Cu-CHA SCR catalyst with specific lattice strain and domain size characteristics

Abstract

The present disclosure relates to the detection of nitrogen oxides (NO x The present invention provides a catalyst composition capable of reducing NOx emissions in an exhaust gas stream. The catalyst composition comprises a metal ion-exchanged zeolite having a domain size of less than about 1500 angstroms (Å), a crystallographic strain of less than about 0.7%, or both. Catalytic articles coated with such compositions, processes for preparing such catalyst compositions and articles, exhaust gas treatment systems including such catalytic articles, and methods for reducing NOx emissions in an exhaust gas stream using such catalytic articles and systems are also provided. x Further provided is a method for reducing

Description

[Technical Field]

[0001] The present disclosure relates generally to the field of exhaust gas treatment catalysts, specifically to catalyst compositions capable of selectively reducing nitrogen oxides in engine exhaust, catalyst articles coated with such compositions, and processes for preparing such catalyst compositions. More specifically, improved metal-promoted zeolites that may be useful as selective catalytic reduction (SCR) catalysts and processes for preparing them are provided. [Background technology]

[0002] Over the years, nitrogen oxides (NO x ) harmful components have caused air pollution. x is contained in exhaust gases from internal combustion engines (eg, cars and trucks), combustion facilities (eg, power plants heated by natural gas, oil, or coal), and nitric acid production plants.

[0003] NO x Various treatment methods are used to treat contained gas mixtures to reduce air pollution. One type of treatment involves catalytic reduction of nitrogen oxides. There are two processes: (1) non-selective reduction processes, in which carbon monoxide, hydrogen, or low molecular weight hydrocarbons are used as reducing agents, and (2) selective reduction processes, in which ammonia or an ammonia precursor is used as a reducing agent. In selective reduction processes, high levels of nitrogen oxide removal can be achieved using stoichiometric amounts of reducing agent.

[0004] The selective reduction process is referred to as the SCR (Selective Catalytic Reduction) process. The SCR process uses catalytic reduction of nitrogen oxides with a reducing agent (e.g., ammonia) in the presence of atmospheric oxygen, resulting in the formation of primarily nitrogen and steam: 4NO + 4NH3 + O2 → 4N2 + 6H2O (standard SCR reaction) 2NO2 + 4NH3 + O2 → 3N2 + 6H2O (slow SCR reaction) NO + NO2 + 2NH3 → 2N2 + 3H2O (high-speed SCR reaction)

[0005] Catalysts used in SCR processes ideally need to be able to maintain good catalytic activity under hydrothermal conditions over a wide operating temperature range, e.g., from 200°C to over 600°C. SCR catalysts are commonly used under hydrothermal conditions, such as during the regeneration of soot filters, a component of exhaust gas treatment systems used to remove particulates.

[0006] Current catalysts used in SCR processes include metal-promoted zeolites, which are used in the SCR of nitrogen oxides with reducing agents such as ammonia, urea, or hydrocarbons in the presence of oxygen. Among these, metal-promoted zeolite SCR catalysts, including iron- and copper-promoted zeolite catalysts, are known. For example, iron-promoted zeolite beta has been an effective commercial catalyst for the selective reduction of nitrogen oxides with ammonia. Unfortunately, under severe hydrothermal conditions (e.g., as exhibited during soot filter regeneration at temperatures exceeding 700°C locally), the activity of many metal-promoted zeolites has been found to begin to decline. This decline is due to dealumination of the zeolite and the resulting loss of metal-containing active centers in the zeolite. Metal-promoted zeolites with the CHA structure type, specifically copper-promoted aluminosilicate zeolites, have attracted considerable interest as catalysts for SCR of nitrogen oxides in lean-burn engines using nitrogenous reducing agents. These materials exhibit activity within a wide temperature window and excellent hydrothermal durability, as described in U.S. Patent No. 7,601,662.

[0007] Although the catalyst described in U.S. Patent No. 7,601,662 exhibits excellent properties, making it useful, for example, in SCR catalysis, there remains a need for metal-promoted zeolitic SCR catalysts with improved low-temperature performance and enhanced hydrothermal stability compared to currently available metal-promoted zeolitic SCR catalysts. Light-duty diesel (LDD) applications, in which SCR catalysts are often exposed to temperature fluctuations associated with soot filter regeneration, place special demands on the hydrothermal stability of zeolites. Hydrothermal stability generally increases with decreasing framework alumina content (i.e., increasing the silica-to-alumina molar ratio, or SAR), but the latter also limits the amount of catalytically active Cu sites. Therefore, improving the hydrothermal stability of frameworks with lower SAR would represent an effective strategy for improving LDD performance. Summary of the Invention

[0008] The present disclosure generally provides zeolite materials characterized by specific domain sizes and crystallographic distortion values. Such zeolite materials are metal-promoted and have been shown to produce enhanced NO x Surprisingly, according to the present disclosure, zeolite materials characterized by domain sizes of less than about 1500 angstroms (Å), crystallographic strain of less than about 0.7%, or both, exhibit excellent NO reduction performance at both high and low temperatures. x It has been found to result in metal-promoted SCR catalyst compositions with reducing properties.

[0009] Thus, in one aspect, a zeolite material is provided characterized by one or more of the following: a domain size of less than about 1500 Å, and a crystallographic distortion of less than about 0.7% as determined from LY parameters by General Structure Analysis System (GSAS) Rietveld refinement of powder X-ray diffraction data. In some embodiments, the domain size is less than about 1400 Å. In some embodiments, the domain size is less than about 1300 Å. In some embodiments, the domain size is between about 800 and about 1400 Å. In some embodiments, the crystallographic distortion is less than about 0.6%.

[0010] In some embodiments, the crystallographic strain is less than about 0.5%. In some embodiments, the crystallographic strain is less than about 0.4%.

[0011] In some embodiments, the domain size is about 800 to about 1200 Å and the crystallographic strain is about 0.2% to about 0.6%. In some embodiments, the domain size is about 800 to about 1100 Å and the crystallographic strain is about 0.3% to about 0.5%.

[0012] In some embodiments, the zeolitic material is selected from the group consisting of aluminosilicate zeolites, borosilicates, gallosilicates, SAPO, and ALPO, MeAPSO, and MeAPO. In some embodiments, the zeolitic material is an aluminosilicate zeolite. In some embodiments, the zeolitic material is an aluminosilicate zeolite having a silica-to-alumina ratio (SAR) in the range of about 10 to about 45. In some embodiments, the SAR is in the range of about 15 to about 20.

[0013] In some embodiments, the zeolitic material has a CHA crystalline framework. In some embodiments, the zeolitic material is selected from the group consisting of SSZ-13, SSZ-62, natural chabazite, zeolite KG, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-4, SAPO-47, and ZYT-6. In some embodiments, the zeolitic material is chabazite (CHA).

[0014] In another aspect, nitrogen oxides (NO x A selective catalytic reduction (SCR) catalyst composition effective for mitigating CO2 emissions is provided, the SCR catalyst composition comprising a zeolitic material as disclosed herein promoted with a metal selected from iron, copper, and combinations thereof. In some embodiments, the promoter metal is present in an amount of about 1.0 wt. % to about 10 wt. %, calculated as metal oxide, based on the total weight of the SCR catalyst. In some embodiments, the promoter metal is present in an amount of about 4 wt. % to about 6 wt. %. In some embodiments, the promoter metal is copper.

[0015] In another aspect, nitrogen oxides (NO) from lean-burn engine exhaust gases are x A selective catalytic reduction (SCR) catalyst article effective for mitigating CO2 emissions is provided, the SCR catalyst article including a substrate having disposed on at least a portion thereof a selective catalytic reduction (SCR) catalyst composition as disclosed herein. In some embodiments, the substrate is a honeycomb substrate. In some embodiments, the honeycomb substrate is a flow-through substrate or a wall-flow filter.

[0016] In some embodiments, NO in the exhaust gas stream x At least a portion of the NO in the exhaust gas stream is reduced to N at a temperature between about 200° C. and about 600° C. x The levels are reduced by at least 50% at 200° C. In some embodiments, the NO 2 in the exhaust gas stream x The levels are reduced by at least 70% at 600°C.

[0017] In some embodiments, the SCR catalyst article is subjected to a thermal aging treatment at 800° C. for 16 hours in the presence of 10% by volume steam and the remainder air, after which the SCR catalyst composition is tested for 80,000 hours under pseudo-steady-state conditions. -1 At an exhaust gas volumetric hourly space velocity of 2.1 g / in 3 When the SCR catalyst article is placed on a cellular ceramic monolith having a cell density of 400 cpsi and a wall thickness of 6 mils with a catalyst loading of 100 ppm, and the exhaust gas contains a gas mixture of 500 ppm NO, 500 ppm NH, 10% O, 5% H, and the remainder N, the SCR catalyst article exhibits a reduction of NO in the exhaust gas stream of about 72% or more at 200°C, about 81% or more at 600°C, or both.

[0018] In another aspect, an exhaust gas treatment system is provided that includes an SCR catalyst article as disclosed herein located downstream of and in fluid communication with a lean-burn engine generating an exhaust gas stream. In some embodiments, the exhaust gas treatment system further includes one or more of a diesel oxidation catalyst (DOC) located upstream of the SCR catalyst article, a soot filter located upstream of the SCR catalyst article, and an ammonia oxidation catalyst (AMOx) located downstream of the SCR catalyst article.

[0019] In another aspect, a method for treating an exhaust gas stream from a lean-burn engine is provided, the method comprising contacting the exhaust gas stream with a catalytic article or an exhaust gas treatment system as disclosed herein for a time and at a temperature sufficient to reduce the level of nitrogen oxides (NOx) in the exhaust gas stream. In some embodiments, NOx in the exhaust gas stream is reduced. x The level is reduced to N2 at a temperature of about 200°C to about 600°C.

[0020] The present invention includes, but is not limited to, the following embodiments. Embodiment 1: A zeolitic material characterized by one or more of: a domain size of less than about 1500 angstroms (Å); and a crystallographic distortion of less than about 0.7% as determined from LY parameters by General Structure Analysis System (GSAS) Rietveld refinement of powder X-ray diffraction data. Embodiment 2: The zeolitic material of embodiment 1, wherein the domain size is less than about 1400 Å. Embodiment 3: The zeolitic material of embodiment 1 or 2, wherein the domain size is less than about 1300 Å. Embodiment 4: The zeolitic material according to any one of embodiments 1 to 3, wherein the domain size is from about 800 to about 1400 Å. Embodiment 5: The zeolitic material of any one of embodiments 1-4, having a crystallographic strain of less than about 0.6%. Embodiment 6: The zeolitic material of any one of embodiments 1 to 5, wherein the crystallographic strain is less than about 0.5%. Embodiment 7: The zeolitic material of any one of embodiments 1 to 6, wherein the crystallographic strain is less than about 0.4%. Embodiment 8: The zeolitic material according to any one of embodiments 1 to 7, wherein the domain size is from about 800 to about 1200 Å and the crystallographic distortion is from about 0.2% to about 0.6%. Embodiment 9: The zeolitic material of any one of embodiments 1 to 8, wherein the domain size is from about 800 to about 1100 Å and the crystallographic distortion is from about 0.3% to about 0.5%. Embodiment 10: The zeolitic material of any one of embodiments 1 to 9, wherein the zeolitic material is an aluminosilicate zeolite. Embodiment 11: The zeolitic material of any one of embodiments 1 to 10, having a silica-to-alumina ratio (SAR) ranging from about 10 to about 45. Embodiment 12: The zeolitic material of any one of embodiments 1 to 11, having an SAR in the range of about 15 to about 20. Embodiment 13: The zeolitic material of any one of embodiments 1 to 12, wherein the zeolitic material has a CHA crystalline framework. Embodiment 14: The zeolitic material of any one of embodiments 1 to 13, wherein the zeolitic material is selected from the group consisting of SSZ-13, SSZ-62, natural chabazite, Zeolite KG, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-4, SAPO-47, and ZYT-6. Embodiment 15: Nitrogen oxides (NO x 15. A selective catalytic reduction (SCR) catalyst composition effective for mitigating CO2 emissions from diesel engines, comprising the zeolitic material of any one of embodiments 1-14 promoted with a metal selected from iron, copper, and combinations thereof. Embodiment 16: The SCR catalyst composition of embodiment 15, wherein the promoter metal is present in an amount of about 1.0 wt. % to about 10 wt. %, calculated as metal oxide, based on the total weight of the SCR catalyst. Embodiment 17: The SCR catalyst of embodiment 15 or 16, wherein the promoter metal is present in an amount of about 4 to about 6 weight percent. Embodiment 18: The SCR catalyst composition of any one of Embodiments 15-17, wherein the promoter metal is copper. Embodiment 19: Nitrogen oxides (NO) from lean-burn engine exhaust x 19. A selective catalytic reduction (SCR) catalyst article effective for mitigating CO2 emissions, the SCR catalyst article comprising a substrate having disposed thereon at least a portion of the selective catalytic reduction (SCR) catalyst composition of any one of embodiments 15-18. Embodiment 20: The SCR catalyst article of embodiment 19, wherein the substrate is a honeycomb substrate. Embodiment 21: The SCR catalyst article of embodiment 19, wherein the honeycomb substrate is a flow-through substrate or a wall-flow filter. Embodiment 22: NO in the exhaust gas stream x 22. The SCR catalyst article of any one of embodiments 19-21, wherein at least a portion of the carbon dioxide is reduced to N2 at a temperature between about 200°C and about 600°C. Embodiment 23: NO in the exhaust gas stream x 23. The SCR catalyst article of embodiment 22, wherein the level is reduced by at least 50% at 200°C. Embodiment 24: NO in the exhaust gas stream x 24. The SCR catalyst article of embodiment 22 or 23, wherein the level is reduced by at least 70% at 600°C. Embodiment 25: After an SCR catalyst article is subjected to a thermal aging treatment at 800°C for 16 hours in the presence of 10% by volume steam and the remainder air, the SCR catalyst composition is maintained at 80,000h under pseudo-steady-state conditions. -1 At an exhaust gas volumetric hourly space velocity of 2.1 g / in 3 and the catalyst article is placed on a cellular ceramic monolith having a cell density of 400 cpsi and a wall thickness of 6 mils with a catalyst loading of 100 ppm NO, 500 ppm NH, 10% O, 5% H, and the remainder N, the SCR catalyst article reduces the NO in the exhaust gas stream by about 72% or more at 200°C, by about 81% or more at 600°C, or by both, when tested under conditions in which the exhaust gas contains a gas mixture of 500 ppm NO, 500 ppm NH, 10% O, 5% H, and the remainder N. x 25. The SCR catalyst article of any one of embodiments 19-24, exhibiting a reduction in: Embodiment 26: An exhaust gas treatment system comprising the SCR catalyst article of any one of embodiments 19-25 located downstream of and in fluid communication with a lean-burn engine producing an exhaust gas stream. Embodiment 27: The exhaust gas treatment system of embodiment 26, further comprising one or more of a diesel oxidation catalyst (DOC) located upstream of the SCR catalyst article, a soot filter located upstream of the SCR catalyst article, and an ammonia oxidation catalyst (AMOx) located downstream of the SCR catalyst article. Embodiment 28: The exhaust gas stream is treated with a catalytic article according to any one of Examples 19-25 or an exhaust gas treatment system according to Embodiment 26 or 27 to detect nitrogen oxides (NO) in the exhaust gas stream. x 2. A method for treating an exhaust gas stream from a lean-burn engine comprising contacting with a solvent containing methyl methyl stearate and a methyl stearate-containing fluorine-containing compound (III) for a time and at a temperature sufficient to reduce the level of methyl methyl stearate. Embodiment 29: NO in the exhaust gas stream x 29. The method of embodiment 28, wherein the level is reduced to N2 at a temperature of about 200°C to about 600°C.

[0021] 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 invention includes any combination of two, three, four, or more of the above-described embodiments, as well as combinations of any two, three, four, or more features or elements described in this disclosure, regardless of whether such features or elements are explicitly combined in the description of a specific embodiment herein. This disclosure is intended to be read as a whole, such that separable features or elements of the disclosed invention are to be considered combinable in any of its various aspects and embodiments, unless the context clearly dictates otherwise. Other aspects and advantages of the present invention will become apparent hereinafter. [Brief explanation of the drawings]

[0022] To provide an understanding of embodiments of the present invention, reference is made to the accompanying drawings, in which reference numerals indicate components of exemplary embodiments of the invention. The drawings are merely examples and should not be construed as limiting the invention. The disclosure set forth herein is illustrated by way of example, and not by way of limitation, in the accompanying figures. For simplicity and clarity of the figures, features shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some features may be exaggerated relative to other features for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0023] [Figure 1] FIG. 1 is a perspective view of a wall-flow filter substrate. [Figure 2] 1a is an enlarged cross-sectional cutaway view of FIG. 1a, in which the honeycomb-type substrate in FIG. 1a represents a wall-flow filter. [Figure 3A] 1A-1C are diagrams of three possible coating configurations according to certain embodiments. [Figure 3B] 1A-1C are diagrams of three possible coating configurations according to certain embodiments. [Figure 3C] 1A-1C are diagrams of three possible coating configurations according to certain embodiments. [Figure 4] 1 shows a schematic diagram of an embodiment of an emissions treatment system in which the SCR catalyst article of the present invention is utilized. [Figure 5] 1 is a plot of domain size versus % strain and NOx reduction at 200° C. according to certain embodiments. [Figure 6] 1 is a plot of domain size versus strain % and NOx reduction at 600° C. according to certain embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present disclosure generally provides zeolitic materials characterized by specific domain sizes and crystallographic distortion values ​​that exhibit improved NO production, particularly at low temperatures, compared to standard Cu-chabazite reference SCR catalyst compositions and articles. x The disclosed zeolitic materials can be useful as selective catalytic reduction (SCR) catalyst compositions and articles with enhanced conversion. Methods for preparing the disclosed zeolitic materials are further provided, as well as SCR catalyst compositions, catalytic articles, exhaust treatment systems, and methods for treating exhaust streams, each comprising the disclosed zeolitic materials.

[0025] Before describing some exemplary embodiments, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description as the invention is capable of other embodiments and of being practiced or carried out in various ways.

[0026] definition The articles "a" and "an" herein refer to one or more than one (e.g., at least one) of the grammatical object. All ranges cited herein are inclusive. The term "about" is used throughout to express and account for small variations. For example, "about" can mean that a numerical value may vary by ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, ±0.1%, or ±0.05%. All numerical values, whether explicitly stated or not, are modified by the term "about." Numeric values ​​modified by the term "about" include the specific identified value. For example, "about 5.0" includes 5.0. The recitation of ranges of values ​​herein, unless otherwise indicated herein, is intended to serve as a shorthand method of individually referring to each separate value falling within the range, and each separate value is incorporated herein as if it were individually recited herein.

[0027] The term "reduction" means a decrease in quantity caused by some means.

[0028] "AMOx" refers to a selective ammonia oxidation catalyst, which is a catalyst containing one or more metals (typically, but not limited to, Pt) and an SCR catalyst suitable for converting ammonia to nitrogen.

[0029] The term "coupled" means, for example, "comprised," "connected," or "in communication," e.g., "electrically connected" or "fluid communication," or otherwise connected to perform a function. The term "associated" can mean, for example, directly related or indirectly related through one or more other items or elements.

[0030] "Average particle size" is D 50"D" is synonymous with "larger particle size" (D=0.5), meaning that half the number of particles have a larger particle size and half have a smaller particle size. Particle size refers to primary particles. Particle size can be measured, for example, by laser light scattering techniques using dispersed or dry powders according to ASTM method D4464. 90 The particle size distribution of, as measured by scanning electron microscope (SEM) or transmission electron microscope (TEM) for submicron-sized particles, and by particle size analyzer for carrier-containing particles (micron-sized), shows that 90% of the particles (by number) have a ferret diameter smaller than a certain size.

[0031] As used herein, "BET surface area" has its ordinary meaning associated with the Brunauer, Emmett, and Teller method for determining surface area by N adsorption. Pore size and pore volume can also be determined using BET-type N adsorption or desorption experiments.

[0032] The term "catalyst" refers to a material that promotes a chemical reaction. Catalytically active species are also called "promoters" because they accelerate the chemical reaction.

[0033] The terms "catalytic article" or "catalyst article" refer to a component used to promote a desired reaction. The catalytic article includes a "substrate" having at least one catalytic coating disposed thereon.

[0034] As used herein, "crystal size" refers to the length of one edge of a crystal's face, preferably the longest edge, provided the crystal is not needle-shaped. Direct measurement of crystal size can be performed using microscopy techniques such as SEM and TEM. For example, SEM measurement involves examining the morphology of the material at high magnification (typically 1000x to 10,000x). SEM can be performed by distributing a representative portion of the zeolite powder on a suitable mount, so that individual particles are spread fairly uniformly across the entire field of view at 1000x to 10,000x magnification. From this population, a statistically significant sample of random individual crystals (e.g., 50-200) is examined, and the longest dimension of each individual crystal parallel to the horizontal line of the straight edge is measured and recorded. Particles that are clearly large polycrystalline agglomerates are not included in the measurement. Based on these measurements, the arithmetic mean crystal size of the sample is calculated.

[0035] As used herein, "crystallite size" refers to the size of a discrete diffraction domain that consistently scatters X-rays. As used herein, "crystallite size" is used synonymously with "domain size." The actual crystal size, as defined above, determined by scanning electron microscope (SEM) imaging is much larger than the domain size (e.g., much larger than 1000-2000 Å). Estimation of crystallite size can be performed from analysis of powder XRD using the Scherrer equation (Eq. 1), which relates the width of a powder diffraction peak to the average (volume) dimension of the crystallites in a polycrystalline powder: β s (2θ) hkl =Kλ / T cosθ hkl (Eq.1), In the formula, β sis the crystallite size contribution to the peak width (integral width or full width at half maximum) in radians, K is a constant close to 1, and T is the average thickness of the crystals in the direction perpendicular to the diffraction plane hkl. Determination of crystallite size for certain zeolitic materials is described, for example, in Burton et al., Microporous and Mesoporous Materials 117 (2009), 75-90, the disclosure of which is incorporated herein by reference in its entirety.

[0036] "CSF" refers to a catalyzed soot filter, which is a wall-flow monolith. Wall-flow filters consist of alternating inlet and outlet channels, with the inlet channel inserted into the outlet end and the outlet channel inserted into the inlet end. The soot-carrying exhaust gas flow entering the inlet channel is passed through the filter wall before exiting the outlet channel. In addition to soot filtration and regeneration, the CSF may carry oxidation catalysts to oxidize CO and HC to CO2 and HO or NO to NO2 to accelerate downstream SCR catalysts or promote soot particle oxidation at lower temperatures. When placed after an LNT catalyst, the CSF can also perform H2S oxidation, suppressing H2S emissions during the LNT desulfurization process. SCR catalyst compositions can also be coated directly onto the wall-flow filter, called SCRoF.

[0037] "DOC" refers to a diesel oxidation catalyst that converts hydrocarbons and carbon monoxide in the exhaust gas of a diesel engine. Typically, a DOC includes one or more platinum group metals, such as palladium and / or platinum; a support material, such as alumina; a zeolite for HC storage; and optionally, a promoter and / or stabilizer.

[0038] Generally, the term "effective" means, for example, about 35% to 100% effective, e.g., about 40%, about 45%, about 50%, or about 55% to about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95% effective in terms of a defined catalytic activity or storage / release activity by weight or mole.

[0039] The term "exhaust stream" or "exhaust gas stream" refers to any combination of flowing gases that may contain solid or liquid particulate matter. The stream is, for example, the exhaust of a lean-burn engine, which includes gaseous components and may also contain certain non-gaseous components, such as liquid droplets, solid particulates, etc. The exhaust gas stream of a combustion engine typically contains combustion products (CO and HO), incomplete combustion products (carbon monoxide (CO) and hydrocarbons (HC)), nitrogen oxides (NO x ), combustible and / or carbonaceous particulate matter (soot), and unreacted oxygen and nitrogen.

[0040] The term "high surface area refractory metal oxide support" specifically refers to support particles having pores greater than 20 Å and a broad pore distribution. High surface area refractory metal oxide supports, such as alumina support materials also referred to as "gamma alumina" or "activated alumina," typically have a surface area of ​​60 square meters per gram ("m 2 / g), often up to about 200m 2 / g or greater virgin material BET surface area. Such activated aluminas are typically mixtures of gamma and delta phases of alumina, but may also contain significant amounts of eta, kappa, and theta alumina phases.

[0041] As used herein, "impregnated" or "impregnation" refers to the infiltration of a catalytic material into the porous structure of a support material.

[0042] The term "fluid communication" is used to refer to articles positioned in 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 in the exhaust line. Alternatively, articles in fluid communication may be separated by one or more articles, also referred to as "washcoat monoliths."

[0043] "LNT" refers to platinum group metals, ceria, and NO under lean conditions. x Lean NO catalysts containing alkaline earth metal trap materials (e.g., BaO or MgO) suitable for adsorbing NO x Under rich conditions, NO x is released and reduced to nitrogen.

[0044] As used herein, the term "molecular sieve" refers to framework materials such as zeolites and other framework materials (e.g., isomorphously substituted materials) that, in particulate form, can be used as catalysts in combination with one or more promoter metals. Molecular sieves are generally oxygen ion-based materials containing tetrahedral sites and having an extensive three-dimensional network structure with a substantially uniform pore distribution and an average pore size of 20 angstroms (Å) or less.

[0045] Molecular sieves can be distinguished primarily according to the shape of the pores formed by a robust network of (SiO4) / AlO4 tetrahedra. The entrances to the pores are formed from 6, 8, 10, or 12 ring atoms, with the atoms forming the entrance openings. Molecular sieves are crystalline materials with fairly uniform pore sizes ranging from about 3 to 10 Å in diameter, depending on the type of molecular sieve and the type and amount of cations contained in the molecular sieve lattice.

[0046] As used herein, the term "zeolite" refers to a specific example of a molecular sieve. Zeolites are generally defined as aluminosilicates with an open three-dimensional framework structure composed of corner-sharing T0 tetrahedra (where T is Al or Si, or optionally P). Aluminosilicate zeolite structures do not contain phosphorus or other metals isomorphously substituted in the framework. That is, "aluminosilicate zeolites" excludes aluminophosphate materials such as SAPO, AlPO, and MeAlPO materials, while the broader term "zeolite" includes aluminosilicates and aluminophosphates. For purposes of this disclosure, SAPO, AlPO, and MeAlPO materials are considered non-zeolitic molecular sieves. Zeolites may contain SiO / AlO tetrahedra linked by common oxygen atoms to form a three-dimensional network. Anionic framework charge-balancing cations are loosely associated with framework oxygens, and the remaining pore volume is filled with water molecules. Non-framework cations are generally exchangeable, and water molecules are removable. A wide variety of cations can occupy these pores and migrate through these channels.

[0047] "NO x The term "refers to nitrogen oxide compounds such as NO, NO2, or N2O.

[0048] The terms "on" and "above" in relation to coating layers can be used synonymously. The term "directly on" means in direct contact. Although the disclosed articles are, in certain embodiments, referred to as including one coating layer "on" a second coating layer, such language is 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").

[0049] As used herein, the term "promoted" refers to components that are intentionally added to the zeolitic material, for example, typically by ion exchange, as opposed to inherent impurities in the zeolite. Zeolites may be promoted with, for example, copper (Cu) and / or iron (Fe), although other catalytic metals such as manganese, cobalt, nickel, cerium, platinum, palladium, rhodium, or combinations thereof can be used.

[0050] The term "promoter metal" in the context of zeolite SCR catalysts refers to one or more metals added to an ion-exchanged zeolite to produce a modified "metal-promoted" molecular sieve. The addition of a promoter metal to an ion-exchanged zeolite enhances the catalytic activity of the active metal present at the exchange sites in the zeolite compared to an ion-exchanged zeolite that does not contain the promoter metal; for example, the addition of aluminum or alumina oxide as a "promoter metal" to a copper ion-exchanged zeolite enhances the catalytic activity of copper by preventing and / or reducing the formation of catalytically less active copper oxide clusters.

[0051] The promoter metal can be exchanged into the zeolite by a liquid-phase exchange process, in which soluble metal ions exchange for protons or ammonium or sodium ions associated with the zeolite. The exchange can also be carried out by a solid-state process, in which solid particles of the promoter metal oxide or metal salt are mixed with zeolite powder and treated under a specific temperature and gas environment, which may or may not contain steam. The exchange process can also be achieved via an in situ process during slurry preparation, in which fine metal oxide particles are suspended in a zeolite slurry under conditions favorable for solid-liquid interaction.

[0052] As used herein, the term "selective catalytic reduction" (SCR) refers to a catalytic process that uses a nitrogenous reductant to reduce nitrogen oxides to dinitrogen (N2).

[0053] "SCRoF" refers to an SCR catalyst composition coated directly onto a wall-flow filter.

[0054] As used herein, the term "strain" refers to distortions in the lattice of a crystalline material that result in measurable broadening of diffraction peaks. Such strain can arise from compressive and tensile forces that create a distribution of d-spacings around the normally observed d-spacing of the material. Compressive and tensile forces can be the result of mechanical forces or dislocations within the crystal, crystal twinning, compositional gradients due to heteroatom substitution, changes in the density of silanol / siloxy defects, or changes in pore filling due to organic or inorganic SDA cations. Crystal twinning creates a stress gradient with a concomitant strain gradient. Diffraction peak broadening is related to both stress and domain size and is related to strain according to Equation 2: β ε (2θ)=4εtanθ (Eq.2), where ε represents the residual strain and βε is the peak broadening caused by stress. The calculated strain can be reported as a fraction or percentage, which indicates the degree of d-spacing variation within the sample. Approximation of both domain size and strain for certain zeolitic materials by analysis of Williamson-Hall plots is described, for example, in Burton et al., Microporous and Mesoporous Materials 117 (2009), 75-90, the disclosure of which is incorporated herein by reference in its entirety.

[0055] "Substantially free" means "little or no" or "not intentionally added," and also means having only trace and / or incidental amounts. For example, in certain embodiments, "substantially free" means less than 2% by weight (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 indicated.

[0056] As used herein, the term "substrate" refers to a monolithic material upon which a catalyst composition, i.e., a catalytic coating, is disposed, typically in the form of a washcoat. In one or more embodiments, the substrate is a flow-through monolith and a monolith wall-flow filter. Reference to a "monolithic substrate" means a single structure that is homogeneous and continuous from the inlet to the outlet.

[0057] As used herein, the terms "support" or "support material" refer to any material, typically a high surface area material, usually a refractory metal oxide material, onto which metals (e.g., PGMs, stabilizers, promoters, binders, etc.) are applied by precipitation, association, dispersion, impregnation, or other suitable method. Exemplary supports include porous refractory metal oxide supports as described herein below. The term "supported" means "dispersed on," "incorporated in," "impregnated in," "impregnated onto," "impregnated into," "deposited on," or otherwise associated.

[0058] As used herein, the terms "upstream" and "downstream" refer to relative directions relative to the flow of engine exhaust gas stream from the engine toward the tailpipe, with the engine being in the upstream position and the tailpipe and any pollution abatement items, such as filters and catalysts, being 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 near the engine or manifold, and the downstream zone may be further away from the engine or manifold.

[0059] "Washcoat" has its conventional meaning in the art of a thin, adherent coating of material (e.g., catalyst) applied to a "substrate," such as a honeycomb flow-through monolith substrate or a filter substrate that is sufficiently porous to allow the 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, a washcoat layer comprises a compositionally distinct layer of material disposed on the surface of a monolith substrate or an underlying washcoat layer. A washcoat is formed by preparing a slurry containing a specific solids content (e.g., 10% to 50% by weight) of catalyst in a liquid, which is then coated onto the substrate and dried to provide the washcoat layer. A substrate can contain one or more washcoat layers, each of which can differ in some aspect (e.g., the physical properties of the washcoat, such as particle size or crystallite phase, can differ) and / or the chemical catalytic function can differ.

[0060] Unless otherwise stated, all parts and percentages are by weight. Unless otherwise indicated, "weight percent (wt%)" is based on the total composition, excluding volatile materials, i.e., dry solids content.

[0061] All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better describe the materials and methods and does not limit the scope unless otherwise claimed. No language herein should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods. All U.S. patent applications, published patent applications, and patents referenced herein are incorporated herein by reference.

[0062] Zeolitic Materials and Properties In one or more embodiments, the zeolitic material as disclosed herein comprises an eight-ring small-pore aluminosilicate zeolite. As used herein, "small pore" refers to a pore opening smaller than about 5 Å, e.g., about 3.8 Å. The phrase "eight-ring" zeolite refers to a zeolite having an eight-ring pore opening and double six-ring secondary structural units, and a cage-like structure resulting from the connection of double six-ring structural units with four rings. Zeolitic structural types having d6r secondary structural units 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, and WEN.

[0063] In one or more embodiments, the zeolitic material as disclosed herein is a small pore zeolite having a maximum ring size of eight tetrahedral atoms. In other embodiments, the small pore molecular sieve comprises d6r units. Thus, in one or more embodiments, the small pore zeolite has a structure type selected from AEI, AFT, AFX, CHA, EAB, ERI, KFI, LEV, LTN, MSO, SAS, SAT, SAV, SFW, TSC, and combinations thereof. In some embodiments, the small pore zeolitic material has a structure type selected from the group consisting of CHA, AEI, AFX, ERI, KFI, LEV, and combinations thereof. In some embodiments, the small pore zeolitic material has a structure type selected from CHA, AEI, and AFX. In one embodiment, the zeolitic material has a chabazite (CHA) structure type. In one or more embodiments, the zeolite material as disclosed herein has a CHA crystal structure and is selected from aluminosilicate zeolites, borosilicates, gallosilicates, SAPO, and ALPO, MeAPSO, and MeAPO. In some embodiments, the zeolite material having the CHA crystal structure is an aluminosilicate zeolite. Specific, non-limiting examples of zeolites having the CHA structure that are useful in the present disclosure include, but are not limited to, SSZ-13, SSZ-62, natural chabazite, zeolite KG, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, CuSAPO-34, CuSAPO-44, CuSAPO-47, and ZYT-6. In one embodiment, the zeolite material is chabazite (CHA).

[0064] Zeolitic materials as disclosed herein typically exist in the form of highly crystalline materials, hi some embodiments, the zeolitic materials are at least about 75% crystalline, at least about 80% crystalline, at least about 85% crystalline, at least about 90% crystalline, at least about 95% crystalline, at least about 98% crystalline, at least about 99% crystalline, or at least about 99.5% crystalline.

[0065] The zeolitic materials as disclosed herein are characterized by a relatively low mesopore surface area (MSA) combined with a zeolite surface area (ZSA) that provides good catalytic performance. In some embodiments, the MSA of the zeolitic material is about 25 m 2 / g or less than 15m 2 / g or less (e.g., about 5 to about 25 m 2 The ZSA of the zeolite material is typically at least about 400 m 2 / g, or at least about 450m 2 / g, or at least about 500m 2 / g, and an exemplary ZSA range is about 400 to about 600 m 2 / g or approximately 450 to 600m 2 / g. Pore volume and surface area properties can be determined by nitrogen adsorption (BET surface area method).

[0066] Zeolitic materials as disclosed herein typically have an average crystal size of up to about 3 μm, or in the range of about 200 nm to about 3 μm, or about 500 nm to about 2 μm, or about 800 nm to about 1.5 μm. Average crystal size can be measured, for example, using microscopy, such as scanning electron microscopy (SEM).

[0067] The silica-to-alumina ratio (SAR) of the present zeolitic materials can vary over a range. In some embodiments, the zeolitic materials can be characterized by an SAR range of about 10 to about 45, e.g., about 10 to about 30, about 15 to about 25, or about 15 to about 20. In some embodiments, the SAR range is about 15, about 16, or about 17 to about 18, about 19, or about 20.

[0068] As noted above, in one embodiment, the zeolite material is characterized by a domain size of less than about 1500 Å, a crystallographic distortion of less than about 0.7%, or both. Surprisingly, in accordance with the present disclosure, domain and / or distortion values ​​in these ranges associated with CHA framework-type zeolites prepared as disclosed herein, when ion-exchanged with copper, provide excellent NOx performance. x It has been found that this resulted in SCR catalytic materials with reducing performance. In some embodiments, the domain size is less than about 1400 Å, less than about 1300 Å, less than about 1200 Å, less than about 1100 Å, less than about 1000 Å, less than about 900 Å, or less than about 800 Å. In some embodiments, the domain size is about 800 to about 1500 Å, e.g., about 800 Å, about 900 Å, about 1000 Å, or to about 1100 Å, to about 1200 Å, about 1300 Å, about 1400 Å, or about 1500 Å. In some embodiments, the domain size is about 800 to about 1400 Å. In some embodiments, the domain size is about 800 to about 1200 Å. In some embodiments, the domain size is about 800 to about 1100 Å. In some embodiments, the domain size is about 900 to about 1000 Å, about 1000 to about 1100 Å, about 1100 to about 1200 Å, about 1200 to about 1300 Å, or about 1300 to about 1400 Å.

[0069] In some embodiments, the crystallographic strain is less than about 0.7%, e.g., less than about 0.6%, less than about 0.5%, less than about 0.4%, or less than about 0.3%. In some embodiments, the crystallographic strain is between about 0.2% and about 0.7%, e.g., between about 0.2%, about 0.3%, or between about 0.4% and about 0.5%, or about 0.6%, or about 0.7%.

[0070] In some embodiments, the domain size is about 1300 Å to about 1500 Å, and the crystallographic strain is about 0.4% or less, e.g., about 0.2% to about 0.4%. In some embodiments, the domain size is about 1100 Å to about 1200 Å, and the crystallographic strain is about 0.6% or less, e.g., about 0.2% to about 0.6%. In certain embodiments, the domain size is about 900 Å to about 1000 Å, and the crystallographic strain is about 0.7% or less, e.g., about 0.2% to about 0.7%. In some embodiments, the domain size is about 800 Å to about 1200 Å, and the crystallographic strain is about 0.2% to about 0.6%. In some embodiments, the domain size is about 800 Å to about 1100 Å, and the crystallographic strain is about 0.3% to about 0.5%.

[0071] Method for preparing zeolitic materials The synthesis of zeolitic materials varies depending on the specific structure type, but typically involves combining several components (e.g., silica, alumina, phosphorus, alkali, structure directing agent (SDA), etc.) to form a synthesis gel, which is then hydrothermally crystallized to form the final product. During crystallization, the tetrahedral units organize around the SDA to form the desired framework, which is often embedded within the pore structure of the zeolite crystal. In one or more embodiments, crystallization of the molecular sieve material can be achieved by the addition of structure directing agents / templates, crystal nuclei, or elements.

[0072] The method for preparing the zeolitic material as disclosed herein generally comprises forming a reaction mixture comprising at least one alumina source comprising a zeolite (typically a zeolite having an FAU crystalline framework), at least one silica source (such as a source comprising an alkali metal silicate solution and / or colloidal silica), at least one organic structure directing agent (OSDA), and, optionally, a secondary alkali metal cation source to increase the alkali metal content of the reaction mixture. The reaction mixture is typically provided under alkaline aqueous conditions. Each component of the reaction mixture (also referred to herein as the "synthesis gel") is further described below.

[0073] Alumina Source The at least one alumina source generally comprises a zeolite. The zeolite used as the alumina source can vary but will include various zeolite materials known in the art, particularly various silicoaluminozeolites. In certain embodiments, zeolites having the FAU crystal structure are used, which are formed by a 12-ring structure and have channels of approximately 7.4 Å. Examples of such zeolites include faujasite, zeolite X, zeolite Y, LZ-210, and SAPO-37. Such zeolites are characterized by a three-dimensional pore structure with pores running perpendicular to each other in the x, y, and z planes, with secondary building units of 4, 6, and 6-6. Exemplary silica-to-alumina ratios (SAR) for bulk FAU zeolite materials range from about 3 to about 6, and typically have unit cell sizes ranging from 24.35 to 24.65, as determined by XRD. Zeolite Y is particularly useful in certain embodiments. FAU zeolites typically contain Na. + In one particular embodiment, the FAU zeolite is in the sodium form and contains about 2.5% to 13% NaO by weight.

[0074] Silica Source At least one silica source is typically an alkali metal silicate solution, such as sodium silicate. The alkali metal silicate solution used in the reaction mixture can provide all of the alkali metal content necessary to achieve the desired alkali metal to Si, Al, and OSDA ratio. However, the alkali metal content of the reaction mixture can optionally be supplemented with a secondary alkali metal cation source, including, for example, alkali metal sulfates (e.g., Na2SO4), alkali metal acetates (e.g., sodium acetate), and alkali metal bromides (e.g., sodium bromide). Optionally, in certain embodiments, the alkali metal silicate solution can be supplemented or replaced with other silica sources, such as colloidal silica, fumed silica, tetraethyl orthosilicate (TEOS), and combinations thereof.

[0075] The molar ratio of alkali metal to silicon (M / Si, where M is the moles of alkali metal) in the synthesis gel can vary. In certain embodiments, M / Si is at least about 0.4, or at least about 0.5, or at least about 0.6, or at least about 0.7, or at least about 0.8, with exemplary ranges being about 0.4 to about 1.2, or about 0.6 to about 1.0, or about 0.7 to about 0.9. The alkali metal can be, for example, lithium, sodium, potassium, rubidium, or cesium. In certain embodiments, the alkali metal is sodium or potassium. In certain embodiments, the alkali metal is sodium.

[0076] The molar ratio of hydroxide ions to silicon in the synthesis gel (OH - / Si, in the formula, OH - / Si is the moles of hydroxide ions) can vary. In some embodiments, OH - The / Si molar ratio is less than about 0.7, or less than about 0.65, or less than about 0.6, or less than about 0.55, with exemplary ranges being about 0.3 to about 0.7 or about 0.4 to about 0.65. Hydroxide ions are the only necessary mineralizer required in the reaction mixture, and the amount of hydroxide required to achieve the above ratios can be provided solely from the alkali metal silicate solution and, to a lesser extent, from the organic structure directing agent source. If necessary, the hydroxide ion content can be supplemented with an additional hydroxide ion source, such as NaOH or KOH.

[0077] In certain embodiments, the total molar ratio of alkali metal to Si (M / Si, where M is the number of moles of alkali metal) and the molar ratio of organic structure directing agent to Si (R / Si, where R is the number of moles of organic structure directing agent) is greater than or equal to the molar ratio of hydroxide ions to Si (OH - / Si). In other words, the total molar ratio of M / Si+R / Si is - / Si molar ratio is larger.

[0078] In certain embodiments, the total ratio of M / Si+R / Si is greater than about 0.75, or greater than about 0.80, or greater than about 0.82, or greater than about 0.85, with exemplary ranges being from about 0.75 to about 0.95, or from about 0.80 to about 0.95, or from about 0.85 to about 0.95.

[0079] The molar ratio of silica to alumina (SAR) in the synthesis gel can vary. In some embodiments, the SAR range is typically from about 25 to about 40, for example, from about 25 to about 35.

[0080] The molar ratio of water to Si (H2O / Si) in the synthesis gel can vary. In some embodiments, the H2O / Si molar ratio ranges from about 12 to about 40.

[0081] organic structure directing agent The organic structure-directing agents (OSDAs) present in the synthesis gel are typically amines and / or quaternary ammonium salts. Examples include quaternary ammonium cations with substituents selected from the group consisting of alkyl, adamantyl, cyclohexyl, aromatic, and combinations thereof. Non-limiting examples of OSDAs include adamantyltrimethylammonium, cyclohexyltrimethylammonium, benzyltrimethylammonium, and dimethylpiperidinium hydroxide. In some embodiments, the OSDA is adamantyltrimethylammonium hydroxide (TMAdaOH).

[0082] The amount of OSDA present can vary and can be expressed as a ratio relative to other components present (e.g., silica). In certain embodiments, the OSDA / Si molar ratio is less than about 0.12, or less than about 0.11, or less than about 0.10, or less than about 0.08, or less than about 0.06, with exemplary ranges being from about 0.04 to about 0.12, or from about 0.06 to about 0.10.

[0083] The reaction mixture may be characterized by its solids content, expressed as a weight percentage of silica (SiO) and alumina (AlO). The solids content can vary, with exemplary ranges being from about 5 to about 25%, or from about 8 to about 20%.

[0084] Generally, the synthesis of zeolitic materials as described herein is carried out by heating a reaction mixture as described above in a pressure vessel with stirring to obtain the desired crystalline zeolitic product. Typical reaction temperatures range from about 100°C to about 160°C, e.g., from about 120°C to about 160°C, at the corresponding autogenous pressure. Typical reaction times are from about 30 hours to about 3 days. Optionally, the product may be centrifuged. Organic additives may be used to aid in handling and isolation of the solid product. Spray drying is an optional step in the processing of the product. The solid zeolitic product may then be heat treated or calcined in air or nitrogen. Typical calcination temperatures are from about 400°C to about 850°C (e.g., from about 500°C to about 700°C) for 1 to 10 hours. Following the initial calcination, the zeolitic material is dissolved in a solvent containing zeolitic acid, primarily in the alkali metal form (e.g., Na). + Optionally, single or multiple ammonium ion exchanges are used to convert the zeolite to NH4 + The form can be obtained. NH4 + Ion exchange can be carried out according to various techniques known in the art, for example, Bleken, et al., Topics in Catalysis 52, (2009), 218-228. Optionally, the NH4-exchanged zeolite can be further calcined to remove H + Morphology can be formed.

[0085] SCR catalyst composition The present disclosure relates to the reduction of NO from lean-burn engine exhaust gas in the presence of a reductant. x

[0009] Provided is a selective catalytic reduction (SCR) catalyst composition effective for catalyzing the reduction of H, wherein the catalyst composition comprises a zeolitic material as disclosed herein promoted with a metal. As used herein, "promoted" refers to a component that is intentionally added to the zeolitic material, as opposed to an inherent impurity in the zeolitic material. Thus, the promoter is intentionally added to improve the activity of the catalyst compared to a catalyst that does not have the promoter intentionally added. In some embodiments, a zeolitic material as disclosed herein (e.g., H) is used to promote the reduction of H. + The zeolitic material (in the form of a catalyst) may be ion-exchanged with a promoter metal to form a metal-promoted zeolite catalyst. Thus, to promote SCR of nitrogen oxides, in one or more embodiments, the zeolitic material may be ion-exchanged with one or more promoter metals, such as copper (Cu), cobalt (Co), nickel (Ni), lanthanum (La), manganese (Mn), iron (Fe), vanadium (V), silver (Ag), and cerium (Ce), neodymium (Nd), praseodymium (Pr), titanium (Ti), chromium (Cr), zinc (Zn), tin (Sn), niobium (Nb), molybdenum (Mo), hafnium (Hf), yttrium (Y), and tungsten (W). In some embodiments, the zeolitic material is promoted with Cu, Fe, or a combination thereof. In some embodiments, the zeolitic material is promoted with Cu.

[0086] In one or more embodiments, the promoter metal content of the zeolitic material, calculated as oxide, is at least about 0.1 wt. %, reported on a volatile-free basis. In one or more embodiments, the promoter metal is present in an amount ranging from about 1 to about 10 wt. %, including from about 2 to about 5 wt. %, and from about 4 to about 6 wt. %, in all cases based on the total weight of the zeolitic material. In one or more specific embodiments, the promoter metal comprises Cu, and the Cu content, calculated as CuO, ranges up to about 10 wt. %, including 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, and 0.1 wt. %, in each case based on the total weight of the calcined zeolitic material, reported on a volatile-free basis. In specific embodiments, the Cu content, calculated as CuO, ranges from about 2 to about 6 wt. %.

[0087] SCR catalytic articles In another aspect, nitrogen oxides (NO) from lean-burn engine exhaust gases are x An SCR catalyst article effective for mitigating CO2 emissions is provided, the SCR catalyst article including a substrate, and a first washcoat including an SCR catalyst composition as disclosed herein disposed on at least a portion of the substrate.

[0088] Base material In one or more embodiments, the SCR catalyst composition is disposed on a substrate to form a catalytic article of an SCR catalyst. Catalytic articles including the substrate are typically used as part of an exhaust gas treatment system (e.g., catalytic articles include, but are not limited to, articles including the SCR catalyst composition disclosed herein). Useful substrates are three-dimensional, having 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 the inlet and outlet ends.

[0089] According to one or more embodiments, the substrate for the disclosed catalyst may be composed of any material typically used to prepare automotive catalysts, and typically includes a metal or ceramic honeycomb structure. The substrate typically provides multiple walls to which the catalytic washcoat is applied and adhered, thereby serving as the substrate for the catalyst.

[0090] The ceramic substrate may be made from any suitable refractory material, such as cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicates, and the like.

[0091] The substrate can also be metallic and include one or more metals or metal alloys. Metal substrates can include any metallic substrate having openings or "punchouts" in the channel walls. Metallic substrates can be used in various shapes, such as pellets, compressed metallic fibers, corrugated sheets, or monolith forms. Specific examples of metallic substrates include heat-resistant base metal alloys, particularly alloys in which iron is a substantial or major component. Such alloys can contain one or more of nickel, chromium, and aluminum, the total of which metals advantageously comprises at least about 15 wt. % (weight percent) of the alloy, in each case based on the weight of the substrate, e.g., about 10 to about 25 wt. % chromium, about 1 to about 8 wt. % aluminum, and 0 to about 20 wt. % nickel. Examples of metallic substrates include those with straight channels, those with protruding blades along the axial channels to disrupt gas flow and open gas flow communication between channels, and those with holes to enhance gas transport between channels, allowing radial gas transport throughout the blades and monolith.

[0092] Any substrate suitable for the SCR catalytic article disclosed herein may be used, such as a monolithic substrate of the type having fine, parallel gas passages extending from an inlet or outlet face of the substrate through which the passages are open to the fluid flow (a "flow-through substrate"). Another suitable substrate is one having a plurality of fine, substantially parallel gas passages extending along the longitudinal axis of the substrate, typically with each passage blocked at one end of the substrate body and every other passage blocked at the opposite end face (a "wall-flow filter"). Flow-through and wall-flow substrates are also disclosed, for example, in International Patent Application Publication No. 2016 / 070090, the entire contents of which are incorporated herein by reference.

[0093] In some embodiments, the catalytic substrate comprises a honeycomb substrate in the form of a wall-flow filter or a flow-through substrate. In some embodiments, the substrate is a wall-flow filter. In some embodiments, the substrate is a flow-through substrate. Flow-through substrates and wall-flow filters are discussed further herein below.

[0094] Flow-Through Substrate In some embodiments, the substrate is a flow-through substrate (e.g., a monolith substrate, including a flow-through honeycomb monolith substrate). Flow-through substrates have fine, parallel gas flow passages extending from the inlet end to the outlet end of the substrate such that the passages are open to fluid flow. The passages, which are essentially straight-line paths from the fluid inlet to the fluid outlet, are defined by walls, and catalytic coatings are disposed on or within the walls such that gas flowing through the passages contacts the catalytic material. The flow passages in flow-through substrates are thin-walled channels and can be of any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, etc. Flow-through substrates can be ceramic or metallic, as described above.

[0095] The flow-through substrate may be, for example, about 50 in 3 ~About 1200in3 and a cell density (inlet opening) of about 60 cells per square inch (cpsi) to about 500 cpsi or up to 900 cpsi, e.g., about 200 to about 400 cpsi, and a wall thickness of about 50 to about 200 microns or about 400 microns.

[0096] Wall flow filter substrate In some embodiments, the substrate is a wall-flow filter, which generally has a plurality of fine, substantially parallel gas passages extending along the substrate's longitudinal axis. Typically, each passage is blocked at one end of the substrate body, and every other passage is blocked at the opposite end. Such monolithic wall-flow filter substrates may contain up to about 900 or more passages (or "cells") per square inch of cross section, although much smaller numbers may be used. For example, the substrate may have about 7 to 600, more typically about 100 to 400, cells per square inch ("cpsi"). The cells may have rectangular, square, circular, oval, triangular, hexagonal, or other polygonal cross sections. Wall-flow filter substrates may be ceramic or metallic, as described above.

[0097] Referring to FIG. 1, an exemplary wall-flow filter substrate has a cylindrical shape, with the cylindrical outer surface having a diameter D and an axial length L. FIG. 2 is a perspective view of an exemplary wall-flow filter. A cross-sectional view of a monolithic wall-flow filter substrate section is illustrated in FIG. 2, showing alternating blocked and open flow passages (cells). Blocked or blocked ends 100 alternate with open flow passages 101, with each opposing end being open and blocked, respectively. The filter has an inlet end 102 and an outlet end 103. Arrows across the porous cell walls 104 represent exhaust gas flow entering the open cell ends, diffusing through the porous cell walls 104, and exiting the open outlet cell ends. The blocked ends 100 impede gas flow and promote diffusion through the cell walls. Each cell wall has an inlet side 104a and an outlet side 104b. The passages are enclosed by the cell walls.

[0098] The wall flow filter article substrate may be, for example, about 50 cm 3 , about 100in 3 , approximately 200in 3 , about 300in 3 , approximately 400 in 3 , approximately 500in 3 , approximately 600in 3 , approximately 700 in 3 , approximately 800 in 3 , approximately 900in 3 , or about 1000 in 3 From about 1500 in 3 , approximately 2000 in 3 , about 2500in 3 , about 3000in 3 , about 3500in 3 , approximately 4000in 3 , approximately 4500 in 3 , or about 5000 in 3 Wall-flow filter substrates typically have a wall thickness of from about 50 microns to about 2000 microns, for example, from about 50 microns to about 450 microns, or from about 150 microns to about 400 microns.

[0099] The walls of a wall-flow filter are porous and generally have a wall porosity of at least about 40% or at least about 50% and an average pore size of at least about 10 microns before the functional coating is applied. For example, the wall-flow filter article substrate in some embodiments may have a porosity of ≥40%, ≥50%, ≥60%, ≥65%, or ≥70%. For example, the wall-flow filter article substrate may have a wall porosity of about 50%, about 60%, about 65%, or about 70% to about 75% and an average pore size of about 10 microns or about 20 microns to about 30 microns or about 40 microns before the catalytic coating is applied. The terms "wall porosity" and "substrate porosity" are interchangeable and mean the same thing. Porosity is the ratio of the void volume (or pore volume) divided by the total volume of the substrate material. Pore size and pore size distribution are typically determined by Hg porosimetry measurements.

[0100] Substrate Coating Process To produce the SCR catalytic article of the present disclosure, a substrate as described herein is contacted with an SCR catalytic composition as disclosed herein to provide a coating (i.e., a slurry containing particles of metal-promoted zeolitic material is disposed on the substrate). The coating is a "catalytic coating composition" or "catalytic coating." "Catalyst composition" and "catalytic coating composition" are synonymous.

[0101] In addition to the metal-promoted zeolitic material, the coating slurry may optionally contain a binder in the form of alumina, silica, zirconium acetate, colloidal zirconia, or zirconium hydroxide, an associative thickener, and / or a surfactant (including anionic, cationic, nonionic, or amphoteric surfactants). Other exemplary binders include bohemite, gamma alumina, or delta / theta alumina, as well as silica sol. When present, the binder is typically used in an amount of about 1 to 5 wt.% of the total washcoat loading. Acidic or basic species may be added to the slurry to adjust the pH. For example, in some embodiments, the pH of the slurry is adjusted by the addition of aqueous ammonium hydroxide or nitric acid. The typical pH range for the slurry is about 3 to 6.

[0102] The slurry may be milled to reduce particle size and promote particle mixing. Milling can be accomplished in a ball mill, continuous mill, or other similar equipment, and the solids content of the slurry may be, for example, about 20 to 60% by weight, more specifically, about 20 to 40% by weight. In one embodiment, the milled slurry has a D of about 10 to about 40 microns, preferably 10 to about 30 microns, and more preferably about 10 to about 15 microns. 90 Characterized by particle size. D 90 is determined using a dedicated particle size analyzer, manufactured by Sympatec in 2010, which uses laser diffraction to measure particle size in small amounts of slurry.

[0103] The SCR catalyst composition may typically be applied in the form of one or more washcoats containing the SCR catalyst composition as disclosed herein. The washcoat is formed by preparing a slurry containing a particular solids content (e.g., about 10 to about 60 wt.%) of the catalyst in a liquid vehicle, which is then applied to the substrate using any washcoating technique known in the art, dried, and calcined to provide a coating layer. If multiple coatings are applied, the substrate is dried and / or calcined after each washcoat is applied, and / or after a desired number of multiple washcoats are applied. In one or more embodiments, the catalyst material is applied to the substrate as a washcoat.

[0104] In some embodiments, drying is carried out at a temperature of about 100 to about 150° C. In some embodiments, drying is carried out in a gas atmosphere. In some embodiments, the gas atmosphere comprises oxygen. In some embodiments, drying is carried out for a period ranging from 10 minutes to 4 hours, more preferably from 20 minutes to 3 hours, more preferably from 50 minutes to 2.5 hours.

[0105] In some embodiments, the calcination is carried out at a temperature of about 300 to about 900°C, about 400 to about 650°C, or about 450 to about 600°C. In some embodiments, the calcination is carried out in a gas atmosphere. In some embodiments, the gas atmosphere comprises oxygen. In some embodiments, the calcination is carried out for a period ranging from 10 minutes to about 8 hours, from about 20 minutes to about 3 hours, or from about 30 minutes to about 2.5 hours.

[0106] After calcination, the catalyst loading achieved by the washcoat technique described above can be determined by calculating the difference between the coated and uncoated weights of the substrate. As will be apparent to those skilled in the art, catalyst loading can be modified by altering the rheology of the slurry. Furthermore, the coating / drying / calcination process to produce a washcoat layer can be repeated as necessary to build the coating to a desired loading level or thickness; i.e., more than one washcoat can be applied. In some embodiments, catalyst washcoat loadings range from about 0.8 to 2.6 g / in. 3 , about 1.2~2.2g / in 3 , or about 1.5 to about 2.2 g / in 3 is in the range.

[0107] The SCR catalytic coating can comprise one or more coating layers, at least one of which comprises the SCR catalyst composition. The catalytic coating can comprise one or more thin, adherent coating layers disposed on and adhering to at least a portion of a substrate. The entire coating comprises individual "coating layers."

[0108] Coating composition In some embodiments, the SCR catalytic article may include the use of one or more catalytic layers, as well as combinations of one or more catalytic layers. The catalytic material may be present only on the inlet side, only on the outlet side, on both the inlet and outlet sides of the substrate wall, or the wall itself may be composed entirely or partially of catalytic material. The catalytic 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 "washcoat disposed on a substrate" refers to any surface, e.g., on the wall surface and / or pore surfaces.

[0109] Washcoats can be applied so that the different coating layers are in direct contact with the substrate. Alternatively, one or more "undercoats" may be present, whereby the catalytic coating layer or at least a portion of the coating layer is not in direct contact with the substrate (rather, it is in contact with the undercoat). One or more "overcoats" may be present so that at least a portion of the coating layer is not directly exposed to the gas stream or atmosphere (rather, it is in contact with the overcoat).

[0110] Alternatively, the catalyst composition may be present in a top coating layer that overlies the bottom coating layer. The catalyst composition may be present in both the top and bottom layers. Any one layer may extend the entire axial length of the substrate; for example, the bottom layer may extend the entire axial length of the substrate, and the top layer may also extend the entire axial length of the substrate above the bottom layer. The top and bottom layers may each extend from either the inlet end or the outlet end.

[0111] For example, both the bottom coating layer and the top coating layer can extend from the same substrate edge, with the top layer partially or completely overlaying the bottom layer, with the bottom layer extending a partial or full length of the substrate, and the top layer extending a partial or full length of the substrate. Alternatively, the top layer can overlay a portion of the bottom layer. For example, the bottom layer can extend the full length of the substrate, and the top layer can extend from either the inlet or outlet edge for about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the length of the substrate.

[0112] Alternatively, the bottom layer may extend from either the inlet end or the outlet end up to 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 length of the substrate, and the top layer may extend from either the inlet end or the outlet end up to 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 length of the substrate, with at least a portion of the top layer overlaying the bottom layer. This "overlay" zone can extend, for example, from about 5% to about 80%, e.g., about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60, or about 70%, of the length of the substrate.

[0113] In some embodiments, an SCR catalyst composition as disclosed herein disposed on a substrate as disclosed herein includes a first washcoat disposed on at least a portion of the length of the catalyst substrate.

[0114] In some embodiments, a first washcoat is disposed directly on the catalytic substrate, and a second washcoat (comprising the same or a different catalyst or catalyst component) is disposed on at least a portion of the first washcoat. In some embodiments, a second washcoat is disposed directly on the catalytic substrate, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, a first washcoat is disposed directly on the catalytic substrate from the inlet end for about 10% to about 50% of the total length, and a second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, a second washcoat is disposed directly on the catalytic substrate from the inlet end for about 50% to about 100% of the total length, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, a first washcoat is disposed directly on the catalyst substrate from the inlet end for about 20% to about 40% of the total length, and a second washcoat extends from the inlet end to the outlet end. In some embodiments, a first washcoat is disposed directly on the catalyst substrate from the outlet end for about 10% to about 50% of the total length, and a second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, a first washcoat is disposed directly on the catalyst substrate from the outlet end for about 20% to about 40% of the total length, and a second washcoat extends from the inlet end to the outlet end. In some embodiments, a second washcoat is disposed directly on the catalyst substrate from the outlet end for about 50% to about 100% of the total length, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, a first washcoat is disposed directly on the catalytic substrate covering 100% of the overall length, and a second washcoat is disposed on the first washcoat covering 100% of the overall length.In some embodiments, the second washcoat is disposed directly on the catalytic substrate covering 100% of the total length, and the first washcoat is disposed on the second washcoat covering 100% of the total length.

[0115] The catalytic coating can advantageously be "zoned" and include zoned catalytic layers, i.e., the catalytic coating contains different compositions across the axial length of the substrate. This can also be described as "laterally zoned." For example, a layer can extend from the inlet end toward the outlet end and can extend over 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 can extend from the outlet end toward the inlet end and can extend over 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 can be adjacent to each other and not overlay each other. Alternatively, different layers can overlay portions of each other to provide a third, "intermediate" zone. The intermediate zone may, for example, extend over about 5% to about 80% of the length of the substrate, e.g., about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% of the length of the substrate.

[0116] The zones in this disclosure are defined by the relationship between coating layers. There are several possible zoning configurations for different coating layers. For example, there may be an upstream zone and a downstream zone; an upstream zone, an intermediate zone, and a downstream zone; or four different zones. When two layers are adjacent and do not overlap, there are upstream and downstream zones. When two layers overlap to some extent, there are upstream, downstream, and intermediate zones. For example, when a coating layer extends over the entire length of the substrate and a different coating layer extends a certain length from the exit end and overlays a portion of the first coating layer, there are upstream and downstream zones.

[0117] For example, an SCR article may include an upstream zone that includes a first washcoat layer and a downstream zone that includes a second washcoat layer that includes a different catalytic material or component, or the upstream zone may include the second washcoat layer and the downstream zone may include the first washcoat layer.

[0118] In some embodiments, the first washcoat is disposed on the catalyst substrate from the inlet end for about 10% to about 50% of its total length, and the second washcoat is disposed on the catalyst substrate from the outlet end for about 50% to about 90% of its total length. In some embodiments, the first washcoat is disposed on the catalyst substrate from the outlet end for about 10% to about 50% of its total length, and the second washcoat is disposed on the catalyst substrate from the inlet end for about 50% to about 90% of its total length.

[0119] Figures 3a, 3b, and 3c show several possible coating layer configurations with two coating layers. Shown is a substrate wall 200 on which coating layers 201 (top coat) and 202 (bottom coat) are disposed. This is a simplified illustration; in the case of a porous wall-flow substrate, the pores and coatings attached to the pore walls are not shown, and plugged ends are not shown. In Figure 3a, coating layers 201 and 202 each extend the entire length of the substrate, with top layer 201 overlaying bottom layer 202. The substrate in Figure 3a does not include a zoned coating configuration. Figure 3b illustrates a zoned configuration with coating layer 202 extending approximately 50% of the substrate length from the outlet to form downstream zone 204, and coating layer 201 extending approximately 50% of the substrate length from the inlet to provide upstream zone 203. In Figure 3c, bottom coating layer 202 extends approximately 50% of the substrate length from the outlet, and top coating layer 201 extends more than 50% of the length from the inlet and overlays a portion of layer 202, providing upstream zone 203, intermediate overlay zone 205, and downstream zone 204. Figures 3a, 3b, and 3c can be useful for illustrating SCR catalyst composition coatings on wall-through or flow-through substrates.

[0120] In some embodiments, the substrate is a honeycomb substrate. In some embodiments, the honeycomb substrate is a flow-through substrate or a wall-flow filter. In certain embodiments, the metal-promoted zeolite material as disclosed herein, when incorporated into an SCR catalytic article as disclosed herein, can be characterized by SCR activity at various temperatures. For example, in some embodiments, at least a portion of the NOx in the exhaust gas stream is reduced to N2 at temperatures between about 200°C and about 600°C. In some embodiments, the NOx level in the exhaust gas stream is reduced by at least 50% at 200°C. In some embodiments, the NOx level in the exhaust gas stream is reduced by at least 70% at 600°C. In some embodiments, the SCR catalytic article is subjected to a thermal aging treatment at 800°C for 16 hours in the presence of 10% by volume steam and the remainder air, followed by an 80,000-hour test under simulated steady-state conditions. -1 At an exhaust gas volumetric hourly space velocity of 2.1 g / in 3 and the SCR catalyst article, when tested under conditions where the exhaust gas contains a gas mixture of 500 ppm NO, 500 ppm NH, 10% O, 5% H, and the remainder N, exhibits a reduction of NO in the exhaust gas stream of about 72% or more at 200°C, about 81% or more at 600°C, or both.

[0121] Exhaust Gas Treatment Systems In a further aspect, an exhaust gas treatment system is provided that includes an SCR article as disclosed herein positioned downstream of and in fluid communication with a lean-burn engine that generates an exhaust gas stream. The engine may be, for example, a diesel engine operating under combustion conditions with more air than required for stoichiometric combustion, i.e., lean conditions. In other embodiments, the engine may be an engine associated with a stationary source (e.g., a generator or pumping station). In some embodiments, the emissions treatment system further includes one or more additional catalytic components. The relative placement of the various catalytic components present in the emissions treatment system may vary.

[0122] In the present exhaust gas treatment systems and methods, the exhaust gas stream is received into the article or treatment system by entering at an upstream end and exiting at a downstream end. The inlet end of the substrate or article is synonymous with the "upstream" end or "front" end. The outlet end is synonymous with the "downstream" end or "rear" end. The treatment system is generally downstream of and in fluid communication with the internal combustion engine.

[0123] The systems disclosed herein include an SCR catalytic article as disclosed herein and may further include one or more additional components. In some embodiments, the one or more additional components include a diesel oxidation catalyst (DOC), a soot filter (which may be catalyzed or uncatalyzed), a urea injection component, an ammonia oxidation catalyst (AMOx), a low temperature NOx, or a combination thereof. x Absorbent (LT-NA), Lean NO x The system may be selected from the group consisting of a selective catalytic reduction catalyst (SCR) as disclosed herein, a diesel oxidation catalyst (DOC), a reductant injector, a soot filter, an ammonia oxidation catalyst (AMOx), or a lean NOx trap (LNT), and combinations thereof. x The treatment system may include one or more items including a reductant injector and / or ammonia oxidation catalyst. An item including a reductant injector is a reduction item. The reduction system includes a reductant injector and / or a pump and / or a reservoir, etc. The treatment system may further include a soot filter and / or an ammonia oxidation catalyst. The soot filter may be uncatalyzed or catalyzed (CSF). For example, the treatment system may include, from upstream to downstream, an item including a DOC, a CSF, a urea injector, an SCR item, and an item including AMOx. x A trap (LNT) may also be included.

[0124] The relative placement of the various catalytic components present within an emissions treatment system can vary. In the present exhaust gas treatment systems and methods, the exhaust gas stream is received by the article or treatment system by entering at an upstream end and exiting at a downstream end. The inlet end of the substrate or article is synonymous with the "upstream" end or "front" end. The outlet end is synonymous with the "downstream" end or "rear" end. The treatment system is generally downstream of and in fluid communication with the internal combustion engine.

[0125] One exemplary emissions treatment system is illustrated in FIG. 4, which depicts a schematic diagram of an emissions treatment system 20. As shown, the emissions treatment system may include multiple catalyst components in series downstream of an engine 22, such as a lean-burn gasoline engine. At least one of the catalyst components will be an SCR catalyst article as described herein. The SCR catalyst article may be combined with multiple additional catalyst materials and may be located in various positions relative to the additional catalyst materials. While FIG. 4 illustrates five catalyst components 24, 26, 28, 30, and 32 in series, the total number of catalyst components may vary, and five components is merely an example. Those skilled in the art will recognize that it may be desirable to arrange the relative positions of each item in a different order than illustrated herein. Such alternative orderings are contemplated by the present disclosure.

[0126] Without limitation, Table 1 presents various exhaust gas treatment system configurations of one or more embodiments. Note that each catalyst is connected to the next catalyst via an exhaust conduit such that the engine is upstream of catalyst A, which is upstream of catalyst B, which is upstream of catalyst C, which is upstream of catalyst D, and which is upstream of catalyst E (if present). References to components A-E in the table may be cross-referenced with the same symbols in FIG. 4.

[0127] The LNT catalysts listed in Table 1 xThe catalyst can be any catalyst conventionally used as a trap, typically including base metal oxides (such as BaO, MgO, CeO, etc.) and platinum group metals (e.g., Pt and Rh) for catalytic oxidation and reduction of NO. x The adsorbent composition includes:

[0128] The LT-NA catalysts listed in Table 1 produce NO at low temperatures (<250°C). x It can be any catalyst that can adsorb NO (e.g., NO or NO2) and release it into the gas stream at high temperatures (>250°C). x is generally converted to N2 and HO over a downstream SCR or SCRoF catalyst as disclosed herein. Typically, the LT-NA catalyst comprises a Pd-promoted zeolite or a Pd-promoted refractory metal oxide.

[0129] References to SCR in the tables refer to an SCR catalyst, which may include the SCR catalyst composition of the present disclosure. References to SCRoF (or SCR over filter) refer to a particulate or soot filter (e.g., a wall-flow filter), which may include the SCR catalyst composition of the present disclosure. When both an SCR and an SCRoF are present, one or both may include the SCR catalyst of the present disclosure, or one of the catalysts may include a conventional SCR catalyst.

[0130] References to AMOx in the tables refer to an ammonia oxidation catalyst that can be provided downstream of the catalyst of one or more embodiments of the present invention to remove any fugitive ammonia from the exhaust gas treatment system. In certain embodiments, the AMOx catalyst can include a PGM component. In one or more embodiments, the AMOx catalyst can include a bottom coat having a PGM and a top coat having SCR functionality.

[0131] As will be appreciated by those skilled in the art, in the configurations listed in Table 1, any one or more of components A, B, C, D, or E can be disposed on a particulate filter, such as a wall-flow filter, or on a flow-through honeycomb substrate. In one or more embodiments, the engine exhaust system includes one or more catalyst components mounted in a location near the engine (direct-coupled location, CC), with an additional catalyst component mounted in an underbody location (underfloor location, UF). In one or more embodiments, the exhaust gas treatment system may further include a urea injection component. [Table 1]

[0132] How to treat engine exhaust Another aspect of the present invention is directed to a method for treating an exhaust gas stream from a lean-burn engine, particularly a lean-burn gasoline or diesel engine. Generally, the method includes contacting the exhaust gas stream with a catalytic article of the present disclosure or an emissions treatment system of the present disclosure. The method can include placing an SCR catalyst article according to one or more embodiments of the present invention downstream of the engine and flowing the engine exhaust gas stream over the catalyst. In one or more embodiments, the method further includes placing an additional catalyst component downstream of the engine, as described above. In some embodiments, the method includes contacting the exhaust gas stream with a catalytic article or an exhaust gas treatment system of the present disclosure and one or more NOx-containing compounds that may be present in the exhaust gas stream. x This involves contacting for a time and at a temperature sufficient to reduce the level of the component.

[0133] The catalyst compositions, articles, systems, and methods are suitable for treating exhaust gas streams from internal combustion engines, such as gasoline, light-duty diesel, and heavy-duty diesel engines. The catalyst compositions are also suitable for treating emissions from stationary industrial processes, removing harmful or toxic substances from indoor air, or catalyzing chemical reaction processes.

[0134] It will be readily apparent to those skilled in the relevant art that suitable modifications and adaptations to the compositions, methods, and applications described herein can be made without departing from the scope of any embodiment or aspect thereof. The compositions 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 scope of the compositions, formulations, methods, and processes 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 by reference for their specific teachings, as set forth, unless other specific statements of incorporation are specifically provided. [Example]

[0135] Aspects of the present invention are more fully illustrated by the following examples, which are set forth to illustrate certain aspects of the invention and should not be construed as limiting the invention. Before describing certain exemplary embodiments, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description, and that other embodiments are possible and that the invention may be practiced or carried out in various ways. Unless otherwise specified, all parts and percentages are by weight, and all weight percentages are expressed on a dry basis, meaning that water content is excluded unless otherwise indicated.

[0136] Example 1. CHA zeolite synthesis A series of CHA zeolites (Examples 1A-1D) were synthesized. For the crystallization of zeolites 1A-1D, aluminosilicate synthesis gels with the following compositions were prepared: SiO2 / Al2O3 = 35, Na / Si = 0.81, TMAda + / Si=0.09, OH / Si=0.50. The HO / Si ratio was 32 in Example 1A, 12 in Example 1B, and 34 in Examples 1C and 1D. Trimethyladamantylammonium hydroxide (TMAdaOH) was used as the organic structure directing agent (OSDA) for each preparation. Sodium silicate solution (SiO / NaO=2.6 (Examples 1A-1C) or SiO / NaO=3.3 (Example 1D)) and Na-FAU (SiO / AlO=5.1) were used as the Si and Al sources, respectively. The Na content of the gel was 0.1. + The content was supplemented with NaSO to achieve the desired Na / Si ratio. CHA seeds (SAR=20; 5% of the total SiO content) were added to the gel composition of Example 1C. Additionally, excess OH was removed using HSO. - to obtain the desired OH / Si ratio. + and OH - Assuming a 1:1 ratio between OH - The / SiO ratio was calculated. All crystallizations were carried out in a 2 L stirred autoclave at 140 °C for 36 h (Example 1C) or 72 h (Examples 1A, 1B, and 1D) at autogenous pressure. The product was isolated by filtration, dried, and calcined (540 °C, 6 h) to obtain Na + The SiO2 / Al2O3 ratio of each product was 17-20 (Table 2).

[0137] Example 2. Zeolite properties The products were characterized by XRD and N2-physisorption (Table 2). All crystallizations showed primary phase crystallinity of >90% and corresponding high micropore surface area (>500 m2). 2A product with a pore size of 0.08 / g was obtained. The surface areas of the mesopores and zeolite (micropores) were determined by N2 adsorption porosimetry on a Micromeritics TriStar 3000 series instrument according to ISO 9277. The samples were degassed for a total of 6 hours in a Micromeritics SmartPrep degasser (a 2-hour ramp to 300°C under a dry nitrogen flow, followed by a 4-hour hold at 300°C). The nitrogen BET surface area was determined using five partial pressure points from 0.08 to 0.20. The surface areas of the zeolite and matrix were determined using the same five partial pressure points and calculated using Harkins and Jura t-plots. Pores with diameters greater than 20 Å are considered to contribute to the matrix surface area.

[0138] Crystallographic strain was measured using Rietveld refinement of powder X-ray diffraction data. Specifically, strain was calculated from the LY parameter by General Structure Analysis System (GSAS) Rietveld refinement of X-ray diffraction data. The GSAS method used was similar to that in International Patent Application Publication No. 2018 / 201046, the disclosure of which is incorporated herein by reference. The GSAS software was created at Los Alamos National Laboratory and is disclosed in A. C. Larson and R. B. Von Dreele, General Structure Analysis System (GSAS), Los Alamos National Laboratory Report LAUR 86-748 (2004), which is incorporated herein by reference. For example, the GSAS manual provides the calculation of strain when determined from the parameter LY of profile function 2 as follows: S = (π / 18000) * (LY - LYi) 100%.

[0139] In this particular example, for the diffractometer used in the analysis, LYi was determined to be zero, i.e., the instrument used did not contribute to the parameter LY.

[0140] The domain size was also estimated using the GSAS method. For the domain size, the GSAS LX parameter was used. For example, the GSAS manual provides the calculation of the domain size from the parameter LX as follows: p=18000Kλ / πLX where p is the domain size in angstroms (Å). [Table 2]

[0141] Example 3. SCR catalyst composition. To prepare SCR catalysts from the aforementioned materials, Cu ions were ion-exchanged into H of CHA zeolites A to D. + The catalytic coating containing Cu-CHA zeolite catalyst, zirconium oxide, and pseudoboehmite (PB-250) binder was deposited by a washcoat process onto a cellular ceramic monolith with a cell density of 400 cpsi and a wall thickness of 6 mil. The coated monolith was dried at 110°C and calcined at approximately 550°C for 1 hour. The coating process was carried out at a rate of 2.1 g / in. 3 of catalyst loading, of which 5% was zirconium oxide and 5% was aluminum oxide binder. Prior to SCR testing, the coated monoliths were hydrothermally aged at 800°C for 16 hours in the presence of 10% HO / air.

[0142] NO x The conversion (Table 3) was carried out under pseudo-steady-state conditions for 80,000 h in a gas mixture of 500 ppm NO, 500 ppm NH, 10% O, 5% H, O, and the remainder N, with a temperature increase of 0.5°C / min from 200 to 600°C. -1 The data in Table 3 show that higher levels of NO were observed at both 200°C and 600°C. xConversion was shown to be generally obtained with zeolite domain sizes smaller than about 1000 Å (Examples 1A and 1C). The actual crystallite sizes, determined by scanning electron microscope (SEM) imaging, were much larger than 1000-2000 Å. The data in Table 3 show that zeolites with strain values ​​less than about 0.50% resulted in higher levels of NO at both 200°C and 600°C. x It was further shown that conversion was achieved (Example 1A). [Table 3]

[0143] Domain size, strain, and NO at 200°C and 600°C x The conversion performance relationships are further illustrated graphically in Figures 5 and 6, respectively, from which the data in Table 3 was derived. Without wishing to be bound by theory, Cu-CHA zeolite catalyst compositions characterized by relatively small domain sizes (e.g., less than about 1200 Å), low strain (e.g., less than about 0.40-0.45%), or both, exhibit enhanced NO production at both low and high temperatures. x It is believed to provide SCR performance.

Claims

1. 1. A CHA-type zeolite material having a silica-to-alumina ratio (SAR) in the range of 10 to 45, a. a domain size of 800 to 1200 Angstroms (Å), and b. Crystallographic strain of less than 0.2% to 0.5%, as determined from LY parameters by General Structural Analysis System (GSAS) Rietveld refinement of powder X-ray diffraction data; The CHA-type zeolite material has a mesopore surface area (MSA) of 5 to 25 m ２ / g), and the zeolite surface area (ZSA) of the CHA-type zeolite material is 450 to 600 m ２ / g of the zeolite material.

2. 2. The zeolitic material of claim 1, wherein the crystallographic strain is less than 0.4%.

3. 3. The zeolitic material according to claim 1, wherein the domain size is between 800 and 1100 Å and the crystallographic distortion is between 0.3% and 0.5%.

4. The zeolitic material according to any one of claims 1 to 3, wherein the zeolitic material is an aluminosilicate zeolite.

5. 2. The zeolitic material of claim 1 having an SAR in the range of 15 to 20.

6. 6. The zeolitic material of any one of claims 1 to 5, wherein the zeolitic material is selected from the group consisting of SSZ-13, SSZ-62, natural chabazite, zeolites K-G, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-4, SAPO-47, and ZYT-6.

7. Nitrogen oxides (NO ｘ 7. A selective catalytic reduction (SCR) catalyst composition effective for the mitigation of CO₂ emissions, comprising the zeolitic material of any one of claims 1 to 6 promoted with a metal selected from iron, copper, and combinations thereof.

8. 8. The SCR catalyst composition of claim 7, wherein the metal is present in an amount of 1.0 wt. % to 10 wt. %, calculated as metal oxide, based on the total weight of the SCR catalyst.

9. 9. The SCR catalyst of claim 8, wherein the metal is present in an amount of 4 to 6 wt. %.

10. The SCR catalyst composition according to any one of claims 7 to 9, wherein the metal is copper.

11. Nitrogen oxides (NO) from lean-burn engine exhaust ｘ 11. A selective catalytic reduction (SCR) catalyst article effective for mitigating a selective catalytic reduction (SCR) catalyst composition comprising a substrate having disposed on at least a portion thereof the selective catalytic reduction (SCR) catalyst composition of any one of claims 7 to 10.

12. The SCR catalyst article of claim 11 , wherein the substrate is a honeycomb substrate.

13. The SCR catalyst article of claim 12, wherein the honeycomb substrate is a flow-through substrate or a wall-flow filter.

14. The NO in the exhaust gas stream ｘ At least a portion of the ２ The SCR catalyst article according to any one of claims 11 to 13, wherein the SCR catalyst article is reduced to

15. The NO in the exhaust gas stream ｘ 15. The SCR catalyst article of claim 14, wherein the level is reduced by at least 50% at 200°C.

16. The NO in the exhaust gas stream ｘ 16. The SCR catalyst article of claim 14 or 15, wherein the level is reduced by at least 70% at 600°C.

17. The SCR catalyst article was subjected to a thermal aging treatment at 800°C for 16 hours in the presence of 10% by volume steam and the remainder air, after which the SCR catalyst composition was subjected to an 80,000 h test under pseudo-steady state conditions. －１ 2.1 g / in ３ and the exhaust gas was mixed with 500 ppm NO, 500 ppm NH, and 100 ppm NH. ３ , 10% O ２ , 5% H ２ O, and the rest is N ２ and / or ｘ The SCR catalyst article of any one of claims 11 to 16, exhibiting a reduction in:

18. An exhaust gas treatment system comprising the SCR catalyst article of any one of claims 11 to 17 located downstream of and in fluid communication with a lean-burn engine producing an exhaust gas stream.

19. a. a diesel oxidation catalyst (DOC) located upstream of the SCR catalyst article; b. a soot filter located upstream of the SCR catalyst article; 20. The exhaust gas treatment system of claim 18, further comprising one or more of: a) an ammonia oxidation catalyst (AMOx) located downstream of said SCR catalyst article;

20. 20. A method for treating an exhaust gas stream from a lean-burn engine, comprising: passing the exhaust gas stream through a catalytic article according to any one of claims 11 to 17 or an exhaust gas treatment system according to claim 18 or 19; and detecting nitrogen oxides (NO) in the exhaust gas stream. ｘ for a time and at a temperature sufficient to reduce the level of

21. The NO in the exhaust gas stream ｘ At least a portion of the ２ 21. The method of claim 20, wherein

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