in some embodiments, a vanadium-based SCR composition suitable for use in the disclosed systems includes vanadium and antimony. Such vanadium-based SCR compositions can include, in certain embodiments, a composite oxide including vanadium and antimony that can be supported on a refractory metal oxide (e.g., TiO2, SiO2, WO3, Al2O3, ZrO2, or combinations thereof). Exemplary vanadium-based SCR compositions including vanadium and antimony are disclosed in U.S. Patent No. 4,221,768 to Inoue et al., U.S. Patent Application Publication No. 2018 / 0304236 to Zhao et al., and U.S. Patent Application Publication No. 2019 / 0344247 to Zhao et al., all of which are hereby incorporated by reference in their entirety.

[0081] Various additional SCR catalyst compositions are also described, for example, in U.S. Patent No. 7,998,423 to Boorse et al., U.S. Patent No. 9,017,626 to Tang et al., U.S. Patent No. 9,242,238 to Mohanan et al., and U.S. Patent No. 9,352,307 to Stiebels et al., which are hereby incorporated by reference herein. The amount of SCR catalyst used on the substrate can vary, but can be supported in an amount of about 1-10 g / in 3 , for example 1-7 g / in 3 or 2-5.5 g / in 3 .

[0082] According to the present disclosure, an SCR catalyst composition is generally prepared by providing a metal-promoted molecular sieve material. Molecular sieves having a CHA structure may be prepared according to various techniques well known in the art, such as U.S. Patent No. 4,544,538 to Zones and U.S. Patent No. 6,709,644 to Zones, and U.S. Patent No. 8,883,119 to Bull et al., which are hereby incorporated by reference in their entirety. Methods for preparing other types of molecular sieves are well known in the art and can be readily used to provide the desired zeolite framework for inclusion within the disclosed compositions.

[0083] For preparing a metal-promoted molecular sieve according to various embodiments, a metal (e.g., copper) is ion-exchanged into the molecular sieve. Such a metal can be ion-exchanged into an alkali metal or NH4 molecular sieve (which can be prepared by methods well known in the art, as disclosed, for example, by Bleken, F et al., Topics in Catalysis 2009, 52, 218 - 228, the ion-exchange of NH4 into an alkali metal molecular sieve, which is hereby incorporated by reference herein). + by ion-exchange, which is hereby incorporated by reference herein).

[0084] The preparation of the metal-promoted molecular sieve can include an ion-exchange process of the molecular sieve in particulate form using a metal precursor solution. For example, a copper salt can be used to provide copper. When copper acetate is used to provide copper, the copper concentration of the liquid copper solution used in the copper ion-exchange is, in some embodiments, in the range of about 0.01 mol to about 0.4 mol, such as in the range of about 0.05 mol to about 0.3 mol, in the range of about 0.1 mol to about 0.25 mol, in the range of about 0.125 mol to about 0.25 mol, in the range of about 0.15 mol to about 0.225 mol, and approximately about 0.2 mol. In some embodiments, a metal such as copper is ion-exchanged into an alkali metal or NH4 + -chabazite to form Cu-chabazite.

[0085] For further promotion of SCR of nitrogen oxides, in some embodiments, the molecular sieve can be promoted with two or more metals (e.g., copper in combination with one or more other metals). When two or more metals are included in the molecular sieve material promoted with metal ions, a plurality of metal precursors (e.g., copper and iron precursors) can be ion-exchanged simultaneously or separately in a plurality of exchange steps. In certain embodiments, the second metal can be exchanged into the molecular sieve material first promoted with the first metal (e.g., the second metal can be exchanged into the molecular sieve material promoted with copper). The second molecular sieve material can vary and, in some embodiments, can be a transition metal (e.g., iron or manganese) or an alkaline earth or alkali metal.

[0086] The SCR catalyst can, in some embodiments, be in the form of an integrated SCR / AMOx catalyst. Exemplary SCR / AMOx catalysts are described, for example, in U.S. Patent No. 8,524,185 to Caudle et al., U.S. Patent No. 8,283,182 to Boorse et al., and U.S. Patent No. 5,516,497 to Speronello et al., which are incorporated herein by reference. Suitable SCR / AMOx catalysts can be zoned or layered such that the SCR catalyst and the AMOx catalyst are at least partially separated. For example, in certain embodiments, an SCR / AMOx catalyst is provided where the SCR catalyst is on a substrate having an inlet end and an outlet end, the SCR catalyst is located at the inlet (upstream) end, and the AMOx catalyst is located at the outlet (downstream) end. In other embodiments, the SCR / AMOx catalyst can include a bottom coat containing the AMOx catalyst and a top coat having SCR functionality. In some embodiments, the AMOx catalyst composition extends less than the full length of the SCR / AMOx catalyst, and the SCR catalyst composition extends over the full length of the SCR / AMOx catalyst (e.g., as a top wash coat). These relative positions advantageously allow the AMOx catalyst to remove ammonia that has slipped from the SCR catalyst.

[0087] Low-temperature NO x Adsorbent (LT-NA) The LT-NA components disclosed herein may include a molecular sieve containing a platinum group metal component. Such LT-NA components may be effective for storing NO at a temperature below 200 °C and releasing the stored NO at a higher temperature. Any of the molecular sieves described herein may be used in the LT-NA components. In certain embodiments, the molecular sieve may include a framework type selected from CHA (chabazite), FER (ferrierite), AEI, and LEV (levyne). The LT-NA components disclosed herein may also include a metal organic framework (MOF). Such LT-NA components are effective for adsorbing NO at a temperature below 200 °C and releasing the adsorbed NO at a temperature suitable for a downstream SCR catalyst. x and releasing the stored NO x The molecular sieve of the LT-NA component may be impregnated with a platinum group metal component. As used herein, reference to impregnation with a platinum group metal component includes all forms of association between the platinum group metal component and the molecular sieve, such as when the platinum group metal component is present at either the ion exchange sites of the molecular sieve or other internal locations within the molecular sieve, or when the platinum group metal is present on the surface of the molecular sieve, or any combination of the above positions. x and releasing the adsorbed NO x at a temperature suitable for a downstream SCR catalyst.

[0088] The molecular sieve of the LT-NA component may be impregnated with a platinum group metal component. As used herein, reference to impregnation with a platinum group metal component includes all forms of association between the platinum group metal component and the molecular sieve, such as when the platinum group metal component is present at either the ion exchange sites of the molecular sieve or other internal locations within the molecular sieve, or when the platinum group metal is present on the surface of the molecular sieve, or any combination of the above positions.

[0089] The term "platinum group metal component" refers to any component containing platinum group metals (e.g., Ru, Rh, Os, Ir, Pd, Pt). "Platinum group metal component" means that the platinum group metals exist in any valence state. For example, the platinum group metals may be in the metallic form with zero valence, or the platinum group metals may be in the form of oxides. Terms such as "platinum (Pt) component", "rhodium (Rh) component", "palladium (Pd) component", "iridium (Ir) component", "ruthenium (Ru) component", etc. refer to their respective platinum group metal compounds, complexes, etc., which decompose or otherwise convert to a catalytically active form, usually a metal or metal oxide, during firing or use of the catalyst. In some embodiments, the platinum group metal component is palladium as the sole platinum group metal component, but mixtures of platinum group metal components may also be used.

[0090] The concentration of the platinum group metal component can be varied, for example, from about 0.01 wt% to about 6 wt% based on the total dry weight of the molecular sieve. The platinum group metal component may be present in the molecular sieve, based on the total dry weight of the molecular sieve, for example, at about 0.1 wt%, about 0.2 wt%, about 0.5 wt%, about 0.7 wt%, about 0.9 wt%, or from about 1.0 wt% to about 1.5 wt%, about 2.0 wt%, about 2.5 wt%, about 3.0 wt%, about 3.5 wt%, about 4.0 wt%, about 4.5 wt%, about 5.0 wt%, or about 6 wt%. The weight of the platinum group metal component is measured and reported as the metal (e.g., the weight of palladium). The total dry weight of the molecular sieve includes any added / exchanged metal (i.e., palladium).

[0091] Alternatively, the amount of the platinum group metal component in the LT-NA composition can be expressed as the weight per unit volume of the substrate. For example, in certain embodiments, the amount of the platinum group metal component in LT-NA is from about 10 g / ft 3 ~about 140 g / ft 3 , for example, from about 40 g / ft 3 ~about 100 g / ft 3etc. (based on the volume of the substrate under which the catalyst is disposed).

[0092] The LT-NA component is generally, for example, based on the volume of the substrate, about 0.3 g / in 3 to about 0.4 g / in 3 about 0.5 g / in 3 about 0.6 g / in 3 about 0.7 g / in 3 about 0.8 g / in 3 about 0.9 g / in 3 or about 1.0 g / in 3 ~about 1.5 g / in 3 about 2.0 g / in 3 about 2.5 g / in 3 about 3.0 g / in 3 about 3.5 g / in 3 about 4.0 g / in 3 about 4.5 g / in 3 about 5.0 g / in 3 or about 5.5 g / in 3 and is present on the substrate at a concentration of.

[0093] The LT-NA components disclosed herein may be readily prepared by processes well known in the art. The disclosed LT-NA components may, in some embodiments, be prepared via an incipient wetness impregnation method. For example, a metal precursor (e.g., a platinum group metal component) may be dissolved in an aqueous or organic solution, and then the metal-containing solution is added to the material to be impregnated (e.g., a molecular sieve), which contains a pore volume essentially the same as the volume of the added solution. By capillary action, the solution is drawn into the pores of the material. Solution added in excess of the material pore volume changes the solution transport from a capillary action process to a much slower diffusion process. Thereafter, the impregnated material is dried and optionally calcined to remove volatile components in the solution and deposit the metal on the surface of the material. The maximum addition amount is limited by the solubility of the precursor in the solution. The concentration profile of the impregnated material depends on the mass transfer conditions within the pores during impregnation and drying.

[0094] For example, a platinum group metal component precursor (e.g., palladium nitrate, etc.) may be supported on a molecular sieve by impregnation, adsorption, ion exchange, incipient wetness, precipitation, etc. Non-limiting examples of suitable PGM precursors include palladium nitrate, tetraamine palladium nitrate, tetraamine platinum acetate, and platinum nitrate. Alternatively, a platinum group metal colloid dispersion as described below can also be used. During the calcination step, or at least during the initial stage of catalyst use, such compounds are converted into a catalytically active form of the metal or its compound.

[0095] Low-temperature NH3 adsorbent (LT-AA) The LT-AA components disclosed herein may include a molecular sieve. Such LT-AA components are effective for storing NH3 at temperatures below 200°C and releasing the stored NH3 at higher temperatures when the SCR catalyst becomes functional. Any of the molecular sieves described herein can be used in the LT-AA components. In certain embodiments, the LT-AA component is a zeolite, which can be natural or synthetic, such as faujasite, chabazite, clinoptilolite, mordenite, silicalite, zeolite X, zeolite Y, ultrastable zeolite Y, ZSM-5 zeolite, offretite, or beta zeolite. An exemplary beta zeolite that can be used is disclosed in U.S. Patent No. 6,171,556 to Burke et al., which is hereby incorporated by reference in its entirety. When present, the LT-AA component is used, for example, in an amount of about 0.05 g / in 3 ~ about 1 g / in 3 The LT-AA components disclosed herein may also include a metal-organic framework (MOF). Such LT-AA components are effective for storing ammonia at temperatures below 200°C and releasing the stored NO x to the downstream SCR catalyst at a suitable temperature. In certain embodiments, the LT-AA component can be characterized as substantially free of catalytic metals such as platinum group metal components.

[0096] Low-temperature water vapor adsorption device (LT-WA) The LT-WA components disclosed herein may include a desiccant material that is thermally stable under typical operating conditions of an ammonia fuel engine. Such LT-WA components are effective for storing H2O at temperatures below 150°C and releasing the stored H2O at higher temperatures. Any of the molecular sieves described herein may be used in the LT-WA components. Alternatively, silica, activated carbon, activated alumina, clay materials (e.g., montmorillonite), calcium sulfate, or calcium chloride may be used. When present, the LT-WA components are used, for example, in an amount of about 0.05 g / in 3 ~ about 3 g / in 3 Specific embodiments may be characterized in that the LT-WA components are substantially free of catalytic metals such as platinum group metal components. The LT-WA components disclosed herein may also include metal-organic frameworks (MOFs).

[0097] Oxidation catalyst The oxidation catalyst component of the exhaust treatment system may be a diesel oxidation catalyst (DOC) or an ammonia oxidation catalyst (AMOx).

[0098] The DOC is suitable, for example, for oxidizing the NO and / or CO and / or HC components of the exhaust gas. In the DOC, most of the unburned gaseous and non-volatile hydrocarbons and carbon monoxide are burned to form carbon dioxide and water. Note that a part of the NO in the NOx component may be oxidized to NO2. The DOC catalyst is described, for example, in U.S. Patent Application Publication No. 2019 / 0015781 by Wei et al., which is incorporated herein by reference. The DOC may be formed in a single layer or multiple layers. A suitable DOC composition preferably contains one or more platinum group metals impregnated on a porous refractory metal oxide support, as disclosed herein. A suitable DOC composition may further contain one or more non-PGM transition metals such as Mn, or alkaline earth metals such as Ba, impregnated on a porous refractory metal oxide support, as disclosed herein. The DOC may be coated on the flow-through type monolith substrate or wall-flow type filter substrate described herein. The DOC is typically disposed upstream of the SCR and may optionally be disposed after the close-coupled SCR.

[0099] The DOC is preferably in a close-coupled position. The close-coupled position is, for example, within about 12 inches (in) from the exhaust manifold (i.e., the place where the individual cylinder exhaust pipes are joined together). In some embodiments, the distance from the exhaust manifold to the upstream end of the DOC unit is from about 0.5 inch to about 12 inches. In some embodiments, the distance is about 0.5 inch, about 1 inch, about 2 inches, about 3 inches, about 4 inches, about 5 inches, about 6 inches, about 7 inches, about 8 inches, about 9 inches, about 10 inches, about 11 inches, or about 12 inches. In some embodiments, the distance is from about 0.5 inch, about 1 inch, about 2 inches, about 3 inches, about 4 inches, or about 5 inches to about 6 inches, about 7 inches, about 8 inches, about 9 inches, about 10 inches, about 11 inches, or about 12 inches, and each combination of the lower and upper endpoints clearly defines the scope contemplated as embodiments of the present invention.

[0100] Ammonia oxidation (AMOx) generally refers to the process in which NH3 reacts with oxygen to produce NO, NO2, N2O, or N2. The AMOx catalyst used in the present disclosure may include a platinum group metal component impregnated on a porous refractory metal oxide support. The AMOx catalyst may further include a hydrocarbon adsorbent such as zeolite (e.g., Fe-beta zeolite), and / or a stabilizer or promoter (e.g., barium oxide). The AMOx catalyst is taught, for example, in U.S. Patent Application Publication No. 2011 / 0271664 to Boorse et al., which is incorporated herein by reference. The AMOx catalyst is typically located downstream of the SCR.

[0101] As used herein, "platinum group metal" refers to a platinum group metal or its oxide, including platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), osmium (Os), iridium (Ir), and mixtures thereof. In certain embodiments, the platinum group metal includes a combination of platinum and palladium in a weight ratio of from about 1:10 to about 10:1, such as from about 1.5:1 or more, from about 2:1 or more, or from about 5:1 or more. The concentration of the platinum group metal component (e.g., Pt, Pd, or a mixture thereof) can vary, but is, for example, from about 0.1 wt% to about 10 wt% (e.g., from about 1 wt% to about 6 wt% based on the weight of the porous refractory oxide support material). In certain embodiments, the platinum group metal may further include rhodium.

[0102] As used herein, "porous refractory metal oxide" refers to a porous metal-containing oxide material that exhibits chemical and physical stability at high temperatures, such as the temperatures associated with diesel engine exhaust. Exemplary refractory oxides include alumina, silica, zirconia, titania, ceria, and combinations thereof. The combination may be in the form of a physical or chemical mixture. Exemplary refractory oxides include atomically doped combinations and include active compounds such as high surface area or activated alumina. Exemplary combinations of metal oxides include alumina-zirconia, ceria-zirconia, alumina-ceria-zirconia, lanthana-alumina, lanthana-zirconia-alumina, barrier-alumina, barrier-lanthana-alumina, barrier-lanthana-neodymia alumina, and alumina-ceria. Exemplary aluminas include macroporous boehmite, gamma-alumina, and delta / theta alumina. Useful commercially available aluminas include high bulk density gamma alumina, low or medium bulk density macroporous gamma alumina, and activated aluminas such as low bulk density macroporous boehmite and gamma alumina.

[0103] High surface area refractory oxide supports, such as alumina support materials also referred to as "gamma alumina" or "activated alumina", may exhibit a BET specific surface area in excess of 60 m 2 / g and often up to about 200 m 2 / g or more. Such activated alumina is typically a mixture of the gamma and delta phases of alumina, but may contain significant amounts of the eta, kappa, and theta alumina phases. "BET surface area" has its ordinary meaning and refers to the multi-layer adsorption (Brunauer-Emmett-Teller) method for determining surface area by N2 adsorption. Desirably, the activated alumina has a specific surface area of from 60 m 2 / g to 350 m 2 / g, such as from 90 m 2 / g to 250 m 2 / g.

[0104] The amount of platinum group metal can vary, but in certain embodiments, the amount of platinum group metal is about 10 g / ft 3 ~100 g / ft 3 (based on the volume of the underlying substrate on which the catalyst is disposed), and is at least about 40 g / ft 3 , at least about 45 g / ft 3 , at least about 50 g / ft 3 , at least about 55 g / ft 3 , at least about 60 g / ft 3 , at least about 65 g / ft 3 , at least about 70 g / ft 3 , at least about 75 g / ft 3 , or at least about 80 g / ft 3 and includes ranges such as. The concentration of platinum group metal or any other composition on the substrate refers to the concentration per any one three-dimensional section or zone, e.g., per any cross-section of the substrate or the entire substrate, and is typically expressed as g / ft 3 or g / in 3 .

[0105] In some embodiments, the entire oxidation catalyst composition is, for example, based on the volume of the substrate, from about 0.3 g / in 3 to about 0.4 g / in 3 , about 0.5 g / in 3 , about 0.6 g / in 3 , about 0.7 g / in 3 , about 0.8 g / in 3 , about 0.9 g / in 3 , or about 1.0 g / in 3 ~about 1.5 g / in 3 , about 1.7 g / in 3 , about 1.8 g / in 3 , about 1.9 g / in 3 , about 2.0 g / in 3 , about 2.1 g / in 3 , about 2.2 g / in 3 , about 2.3 g / in 3 , or about 2.5 g / in 3 and is present on the substrate at a concentration of.

[0106] The preparation of the platinum group metal-impregnated refractory oxide material may include impregnating a refractory oxide support material in particulate form with one or more platinum group metal solutions, such as a platinum solution and a palladium solution. A plurality of platinum group metal components (e.g., platinum, palladium, and / or rhodium) may be impregnated simultaneously or separately, using the incipient wetness technique, onto the same support particles or separate support particles. The support particles may be dried to such an extent that they absorb substantially all of the solution to form a wet solid. An aqueous solution of a water-soluble compound or complex of a platinum group component such as palladium nitrate or platinum nitrate, tetraamminepalladium nitrate or platinum nitrate, or tetraamminepalladium, or platinum acetate may be utilized.

[0107] After treating the support particles with the platinum group metal solution, the particles are dried, for example, by heat-treating the particles at a high temperature (e.g., 100 - 150 °C) for a certain period of time (e.g., 1 - 3 hours), and then fired to convert the platinum group metal components into a more catalytically active form. An exemplary firing process includes heat-treating at a temperature of about 400 - 550 °C in air for 1 - 3 hours. The above process may be repeated as necessary to achieve the desired level of platinum group metal impregnation. The resulting material may be stored as a dry powder or in slurry form.

[0108] Alternatively, the platinum group metal starting material may be in the form of a colloidal dispersion of platinum group metal nanoparticles rather than in solution form. Such a colloidal suspension may be applied to the support in the incipient wetness technique as described above. Methods for impregnating the support with the colloidal platinum group metal material are described in U.S. Patent Application Publication No. 2017 / 0304805 to Xu et al. and U.S. Patent Application Publication No. 2019 / 0015781 to Wei et al., both of which are hereby incorporated by reference in their entirety.

[0109] Substrate The exhaust treatment component can be disposed on a substrate. The useful substrate may be three-dimensional and have a length, diameter, and volume similar to a cylinder. The shape does not necessarily have to conform to a cylinder. The length is the axial length defined by an inlet end and an outlet end.

[0110] According to one or more embodiments, the substrate for the disclosed component(s) can be composed of any material typically used to prepare automotive catalysts and can include a metallic or ceramic honeycomb structure. The substrate provides a plurality of wall surfaces to which a washcoat composition is applied and adhered, thereby acting as a carrier for the catalyst composition. In some embodiments, the substrate includes a honeycomb-type substrate in the form of a wall flow type filter or a flow-through type substrate.

[0111] The ceramic substrate may be made of any suitable refractory material, such as cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon mullite, diopside, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicate, and the like.

[0112] The substrate may further be metallic and include one or more metals or metal alloys. The metallic substrate may include any metallic substrate such as one having openings or "punch-outs" in the channel walls. In some embodiments, the metallic substrate may be used in various shapes such as pellets, corrugated sheets, or monolithic foams. Examples of metallic substrates include heat-resistant base metal alloys, particularly those in which iron is a substantial or major constituent. Such alloys may contain one or more of nickel, chromium, and aluminum, and the total of these metals is preferably at least about 15 weight percent (wt%) of the alloy, in each case based on the weight of the substrate, for example, about 10 wt% to about 25 wt% chromium, about 1 wt% to about 8 wt% aluminum, and 0 wt% to about 20 wt% nickel. In some embodiments, the metallic substrate includes those having straight channels, those having blades that project along the axial channels to divide the gas flow and open the communication of the gas flow between channels, and those having blades and holes to enhance the gas transport between channels that enables radial gas transport across the monolith. The metallic substrate can advantageously be used in intimate contact positions in certain embodiments, enabling rapid heating of the substrate and, correspondingly, rapid heating of the catalyst composition coated therein.

[0113] Any suitable substrate for the catalyst articles disclosed herein may be used, such as a monolithic substrate of the type having fine parallel gas flow channels extending from the inlet face to the outlet face of the substrate so that the flow channels are open to the flow of fluid passing therethrough ("flow-through substrate"). Another suitable substrate is of the type having a plurality of fine and substantially parallel gas flow channels extending along the longitudinal axis of the substrate, each flow channel being blocked at one end of the substrate body and the flow channels being alternately blocked at the opposing end faces ("wall-flow type filter"). Flow-through and wall-flow substrates are also taught, for example, in U.S. Patent Application Publication No. 2017 / 0333883 to Mohanan et al., which is hereby incorporated by reference in its entirety.

[0114] Flow-through type substrate In some embodiments, the substrate is a flow-through type substrate (e.g., a flow-through type monolithic substrate including a monolithic flow-through type honeycomb substrate). The flow-through type substrate has fine parallel gas flow paths extending from an inlet end to an outlet end of the substrate such that the flow paths are open to the flow of fluid. The passage is an essentially straight path from the fluid inlet to the fluid outlet and is defined by walls on which a coating (e.g., a catalyst coating) is disposed such that the gas flowing through the passage contacts the coating material. The flow paths of the flow-through type substrate are thin-walled channels, which can have any suitable cross-sectional shape and size such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, etc. The flow-through type substrate may be ceramic or metal as described above.

[0115] The flow-through type substrate can have, for example, a volume of about 50 in 3 ~ about 1200 in 3 , a cell density (inlet opening) of about 60 cells per square inch (cpsi) to about 500 cpsi or up to about 900 cpsi, for example about 200 cpsi to about 400 cpsi, and a wall thickness of about 50 micrometers to about 200 micrometers or about 400 micrometers.

[0116] Figures 1A and 1B illustrate an exemplary substrate 2 in the form of a through-flow type substrate coated with the coating composition described herein. Referring to Figure 1A, the exemplary substrate 2 has a cylindrical shape and has a cylindrical outer surface 4, an upstream end face 6, and a corresponding downstream end face 8 that is identical to the end face 6. A plurality of fine and parallel gas flow paths 10 are formed therein in the substrate 2. As can be seen from Figure 1B, the flow paths 10 are formed by walls 12, extend from the upstream end face 6 to the downstream end face 8 through the carrier 2, and the flow paths 10 are not blocked so that a fluid, such as a gas flow, can flow longitudinally through the substrate 2 through the flow paths 10. As can be more easily seen in Figure 1B, the walls 12 are dimensioned and configured such that the flow paths 10 have a substantially regular polygonal shape. As shown, the coating composition can be applied in a plurality of separate layers if desired. In the illustrated embodiment, the coating composition consists of both a separate lower layer 14 (e.g., an LT-NA component) adhered to the wall 12 of the carrier member and a second separate upper layer 16 (e.g., an LT-WA component) coated on the lower layer 14. The present disclosure can be implemented with one or more (e.g., two, three, or four or more) composition layers and is not limited to the two-layer embodiment shown in Figure 1B.

[0117] Wall flow type filter substrate In some embodiments, the substrate is a wall flow type filter and has a plurality of fine and substantially parallel gas flow passages extending along the longitudinal axis of the substrate. Each passage may be blocked at one end of the substrate body, and the passages may be alternately blocked at the opposing end faces. Such a monolithic wall flow type filter substrate may include up to about 900 or more flow paths (or "cells") per square inch of cross-section, but even fewer flow paths may be used. For example, the substrate may have from about 7 to 600, more typically from about 100 to 400 cells per square inch ("cpsi"). The cells may have a rectangular, square, circular, elliptical, triangular, hexagonal, or other polygonal cross-section.

[0118] A cross-sectional view of the monolithic wall flow filter substrate portion is shown in FIG. 2, showing alternately blocked / closed passages (cells) and open passages (cells). The blocked or closed ends 100 alternate with the open passages 101, and each pair of opposing ends is respectively open and closed. The filter has an inlet end 102 and an outlet end 103. The arrow across the porous cell wall 104 represents the exhaust gas flow that enters the open cell end, diffuses through the porous cell wall 104, and exits from the open outlet cell end. The blocked end 100 prevents gas flow and promotes diffusion through the cell wall. Each cell wall has an inlet side 104a and an outlet side 104b. The passages are surrounded by the cell walls.

[0119] The wall flow filter article substrate can have a volume of, for example, about 50 cm 3 to about 100 cm 3 about 200 cm 3 about 300 cm 3 about 400 cm 3 about 500 cm 3 about 600 cm 3 about 700 cm 3 about 800 cm 3 about 900 cm 3 or about 1000 cm 3 to about 1500 cm 3 about 2000 cm 3 about 2500 cm 3 about 3000 cm 3 about 3500 cm 3 about 4000 cm 3 about 4500 cm 3 or about 5000 cm 3 The wall flow filter substrate can have a wall thickness of about 50 micrometers to about 2000 micrometers, such as about 50 micrometers to about 450 micrometers or about 150 micrometers to about 400 micrometers.

[0120] The walls of the wall flow type filter are porous and may have a wall porosity of at least about 50% or at least about 60% before the placement of the functional coating, and the average pore diameter is at least about 5 micrometers. For example, the wall flow type filter substrate in some embodiments has a porosity of ≧50%, ≧60%, ≧65%, or ≧70%. For example, the wall flow type filter article substrate has a wall porosity of about 50%, about 60%, about 65%, or about 70% to about 75%, about 80%, or about 85%, and an average pore diameter of about 5 microns, about 10 microns, about 20 microns, about 30 microns, about 40 microns, or about 50 microns to about 60 microns, about 70 microns, about 80 microns, about 90 microns, or about 100 microns before the placement of the catalyst coating. The terms "wall porosity" and "substrate porosity" are interchangeable. Porosity is the ratio of the void volume divided by the total volume of the substrate. The pore diameter can be determined according to the ISO15901-2 (static volume measurement) procedure for nitrogen pore diameter analysis. The nitrogen pore diameter may be determined with a Micromeritics TRISTAR 3000 series instrument. The nitrogen pore diameter may be determined using the BJH (Barrett-Joyner-Halenda) calculation and 33 desorption points. Useful wall flow type filters have high porosity and allow for high loading of the catalyst composition without excessive backpressure during operation.

[0121] Coating The compositions disclosed herein are coated on a substrate such as the substrate described herein. The coating may include one or more thin adhesive coating layers disposed on and adhered to at least a portion of the substrate. The coating may be on the substrate wall surface and / or within the pores of the substrate wall, i.e., "in" and / or "on" the substrate wall. Thus, the phrase "a coating disposed on the substrate" means on any surface, e.g., on the wall surface and / or on the pore surface.

[0122] The composition can be applied in the form of a washcoat. The washcoat is formed by preparing a slurry containing a predetermined solid content (e.g., about 10 wt% to about 60 wt%) in a liquid vehicle, applying this to a substrate, and drying and firing to provide a coating layer. When applying a plurality of coating layers, the substrate can be dried and fired after applying each layer and / or after applying a desired number of the plurality of layers.

[0123] The washcoat slurry may optionally contain a binder (e.g., alumina, silica), a water-soluble or water-dispersible stabilizer, an accelerator, an associative thickener, and / or a surfactant (including anionic, cationic, non-ionic or amphoteric surfactants). For example, the washcoat may contain a ZrO2 binder derived from a suitable precursor such as zirconyl acetate, zirconium acetate, or any other suitable zirconium precursor such as zirconyl nitrate and zirconium nitrate. The zirconyl acetate binder provides a coating that remains homogeneous and intact after thermal aging. Other potentially suitable binders include, but are not limited to, alumina and silica. Examples of alumina binders include aluminum oxide, aluminum hydroxide, and aluminum oxyhydroxide. Aluminum salts and colloidal forms of alumina may also be used. Examples of silica binders include various forms of SiO2 including silicates and colloidal silica. The binder composition may include any combination of zirconia, alumina, and silica. When present, the binder can be used in an amount of about 1 to 5 wt% of the total washcoat load.

[0124] The pH range of the slurry can be from about 3 to about 6. Accordingly, the addition of acidic or basic species to the slurry can be carried out to adjust the pH. For example, in some embodiments, the pH of the slurry is adjusted by the addition of ammonium hydroxide or an aqueous nitric acid solution.

[0125] The slurry can be pulverized to facilitate the mixing of particles and the formation of a homogeneous material. The pulverization can be achieved with a ball mill, a continuous mill, or other similar devices, and the solid content of the slurry can be, for example, about 20 - 60 wt%, about 20 - 40 wt%, etc. In one embodiment, the slurry after pulverization is characterized by a D90 particle size of about 10 microns to about 40 microns, for example, about 10 microns to about 30 microns or about 10 microns to about 15 microns.

[0126] Thereafter, the slurry is coated on the substrate using washcoat technology well-known in the art. In one embodiment, the substrate is immersed one or more times in the slurry or is otherwise coated with the slurry. Thereafter, the coated substrate is dried at a high temperature (e.g., 100 - 150 °C) for a certain period of time (e.g., 10 minutes - 3 hours), and then fired by heating at, for example, 400 - 600 °C for about 10 minutes to about 3 hours. After drying and firing, the final washcoat coating layer can be considered to be essentially solvent-free.

[0127] After firing, the washcoat loading obtained by the above washcoat technology can be determined by calculating the difference between the coated weight and the uncoated weight of the substrate. As will be apparent to those skilled in the art, the loading can be changed by varying the slurry rheology. Note that the coating / drying / firing process for generating the washcoat may be repeated as necessary to build up the coating to the desired loading level or thickness, which means that more than one washcoat may be applied.

[0128] A wash coat(s) can be applied such that different coating layers can directly contact the substrate. Alternatively, there may be one or more "undercoats", whereby at least a portion of one or more catalyst coating layers or adsorbent coating layers do not directly contact the substrate (rather, they contact the undercoat). There may be one or more "overcoats", whereby at least a portion of the coating layer(s) is not directly exposed to the gas stream or atmosphere (rather, it contacts the overcoat).

[0129] The different coating layers may be in direct contact with each other. Alternatively, the different coating layers may not be in direct contact. The various coating layers can be regarded as an undercoat, an overcoat, or an intermediate layer. An undercoat is the "under" layer of the coating layer, an overcoat is the "over" layer of the coating layer, and an intermediate layer is the "between" layer of two coating layers. The intermediate layer(s), undercoat(s), undercoat(s), and overcoat(s) may or may not contain one or more functional compositions.

[0130] Various coatings may advantageously be "zoned", including zoned layers. This may also be described as "laterally zoned". For example, a layer may extend from an inlet end to an outlet end by about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the substrate length. Another layer may extend from the outlet end to the inlet end by about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the substrate length. Different coating layers may be adjacent to each other and may not overlap with each other. Alternatively, different layers may cover a part of each other to provide a third "middle" zone. The middle zone may extend, for example, from about 5% to about 80% of the substrate length, for example, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% of the substrate length.

[0131] Method for treating exhaust gas flow In another aspect, for NOx reduction, etc., a method for treating a gaseous exhaust gas stream containing a mixture of nitrogen oxides NO x flowing from the exhaust manifold of an ammonia-fueled engine is provided. In some embodiments, such a method is effective not only to reduce NO x emissions associated with such an engine, but also to adsorb certain gaseous components of the exhaust gas stream emitted by such an engine to improve the effectiveness of the system. For example, the method includes contacting the gaseous exhaust gas stream with an SCR catalyst and one or more adsorption components disposed upstream of the SCR catalyst, and the adsorption components are selected from the group consisting of low-temperature NO x adsorption (LT-NA), low-temperature ammonia adsorbent (LT-AA), low-temperature water vapor adsorbent (LT-WA), and combinations thereof. The method may further typically include treating the exhaust gas stream with one or more oxidation catalysts, such as an AMOx catalyst, disposed downstream of the SCR catalyst.

[0132] In some embodiments, the LT-NA component is effective for releasing one or both of NO and NO2 at a temperature above about 300°C. In some embodiments, the LT-NA component is effective for releasing one or both of NO and NO2 at a temperature above about 325°C.

[0133] The compositions, components, systems, and methods are suitable for treating exhaust gas streams from mobile emission sources such as trucks and automobiles. The compositions, components, systems, and methods of the present invention are also suitable for treating exhaust gas streams from stationary sources such as power plants.

[0134] It will be readily apparent to those skilled in the art that suitable modifications and adaptations can be made to the compositions, components, systems, and methods described herein without departing from the scope of any embodiment or aspect thereof. The compositions, components, systems, and methods provided are exemplary and are not intended to limit the scope of the claimed embodiments. All of the various embodiments, aspects, and options disclosed herein can be combined in all variations. The compositions, components, systems, and methods described herein include all actual or potential combinations of all embodiments, aspects, options, examples, and preferences herein. All patents and publications cited herein are incorporated herein by reference for their specific teachings as recited, unless otherwise specifically provided for other specific incorporations.

Examples

[0135] The following examples are intended to be illustrative and are in no way meant to limit the scope of the present disclosure.

[0136] Example 1: DOC Articles A bottom coat catalyst slurry containing pulverized alumina powder impregnated with Pd (0.5 wt%), Ba (0.8 wt%) and Pt (0.3 wt%) was prepared and adjusted to a pH of 4.5 - 5.0 with nitric acid. The bottom coat slurry had a solids content of 38 wt%. A top coat slurry containing alumina, Mn (5 wt%), and Pt-amine (3.3 wt%) was prepared, pulverized, and adjusted to a pH of 4.5 - 5.0 with nitric acid. The solids concentration of the top coat slurry was 37 wt%. Zeolite beta (0.35 g / in 3 ) was added to the top coat slurry.

[0137] The bottom coat slurry was applied to the entire core length of a 1”×3”, 400 cpsi (cells per square inch) honeycomb-type substrate by the washcoat technique. The coated substrate was air-dried at 120 °C and calcined at 500 °C for 1 hour to obtain a coating loading of 1.6 g / in 3 . The top coat slurry was applied over the entire bottom coat, dried, and calcined as the bottom coat to obtain a total coating loading of 2.5 g / in 3 and a Pt / Pd weight ratio of 3 / 1.

[0138] Example 2: LT-NA-DOC article (NOx adsorber-containing DOC, zone design) This article had a zoned design in which the entire core length of a 1-inch × 3-inch, 400 cpsi (cells per square inch) honeycomb-type substrate was coated with a Pd / ferrierite (FER) bottom coat containing 120 g / ft 3 of PGM (platinum group metal) loading and a Pt / Pd weight ratio of 0 / 1, functioning as a NOx adsorber (LT-NA). The second half of the substrate was a mixture of 5 wt% Mn on an alumina support and 5 wt% Si on an alumina support (1.4 g / in 3 ), a mixture impregnated with Pt and Pd (Pt / Pd weight ratio 9 / 1, PGM loading 80 g / ft 3 ), and an HC molecular sieve, 2 wt% Fe / beta (0.7 g / in 3) was coated with a DOC topcoat containing. The total PGM loading of this LT-NA-DOC was 160 g / ft 3 and the Pt / Pd distribution was 36 / 124.

[0139] Example 3: LT-NA-DOC article (NOx adsorber-containing DOC, layered design) The article included a layered design different from that of Example 2, where the entire core length of a 1-inch × 3-inch honeycomb-type substrate with 400 cpsi cells per square inch had a PGM loading of 80 g / ft 3 and was coated with an LT-NA-DOC article consisting of a Pd / ferrierite (FER) bottom coat having a PGM loading of, and functioned as a NOx adsorber (LT-NA). The DOC topcoat consisted of a mixture of 5 wt% Mn on an alumina support and 5 wt% Si on an alumina support (1.4 g / in 3 ), and this mixture was impregnated with Pt and Pd (Pt / Pd weight ratio 9 / 1, PGM loading 60 g / ft 3 ). The total PGM loading of this LT-NA-DOC was 140 g / ft 3 and the Pt / Pd distribution was 54 / 86.

[0140] Example 4: Selective catalytic reduction on filter (SCRoF) article A catalyst slurry containing ground Cu / CHA (3.3 wt% Cu) and 5 wt% zirconium acetate binder was prepared and applied by washcoat technology to a 300 / 12, 1-inch diameter × 5.5-inch long honeycomb-type substrate filter having alternating channel openings with a volume of 70.8 cm 3 . The coated core was dried at 130 °C and calcined at 550 °C for 1 hour to obtain a coating loading of 1.75 g / in 3 .

[0141] Example 5: Pollution reduction The coated DOC article of Example 1 was hydrothermally aged in a tubular furnace at 800 °C for 16 hours using a feed gas composition of 10% H2O, 10% O2, and the balance N2. The coated LT-NA-DOC articles of Example 2 and Example 3 were hydrothermally aged in a tubular furnace at 800 °C for 16 hours and 750 °C for 25 hours, respectively, using a feed gas composition of 10% H2O, 10% O2, and the balance N2. The SCR article was further hydrothermally aged in a tubular furnace at 750 °C for 16 hours using a feed gas composition of 10% H2O, 10% O2, and the balance N2. Samples were evaluated in a laboratory reactor as a DOC+SCR or LT-NA-DOC+SCR system, where the SCR article was installed downstream of the DOC or LT-NA-DOC article. THC, CO, and NO x of the engine-out emissions to reproduce the simulated Worldwide Harmonized Light-Duty Vehicles Test Cycle (WLTC) with a 1 Hz-based dynamic temperature and flow trace, a laboratory reactor was equipped. NH3 was injected per second at an NH3 / NO x ratio = 1, upstream of the SCR article. To measure the effectiveness of the proposed exhaust gas treatment system for the NH3-fueled vehicle, two sampling lines were installed in the laboratory reactor. One sampling line was taken between the DOC or LT-NA-DOC article and the SCR article, and the second sampling line was taken after the combined system.

[0142] To measure the effectiveness of the proposed exhaust gas treatment system for NH3-fueled vehicles, three experiments were conducted.

[0143] Experiment 1. A baseline was established using conventional diesel vehicle exhaust gas with an exhaust treatment system composed of the DOC articles of Examples 1 and 2 alone or in combination with the SCR article of Example 4.

[0144] Experiment 2. The catalyst systems composed of the DOC or LT-NA-DOC articles of Examples 1 and 3 were used, either alone or in combination with the SCR article of Example 4, for the treatment of simulated NH3 fuel vehicle emissions containing no HC / CO / NO2 / CO2 in the exhaust feed. It was assumed that the NH3 fuel had the same combustion efficiency as diesel.

[0145] Experiment 3. The catalyst system of Experiment 2 was used for the treatment of simulated NH3 fuel vehicle emissions with a higher amount of NO in the exhaust gas. Additional NH3 fuel was used in the cylinder to produce the same heating efficiency as diesel, since NH3 has a lower calorific value compared to diesel on a volume basis. x For an understanding of the experiments, refer to the accompanying figures. The disclosure described herein is shown by way of example and not limitation in the accompanying drawings.

[0146] Refer to the accompanying figures for an understanding of the experiments. The disclosure described herein is shown by way of example and not limitation in the accompanying drawings.

[0147] Figure 4 depicts the temperature traces at the inlet of the DOC, after the DOC, and before the SCR, and the space velocity (SV) traces simulating various vehicle exhausts (including the diesel exhaust of Experiment 1) for a system comprising the DOC article of Example 1 in combination with the SCR article of Example 4. The average of three repetitions is shown.

[0148] Figure 5 depicts the inlet NO profile of an experiment of an exhaust treatment system comprising the DOC article of Example 1 in combination with the SCR article of Example 4. The average of three repetitions is shown. x Figure 5 depicts the inlet NO profile of an experiment of an exhaust treatment system comprising the DOC article of Example 1 in combination with the SCR article of Example 4. The average of three repetitions is shown.

[0149] Figure 6 depicts the NO conversion performance under the WLTC protocol for three experiments on an exhaust treatment system comprising the DOC article of Example 1, either alone or in combination with the SCR article of Example 4. The inlet NO profiles correspond to 0.98 g and 1.26 g of NO engine-out emissions for Experiments 1 and 2 and Experiment 3, respectively. x Figure 6 depicts the NO conversion performance under the WLTC protocol for three experiments on an exhaust treatment system comprising the DOC article of Example 1, either alone or in combination with the SCR article of Example 4. The inlet NO profiles correspond to 0.98 g and 1.26 g of NO engine-out emissions for Experiments 1 and 2 and Experiment 3, respectively. x Figure 6 depicts the NO conversion performance under the WLTC protocol for three experiments on an exhaust treatment system comprising the DOC article of Example 1, either alone or in combination with the SCR article of Example 4. The inlet NO profiles correspond to 0.98 g and 1.26 g of NO engine-out emissions for Experiments 1 and 2 and Experiment 3, respectively. x Figure 6 depicts the NO conversion performance under the WLTC protocol for three experiments on an exhaust treatment system comprising the DOC article of Example 1, either alone or in combination with the SCR article of Example 4. The inlet NO profiles correspond to 0.98 g and 1.26 g of NO engine-out emissions for Experiments 1 and 2 and Experiment 3, respectively.

[0150] CO, HC, and NO for DOC articles only x The results of the % conversion rates are shown in Table 2 below.

[0151]

Table 2

[0152] The results of the conversion rates (%) of CO, HC, and NOx in the DOC + SCR exhaust treatment system are shown in Table 3 below.

[0153]

Table 3

[0154] The above results indicate that the DOC + SCR exhaust treatment system can manage NH3-fueled vehicle applications for Euro 7 use.

[0155] Regarding Examples 2 and 3, Figure 7 shows the NOx conversion rates under the WLTC protocol for three experiments, where the LT-NA-DOC article of Example 2 is either alone or in combination with the SCR article of Example 4 under the conditions of Experiment 1, and the LT-NA-DOC article of Example 3 is either alone or in combination with the SCR article of Example 4 under the conditions of Experiments 2 and 3. The inlet NOx profiles correspond to 0.98 g and 1.26 g of NOx engine-out emissions for Experiments 1 and 2 and Experiment 3, respectively.

[0156] For both LT-NA-DOC articles only, CO, HC, and NO x The results of the % conversion rates are shown in Table 4 below.

[0157]

Table 4

[0158] The results of the conversion rates (%) of CO, HC, and NOx for both LN-NADOC + SCR exhaust treatment systems are shown in Table 5 below.

[0159]

Table 5

[0160] The above results indicate that the LT-NA-DOC+SCR exhaust treatment system can manage NH3-fueled vehicle applications for Euro7 use.

[0161] Figure 8 shows the cumulative NOx emissions under the FTP cold start US06 protocol after the DOC+SCR systems of Examples 1 and 4, and after the LT-NA-DOC+SCR exhaust treatment systems of Examples 3 and 4, for the first 500 seconds of the FTP cycle.

[0162] Figure 9 shows the NOx conversion rate under the FTP cold start US06 protocol after the DOC+SCR systems of Examples 1 and 4, and after the LT-NA-DOC+SCR exhaust treatment systems of Examples 3 and 4, for the first 500 seconds of the FTP cycle.

[0163] The results of Figures 8 and 9 indicate that the LT-NA-DOC+SCR exhaust treatment system can manage the exhaust of NH3-fueled vehicles for Euro7 use, and provide further evidence that the LT-NA-DOC article can improve the overall exhaust treatment system performance for NOx reduction.

[0164] The NOx conversion performance of the LT-NA-DOC+SCR system shown in Figures 8 and 9 suggests that the use of the LT-NA-DOC article reduces more than 50% of the cold start NOx emissions during the first 500 seconds of the FTP cycle (Figure 8). Overall, the application of the LT-NA-DOC article improves the NOx conversion rate of the entire exhaust treatment system by 6% (from 82% to 88%), as shown in Figure 9 and reported in Table 6 below.

[0165]

Table 6

[0166] Example 6: Selective Catalytic Reduction (Cu-CHA-SCR) Articles A catalyst slurry containing pulverized Cu-CHA (3.3 wt% Cu) and 5 wt% zirconium acetate binder was prepared and applied by washcoat technology to a 400 cpsi, 1-inch diameter × 5-inch length honeycomb flow-through substrate having a volume of 64.4 cm 3 The coated core was dried at 130 °C and calcined at 550 °C for 1 hour to obtain a coating loading of 2.85 g / in 3

[0167] Example 7: Selective Catalytic Reduction (Fe-CHA-SCR) Articles A catalyst slurry containing pulverized Fe-CHA (2.5 wt% Fe) and 5 wt% zirconium acetate binder was prepared and applied by washcoat technology to a 600 cpsi, 1-inch diameter × 1.5-inch length flow-through honeycomb substrate having a volume of 19.3 cm 3 The coated core was dried at 130 °C and calcined at 550 °C for 1 hour to obtain a coating loading of 2.85 g / in 3

[0168] Example 8: Ammonia Oxidation Catalyst Articles An AMOx catalyst article having a layered design was prepared on a flow-through honeycomb substrate having a volume of 12.9 cm 3 First, a bottom layer of (Pt 2 g / ft 3 ) supported on silica-alumina oxide (0.5 g / in 3 ) was prepared and applied over the entire length of the substrate by washcoat technology. Second, a top layer of Cu-CHA (5.1 wt% CuO loading) having a loading of 2.75 g / in 3 and containing 5 wt% zirconium acetate binder was prepared and applied to the coated support by washcoat technology. The coated core was dried and calcined at 450 °C for 1 hour.

[0169] ​​Example 9: Pollution Reduction The Cu-CHA SCR article of Example 6 was hydrothermally aged in a tubular furnace at 750 °C for 16 hours using a feed gas composition of 10% H2O, 10% O2, and the balance N2. The Fe-CHA SCR article and the AMOx article of Example 7 and Example 8 were hydrothermally aged in a tubular furnace at 650 °C for 100 hours using a feed gas composition of 10% H2O, 10% O2, and the balance N2. The SCR articles were further hydrothermally aged in a tubular furnace at 750 °C for 16 hours using a feed gas composition of 10% H2O, 10% O2, and the balance N2. Samples were evaluated in a laboratory reactor as a Cu-CHA SCR+AMOx or Fe-CHA SCR+Cu-CHA SCR+AMOx system. The laboratory reactor was equipped to simulate the dynamic temperature, flow rate, and engine exhaust conditions of the WLTC (Worldwide Harmonized Light Vehicles Test Cycle) on a second-by-second basis. The WLTC driving cycle represents a 23 km drive under various speed and load conditions. One sampling line was installed in the laboratory reactor to measure the effectiveness of the proposed exhaust gas treatment system for the NH3 fuel scenario after the combined system. The engine-out NOx profile of this example corresponds to 18.8 g of engine exhaust NOx. Ammonia was injected in front of the first SCR catalyst at an NH3 / NO X ratio of 1.05 unless otherwise specified.

[0170] Experiment 4. A baseline was established using Cu-CHA SCR+AMOx (System 1).

[0171] Experiment 5. System 1 was adjusted to an NH3 / NOx ratio of 1.25 between 1140 and 1260 seconds and between 1500 and 1740 seconds.

[0172] Experiment 6. System 1 had (i) ammonia dosing adjusted to an NH3 / NOx ratio of 1.25 over 0 to 600 seconds and between 1140 and 1260 seconds, and (ii) an air-fuel ratio (λ) adjusted to 1.00 when NOx emissions were zero and 1.05 when NOx emissions were >0 between 1500 and 1740 seconds.

[0173] Experiment 7. A baseline was established using Fe-CHA SCR + Cu-CHA SCR + AMOx (System 2).

[0174] Experiment 8. Over the entire WLTC cycle, System 2 had (i) ammonia dosing adjusted to an NH3 / NOx ratio of 1.25 over 1140 - 1260 seconds and 1500 - 1740 seconds, and (ii) an air-fuel ratio (λ) adjusted to 1.00 when NOx emissions were zero or 1.05 when NOx emissions were greater than 0.

[0175] For an understanding of the experiments, refer to the attached figures. The disclosure described herein is shown in the accompanying drawings by way of example and not limitation.

[0176] FIG. 10 is a diagram showing temperature traces for inlet temperature, outlet temperature, and space velocity (SV) for the WLTC cycle simulating vehicle exhaust for the systems of Experiments 4 - 8. The average of three repetitions is shown.

[0177] FIG. 11 shows the total NOx conversion rates from Experiments 4 - 8. In all cases, the overall NOx conversion meets or exceeds the current Euro7 NOx emission regulation of 0.09 mg / km.

[0178] FIG. 12 shows the inlet NO x and outlet NOx profiles for Experiments 4 and 7 over the range of 1140 - 1800 seconds. FIG. 13 shows the inlet NOx and outlet NOx profiles for Experiments 4 and 5 over the range of 1140 - 1800 seconds. The average of three repetitions is shown.

[0179] The NOx emission profiles shown in FIGS. 12 and 13 demonstrate the benefits of the addition of Fe-CHA SCR to the system (Experiment 4 vs. Experiment 7) by improving the high-temperature NOx conversion rate and reducing undesirable N2O emissions (not shown). FIGS. 12 and 13 further reveal the benefits of the increased NH3 dosing in the 1140 - 1260 s and 1500 - 1740 s intervals of the driving cycle (Experiment 4 vs. Experiment 5). This is because it results in an improved NOx conversion rate. These results indicate that NOx emissions from an NH3-fueled engine can be further eliminated using smart NH3 dosing strategies such as adjusting the ANR based on vehicle speed, load, and exhaust temperature.

[0180] FIG. 14 shows the cumulative NOx emissions for Experiments 7 and 8, and the inset shows the air-fuel ratio (λ) with a visual cutoff of 2.00. As observed, adjusting the air-fuel ratio (λ) from >2.00, typically observed in diesel applications, to 1.00 or 1.05, typically observed in gasoline applications, based on the presence or absence of NOx, shows no significant effect on the NOx conversion efficiency or NOx emissions, indicating that the application of such technologies can encompass air-fuel ratios typical of gasoline or diesel engine operation.

Claims

1. NO in the exhaust stream of an ammonia-fueled engine ｘ 1. An emission treatment system for reducing carbon dioxide emissions, the emission treatment system comprising: a selective catalytic reduction (SCR) catalyst disposed on a substrate in fluid communication with the exhaust stream of the ammonia-fueled engine; an oxidation catalyst disposed on a substrate positioned upstream and / or downstream of the SCR catalyst and in fluid communication with the exhaust stream and the SCR catalyst.

2. 10. The emissions treatment system of claim 1, wherein the oxidation catalyst comprises a refractory metal oxide support impregnated with a platinum group metal (PGM).

3. The emissions treatment system of claim 2 , wherein the PGM comprises platinum, palladium, rhodium, or a combination thereof.

4. 4. The emission treatment system of claim 2, wherein the oxidation catalyst further comprises a refractory metal oxide support impregnated with a non-PGM transition metal, an alkaline earth metal, or a combination thereof.

5. 5. The emissions treatment system of claim 4, wherein the non-PGM transition metal comprises manganese.

6. 5. The emissions treatment system of claim 4, wherein the alkaline earth metal comprises barium.

7. 4. The emission treatment system of claim 1, wherein each of the oxidation catalysts is selected from a diesel oxidation catalyst (DOC) and a selective ammonia oxidation catalyst (AMOx).

8. 4. The emissions treatment system of claim 1, wherein the SCR catalyst comprises a metal-promoted molecular sieve, a vanadia-based composition, or a combination thereof.

9. The emission treatment system of any one of claims 1 to 3, wherein the SCR catalyst is a copper-containing zeolite, an iron-containing zeolite, or a manganese-containing zeolite.

10. The zeolite is LEV, CHA, AEI, MEI, FER, ＊ 10. The wastewater treatment system of claim 9 having a framework type selected from BEA, FAU, or a combination thereof.

11. An emission treatment system according to any one of claims 1 to 3, wherein the SCR catalyst and the oxidation catalyst are present in the form of an SCR / AMOx catalyst.

12. Low temperature NO ｘ Adsorbent (Low-Temperature NO x 4. The emission treatment system of claim 1, further comprising one or more adsorbent components selected from a Low Temperature Ammonia Adsorber (LT-NA), a Low Temperature Ammonia Adsorber (LT-AA), a Low Temperature Water Vapor Adsorber (LT-WA), or combinations thereof.

13. 13. The emission treatment system of claim 12, wherein the one or more adsorbent components are arranged in any order and combination.

14. 13. The emissions treatment system of claim 12, wherein each of the one or more adsorbent components is disposed on a substrate and positioned upstream or downstream of the SCR catalyst and in fluid communication with the exhaust stream and the SCR catalyst.

15. 13. The emission treatment system of claim 12, wherein each of said one or more adsorbent components is disposed on said same substrate as a mixture, in a zoned configuration, or in a layered configuration.

16. 13. The emission treatment system of claim 12, wherein one or more of the SCR catalyst, the oxidation catalyst, and the one or more adsorption components are disposed on the same substrate as a mixture, in a zoned configuration, or in a layered configuration.

17. 13. The emission treatment system of claim 12, wherein the one or more adsorbent components and the DOC are disposed on the same substrate as a mixture, in a zoned configuration, or in a layered configuration.

18. 13. The emissions treatment system of claim 12, further comprising one or more additional SCR catalysts, one or more additional oxidation catalysts, or a combination thereof.

19. Starting with the emission treatment component closest to the engine, the component comprises: (a) adsorbent component(s), DOC, SCR catalyst, and AMOx; (b) SCR, adsorption component(s), DOC, and AMOx; (c) adsorption component(s), SCR catalyst, DOC, SCR catalyst, and AMOx; (d) adsorption component(s), SCR catalyst, and AMOx; (e) adsorbent component(s), DOC, and SCR catalyst; (f) SCR catalyst, AMOx, and adsorption component(s); (g) SCR catalyst and AMOx; (h) DOC and SCR catalysts, or 20. The emissions treatment system of claim 18, comprising: (i) one of an SCR catalyst, an SCR catalyst, and an AMOx.

20. 13. The emission treatment system of claim 12, wherein the LT-NA is present and comprises a molecular sieve or metal organic framework (MOF) impregnated with at least one platinum group metal component.

21. 13. The emission treatment system of claim 12, wherein the LT-AA is present and comprises a molecular sieve or MOF.

22. 13. The emission treatment system of claim 12, wherein the LT-WA is present and is selected from molecular sieves, clays, activated carbon, activated alumina, silica, calcium sulfate, calcium chloride, MOFs, and combinations thereof.

23. 13. The emissions treatment system of claim 12, wherein one or more of the SCR catalyst, the one or more adsorption components, and the oxidation catalyst are disposed on a flow-through substrate in the form of a honeycomb having a plurality of longitudinally extending gas flow channels extending from an inlet to an outlet, and / or the SCR catalyst, the one or more adsorption components, and the oxidation catalyst are disposed on a wall-flow substrate or optionally a metal substrate having flow-through channels, with a portion of the exhaust gas in fluid communication between the channels.

24. NO in the exhaust stream from an ammonia-fueled engine ｘ 4. A method for reducing CO₂ emissions comprising contacting the exhaust gas stream with the emission treatment system of any one of claims 1 to 3.

Images