Improved Catalyst for Selective NOx Reduction Using Hydrogen

Abstract

The present disclosure relates to a hydrogen selective catalytic reduction catalyst composition effective for reducing nitrogen oxides using hydrogen gas, the hydrogen selective catalytic reduction catalyst composition comprising a first component containing a metal component supported by an oxide carrier and a second component containing zeolite, a selective catalytic reduction article effective for catalyzing the reduction of nitrogen oxides using hydrogen gas comprising such a hydrogen selective catalytic reduction catalyst composition, and a method of treating an exhaust stream containing nitrogen oxides using an exhaust gas treatment system comprising such a hydrogen selective catalytic reduction catalyst composition.

Description

Technical Field

[0001] The present disclosure relates to a hydrogen selective catalytic reduction (H2-SCR) catalyst composition for reducing nitrogen oxides NO from engine exhaust gas in the presence of a hydrogen gas reducing agent. For example, the H2-SCR catalyst composition includes a first component including a metal component supported by an oxide carrier and a second component including zeolite. The present disclosure also relates to a selective catalytic reduction article, an exhaust treatment system for selectively reducing NO x compounds, and a method for treating an exhaust gas stream containing NO x compounds. NOx represents various chemical species of nitrogen oxides including, among others, nitric oxide (NO) and nitrogen dioxide (NO2). x As an example, diesel engine exhaust gas is a heterogeneous mixture of gaseous, liquid, and solid emissions such as carbon monoxide (CO), unburned or partially burned hydrocarbons or their oxides (HC), NOx, and particulate matter. These emissions are subject to government regulations. Accordingly, catalyst compositions and substrates on which the compositions are disposed are provided in diesel engine exhaust systems to convert some or all of these exhaust components into harmless components and reduce the amount of emissions released into the atmosphere.

[0002]

[0003] ​Currently, for diesel NOx control, two commercially available technologies are utilized: (1) selective catalytic reduction (SCR) using urea (or ammonia) and (2) lean NOx trap (LNT). The SCR technology is used in both heavy-duty and light-duty applications. The LNT technology is used only in light-duty applications. The SCR process catalytically reduces nitrogen oxides using a reducing agent (e.g., urea or ammonia) in the presence of excess oxygen, mainly resulting in the formation of nitrogen and water vapor. Alternatively, an H2-SCR catalyst composition that relies on hydrogen gas rather than ammonia as the reducing agent can be used for the reduction of NOx from engine exhaust gases. Hydrogen gas is a more reactive reducing agent than ammonia at low temperatures (e.g., below 200°C). In the case of a diesel engine, a hydrogen gas generator can be provided upstream of the catalyst composition as a source of hydrogen gas for use as a reducing agent.

[0004] Diesel oxidation catalysts (DOCs) are often placed in the exhaust flow path from a diesel engine to treat the exhaust before discharging it to the atmosphere for the conversion of gaseous HC and CO emissions. NO x species in the engine exhaust are mainly in the form of NO. The NH3 (or urea) SCR catalyst is well known to function more efficiently at low temperatures, such as below 250°C, when the NO / NO2 molar ratio is close to about 1. Low-temperature NO x performance on the downstream NH3-SCR catalyst is enhanced by also using a diesel oxidation catalyst to convert a portion of the NO in the exhaust stream to NO2. However, the NO conversion efficiency becomes very low below 250°C.

[0005] NOx emission levels are also a concern regarding the engine exhaust gases of hydrogen internal combustion engines that burn hydrogen gas. With hydrogen gas fuel, there are no CO or unburned or partially burned hydrocarbons or their oxides. However, when hydrogen is burned with air, NOx can be formed as a result of the O2 / N2 reaction in the combustion chamber. Unburned hydrogen gas and / or additional hydrogen gas injected into the exhaust stream can be used as a reducing agent for the H2-SCR catalyst composition.

[0006] However, state-of-the-art SCR catalysts, particularly H2-SCR catalyst compositions, have known problems such as a narrow operating temperature window for effective NOx conversion and an undesirable side effect of high nitrous oxide (N2O) formation. H2-SCR catalyst compositions are more effective at low temperatures, such as about 100 - 250 °C, where hydrogen gas can react selectively with NOx on the catalyst surface. As a result, H2-SCR catalyst compositions are excellent candidates for low-temperature NOx control, particularly when compared to SCR catalyst compositions that rely on ammonia as a reductant. However, at higher temperatures, hydrogen gas preferentially reacts with oxygen, which is present in large amounts in the exhaust of most compression ignition engines. During H2-SCR, the process also produces high levels of N2O by-products, and the N2O yield ranges from 20 - 40%. Since N2O is a potent greenhouse gas that is highly regulated in most of the world's automotive markets, its formation by H2-SCR catalysts should be reduced before H2-SCR catalyst compositions are selected for NOx control.

[0007] One theoretical mechanism for how an H2-SCR catalyst composition reduces nitrogen oxides (NOx) from engine exhaust gases in the presence of a hydrogen gas reductant is presented by the following basic reaction steps. H2+□→2H(a) (Equation 1) NO+□→NO(a) (Equation 2) NO(a)→N(a)+O(a) (Equation 3) O2+□→2O(a) (Equation 4) N(a)+N(a)→N2(Equation 5) NO(a)+N(a)→N2O (Equation 6) 2H(a)+O(a)→H2O (Equation 7) Here, □ represents active catalyst sites on the metal surface, and (a) represents atoms or molecules chemisorbed on the surface. It is theorized that hydrogen molecules adsorb on the surface of the supported metal component and dissociate into hydrogen atoms. NO molecules can undergo associative adsorption and dissociative adsorption on the surface. The combination of two adsorbed N atoms forms an N₂ molecule, and the combination of one NO molecule and an O atom forms N₂O. Surface H atoms capture surface O atoms to form water, and thus keep the metal surface in a reduced or activated state. Oxygen is a competitor of hydrogen rather than a reactant necessary for NO reduction because oxygen increases the hydrogen required to prevent the metal surface from being oxidized or deactivated.

[0008] European Patent No. 3409359 (A2) discloses a quaternary catalyst composition comprising a plurality of metal oxide nanoparticles hybridized to a metal zeolite, and the metal oxide nanoparticles have a maximum dimension of 0.1 - 50 nm.

[0009] International Publication No. 2018 / 073750 (A1) relates to an exhaust treatment system including a hydrogen selective catalytic reduction article and a catalyst article for selectively reducing NOₓ compounds.

[0010] U.S. Patent Application Publication No. 2021 / 102486 (A1) relates to an emissions control system for treating an exhaust gas stream, which includes an oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream, at least one selective catalytic reduction (SCR) composition disposed on the substrate downstream of the oxidation catalyst composition, and a hydrogen injection article configured to introduce hydrogen into the exhaust gas stream upstream of the oxidation catalyst composition or downstream of the oxidation catalyst composition and upstream of at least one SCR composition.

[0011] European Patent No. 2313196 (A2) discloses a binary mixed oxide catalyst suitable for reducing NO x using H₂ as a reducing agent. This catalyst includes those from the A metal oxide of Fe₂O₃ and those from the B metal oxide of MnO₂, which are co-precipitated and mixed.

[0012] As global NOx regulations become stricter and the average engine exhaust temperature continues to decline, it is becoming increasingly difficult to control NOx emissions using current SCR technology. Therefore, in this technical field, it is necessary to identify a more effective NOx reduction H2-SCR technology that can be sufficiently effective over a variety of temperature ranges without producing high yields of N2O gas in order to meet future stringent regulations.

[0013] The present disclosure provides an improved H2-SCR catalyst composition that significantly increases the NOx conversion rate and reduces N2O formation, particularly at low temperatures, compared to a standard baseline H2-SCR catalyst composition. In particular, it has been discovered that by adding a zeolite component to the PGM component on an oxide support, the NOx conversion rate can be significantly increased and N2O formation reduced using the H2-SCR catalyst composition. This simultaneous improvement in activity and selectivity appears to be related to an as-yet unrecognized synergistic effect between the two components. FIG. 11 is a schematic diagram of an embodiment of the H2-SCR catalyst composition of the present disclosure in which a first component comprising a metal component (PGM, black dots) on an oxide support (white oval) is combined with a separate second component comprising zeolite (yellow squares).

[0014] The improved performance was achieved using a variety of compositions including those having a metal component selected from platinum (Pt) and / or palladium (Pd) on a (mixed) oxide support, * including but not limited to those having a zeolite with a zeolite structure such as BEA, FER, MOR, CHA, FAU, and MFI.

[0015] 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. Other aspects and advantages of the disclosed subject matter will become apparent from the following.

Brief Description of the Drawings

[0016] To provide an understanding of embodiments of the present disclosure, the accompanying drawings are referred to. The drawings are merely illustrative and should not 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 the sake of simplicity and clarity of illustration, the features shown in the drawings are not necessarily drawn to scale. For example, the dimensions of some features may be exaggerated relative to other features for clarity.

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[0017] As used herein, the term "a" or "an" entity refers to one or more of that entity; for example, "a carrier" refers to one or more carriers or at least one carrier, unless otherwise specified. Thus, the terms "a" (or "an"), "one or more", and "at least one" are used interchangeably herein.

[0018] As used herein, the term "about" means approximately, nearly, substantially, or around. When the term "about" is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the recited numerical values. In general, the term "about" is used herein to modify numerical values above and below the recited value by a variation of 5%. All numerical values, whether or not explicitly indicated as such, are modified by the term "about". Numerical values modified by the term "about" include the specifically identified value. For example, "about 100" means numbers in the range of 95 to 105, including 95, 100, and 105. The recitation of a range of values herein is merely intended to serve as a shorthand method of referring individually to each separate value within that range, and each separate value is incorporated herein as if it were individually recited herein.

[0019] As used herein, the term "catalyst" or "catalyst material" or "catalytic material" refers to a material that promotes a reaction.

[0020] As used herein, the term "catalyst article" refers to an element used to promote a desired reaction. For example, a catalyst article can include a substrate, such as a honeycomb substrate, having a washcoat containing a catalyst species, such as a catalyst composition.

[0021] As used herein, the term "metal component" refers to any platinum group metal (PGM) other than osmium (i.e., Ru, Rh, Ir, Pd, or Pt). References to PGMs are intended to encompass the presence of PGMs in any valence state. For example, the PGM may be in the zero-valent metal form, or alternatively, the PGM may be in another form such as an oxide form or a nitrate form. Terms such as "platinum (Pt)", "rhodium (Rh)", "palladium (Pd)", "iridium (Ir)", "ruthenium (Ru)", 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, upon calcination or use of the catalyst.

[0022] As used herein, the term "nitrogen oxides" or "NOx" refers to nitrogen oxides. Exemplary nitrogen oxides include oxidized compounds such as NO and NO2.

[0023] As used herein, "catalyst" or "catalyst material" or the "support" of a "catalyst material" refers to a material that receives the "catalyst" or "catalyst material" or "catalyst material" by precipitation, association, dispersion, impregnation, or other suitable means. The term "oxide support" refers to an oxide compound containing a transition metal or lanthanide (e.g., aluminum (Al), vanadium (V), tungsten (W), titanium (Ti), copper (Cu), iron (Fe), nickel (Ni), manganese (Mn), cerium (Ce), lanthanum (La), praseodymium (Pr), zinc (Zn), niobium (Nb), zirconium (Zr), molybdenum (Mo), tin (Sn), silicon (Si), calcium (Ca), yttrium (Y), or combinations thereof) that is catalytically active for the reduction of NOx or promotes another catalyst component to be more active for the reduction of NOx. Oxide supports include, in particular, oxides of copper, iron, manganese, tin, aluminum, zirconium, silicon, titanium, tungsten, molybdenum, nickel, and combinations thereof.

[0024] As used herein, the term "promoted" refers to a metal component (a "promoter metal") that is typically added to the zeolite by ion exchange, for example, and is intentionally added to the zeolite, as contrasted with impurities inherent to the zeolite. In some embodiments, promoter metals that can be used to prepare the promoted zeolite of the disclosed catalyst compositions include, but are not limited to, iron (Fe) and copper (Cu). In some embodiments, both copper and iron can be present as promoter metals.

[0025] As used herein, the term "substrate" refers to a monolithic material on which a catalyst composition is typically disposed in the form of a washcoat containing a plurality of carriers having catalyst species thereon.

[0026] As used herein, the term "zeolite" refers to a specific example of a molecular sieve containing silicon atoms and aluminum atoms. Zeolites are crystalline materials having a fairly uniform pore size in the range of about 3 to 10 angstroms (Å), depending on the type of zeolite and the type and amount of cations contained in the zeolite lattice.

[0027] The term "acidic zeolite" refers to a zeolite that can be converted to an H-zeolite such as a protonated zeolite (H-zeolite) or an NH4-zeolite. The term "H-zeolite" refers to a zeolite having more than 90% exchangeable sites as protons (H+).

[0028] H2-SCR catalyst composition In the present disclosure, a hydrogen selective catalytic reduction (H2-SCR) catalyst composition effective for catalyzing the reduction of NOx from engine exhaust gases in the presence of a hydrogen gas reductant is provided. The H2-SCR catalyst includes a first component including a metal component supported by an oxide carrier and a second component including a zeolite.

[0029] In some embodiments, the metal component is a PGM selected from platinum, palladium, rhodium, iridium, ruthenium, and combinations thereof. For example, the metal component can be selected from platinum, palladium, rhodium, iridium, and combinations thereof. In some embodiments, the metal component is either platinum or palladium, or a combination of platinum and palladium.

[0030] In some embodiments, two or more PGMs can be combined on the same oxide support. For example, both platinum and palladium can be present on the same oxide support. In other embodiments, the composition further includes a third component comprising a second PGM supported on a separate second oxide support. For example, platinum and palladium can be present on different oxide supports, i.e., the oxide supports from the first component and the third component. Regardless of whether they are present on the same or different oxide supports, the weight ratio of platinum to palladium can range from about 1:10 to about 10:1, about 1:5 to about 10:1, about 1:1 to about 10:1, about 2:1 to about 10:1, or about 3:1 to about 5:1.

[0031] Each supported PGM can be prepared separately or multiple PGMs can be impregnated onto the same support in the same process.

[0032] The metal component can be dispersed on the oxide support, for example, by dispersing a soluble precursor (e.g., palladium nitrate) on the oxide support. Alternatively, the metal component is provided in the composition in particulate form, such as fine particles with a diameter of 1 to 15 nanometers or less.

[0033] The amount of the metal component deposited on the oxide support can vary. For example, an exemplary PGM loading for an H2-SCR catalyst composition is about 1 to about 200 g / ft 3 , for example, about 10 to about 50 g / ft 3It can be. The first component of the H2-SCR catalyst composition can contain PGM in an amount of about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 3.0 wt%, about 4.0 wt%, or about 5.0 wt% to about 6.0 wt%, about 7.0 wt%, about 8.0 wt%, about 9.0 wt%, about 10.0 wt%, about 11.0 wt%, about 12.0 wt%, about 13.0 wt%, about 14.0 wt%, about 15.0 wt%, about 16.0 wt%, about 17.0 wt%, about 18.0 wt%, about 19.0 wt%, or about 20.0 wt% based on the weight of the oxide support. In some embodiments, the metal component is present in an amount of about 0.1 wt% to about 10.0 wt% based on the weight of the oxide support.

[0034] In some embodiments, the oxide support is an oxide of Al, V, W, Ti, Cu, Fe, Ni, Mn, Ce, La, Pr, Zn, Nb, Zr, Mo, Sn, Si, Ca, Y, or a combination thereof. Possible oxide supports include Al2O3, SiO2, SnO2, CeO2, ZrO2, MgO, La2O3, CaO, Y2O3, TiO2, SiO2, FeO x , and MnO x are included. In some embodiments, the oxide support is selected from TiO2, ZrO2, Al2O3, and SiO2. The oxides of Co, Cr, Ag, and Au are not suitable oxide supports for the compositions of the present disclosure.

[0035] In other embodiments, the oxide support is a mixed oxide support. Possible mixed oxide supports include TiO2 / ZrO2, CeO2 / MgO, WO3 / ZrO2, WO3 / Al2O3, WO3 / TiO2, WO3 / SiO2, Al2O3 / La2O3, TiO2 / Al2O3, V2O5 / TiO2-Al2O3, Nb2O5 / SiO2, ZnO / Al2O3, SiO2 / TiO2, SiO2 / Al2O3, Mn / TiO2 / Al2O3, and perovskite. In a further embodiment, the oxide support is selected from TiO2 / ZrO2, WO3 / ZrO2, WO3 / Al2O3, WO3 / TiO2, WO3 / SiO2, SiO2 / TiO2, and SiO2 / Al2O3.

[0036] In some embodiments, the metal component of the first component and / or the second PGM of the third component is supported by an oxide / zeolite support. The present disclosure is not directed to an H2-SCR catalyst composition having a first component that includes a zeolite support and does not include an oxide support.

[0037] In some embodiments, the first component and / or the third component of the H2-SCR catalyst composition may further include an acidic oxide modifier (sometimes referred to as a promoter) on an oxide support. When the acidic oxide modifier is present, the mass ratio of the modifier to the PGM can be in the range of about 1:1 to about 1:30. For example, the mass ratio of the modifier to the PGM can be in the range of about 1:3 to about 1:10. The lower limit of the range can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9. The upper limit of the range can be 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, 1:22, 1:24, 1:26, 1:28, and 1:30. In certain embodiments, the acidic oxide modifier on the oxide support can be selected from SiO2, TiO2, Nb2O5, MoO3, and combinations thereof. By way of example, SiO2 may be present as an acidic oxide modifier on a TiO2 or Al2O3 support, or SiO2 and WO3 may be present as an acidic oxide modifier on a ZrO2 support. For example, the acidic modifier may be added to the support as colloidal nanoparticles and thus may not be part of the support. When the oxide is part of a mixed oxide support, " / " is used to indicate combinations such as Pt / SiO2 / TiO2. When the oxide is used as an acidic modifier, this is indicated using "-" such as Pt-SiO2 / TiO2.

[0038] The H2-SCR catalyst composition includes a second component that includes a zeolite. In some embodiments, the second component consists essentially of or consists of a zeolite. The structural type of the zeolite can be various. In certain embodiments, the zeolite has a structural type selected from AEI, AFT, AFX, AVL, * BEA, CHA, DDR, EAB, EEI, ERI, FAU, FER, IFY, IRN, KFI, LEV, LTA, LIN, MOR, MER, MFI, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations thereof.

[0039] In some embodiments, the zeolite is an acidic zeolite. For example, the zeolite can be of a structural type selected from MOR (H-mordenite), * BEA (H-beta), FER (H-ferrierite), CHA (H-chabazite), FAU (H-Y), MFI (H-ZSM-5), and combinations thereof.

[0040] The zeolite has no practical activity for the H2-SCR catalyst composition. However, when the zeolite, particularly the acidic zeolite, is included as a second component of the H2-SCR catalyst composition, a synergistic effect was unexpectedly observed. The presence of the zeolite as the second component improved the NOx conversion rate and reduced the amount of N2O formed during the catalytic reaction with respect to the first component alone. This synergistic effect was not observed when the first component included the zeolite.

[0041] In other embodiments, the second component of the H2-SCR catalyst composition is a metal-promoted zeolite. The metal that promotes the zeolite is generally a base metal (e.g., a transition metal or a lanthanide). In some embodiments, the metal that promotes the zeolite is one or more of Cu, Co, Ni, La, Mn, Fe, V, Ag, Ce, Nd, Mo, Hf, Y, or W. In certain embodiments, the metal that promotes the zeolite is one or more of Cu and Fe. In certain embodiments, the metal that promotes the zeolite is Fe. The reference to "metal" in this context allows for the presence of PGMs in any valence state. For example, the metal that promotes the zeolite may be in the zero-valent metal form, or the metal may be in the oxide form. Generally, the metal that promotes the zeolite is present in the form of an oxide.

[0042] Zeolites generally have a silica to alumina (Si / Al) molar ratio of 2 or more. In some embodiments, the zeolite of the H2-SCR catalyst composition has an Si / Al molar ratio in the range of 2:1 to 100:1. In other embodiments, the zeolite has an Si / Al molar ratio in the range of 10:1 to 15:1. Within the Si / Al molar ratio of 10:1 to 15:1, the H2-SCR catalyst compositions of the present disclosure having a FAU or FER structure type were observed to provide better activity at lower temperatures and a wider reaction temperature window than other structure types. The increased NOx conversion rate is theorized to be related to the Bronsted acidity of the zeolite. The lower the Si / Al molar ratio in the zeolite, the higher the acid density provided by the zeolite. However, the lower the Si / Al molar ratio, typically, the lower the hydrothermal stability of the zeolite.

[0043] In some embodiments, the catalyst composition has a first component to second component ratio in the range of 95:5 to 10:90.

[0044] Preparation of H2-SCR Catalyst Composition According to the present disclosure, the H2-SCR catalyst composition is generally prepared by providing a first component comprising a metal component supported by an oxide carrier and a second component comprising a zeolite. The first and second components are initially separate components. If present, the third component may be separate or may be pre-combined with the first component.

[0045] The components can be combined to form the H2-SCR catalyst composition in various ways. In one embodiment, the components can be physically mixed, such as by dry powder mixing. In another embodiment, the components can be combined by dispersing the components in a solvent such as water to form a slurry. In yet another embodiment, the components can be co-ground, such as by ball milling or wet milling.

[0046] Generally, the catalyst composition is prepared to be coated on a substrate. Typical additional components of the catalyst composition include, but are not limited to, for example, additives for controlling the pH and viscosity of the catalyst composition to be coated. The additional components can include associative thickeners and / or surfactants (including anionic, cationic, nonionic, or amphoteric surfactants). The typical pH range of the catalyst composition is about 3 to 6. Accordingly, acidic or basic species can be added to the catalyst composition to be coated to adjust the pH. For example, in some embodiments, the pH is adjusted downward by the addition of an aqueous acetic acid solution or an aqueous nitric acid solution, or upward by the addition of monoethanolamine.

[0047] The present H2-SCR catalyst composition can also be prepared using a binder, for example, a ZrO2 binder derived from a suitable precursor such as zirconyl acetate or any other suitable zirconium precursor such as zirconyl nitrate. The zirconyl acetate binder provides a coating that remains homogeneous and intact, for example, when the catalyst is exposed to a high temperature of at least about 600 °C to about 800 °C or higher 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 can also be used. Examples of silica binders include various forms of SiO2 including silicates and colloidal silica. The binder composition can include any combination of zirconia, alumina, and silica.

[0048] After the components are combined, the coated catalyst composition can be milled to reduce the particle size, facilitating the mixing of the particles and the formation of a homogeneous material. The milling can be achieved with a ball mill, a continuous mill, or other similar devices, and the solids content of the slurry can be, for example, about 20 to 60 wt%, more specifically about 20 to 40 wt%. In one embodiment, the milled slurry is characterized by a D90 particle size of about 1 to about 40 micrometers, preferably 2 to about 20 micrometers, more preferably about 4 to about 15 micrometers.

[0049] To simulate real-world use scenarios, the catalyst composition can be hydrothermally aged in 10% steam in air at 650 °C for 50 hours prior to testing for NOx conversion and N2O formation rates.

[0050] Catalyst article In another aspect of the present disclosure, a selective catalytic reduction (SCR) article effective to catalyze the reduction of nitrogen oxides (NOx) from an exhaust gas in the presence of a hydrogen gas reductant includes a substrate having disposed thereon the H2-SCR catalyst composition of the present disclosure.

[0051] Substrate In one or more embodiments, the present H2-SCR catalyst composition is disposed on a substrate to form a catalyst article. The catalyst article including the substrate is generally used as part of an exhaust gas treatment system (e.g., catalyst articles including, but not limited to, articles including the SCR compositions disclosed herein). Useful substrates are three-dimensional and have a length, diameter, and volume similar to a cylinder. The shape does not necessarily conform to a cylinder. The length is the axial length defined by an inlet end and an outlet end.

[0052] According to one or more embodiments, the substrate for the disclosed composition(s) can be composed of any material typically used to prepare automotive catalysts and typically includes a metallic or ceramic honeycomb structure. The substrate provides a plurality of walls to which a washcoat composition is applied and adhered, thereby acting as a carrier for the catalyst composition.

[0053] The ceramic substrate can be made of any suitable refractory material, such as cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon mullite, rhodonite, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicate, etc.

[0054] The substrate can also be metallic and include one or more metals or metal alloys. The metal substrate can include any metal substrate, such as those having openings or "punch-outs" in the channel walls. In some embodiments, the metal substrate can be used in various shapes such as pellets, compressed metal fibers, corrugated sheets, or monolithic foams. In some embodiments, the metal substrate includes heat-resistant base metal alloys, particularly those in which iron is a substantial or major component. Such alloys can contain one or more of nickel, chromium, and aluminum, and in each case, the total of these metals is at least about 15 weight percent (wt%) of the alloy, 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 about 0 wt% to about 20 wt% nickel. In some embodiments, the metal 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 the channels, and those having blades and holes to enhance the gas transport between the channels to enable radial gas transport throughout the monolith.

[0055] Any suitable substrate for the catalytic articles disclosed herein may be employed, such as a monolithic substrate (a "flow-through substrate") having fine parallel gas flow channels extending from an inlet face to an outlet face of the substrate so as to be open to the flow of fluid passing therethrough. 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, typically with each flow channel blocked at one end of the substrate body and the flow channels alternately blocked at opposing end faces (a "wall-flow filter").

[0056] In some embodiments, the catalytic substrate includes a honeycomb substrate in the form of a wall-flow filter or a flow-through substrate. In some embodiments, the substrate is a wall-flow filter. In some embodiments, the substrate is a flow-through substrate. Flow-through and wall-flow substrates are also taught, for example, in International Application Publication No. WO 2016 / 070090 and U.S. Patent Application Publication No. US 2012 / 0178380 (A1), which are hereby incorporated by reference in their entirety.

[0057] Substrate Coating Process To manufacture the SCR articles of the present disclosure, the substrate is coated with the H2-SCR catalyst composition disclosed herein.

[0058] The present H2-SCR catalyst composition may typically be applied in the form of one or more washcoats of the H2-SCR catalyst composition. A washcoat is formed by preparing a slurry containing the catalyst composition at a specific solids content (e.g., from about 10 to about 60 wt%) in a liquid vehicle, which is then applied to the substrate using any washcoat technique known in the art, dried, and calcined to provide a coating layer. When multiple coatings are applied, the substrate is dried and / or calcined after each washcoat is applied and / or after the desired multiple washcoats are applied. In one embodiment, the H2-SCR catalyst composition is applied to the substrate as a single washcoat.

[0059] After calcination, the catalyst loading obtained by the above washcoat technique 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 catalyst loading can be changed by varying the slurry rheology. In addition, the coating / drying / calcination process for generating the washcoat layer (coating layer) 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.

[0060] The present catalyst coating may include one or more coating layers, and at least one layer includes the present H2-SCR catalyst composition or one or more components of the catalyst composition. The catalyst coating may include one or more thin adhesive coating layers disposed on and adhered to at least a portion of the substrate. The entire coating includes individual "coating layers".

[0061] In some embodiments, the present catalyst article may include the use of one or more catalyst layers and combinations of one or more catalyst layers. The catalyst material may be present only on the inlet side of the substrate wall, only on the outlet side, both on the inlet side and the outlet side, or the wall itself may consist of all or part of the catalyst material. The catalyst coating may be on the surface of the substrate wall and / or within the pores of the substrate wall, i.e., "within" and / or "on" the substrate wall. Thus, the phrase "washcoat disposed on the substrate" means on any surface, e.g., on the wall surface and / or on the pore surface.

[0062] The washcoat(s) can be applied such that different coating layers can contact the substrate directly. Alternatively, one or more "undercoats" may be present, such that at least a portion of one or more catalyst coating layers do not contact the substrate directly (rather, they contact the undercoat). One or more "overcoats" may be present, such that at least a portion of the coating layer(s) is not directly exposed to the gas stream or atmosphere (rather, it contacts the overcoat).

[0063] Alternatively, the present H2-SCR catalyst composition may be in the upper coating layer on the lower coating layer. The H2-SCR catalyst composition may be present in the upper layer and the lower layer. Any one layer may extend over the entire axial length of the substrate. For example, the lower layer may extend over the entire axial length of the substrate, and the upper layer may also extend over the entire axial length of the substrate on top of the lower layer. Each of the upper layer and the lower layer may extend from either the inlet end or the outlet end.

[0064] For example, both the lower coating layer and the upper coating layer may extend from the same substrate end, the upper layer partially or completely covering the lower layer, the lower layer extending over part or all of the length of the substrate, and the upper layer extending over part or all of the length of the substrate. Alternatively, the upper layer may cover part of the lower layer. For example, the lower layer may extend over the entire length of the substrate, and the upper layer may extend from either the inlet end or the 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.

[0065] Alternatively, the lower layer may extend from either the inlet end or the outlet end by about 10%, about 15%, about 25%, about 30%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, or about 95% of the substrate length, and the upper layer may extend from either the inlet end or the outlet end by about 10%, about 15%, about 25%, about 30%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, or about 95% of the substrate length, with at least a part of the upper layer covering the lower layer. This "coated" zone may extend, for example, by about 5% to about 80% of the substrate length, such as by about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% of the substrate length.

[0066] In some embodiments, the H2-SCR catalyst composition disclosed herein disposed on a substrate disclosed herein includes a first washcoat comprising the H2-SCR catalyst composition, the first washcoat being disposed on at least a portion of the length of the catalyst substrate, and a second washcoat having the same or a different composition is disposed on at least a portion of the length of the catalyst substrate.

[0067] In some embodiments, the first washcoat is disposed directly on the catalyst substrate, and the second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, the second washcoat is disposed directly on the catalyst substrate, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, the first washcoat is disposed directly on the catalyst substrate from about 10% to about 50% of the total length from the inlet end, and the second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, the second washcoat is disposed directly on the catalyst substrate from about 50% to about 100% of the total length from the inlet end, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, the first washcoat is disposed directly on the catalyst substrate from about 20% to about 40% of the total length from the inlet end, and the second washcoat extends from the inlet end to the outlet end. In some embodiments, the first washcoat is disposed directly on the catalyst substrate from about 10% to about 50% of the total length from the outlet end, and the second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, the first washcoat is disposed directly on the catalyst substrate from about 20 to about 40% of the total length from the outlet end, and the second washcoat extends from the inlet end to the outlet end. In some embodiments, the second washcoat is disposed directly on the catalyst substrate from about 50% to about 100% of the total length from the outlet end, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, the first washcoat is disposed directly on the catalyst substrate covering 100% of the total length, and the second washcoat is disposed on the first washcoat covering 100% of the total length. In some embodiments, the second washcoat is disposed directly on the catalyst substrate covering 100% of the total length, and the first washcoat is disposed on the second washcoat covering 100% of the total length.

[0068] The catalyst coating may advantageously be "zoned", i.e., include zoned catalyst layers, that is, the catalyst coating contains various compositions over the axial length of the substrate. This may also be described as "laterally zoned". For example, the layer may extend from the inlet end to the 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. The different coating layers may or may not be adjacent to each other and may or may not overlap each other. Alternatively, different layers may cover a part of each other to provide a third "intermediate" zone. The intermediate zone may extend, for example, from about 5% to about 80% of the substrate length, such as about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% of the substrate length.

[0069] The zones of the present disclosure are defined by the relationship of the coating layers. There are several possible zoning configurations for different coating layers. For example, an upstream zone and a downstream zone may exist, an upstream zone, an intermediate zone, and a downstream zone may exist, or four different zones may exist. When two layers are adjacent and do not overlap, an upstream zone and a downstream zone exist. When two layers overlap to some extent, an upstream zone, a downstream zone, and an intermediate zone exist. For example, when the coating layer extends over the entire length of the substrate, a different coating layer extends from the outlet end by a specific length, and covers a part of the first coating layer, an upstream zone and a downstream zone exist.

[0070] For example, the article may include an upstream zone including a first washcoat layer containing an H2-SCR catalyst composition, and a downstream zone including a second washcoat layer having the same or a different composition.

[0071] Alternatively, the upstream zone may include the second washcoat layer, and the downstream zone may include the first washcoat layer.

[0072] In some embodiments, the first washcoat is disposed on the catalyst substrate from the inlet end to a length of about 10% to about 50% of the total length, and the second washcoat is disposed on the catalyst substrate from the outlet end to a length of about 50% to about 90% of the total length. In some embodiments, the first washcoat is disposed on the catalyst substrate from the outlet end to a length of about 10% to about 50% of the total length, and the second washcoat is disposed on the catalyst substrate from the inlet end to a length of about 50% to about 90% of the total length.

[0073] In some embodiments, the catalyst article may further comprise a diesel oxidation catalyst (DOC) composition, which may be in a zone downstream from the H2-SCR catalyst composition, may be within a lower layer having the H2-SCR catalyst article as an upper layer, or the DOC composition may be admixed with the H2-SCR catalyst composition. In other embodiments, the catalyst article may further comprise a lean NOx adsorbent (LTNA). The LTNA functionality may be part of the DOC composition, part of the H2-SCR catalyst composition, part of both the DOC composition and the H2-SCR catalyst composition, separate from the DOC composition and the H2-SCR catalyst composition, or a combination thereof.

[0074] Exhaust gas treatment system In another aspect of the present disclosure, an emissions treatment system for selectively reducing NOx compounds from an exhaust gas stream includes an SCR article having the H2-SCR catalyst composition disclosed herein. Another embodiment may feature a system that includes an H2-SCR catalyst composition and an NH3-SCR catalyst composition.

[0075] In a further embodiment, the emissions treatment system may further comprise a hydrogen gas generator or a hydrogen gas injector. The hydrogen gas generator or hydrogen may be in fluid communication and upstream of the H2-SCR catalyst article. Such a system may also include components such as pumps and reservoirs. The hydrogen generator may be variable and may be selected from the group consisting of on-board hydrogen, hydrogen generated from alcohol reforming, hydrogen generated from ammonia decomposition, hydrogen generated from hydrocarbon reforming, and mixtures thereof.

[0076] In some embodiments, the emissions treatment system may further comprise a lean NOx trap (LNT) catalyst article comprising a substrate and an LNT catalyst composition, the LNT catalyst article being in fluid communication with and downstream of the H2-SCR catalyst article.

[0077] The relative arrangement of the various components present within the emissions treatment system can be varied. In the present exhaust gas treatment system and method, the exhaust gas stream enters at an upstream end and exits at a downstream end and is received within the SCR article(s) or treatment system. The inlet end of the substrate of the article is synonymous with the “upstream” or “front” end. The outlet end is synonymous with the “downstream” or “rear” end. The treatment system is generally downstream of and in fluid communication with an internal combustion engine, such as a diesel engine or a hydrogen internal combustion engine.

[0078] Method for Treating Engine Exhaust Another aspect of the present invention relates to a method for treating an exhaust gas stream containing NOx compounds. In some embodiments, the method includes treating the exhaust gas stream during a low temperature stage or cold start stage in which the exhaust gas temperature is about 200° C. or less, about 175° C. or less, about 150° C. or less, about 125° C. or less, or about 100° C. or less. In some embodiments, the method includes treating the exhaust gas stream, wherein the exhaust temperature is from about 100° C. to about 250° C.

[0079] The method can include disposing a H2-SCR catalyst article according to the present disclosure downstream of the engine and flowing the engine exhaust gas stream over the catalyst. In one or more embodiments, the method further includes disposing additional catalyst components downstream from the engine as described above.

[0080] The present H2-SCR catalyst compositions, articles, systems, and methods are suitable for treating exhaust gas streams from diesel engines and hydrogen internal combustion engines. The H2-SCR catalyst compositions are also suitable for treating NOx emissions from stationary industrial processes, from indoor air, or for catalytic action in chemical reaction processes.

[0081] It will be readily apparent to those skilled in the art that appropriate modifications and adaptations can be made to the compositions, methods, and uses described herein without departing from the scope of any embodiment or aspect thereof. The provided compositions and methods 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 scope of the compositions, methods, and uses described herein includes all actual or potential combinations of the 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 a specific incorporation of other descriptions is specifically provided.

[0082] Before describing exemplary embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of the configurations or process steps described in the following examples, and that other embodiments are possible and can be practiced or carried out in various ways.

[0083] Embodiment: The present invention is further illustrated by the following sets of embodiments and combinations of embodiments resulting from the dependencies and cross-references shown. In particular, in each case where the scope of an embodiment is referred to, for example, in the context of a term such as "a method according to any one of Embodiments 1 to 4", all embodiments within this scope are meant to be explicitly disclosed to those skilled in the art, that is, it should be noted that the expression of this term is understood by those skilled in the art to be synonymous with "a method according to any one of Embodiments 1, 2, 3, and 4". Furthermore, it should be clearly noted that the following series of embodiments represents a properly structured part of the description directed to the general and preferred aspects of the present invention, rather than a series of claims defining the scope of protection.

[0084] Embodiment 1. Nitrogen oxides (NO from engine exhaust gas in the presence of a hydrogen gas reducing agent xA hydrogen selective catalytic reduction (H2-SCR) catalyst composition effective for reducing

[0085] Embodiment 2. The H2-SCR catalyst composition according to Embodiment 1, wherein the metal component is a PGM selected from platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), and combinations thereof. Exemplary PGM loadings, when coated on a substrate, are about 1 to about 200 g / ft 3 e.g., about 10 to about 50 g / ft 3 and can be. Further, the composition can contain about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 3.0 wt%, about 4.0 wt%, or about 5.0 wt% to about 6.0 wt%, about 7.0 wt%, about 8.0 wt%, about 9.0 wt%, about 10.0 wt%, about 11.0 wt%, about 12.0 wt%, about 13.0 wt%, about 14.0 wt%, about 15.0 wt%, about 16.0 wt%, about 17.0 wt%, about 18.0 wt%, about 19.0 wt%, or about 20.0 wt% of PGM based on the weight of the oxide support.

[0086] Embodiment 3. The H2-SCR catalyst composition according to Embodiment 2, wherein the PGM is Pt.

[0087] Embodiment 4. The H2-SCR catalyst composition according to Embodiment 2, wherein the PGM is Pd.

[0088] Embodiment 5. The H2-SCR catalyst composition according to any one of Embodiments 1 to 4, further comprising a second PGM supported on an oxide support.

[0089] Embodiment 6. The H2-SCR catalyst composition according to Embodiment 5, wherein the second PGM is Pd. For example, when the metal component is Pt, the weight ratio of Pt to Pd can be in the range of about 1:10 to about 10:1, about 1:5 to about 10:1, about 1:1 to about 10:1, about 2:1 to about 10:1, or about 3:1 to about 5:1.

[0090] Embodiment 7. The H2-SCR catalyst composition according to any one of Embodiments 1 to 6, further comprising a third component containing a second PGM supported on a second oxide support.

[0091] Embodiment 8. The H2-SCR catalyst composition according to Embodiment 7, wherein the metal component is Pt and the second PGM is Pd. For example, the weight ratio of Pt to Pd can be in the range of about 1:10 to about 10:1, about 1:5 to about 10:1, about 1:1 to about 10:1, about 2:1 to about 10:1, or about 3:1 to about 5:1.

[0092] Embodiment 9. The H2-SCR catalyst composition according to any one of Embodiments 1 to 8, wherein the metal component is present in an amount of about 0.1 wt% to about 10 wt% based on the weight of the oxide support.

[0093] Embodiment 10. The H2-SCR catalyst composition according to any one of Embodiments 1 to 9, wherein the oxide support is an oxide of aluminum (Al), vanadium (V), tungsten (W), titanium (Ti), copper (Cu), iron (Fe), nickel (Ni), manganese (Mn), cerium (Ce), lanthanum (La), praseodymium (Pr), zinc (Zn), niobium (Nb), zirconium (Zr), molybdenum (Mo), tin (Sn), silicon (Si), calcium (Ca), yttrium (Y), or a combination thereof. For example, the oxide support is an oxide of copper, iron, manganese, tin, aluminum, zirconium, silicon, titanium, tungsten, molybdenum, nickel, or a combination thereof.

[0094] Embodiment 11. The oxide support is Al2O3, SiO2, SnO2, CeO2, ZrO2, MgO, La2O3, CaO, Y2O3, TiO2, SiO2, FeOx and MnO x such as, and the H2-SCR catalyst composition according to Embodiment 10, selected from TiO2, ZrO2, Al2O3, and SiO2.

[0095] Embodiment 12. The H2-SCR catalyst composition according to any one of Embodiments 1 to 10, wherein the oxide carrier is a mixed oxide carrier.

[0096] Embodiment 13. The H2-SCR catalyst composition according to Embodiment 12, wherein the mixed oxide is selected from TiO2 / ZrO2, CeO2 / MgO, WO3 / ZrO2, WO3 / Al2O3, WO3 / TiO2, WO3 / SiO2, Al2O3 / La2O3, TiO2 / Al2O3, V2O5 / TiO2-Al2O3, Nb2O5 / SiO2, ZnO / Al2O3, SiO2 / TiO2, SiO2 / Al2O3, Mn / TiO2 / Al2O3, and perovskite. For example, the mixed oxide is selected from TiO2 / ZrO2, WO3 / Al2O3, WO3 / TiO2, WO3 / SiO2, WO3 / ZrO2, SiO2 / TiO2, and SiO2 / Al2O3.

[0097] Embodiment 14. The H2-SCR catalyst composition according to any one of Embodiments 1 to 13, further comprising an acidic oxide modifier on the oxide carrier.

[0098] Embodiment 15. The H2-SCR catalyst composition according to Embodiment 14, wherein the acidic oxide modifier is selected from SiO2, WO3, Nb2O5, MoO3, and TiO2.

[0099] Embodiment 16. The H2-SCR catalyst composition according to any one of Embodiments 1 to 15, wherein the mass ratio of the metal component to the acidic oxide modifier is in the range of about 1:1 to about 1:30.

[0100] Embodiment 17. The H2-SCR catalyst composition according to any one of Embodiments 1 to 16, wherein the mass ratio of the metal component to the acidic oxide modifier is in the range of about 1:3 to about 1:10.

[0101] Embodiment 18. The H2-SCR catalyst composition according to any one of Embodiments 1 to 17, wherein the zeolite is an acidic zeolite.

[0102] Embodiment 19. The H2-SCR catalyst composition according to any one of Embodiments 1 to 18, wherein the second component consists essentially of an acidic zeolite.

[0103] Embodiment 20. The H2-SCR catalyst composition according to any one of Embodiments 1 to 19, wherein the zeolite is a metal-promoted zeolite. For example, the metal that promotes the zeolite is one or more of Cu, Co, Ni, La, Mn, Fe, V, Ag, Ce, Nd, Mo, Hf, Y, and W.

[0104] Embodiment 21. The H2-SCR catalyst composition according to Embodiment 20, wherein the metal-promoted zeolite is selected from Fe / zeolite, Cu / zeolite, and Fe / Cu / zeolite.

[0105] Embodiment 22. The H2-SCR catalyst composition according to any one of Embodiments 1 to 21, wherein the zeolite contains two or more structure types.

[0106] Embodiment 23. The zeolite is AEI, AFT, AFX, AVL, * The H2-SCR catalyst composition according to any one of Embodiments 1 to 22, which has a structure type selected from BEA, CHA, DDR, EAB, EEI, ERI, FAU, FER, IFY, IRN, KFI, LEV, LTA, LIN, MOR, MER, MFI, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations thereof.

[0107] Embodiment 24. The H2-SCR catalyst composition according to Embodiment 23, wherein the zeolite is selected from FAU, * BEA, MOR, MFI, CHA, FER, and combinations thereof.

[0108] Embodiment 25. The catalyst composition according to any one of Embodiments 1 to 24, wherein the zeolite has an Si / Al molar ratio in the range of 2:1 to 100:1, for example, in the range of 10:1 to 15:1.

[0109] Embodiment 26. The catalyst composition according to any one of Embodiments 1 to 25, wherein the first component and the second component are added in a mass ratio in the range of 95:5 to 10:90.

[0110] Embodiment 27. The H2-SCR catalyst composition according to any one of Embodiments 1 to 26, wherein the first component and the second component are combined into a composite by (1) physically mixing the first and second components, (2) dispersing the first and second components in water to form a slurry, (3) co-grinding the first and second components, or (4) a combination thereof.

[0111] Embodiment 28. A selective catalytic reduction (SCR) article effective for catalyzing the reduction of nitrogen oxides NO x from the exhaust gas in the presence of a hydrogen gas reducing agent, the SCR article comprising a substrate on which the H2-SCR catalyst composition according to any one of Embodiments 1 to 27 is disposed.

[0112] Embodiment 29. An exhaust gas treatment system for selectively reducing NO x compounds from an exhaust gas stream, the exhaust gas treatment system comprising the SCR article according to Embodiment 28.

[0113] Embodiment 30. The exhaust gas treatment system according to Embodiment 29, further comprising a hydrogen gas generator or a hydrogen gas injector.

[0114] Embodiment 31. A method for treating an exhaust gas stream containing NOx compounds, the method comprising passing the exhaust gas stream through the exhaust gas treatment system according to any one of Embodiments 29 to 30.

[0115] Method for treating the exhaust gas stream of Embodiment 31, wherein the exhaust gas stream is the exhaust gas stream of a hydrogen internal combustion engine or the hydrogen-treated exhaust gas stream of a diesel engine.

[0116] Unless otherwise indicated or not apparent from the context, if one, more than one, or all of the members of a group are present in, used in, or related to a given product or process, the conditions of the claims or specification that include "or" or "and / or" between at least one of the members of the group are considered satisfied. This disclosure includes embodiments where exactly one member of a group is present in, used in, or otherwise related to a given product or process. This disclosure includes embodiments where more than one or all of the members of a group are present in, used in, or otherwise related to a given product or process.

[0117] Furthermore, the present disclosure encompasses all modifications, combinations, and substitutions in which at least one limitation, element, clause, and descriptive term from at least one of the recited claims is introduced into another claim. For example, any embodiment / claim that depends on another embodiment / claim may be modified to include at least one limitation found in any other embodiment / claim that depends on the same independent claim. When elements are presented as a list, such as in a Markush group format, each subgroup of the elements is also disclosed, and any element(s) can be removed from the group. Generally, when the present disclosure or an aspect of the present disclosure is referred to as including a particular element and / or feature, it should be understood that embodiments of the present disclosure or aspects of the present disclosure consist of or consist essentially of such elements and / or features. For the sake of brevity, these embodiments are not specifically described herein in these words. When a range is given (e.g., [X] to [Y], etc.), the endpoints (e.g., [X] and [Y] in the phrase "[X] to [Y]") are included unless otherwise indicated. Further, unless otherwise indicated or not apparent from the context and the understanding of those skilled in the art, values expressed as ranges may assume any specific value or sub-range within the recited range in different embodiments of the present disclosure, unless clearly indicated otherwise in the context.

[0118] One of ordinary skill in the art will recognize many equivalents to the particular embodiments of the present disclosure described herein or will be able to confirm them using only routine experimentation. Such equivalents are intended to be encompassed by the following non-limiting examples.

Examples

[0119] The following examples are intended to be illustrative and are in no way meant to limit the scope of the present disclosure.

[0120] Unless otherwise specified, the evaluation of the catalytic activity of the samples listed below was carried out in a continuous flow fixed-bed quartz tube reactor with an inner diameter of 4 mm. 26 mg (40 - 60 mesh) of the catalyst sample was diluted with 0.25 g of inert SiC powder (40 - 60 mesh) to minimize the hot spot. In the case of the zeolite-containing catalyst (PGM / oxide + zeolite), the sample contained the same amount of metal as the PGM / oxide sample. The feed gas mixture contained 500 ppm of NO, 1% of H2, 10% of O2, 5% of CO2, and 5% of H2O and the balance Ar, at a flow rate of 200 cm 3 / min, resulting in a hourly weight space velocity (WHSV) of 461,500 mLg -1 h -1 . Reactants and products were analyzed online using a MultiGas 2030 CEMCert FTIR spectrometer coupled to a mass spectrometer (MS, proprietary analysis). The m / z ratios of 32 and 2 were used for the detection of O2 and H2, respectively. The NO x conversion rate was defined as (C NOx-inlet -C NOx-outlet )) / C NOx-inlet ×100% (where C NOx-inlet and C NOx-outlet are the NO x (NO + NO2) concentrations at the catalyst inlet and outlet, respectively). The N2O yield was defined as C N2O-outlet ×2 / C NOx-inlet ×100% (where C N2O-outlet is the outlet N2O concentration).

[0121] Example 1: Catalyst Preparation and Evaluation of 1Pt-8Si / TiO2 + Zeolite Table 1 lists the two-component catalysts and one-component reference catalysts of the present disclosure. Sample 1 is a reference catalyst, which was prepared by impregnating a mixed solution of colloidal Pt nanoparticles and colloidal SiO2 nanoparticles (acidic oxide modifier) on a TiO2 support using the incipient wetness technique. The particle size of colloidal Pt is in the range of 1 nm to 4 nm. The average particle size of colloidal SiO2 is about 12 nm. After impregnation, the obtained material was calcined in air at 550 °C for 2 hours. The Pt and SiO2 concentrations are 1 wt% and 8 wt%, respectively, based on the weight of the oxide support. Samples 2 to 7 were prepared by mechanically mixing the reference catalyst with the zeolite component at a weight ratio of 1:1. The zeolites of Samples 2 to 7 are the H-forms of beta (Si / Al = 12.5:1), ferrierite (Si / Al = 10:1), chabazite (Si / Al = 14.5:1), Y (Si / Al = 15:1), ZSM-5 (Si / Al = 15:1), and mordenite (Si / Al = 10:1), respectively. All samples including the reference sample were hydrothermally aged at 650 °C for 50 hours using 10% water vapor in air. All samples in Table 1 contain the same amount of Pt.

[0122]

Table 1

[0123] The NO of the samples listed in Table 1 x As shown by Figures 1A and 1B comparing the conversion rates and N2O formation rates, respectively, Samples 2 to 7 exhibit higher NO x conversion rates and lower N2O formation than the reference sample 1 (reference sample) at most test temperatures. Sample 5 (zeolite Y) is the most active in promoting NO x conversion, while Sample 2 (zeolite * beta-containing catalyst) has the lowest N2O formation.

[0124] Example 2: Catalyst Preparation and Evaluation of 1Pt-8SiO2 / TiO2+Y Table 2 lists samples prepared by combinations of two different types of components and their corresponding references. Samples 1 and 5 were prepared as described in Example 1.

[0125] Sample 8 is a reference catalyst, prepared by impregnating colloidal Pt nanoparticles on zeolite H-Y (Si / Al = 15:1) using the incipient wetness technique. 8% SiO2 / TiO2 was prepared by impregnating colloidal SiO2 nanoparticles (acidic oxide modifier) on a TiO2 support. Comparative sample 9 was prepared by mechanically mixing 1Pt / Y and 8% SiO2 / TiO2 in a 1:1 weight ratio. All samples were hydrothermally aged at 650 °C for 50 h with 10% water vapor in air.

[0126]

Table 2

[0127] NO of the samples listed in Table 2 x As shown in FIGS. 2A and 2B comparing the NO conversion rates and N2O formation rates of the samples respectively, the reference sample 8 (with Pt directly supported on zeolite H-Y) results in a lower NOx conversion rate compared to the reference sample 1 (1Pt-8SiO2 / TiO2 reference). Furthermore, the comparative sample 9 (Pt / Y + 8SiO2 / TiO2) improves the NOx conversion rate but increases N2O formation at low temperatures. Overall, the highest NOx conversion rate was observed for sample 5 across the entire temperature window. Samples 5 and comparative sample 9 contain Pt, SiO2, TiO2, and H-Y zeolite, but substantially different NOx conversion rates and N2O formation rates were observed.

[0128] Example 3: Catalyst Preparation and Evaluation of 1Pt-8SiO2 / TiO2+Y with Different Oxide-to-Zeolite Ratios Table 3 lists Reference Sample 1 and catalysts containing 1Pt-8SiO2 / TiO2+Y with different ratios of 1Pt-8SiO2 / TiO2 to Y. The catalysts were prepared in the same manner as in Example 1 and aged under the same conditions. All samples were hydrothermally aged at 650 °C for 50 hours with 10% water vapor in air. All samples in Table 3 contain the same amount of Pt.

[0129]

Table 3

[0130] For each of the samples listed in Table 3, the NO x conversion rate and N2O formation rate are shown in Figures 3A and 3B. As can be seen, all zeolite-containing samples show a higher NO x conversion rate and lower N2O formation relative to the Pt / oxide reference, regardless of the mixing ratio.

[0131] Example 4: Preparation and Evaluation of 0.5Pt-4SiO2 / TiO2 and 0.5Pt / Y Catalysts Table 4 is a list of four catalyst samples. Sample 5 and Comparative Sample 9 were prepared as described in Examples 1 and 2, respectively. Reference Sample 12 was prepared in the same manner as Reference Sample 1 described in Example 1, but with 50% Pt and SiO2 concentration (acidic oxide modifier). Similarly, Reference Sample 13 was prepared in the same manner as Reference Sample 8 described in Example 2, except that the Pt concentration was 50%. All four samples in Table 4 contain the same amount of Pt in the final catalyst, i.e., 0.5 wt% Pt based on the weight of the catalyst. All samples were hydrothermally aged at 650 °C for 50 hours with 10% water vapor in air.

[0132]

Table 4

[0133] The NO of the samples listed in Table 4 xAs shown in FIGS. 4A and 4B comparing the conversion rate and the N2O formation rate respectively, low concentrations of Pt and SiO2 affected the NOx conversion rate and the N2O formation rate. For example, reference sample 13 showed the lowest NO x conversion rate at low temperature, while sample 5 showed the highest NO x conversion rate.

[0134] Example 5: Catalyst Preparation and Evaluation of 1Pt-8SiO2 / TiO2 + 1CuCHA Table 5 lists reference sample 1, two-component sample 4 where the zeolite is H-chabazite, and two-component sample 14 where the H-chabazite of sample 4 is replaced with Cu-chabazite. Reference sample 1 and sample 4 were prepared as described in Example 1. Sample 14 was prepared in the same manner as sample 4, but the H-chabazite (Si / Al = 14.5:1) of sample 4 was replaced with Cu-chabazite (1% CuO). All samples were hydrothermally aged at 650 °C for 50 hours with 10% water vapor in air.

[0135]

Table 5

[0136] As shown in FIGS. 5A and 5B comparing the NO x conversion rate and the N2O formation rate of the samples listed in Table 5 respectively, sample 14 showed a similar NO x conversion rate to that of sample 4 at low temperature. However, at high temperature, sample 14 showed a lower NO x conversion rate than either reference sample 1 or sample 4.

[0137] Example 6: Catalyst Preparation and Evaluation of Pt / Pd and Pd Catalysts Table 6 lists catalysts containing either Pt / Pd or Pd on a TiO2 support. Reference samples 15 and 17 were prepared by impregnating a solution mixture of colloidal Pt, Pd nitrate, and colloidal SiO2 (acidic oxide modifier) with an appropriate component ratio (Pt / Pd weight ratio of 8 / 1 for reference sample 15 and 4 / 1 for reference sample 17, both having 8 wt% SiO2) on TiO2 using the incipient wetness technique. Reference sample 19 was prepared in the same manner as reference sample 1 of Example 1, except that the colloidal Pt of reference sample 1 was replaced with Pd nitrate. Samples 16, 18, and 20 were prepared by mechanically mixing the respective reference catalysts of reference samples 15, 17, and 19 with an H-Y zeolite component at a weight ratio of 1:1. The PGM concentration on the support was 1 wt% for all samples after calcination. All samples, including the reference samples, were hydrothermally aged at 650 °C for 50 h using 10% water vapor in air.

[0138]

Table 6

[0139] The NO of the samples listed in Table 6 x As shown in FIGS. 6A and 6B comparing the conversion rates and N2O formation rates, respectively, sample 20 (Pd catalyst with added H-Y zeolite) has some advantage in the NO x conversion rate compared to reference sample 19 with equivalent N2O formation. Samples 16 and 18 (PtPd catalysts) demonstrate that the addition of H-Y zeolite increases the NO x conversion rate and significantly reduces N2O formation compared to reference samples 15 and 17.

[0140] Example 7: Preparation and Evaluation of 1Pt-8SiO2 / TiO2 + xFeY Catalyst Table 7 lists the zeolite Y of reference sample 1 and the catalyst in which the zeolite Y of sample 5 was replaced with xfEY (Si / Al = 15:1). Reference sample 1 was prepared as described in Example 1. Samples 21 to 24 were prepared in the same manner as sample 5 in Example 1, except that xfEY (Si / Al = 15:1) with various Fe2O3 loadings (x = 0.25 wt%, 0.5 wt%, 1 wt%, and 3 wt% with respect to the weight of the zeolite, respectively) was used instead of zeolite H-Y. All samples were hydrothermally aged at 650 °C for 50 hours with 10% water vapor in air.

[0141]

Table 7

[0142] The NO of the samples listed in Table 7 x As shown in FIGS. 7A and 7B comparing the conversion rates and N2O formation rates respectively, the addition of FeY increases the NO x conversion rate and decreases N2O formation with respect to reference sample 1. The best performance was observed for sample 22.

[0143] Example 8: Preparation and evaluation of 1Pt / Al2O3 + zeolite catalyst Table 8 lists a series of catalysts based on 1Pt / Al2O3. 1Pt / Al2O3 was prepared by impregnating a colloidal Pt nanoparticle solution onto an Al2O3 support. After impregnation, the obtained material was calcined in air at 550 °C for 2 hours. The Pt concentration on the support is 1 wt% with respect to the weight of the calcined support.

[0144] Samples 26 to 31 were prepared by mechanically mixing Sample 25 with a zeolite component at a weight ratio of 1:1. The zeolites of Samples 26 to 31 are, respectively, H-type beta (Si / Al = 12.5:1), ferrierite (Si / Al = 10:1), chabazite (Si / Al = 14.5:1), Y (Si / Al = 15:1), ZSM-5 (Si / Al = 15:1), and mordenite (Si / Al = 10:1). All samples including the reference sample were hydrothermally aged at 650 °C for 50 hours using 10% water vapor in air.

[0145]

Table 8

[0146] NO of the samples listed in Table 8 x As shown in FIGS. 8A and 8B comparing the conversion rates and N2O formation rates, respectively, of all zeolite-containing catalysts (Samples 26 to 31) show higher NO x conversion rates over the temperature range. Samples 27 and 29 show the highest NO x conversion rates. Samples 26, 30, and 31 show the lowest N2O formation.

[0147] Example 9: Catalyst Preparation and Evaluation of WO3 / ZrO2 as a Pt Support Table 9 lists the catalysts prepared using WO3 / ZrO2 as a support. Sample 32 is the reference sample. The 5% WO3 / ZrO2 mixed oxide support was prepared by impregnating Zr(OH)4 with an (NH4)6W 12 O 39 solution, followed by calcination in air at 550 °C for 2 hours to obtain 5% WO3 / ZrO2. Then, a mixed solution of colloidal Pt nanoparticles and colloidal SiO2 nanoparticles (acidic oxide modifier) was added to the WO3 / ZrO2 mixed oxide support using the incipient wetness technique. The resulting material was calcined in air at 550 °C for 2 hours. After calcination, the sample contains 1 wt% Pt and 8 wt% SiO2 based on the weight of the support. The sample was further aged at 650 °C for 50 hours with 10% water vapor in air.

[0148] Samples 33 - 35 were prepared by mechanically mixing the aged 1Pt - 8Si / 5WO3 / ZrO2 powder with fresh H - beta (Si / Al = 12.5:1) powder at oxide - to - zeolite ratios of 2:1, 1:1, and 1:2, respectively. All samples in Table 9 contain the same amount of Pt.

[0149]

Table 9

[0150] The NO x conversion rate and N2O formation rate of the samples listed in Table 9 are shown in Figures 9A and 9B, respectively. As shown, all zeolite - containing samples (Samples 33 - 35) exhibit higher NO x conversion rates relative to the Pt / oxide basis, regardless of the mixing ratio. The formation of N2O on these zeolite - containing catalysts is mixed depending on the temperature range and the oxide / zeolite mixing ratio.

[0151] Example 10: Preparation and Evaluation of 1Pt / SiO2 + Y Catalyst Table 10 lists the catalysts with SiO2 supports. The reference sample 36 was prepared by impregnating a colloidal Pt nanoparticle solution on the SiO2 support. After impregnation, the obtained material was calcined in air at 550 °C for 2 hours. The Pt concentration on the support after calcination is 1 wt%. Sample 37 was prepared by mechanically mixing the reference sample 36 with zeolite H - Y at a weight ratio of 1:1. Both samples were hydrothermally aged at 650 °C for 50 hours with 10% steam in air.

[0152]

Table 10

[0153] The NO x conversion rate and N2O formation rate of the samples listed in Table 10 are shown in Figures 10A and 10B, respectively. As shown, Sample 37 has a similar NO xIt shows the conversion rate. However, the N2O formation on sample 37 is lower.

[0154] Cited prior art documents - European Patent No. 3409359 (A2) - International Patent Application Publication No. 2018 / 073750 (A1) - US Patent Application Publication No. 2021 / 102486 (A1) - European Patent No. 2313196 (A2)

Claims

Claim 1 A hydrogen selective catalytic reduction (H ｘ -SCR) catalyst composition effective for the reduction of nitrogen oxides (NO ２ ) from engine exhaust gas in the presence of a hydrogen gas reducing agent, wherein the H ２ -SCR catalyst composition is (i) a first component comprising a metal component of a platinum group metal (PGM) supported by an oxide carrier; and (ii) a second component comprising a zeolite, the catalyst composition. Claim 2 The H-SCR catalyst composition according to claim 1, wherein the first component further comprises a second PGM component supported on the oxide carrier. ２ -SCR catalyst composition. Claim 3 The H according to claim 1, further comprising a third component comprising a second PGM supported on a second oxide support. ２ -SCR catalyst composition. Claim 4 The H-SCR catalyst composition according to claim 1, wherein the oxide carrier is a mixed oxide carrier. ２ -SCR catalyst composition. Claim 5 The mixed oxide of the mixed oxide carrier is TiO ２ / ZrO ２ 、CeO ２ / MgO、WO ３ / ZrO ２ 、WO ３ / Al ２ O ３ 、WO ３ / TiO ２ 、WO ３ / SiO ２ 、Al ２ O ３ / La ２ O ３ 、TiO ２ / Al ２ O ３ 、V ２ O ５ / TiO ２ -Al ２ O ３ 、Nb ２ O ５ / SiO ２ 、ZnO / Al ２ O ３ 、SiO ２ / TiO ２ 、SiO ２ / Al ２ O ３ 、Mn / TiO ２ / Al ２ O ３ 、and a perovskite, the H ２ -SCR catalyst composition according to claim 4. Claim 6 The mixed oxide is TiO ２ / ZrO ２ 、WO ３ / Al ２ O ３ 、WO ３ / TiO ２ 、WO ３ / SiO ２ 、WO ３ / ZrO ２ 、SiO ２ / TiO ２ 、and SiO ２ / Al ２ O ３ selected from the group consisting of the H ２ -SCR catalyst composition according to claim 4 or 5. Claim 7 The H-SCR catalyst composition according to claim 1, further comprising an acidic oxide modifier on the oxide carrier. ２ -SCR catalyst composition. Claim 8 The H-SCR catalyst composition according to claim 1, wherein the zeolite is an acidic zeolite. ２ -SCR catalyst composition. Claim 9 The H-SCR catalyst composition according to claim 1, wherein the zeolite is a metal-promoted zeolite. ２ -SCR catalyst composition. Claim 10 The H-SCR catalyst composition according to claim 1, wherein the zeolite contains two or more structure types. ２ -SCR catalyst composition. Claim 11 The H ２ -SCR catalyst composition according to claim 1, wherein the first component and the second component are added in a mass ratio in the range of 95:5 to 10:

90. Claim 12 The first component and the second component are combined in a composite by (1) physically mixing the first and second components, (2) dispersing the first and second components in water to form a slurry, (3) co-grinding the first and second components, or (4) a combination thereof, the H according to claim 1 ２ -SCR catalyst composition. Claim 13 Nitrogen oxides NO from exhaust gas in the presence of a hydrogen gas reducing agent ｘ A selective catalytic reduction (SCR) article effective for catalyzing the reduction of ２ - The SCR article comprising a substrate on which the SCR catalyst composition is disposed. Claim 14 NO from the exhaust gas stream ｘ An emissions treatment system for selectively reducing NO ｘ compounds from an exhaust gas stream, the emissions treatment system comprising the SCR article of claim 13. Claim 15 NO ｘ A method for treating an exhaust stream containing a compound, the method comprising passing the exhaust gas stream through the emissions treatment system according to claim 14.

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