Zeolite structure synthesized using mixture of organic structure directing agent

Abstract

To provide a small pore zeolite, an SCR catalyst composition, an SCR catalyst article, and an exhaust gas treatment system and method.SOLUTION: Provided is a small pore zeolite, wherein at least a part of the pores of the small pore zeolite are occupied by bis-quaternary ammonium cations, and at least a part of the pores are occupied by mono-quaternary ammonium cations; optionally, the small pore zeolite has a cage-containing structure; optionally, the largest possible sphere that can be included in the cage-containing structure is from about 4.4 Å to about 15 Å; optionally, from about 1 to about 99% of the pores are occupied by the bis-quaternary ammonium cations and from about 99 to about 1% of the pores are occupied by the mono-quaternary ammonium cations; or optionally, from about 60 to about 40% of the pores are occupied by the bis-quaternary ammonium cations and from about 40 to about 60% of the pores are occupied by the mono-quaternary ammonium cations.SELECTED DRAWING: None

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of priority to U.S. Provisional Application No. 62 / 916,992, filed October 18, 2019, in its entirety.

[0002] The present disclosure relates to zeolites, methods for preparing catalyst compositions containing such zeolites, and catalyst articles and catalyst systems using such catalyst compositions.

Background Art

[0003] NO x To treat gas mixtures containing NO to reduce air pollution, various treatment methods have been used. One type of treatment involves the catalytic reduction of nitrogen oxides. There are two processes: (1) a non - selective reduction process in which carbon monoxide, hydrogen, or hydrocarbons are used as reducing agents, and (2) a selective reduction process in which ammonia or ammonia precursors are used as reducing agents. In the selective reduction process, a small amount of reducing agent can be used to achieve a high degree of nitrogen oxide removal, and mainly nitrogen and steam are formed according to the following equations: 4NO + 4NH3+O2→4N2 + 6H2O (standard SCR reaction) 2NO2 + 4NH3→3N2 + 6H2O (slow SCR reaction) NO + NO2+2NH3→2N2 + 3H2O (fast SCR reaction)

[0004] The catalysts used in the SCR process should ideally maintain good catalytic activity under hydrothermal conditions over a wide range of operating temperature conditions, for example, from 200 °C to 600 °C or higher. SCR catalysts are generally used under hydrothermal conditions, such as during the regeneration of soot filters, which are components of exhaust gas treatment systems used for particle removal.

[0005] Current catalysts used in the SCR process include molecular sieves such as zeolites ion-exchanged with a catalytic metal such as iron or copper. In particular, metal-promoted zeolite catalysts, including iron-promoted and copper-promoted zeolite catalysts, are known for the selective catalytic reduction of nitrogen oxides by ammonia. In particular, for example, copper-exchanged small-pore zeolites having a chabazite (CHA) and AEI framework function as catalysts for the selective catalytic reduction (SCR) of NO x with ammonia or a secondary ammonia source.

[0006] Due to increasingly stringent emission regulations, there is a growing need, in particular, for an SCR catalyst that exhibits sufficient high-temperature thermal stability while managing NO x emissions, especially under lean and low engine exhaust temperature conditions. There is a need for zeolite materials with tuned adsorption and catalytic functions, as well as methods for making small-pore zeolites such as zeolites having a CHA framework that provide materials that are efficient and low-cost but have properties suitable for, for example, SCR catalysis. In particular, in the art, there is a continuing need for SCR catalysts that are effective in efficiently and effectively reducing NO x emissions from exhaust gas streams.

[0007] The catalytic properties of zeolites are defined not only by the connectivity of their frameworks but also by the microscopic atomic arrangement of framework aluminum (Al) atoms that generate catalytically active sites. Specifically, the distribution of aluminum in the zeolite is related to the number and structure of extra-framework metal ions (e.g., Cu 2+ , (CuOH) + ) that can be exchanged onto the zeolite. The density and distribution of catalytically active Cu sites in the zeolite depend on the positioning and proximity of aluminum atoms within the zeolite framework structure. Increasing the useful ratio and density of Cu in the zeolite would help improve the catalytic performance of the zeolite without changing the silica-to-alumina ratio (SAR) of the product.

[0008] Recently, within the CHA cage during synthesis, TMAda + and Na + Since both cations are incorporated, Na containing trimethyladamantylammonium cation (TMAda) as an organic structure directing agent (OSDA) + By using inorganic cations such as, the Al distribution in CHA zeolite can be controlled, and the relative ratio of TMAda + and Na + It has been reported that the degree of Al pairing in the zeolite product can be controlled using. See Gounder and Di Iorio, Chem. Mater., 2016, 28(7), 2236 - 2247.

[0009] Despite such progress, there remains a significant need in the art for synthetic procedures that provide tailored adsorption and catalytic functions to zeolite materials by manipulating, for example, the type and amount of structure - directing agents used in the synthesis gel to control the positioning and proximity of aluminum in the zeolite material. SUMMARY OF THE INVENTION

[0010] The present disclosure generally describes the use of combinations of two organic structure - directing agents (OSDAs) having various structures for templating zeolite synthesis that enable control of the zeolite framework structure and the aluminum distribution in the product zeolite.

[0011] Surprisingly, according to the present disclosure, by using a combination of specific mono - and bis - quaternary ammonium ion organic structure - directing agents (OSDAs) in a zeolite synthesis gel, a zeolite having a CHA crystal framework structure with altered Al positioning and pairing in the zeolite product is provided, as indicated by the difference in equilibrium Cu incorporation compared to CHA zeolite synthesized with a single mono - quaternary ammonium ion organic structure - directing agent.

[0012] Thus, in one aspect, the present disclosure provides a method for synthesizing small-pore zeolites, the method comprising preparing a mixture of water, an aluminum source, a silicon source, a source of a first organic structure-directing agent, and a source of a second organic structure-directing agent to form a synthesis gel, and subjecting the synthesis gel to a crystallization process to crystallize the small-pore zeolites, wherein the first organic structure-directing agent is a bis-quaternary ammonium cation and the second organic structure-directing agent is a mono-quaternary ammonium cation.

[0013] In another aspect, the present disclosure is a method for synthesizing small-pore zeolites, the method comprising preparing a mixture of water, an aluminum source, a silicon source, a source of a first organic structure-directing agent, and a source of a second organic structure-directing agent to form a synthesis gel, and subjecting the synthesis gel to a crystallization process to crystallize the small-pore zeolites, wherein the first organic structure-directing agent comprises a bis-quaternary ammonium cation, a derivative of a bis-quaternary ammonium cation, or a combination thereof, and the second organic structure-directing agent comprises a mono-quaternary ammonium cation, a derivative of a mono-quaternary ammonium cation, or a combination thereof.

[0014] In some embodiments, the small-pore zeolite is a structure containing cages, and the diameter of the largest possible sphere contained in the structure containing the cages is from about 4.4 Å to about 15 Å.

[0015] In some embodiments, the bis-quaternary ammonium cation contains from about 8 to about 20 carbon atoms. In some embodiments, each nitrogen atom of the bis-quaternary ammonium cation has four substituents, and each substituent is independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof. In some embodiments, the bis-quaternary ammonium cation has a structure represented by Formula I,

Chemical formula

[0016] In some embodiments, the bisquaternary ammonium cation is selected from the group consisting of N1,N1,N1,N3,N3,N3-hexaethylpropane-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbutane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexaethylbutane-1,4-diaminium, (E)-N1,N1,N1,N4,N4,N4-hexamethylbut-2-ene-1,4-diaminium, N1,N1,N1,N5,N5,N5-hexamethylpentane-1,5-diaminium, (E)-N1,N1,N1,N5,N5,N5-hexamethylpent-2-ene-1,5-diaminium, N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium, (E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2-ene-1,6-diaminium, (2E,4E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2,4-diene-1,6-diaminium, N1,N1,N1,N7,N7,N7-hexamethylheptane-1,7-diaminium, N1,N1,N1,N8,N8,N8-hexamethyloctane-1,8-diaminium, N1,N1,N1,N3,N3,N3-hexamethylcyclohexane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbicyclo[2.2.1]heptane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbenzene-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylcyclohexane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.1]heptane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.2]octane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbenzene-1,4-diaminium, 1,1,4,4-tetramethylpiperazine-1,4-diium, 1,1,3,3-tetramethylhexahydropyrimidine-1,3-diium, 1,1'-(1,3-phenylene)bis(N,N,N-trimethylmethanaminium), 1,1'-(1,4-phenylene)bis(N,N,N-trimethylmethanaminium), or combinations thereof.

[0017] In some embodiments, the source of the first organic structure-directing agent is a bisquaternary ammonium compound containing a balancing anion selected from the group consisting of bisquaternary ammonium cations and OH - , Cl - , and Br - . In some embodiments, the source of the first organic structure-directing agent contains a hexamethonium or octamethonium cation. In some embodiments, the source of the first organic structure-directing agent is hexamethonium dihydroxide (HMOH) or octamethonium dihydroxide (OMOH).

[0018] In some embodiments, the monoquaternary ammonium cation contains from about 4 to about 14 carbon atoms. In some embodiments, the nitrogen atom of the monoquaternary ammonium cation has four substituents, each of which is independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof. In some embodiments, the monoquaternary ammonium cation has a structure represented by Formula II, [Chemical Formula] wherein R1, R2, and R3 are each methyl or ethyl, R4 is selected from the group consisting of methyl, ethyl, hydroxyethyl, cyclohexyl, azabicycloheptyl, adamantyl, and phenyl, or optionally, R3 and R4 together, or R2, R3, and R4 together are linked to form a monocyclic or bicyclic ring system, which may optionally be substituted with one or more methyl or OH groups.

[0019] In some embodiments, the monoquaternary ammonium cation is selected from the group consisting of tetraethylammonium, 2-hydroxy-N,N,N-trimethylethane-1-aminium, N,N,N-trimethylcyclohexanaminium, N,N,N-trimethyladamantan-1-aminium (TMAda), N,N,N-trimethylbicyclo[2.2.1]heptan-2-aminium, N,N,N-trimethylbenzenaminium, 1,1-dimethylpiperidin-1-ium, 1,1,3,5-tetramethylpiperidin-1-ium, 1-methylquinuclidin-1-ium, 3-hydroxy-1-methylquinuclidin-1-ium, or combinations thereof.

[0020] In some embodiments, the source of the second organic structure-directing agent is a monoquaternary ammonium compound containing a balancing anion selected from the group consisting of a monoquaternary ammonium cation and OH - , Cl - , and Br - . In some embodiments, the source of the second organic structure-directing agent contains an N,N,N-trimethyladamantan-1-aminium cation. In some embodiments, the source of the second organic structure-directing agent is N,N,N-trimethyladamantan-1-aminium hydroxide (TMAdaOH). In some embodiments, the source of the first organic structure-directing agent is HMOH or OMOH, and the source of the second organic structure-directing agent is TMAdaOH.

[0021] In some embodiments, the molar ratio of the first organic structure-directing agent to the second organic structure-directing agent ranges from about 0.001 to about 1000. In some embodiments, the molar ratio of the first organic structure-directing agent to the second organic structure-directing agent is from about 0.1 to about 10. In some embodiments, the molar ratio of the first organic structure-directing agent to the second organic structure-directing agent is from about 0.5 to about 2.

[0022] In some embodiments, the mixture further comprises an inorganic structure directing agent, and the inorganic structure directing agent is an alkali metal cation or an alkaline earth metal cation. In some embodiments, the alkali metal cation is selected from the group consisting of lithium, sodium, potassium, or cesium.

[0023] In some embodiments, the source of aluminum comprises one or more of an aluminum salt, aluminum metal, aluminum oxide, aluminosilicate, or zeolite. In some embodiments, the source of aluminum comprises a zeolite having a FAU, LTA, LTL, MFI, or BEA crystal framework. In some embodiments, the source of aluminum is zeolite Y in the Na+ form.

[0024] In some embodiments, the source of silicon is colloidal silica, a silicon alkoxide compound, an alkali metal silicate, fumed silica, amorphous silica, or an aluminosilicate. In some embodiments, the source of silicon is sodium silicate. In some embodiments, the OH / Si ratio of the synthesis gel is from about 0.03 to about 1.0.

[0025] In some embodiments, the crystallization process comprises maintaining the synthesis gel at a temperature of about 90 °C to about 250 °C. In some embodiments, the crystallization process comprises maintaining the synthesis gel at a temperature of about 120 °C to about 200 °C.

[0026] In some embodiments, the method further comprises filtering the crystals formed during the heating step.

[0027] In some embodiments, the method further comprises calcining the zeolite at a temperature of about 450 °C to about 750 °C.

[0028] In some embodiments, the small pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFT, AFX, AFV, AVL, CHA, EAB, ERI, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV. In some embodiments, the small pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFV, AVL, CHA, EAB, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV. In some embodiments, the small pore zeolite has an AEI or CHA crystal framework structure type. In some embodiments, the small pore zeolite has a CHA crystal framework structure type.

[0029] In some embodiments, the small pore zeolite has a silica to alumina ratio (SAR) of from about 6 to about 100. In some embodiments, the small pore zeolite has a silica to alumina ratio (SAR) of from about 10 to about 30. In some embodiments, the small pore zeolite has an SAR in the range of from about 20 to about 30.

[0030] In some embodiments, the small pore zeolite has an MSA of less than about 75 m 2 / g and a ZSA of at least about 450 m 2 / g.

[0031] In some embodiments, the small pore zeolite has a controlled aluminum distribution, including an altered aluminum positioning and pairing arrangement, characterized by an altered equilibrium Cu + 2 uptake at a concentration greater than 0.25 M compared to a small pore zeolite synthesized with only a monoquaternary OSDA. +2

[0032] In some embodiments, prior to calcination, at least a portion of the pores of the small pore zeolite are occupied by bisquaternary ammonium cations and at least a portion of the pores are occupied by monoquaternary ammonium cations. In some embodiments, about 1 to about 99% of the pores are occupied by bisquaternary ammonium cations and about 99 to about 1% of the pores are occupied by monoquaternary ammonium cations. In some embodiments, about 60 to about 40% of the pores are occupied by bisquaternary ammonium cations and about 40 to about 60% of the pores are occupied by monoquaternary ammonium cations.

[0033] In another aspect, there is provided a small pore zeolite prepared according to the methods disclosed herein.

[0034] In some embodiments, the small pore zeolite has a controlled aluminum distribution, and the controlled aluminum distribution is greater than 0.25M Cu compared to a small pore zeolite synthesized with only a monoquaternary OSDA. +2 Changed equilibrium with concentration Cu +2 The small pore zeolite comprises an array of anionic framework Al centers, including modified aluminum positioning and pairing arrangements characterized by the incorporation of . In some embodiments, the small pore zeolite comprises a cage-containing structure, in which the largest possible sphere within the cage-containing structure has a diameter of about 4.4 Å to about 15 Å.

[0035] In a further aspect, there is provided a small pore zeolite, wherein at least a portion of the pores of the small pore zeolite are occupied by bisquaternary ammonium cations and at least a portion of the pores are occupied by monoquaternary ammonium cations. In some embodiments, the small pore zeolite comprises a cage-containing structure, wherein the largest possible sphere contained in the cage-containing structure has a diameter of about 4.4 Å to about 15 Å.

[0036] In some embodiments, about 1 to about 99% of the pores are occupied by bis-quaternary ammonium cations and about 99 to about 1% of the pores are occupied by mono-quaternary ammonium cations. In some embodiments, about 60 to about 40% of the pores are occupied by bis-quaternary ammonium cations and about 40 to about 60% of the pores are occupied by mono-quaternary ammonium cations.

[0037] In some embodiments, the bis-quaternary ammonium cation contains about 8 to about 20 carbon atoms. In some embodiments, each nitrogen atom of the bis-quaternary ammonium cation has four substituents, and each substituent is independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof. In some embodiments, the bis-quaternary ammonium cation has a structure represented by Formula I,

Chemical formula

[0038] In some embodiments, the bisquaternary ammonium cation is N1,N1,N1,N3,N3,N3-hexaethylpropane-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbutane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexaethylbutane-1,4-diaminium, (E)-N1,N1,N1,N4,N4,N4-hexamethylbut-2-ene-1,4-diaminium, N1,N1,N1,N5,N5,N5-hexamethylpentane-1,5-diaminium, (E)-N1,N1,N1,N5,N5,N5-hexamethylpent-2-ene-1,5-diaminium, N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium (hexamethonium), (E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2-ene-1,6-diaminium, (2E,4E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2,4-diene-1,6-diaminium, N1,N1,N1,N7,N7,N7-hexamethylheptane-1,7-diaminium, N1,N1,N1,N8,N8,N8-hexamethyloctane-1,8-diaminium, N1,N1,N1,N3,N3,N3-hexamethylcyclohexane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbicyclo[2.2.1]heptane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbenzene-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylcyclohexane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.1]heptane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.2]octane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbenzene-1,4-diaminium, 1,1,4,4-tetramethylpiperazine-1,4-diium, 1,1,3,3-tetramethylhexahydropyrimidine-1,3-diium, 1,1'-(1,3-phenylene)bis(N,N,N-trimethylmethanaminium), 1,1'-(1,4-phenylene)bis(N,N,N-trimethylmethanaminium), or a combination thereof.In some embodiments, the bisquaternary ammonium cation is hexamethonium or octamethonium.

[0039] In some embodiments, the monoquaternary ammonium cation contains from about 4 to about 14 carbon atoms. In some embodiments, the nitrogen atom of the monoquaternary ammonium cation has four substituents, each of which is independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof. In some embodiments, the monoquaternary ammonium cation has a structure represented by Formula II, [Chemical formula] wherein, R1, R2, and R3 are each methyl or ethyl, R4 is selected from the group consisting of methyl, ethyl, hydroxyethyl, cyclohexyl, azabicycloheptyl, adamantyl, and phenyl, or optionally, R3 and R4 together, or R2, R3, and R4 together are linked to form a monocyclic or bicyclic ring system, which may optionally be substituted with one or more methyl or OH groups.

[0040] In some embodiments, the monoquaternary ammonium cation is tetraethylammonium, 2-hydroxy-N,N,N-trimethylethane-1-aminium, N,N,N-trimethylcyclohexanaminium, N,N,N-trimethyladamantan-1-aminium (TMAda), N,N,N-trimethylbicyclo[2.2.1]heptan-2-aminium, N,N,N-trimethylbenzenaminium, 1,1-dimethylpiperidin-1-ium, 1,1,3,5-tetramethylpiperidin-1-ium, 1-methylquinuclidin-1-ium, 3-hydroxy-1-methylquinuclidin-1-ium, or a combination thereof. In some embodiments, the monoquaternary ammonium cation is TMAda. In some embodiments, the bisquaternary ammonium cation is hexamethonium or octamethonium, and the monoquaternary ammonium cation is TMAda.

[0041] In some embodiments, the small-pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFT, AFX, AFV, AVL, CHA, EAB, ERI, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV. In some embodiments, the small-pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFV, AVL, CHA, EAB, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV. In some embodiments, the small-pore zeolite has an AEI or CHA crystal framework structure type. In some embodiments, the small-pore zeolite has a CHA crystal framework structure type.

[0042] In some embodiments, the small-pore zeolite has a silica-to-alumina ratio (SAR) of from about 6 to about 100. In some embodiments, the small-pore zeolite has a silica-to-alumina ratio (SAR) of from about 10 to about 30. In some embodiments, the small-pore zeolite has an SAR in the range of from about 20 to about 30.

[0043] In some embodiments, the small pore zeolite has an MSA of less than about 75 m 2 / g and a ZSA of at least about 450 m 2 / g.

[0044] In yet another aspect, a selective catalytic reduction (SCR) catalyst composition effective for reducing nitrogen oxides (NO x ) in an exhaust gas stream is provided, the SCR catalyst comprising a small pore zeolite disclosed herein promoted with a promoter metal. In some embodiments, the promoter metal is present in an amount of about 1.0 wt% to about 10 wt% calculated as the 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 to about 6 wt%. In some embodiments, the promoter metal is selected from iron, copper, and combinations thereof.

[0045] In another aspect, an SCR catalyst article effective for reducing nitrogen oxides (NOx) from an engine exhaust gas stream is provided, the SCR catalyst article comprising a substrate having disposed thereon, at least in part, an SCR catalyst composition 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.

[0046] In yet 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 an engine that generates an exhaust gas stream.

[0047] In yet another aspect, a method of treating an exhaust gas stream is provided, the method including contacting the exhaust gas stream with an SCR catalyst article or an exhaust gas treatment system, as disclosed herein.

[0048] These and other features, aspects, and advantages of the present disclosure will become apparent from the following detailed description, along with the accompanying drawings described briefly below. The present invention includes any combination of two, three, four, or more of the above-described embodiments, and any combination of two, three, four, or more features or elements described in the present disclosure, whether or not such features or elements are explicitly combined in the description of a particular embodiment herein. The present disclosure is intended to be read as a whole such that any separable feature or element of the disclosed invention is considered combinable unless it is clearly shown otherwise in context in any of its various aspects and embodiments. Other aspects and advantages of the present invention will become apparent below.

Brief Description of the Drawings

[0049] To provide an understanding of embodiments of the present invention, reference is made to the accompanying drawings, which are not necessarily drawn to scale, and reference numerals refer to components of exemplary embodiments of the present invention. The drawings are merely examples and are not to be construed as limiting the present invention.

[0050]

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[0051] Before describing some exemplary embodiments of the present invention, 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. The present invention is capable of other embodiments and of being practiced or carried out in various ways. Although the invention is described herein with reference to particular embodiments, these embodiments are merely illustrative of the principles and applications of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatuses of the present disclosure without departing from the spirit and scope of the invention. Accordingly, the invention is intended to cover modifications and variations that come within the scope of the appended claims and their equivalents.

[0052] The following definitions are provided with respect to the terms used in the present disclosure.

[0053] References throughout this specification to "one embodiment," "a particular embodiment," "one or more embodiments," or "an embodiment" mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one or more embodiments," "in a particular embodiment," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0054] The articles "a" and "an" are used herein to refer to one or more than one (i.e., at least one) of the grammatical objects of the article.

[0055] Any range recited in this specification is inclusive.

[0056] The term "about" as used throughout this specification represents and is used to account for small variations. For example, the term "about" can refer to up to ±5%, such as up to ±2%, up to ±1%, up to ±0.5%, up to ±0.2%, up to ±0.1%, or up to ±0.05%. All numerical values, whether or not explicitly indicated, are modified by the term "about". Of course, the value modified by the term "about" includes the specific value. For example, "about 5.0" should include 5.0.

[0057] "AMOx" refers to a selective ammonia oxidation catalyst, which is a catalyst containing one or more metals (typically Pt, but not limited thereto) and an SCR catalyst suitable for converting ammonia to nitrogen.

[0058] The terms "catalyst" or "catalyst material" or "catalyst composition" or "catalytic material" refer to a material that promotes a reaction. To manufacture a catalyst article, the substrates disclosed herein are coated with a catalyst composition. The coating is a "catalyst coating composition" or a "catalyst coating". The terms "catalyst composition" and "catalyst coating composition" are synonymous.

[0059] "CSF" refers to a catalyzed soot filter that is a wall-flow monolith. The wall-flow filter consists of alternately positioned inlet channels and outlet channels, where the inlet channels are inserted into the outlet ends and the outlet channels are inserted into the inlet ends. The exhaust gas flow carrying soot that enters the inlet channels is passed through the filter walls before exiting the outlet channels. In addition to soot filtration and regeneration, the CSF oxidizes CO and HC to CO2 and H2O, or oxidizes NO to NO2 to promote downstream SCR catalysis, or promotes the oxidation of soot particles at lower temperatures. When located behind the LNT catalyst, the CSF has an H2S oxidation function and can suppress H2S emissions during the LNT desulfurization process.

[0060] "DOC" refers to a diesel oxidation catalyst that converts hydrocarbons and carbon monoxide in the exhaust gas of a diesel engine. Typically, the DOC contains one or more platinum group metals, such as palladium and / or platinum; a carrier material, such as alumina; zeolite for HC storage; and optionally promoters and / or stabilizers.

[0061] "LNT" refers to a lean NO x trap catalyst containing a platinum group metal, ceria, and an alkaline earth metal trap material (e.g., BaO or MgO) suitable for adsorbing NO in lean conditions. Under rich conditions, NO x is released and reduced to nitrogen. x

[0062] The term "NO x " refers to nitrogen oxide compounds such as NO or NO2.

[0063] The terms "upper" and "above" related to the coating layer may be used synonymously. The term "directly above" means in direct contact. In certain embodiments, the disclosed article is shown to include one coating layer "above" a second coating layer, and such language is intended to encompass embodiments with intervening layers where direct contact between the coating layers is not required (i.e., "above" is not equivalent to "directly above").

[0064] As used herein, the term "selective catalytic reduction" (SCR) refers to a catalytic process that uses a nitrogenous reducing agent to reduce nitrogen oxides to dinitrogen (N2). As used herein, the terms "nitrogen oxides" and "NO x " mean oxides of nitrogen.

[0065] "SCRoF" refers to an SCR catalyst composition directly coated on a wall flow filter.

[0066] As used herein, the term "structure directing agent" is a compound that is present during the crystallization of zeolite and serves to direct the formation of a desired crystal structure (e.g., CHA).

[0067] As used herein, the term "substrate" refers to a monolithic material on which a catalyst composition, i.e., a catalyst coating, is typically disposed in the form of a washcoat. In one or more embodiments, the substrate is a flow-through monolith and a monolithic wall flow filter. A washcoat is formed by preparing a slurry containing a catalyst with a specific solids content (e.g., 30 - 90 wt%) in a liquid, and then coating this on the substrate and drying to provide a washcoat layer. Reference to a "monolithic substrate" means a single structure that is homogeneous and continuous from inlet to outlet.

[0068] "Washcoat" has its ordinary meaning in the art of a thin, adherent coating of a material (e.g., a catalyst) applied to a "substrate", e.g., a honeycomb flow-through monolith substrate or a filter substrate that is porous enough to allow passage of the gas stream being processed. 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 monolithic substrate or underlying washcoat layer. The substrate can include one or more washcoat layers, and each washcoat layer can differ in some way (e.g., the physical properties of the washcoat, such as particle size or crystallite phase, can be different), and / or the chemical catalytic function can be different.

[0069] "Molecular sieve" is, for example, a framework material that can be used as a catalyst, in particulate form, in combination with one or more promoter metals. A molecular sieve generally includes tetrahedral sites and has a substantially uniform pore distribution, and is a material based on oxygen ions with a wide three-dimensional network structure having an average pore diameter of 20 angstroms (Å) or less. The pore diameter is defined by the ring diameter.

[0070] As used herein, the term "zeolite" refers to a particular example of a molecular sieve containing silicon and aluminum atoms. Zeolites are crystalline materials with fairly uniform pore diameters in the range of about 3 to 10 Å, depending on the type of zeolite, as well as the type and amount of cations contained in the zeolite lattice. Zeolites are understood to be aluminosilicates having an open three-dimensional framework structure composed of corner-sharing TO4 tetrahedra (where T is Al or Si). The cations that balance the charge of the anionic framework are loosely associated with the framework oxygen, and the remaining pore volume is filled with water molecules. Non-framework cations are generally exchangeable, and water molecules are removable.

[0071] In certain embodiments, reference can be made to the "aluminosilicate zeolite" framework type, which limits the material to zeolites that do not contain phosphorus or other metals substituted in the framework, while the broader term "zeolite" is intended to include aluminosilicates and aluminophosphates. In some embodiments, the zeolite is an aluminosilicate zeolite. The term "aluminophosphate" refers to another particular example of a zeolite containing aluminum atoms and phosphate atoms. In some embodiments, the zeolite is a silicoaluminophosphate. Silicoaluminophosphate zeolites contain SiO4 / AlO4 / PO4 tetrahedra and are designated "SAPO". Non-limiting examples of SAPO include SAPO-34 and SAPO-44.

[0072] Zeolites generally contain a silica to alumina (SAR) molar ratio of 2 or more. The zeolites for use in the disclosed catalyst compositions are not particularly limited with respect to the SAR value, although certain SAR values associated with the zeolite can affect the SCR performance of the catalyst composition in which it is incorporated (e.g., especially after aging). In some embodiments, the SAR value of the zeolite ranges from about 5 to about 100, or from about 5 to about 50. In some embodiments, the SAR is from about 5 to about 25, and in other embodiments, the SAR is from about 10 to about 15.

[0073] Zeolites can be classified by the framework topology whose structure is specified. In some embodiments, the present disclosure relates to zeolites having a chabazite (CHA) framework. The zeolite CHA framework type molecular sieve has an approximate formula: (Ca,Na2,K2,Mg)Al2Si4O 12 ·6H2O (e.g., calcium aluminum silicate hydrate). Three synthetic forms of the zeolite CHA-framework type molecular sieve are described in "Zeolite Molecular Sieves" by D.W. Breck, published in 1973 by John Wiley & Sons, which is incorporated by reference. The three synthetic forms reported by Breck are Zeolite K-G described in J. Chem. Soc., p. 2822 (1956), Barrer et al, which is incorporated herein by reference, Zeolite D described in British Patent No. 868,846 (1961), and Zeolite R described in U.S. Patent No. 3,030,181. The synthesis of SSZ-13, another synthetic form of the zeolite CHA framework type, is described in U.S. Patent No. 4,544,538, which is incorporated by reference. In certain embodiments, the CHA framework type zeolite is selected from the group consisting of SSZ-13, SSZ-62, natural chabazite, zeolite K-G, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, and ZYT-6.

[0074] Zeolites consist of secondary building units (SBUs) and composite building units (CBUs) and occur in many different framework structures. The secondary building units contain up to 16 tetrahedral atoms and are not chiral. The composite building units do not necessarily have to be achiral and are not necessarily used in the construction of the entire framework. The CHA framework has a "double 6-ring" (d6r) secondary building unit. The d6r secondary building unit has 12 tetrahedral atoms and is created by joining two "single s6r units", where "6" represents the positions of the silicon and aluminum atoms of the tetrahedron, and the oxygen atoms are between the tetrahedral atoms.

[0075] In some embodiments, the zeolite of the present invention is a small-pore zeolite. As used herein, the term "small pore" refers to pore openings smaller than about 5 Å, for example, pore openings on the order of about 3.8 Å. The pore diameter is defined by the maximum ring diameter. Small-pore zeolites contain channels defined by up to 8 tetrahedral atoms. The term "eight-ring" zeolite refers to a zeolite having eight-ring pore openings and a "double six-ring" (d6r) secondary building unit and having a cage-like structure resulting from the connection of double six-ring structural units by four rings. Exemplary small-pore zeolites include framework types ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, LEV, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON, and mixtures or twins thereof.

[0076] In some cases, the pores of these zeolites open into larger cavities, herein referred to as "cages". Without wishing to be bound by theory, these cages are thought to be catalytically relevant in many systems as they can provide a local volume where reactive molecules and, in some cases, catalytic atoms can interact. To provide more quantitative information on the size of the cages compared to the pore systems present in zeolites, the International Zeolite Association - Structure Commission (IZA-SC) database (accessible, for example, at http: / / www.iza-structure.org / databases, which is incorporated herein by reference) provides the following information: (i) the diameter of the largest included sphere possible, and (ii) the diameter of the largest free sphere that can diffuse along the three crystallographic directions a, b, and c. By comparing the value of the diameter of the largest included sphere possible with the diameter of the largest free sphere that can diffuse within the framework, information can be obtained on the size of the zeolite cages compared to the size of the zeolite pores. However, since cages are often not symmetric in all directions, these numerical values do not always provide a complete description of the cages present in the zeolite structure. For example, the AFX framework has an "aft" cage as a CBU, while the CHA framework has a "cha" cage as a CBU. Both framework structures have 8-ring pore openings, and the diameter of the largest sphere that can be included is very similar (7.76 Å for AFX versus 7.37 Å for CHA). However, in reality, the structures of the two cages are very different. Nevertheless, reference to the diameter of the largest included sphere possible provides a way to distinguish zeolite structures containing cages from those containing only channels.

[0077] Unless otherwise indicated, all parts and percentages are by weight. "Weight percent (wt%)", unless otherwise indicated, is based on the entire composition excluding any volatile substances, i.e., based on the dry solids content.

[0078] All of the methods described in this specification can be carried out in any suitable order, unless otherwise indicated herein or unless the context clearly dictates otherwise. 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 impose a limitation on the scope unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.

[0079] All U.S. patent applications, published patent applications, and patents referred to herein are incorporated herein by reference.

[0080] Small pore zeolite synthesis method By way of non-limiting example, the zeolite materials disclosed herein are prepared from a reaction mixture (synthesis gel) containing a source of a first organic structure directing agent, a source of a second organic structure directing agent, a source of silicon, a source of aluminum, and water. Thus, in one aspect, a method for synthesizing small pore zeolites is provided, the method comprising mixing water, an aluminum source, a silica source, a source of a first organic structure directing agent (OSDA), and a source of a second OSDA, wherein the first OSDA is a bis-quaternary ammonium cation and the second OSDA is a mono-quaternary ammonium cation, to form a synthesis gel, and subjecting the synthesis gel to a crystallization process to crystallize the small pore zeolite. Each component is described in more detail below.

[0081] Organic structure directing agent To prepare microporous zeolites according to the disclosed method, an OSDA, also referred to herein as a "template" or "templating agent", is used. The OSDA is an organic (i.e., carbon-containing) molecule that induces or directs the molecular shape and pattern of the zeolite framework and functions, for example, as a scaffold around which zeolite crystals form. After crystal formation, the OSDA is removed from the internal structure of the crystal (e.g., by calcination), leaving a molecularly porous aluminosilicate cage. The specific type of OSDA used can vary. Typically, the OSDA is selected from cyclic amines and / or ammonium compounds, such as quaternary ammonium cations having various substituents. Suitable OSDAs are disclosed, for example, in Zeolites and Related Microporous Materials: State of the Art 1994, Studies of Surface Science and Catalysis, Vol. 84, p 29-36, Novel Materials in Heterogeneous Catalysis (edited by Baker and Murrell) Chapter 2, p14-24, May 1990, J. Am. Chem. Soc., 2000, 122, p 263-273, and U.S. Patent Nos. 4,544,538 and 6,709,644, each of which is incorporated herein by reference.

[0082] Specifically, the method provided herein utilizes two different OSDAs, a first OSDA that is a bisquaternary ammonium cation and a second OSDA that is a monoquaternary ammonium cation. As used herein, the term "quaternary ammonium cation" refers to an organic molecule having four substituents and thus containing a nitrogen atom with a positive (cationic) charge. The quaternary ammonium cation is associated with an anion, such as a halide (e.g., Cl - , Br - , I - ), bisulfate (HSO4 - ), or hydroxide (OH -) is in equilibrium with the ions and is referred to herein as a "quaternary ammonium salt" or "quaternary ammonium compound" and dissociates in solution into free quaternary ammonium cations and respective anions. As used herein, the term "source" with respect to OSDA refers to a quaternary ammonium compound (e.g., salt) that dissociates under zeolite synthesis conditions to provide a quaternary ammonium cation species that is active as a structure-directing agent.

[0083] As used herein, the term "monoquaternary ammonium" refers to a molecule containing one quaternary ammonium cation as described herein. As used herein, the term "bisquaternary ammonium" refers to a molecule containing two such quaternary ammonium cations as described herein.

[0084] The first OSDA In some embodiments, the first OSDA is a bisquaternary ammonium cation. In some embodiments, the bisquaternary ammonium cation contains from about 8 to about 20 carbon atoms, such as from about 8, 9, 10, 11, 12, 13, 14, or 15 carbon atoms to about 16, 17, 18, 19, or 20 carbon atoms. The bisquaternary ammonium cation can include various structural arrangements, such as acyclic or cyclic structures. In some embodiments, the bisquaternary ammonium cation is acyclic, which means there is no ring system. Non-limiting examples of acyclic bisquaternary ammonium cations include N1,N1,N1,N3,N3,N3-hexaethylpropane-1,3-diaminium and N1,N1,N1,N8,N8,N8-hexamethyloctane-1,8-diaminium. In some embodiments, the bisquaternary ammonium cation is cyclic, which means that the quaternary ammonium group is attached to one or more ring systems or forms it together with two or more substituents. Non-limiting examples of cyclic bisquaternary ammonium cations include N1,N1,N1,N4,N4,N4-hexamethylcyclohexane-1,4-diaminium, 1,1,4,4-tetramethylpiperazine-1,4-diium, and N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.2]octane-1,4-diaminium.

[0085] In some embodiments, each nitrogen atom of the bisquaternary ammonium cation has four substituents, and each substituent is independently selected from the group consisting of alkyl, cycloalkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

[0086] In some embodiments, the bisquaternary ammonium cation has a structure represented by Formula I,

Chemical formula

[0087] In some embodiments, X is an alkyl group. As used herein, the term "alkyl" refers to a straight or branched chain saturated hydrocarbon having 2 to 8 carbon atoms. Representative C2-C8 alkyl groups include, but are not limited to, -ethyl, -n-propyl, -n-butyl, -n-pentyl, and -n-hexyl, while branched C2-C8 alkyl includes, but is not limited to, -isopropyl, -sec-butyl, -isobutyl, -tert-butyl, -isopentyl, and 2-methylbutyl.

[0088] In some embodiments, X is an alkenyl group. As used herein, the term "alkenyl" refers to a normal, secondary, or tertiary carbon atom having at least one site of unsaturation, i.e., a C2-C8 hydrocarbon containing a carbon-carbon, sp 2 double bond. Examples include, but are not limited to, ethylene or vinyl, -allyl, -1-butenyl, -2-butenyl, -isobutenyl, -1-pentenyl, -2-pentenyl, -3-methyl-1-butenyl, -2-methyl-2-butenyl, -2,3-dimethyl-2-butenyl, etc.

[0089] In some embodiments, X is a cycloalkyl group. As used herein, "cycloalkyl" can be monocyclic or bicyclic and refers to a saturated carbocyclic radical containing a ring system having 4 to 8 carbon atoms. Examples of monocyclic cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0090] In some embodiments, X is an aryl group. As used herein, "aryl" is C6-C 20Refers to a carbon cyclic aromatic group. Examples of aryl groups include, but are not limited to, phenyl and naphthyl.

[0091] In some embodiments, X is an arylalkyl group. As used herein, "arylalkyl" refers to an acyclic alkyl radical in which one of the hydrogen atoms bonded to a carbon atom, typically a terminal or sp 3 carbon atom, is replaced by an aryl radical. Typical arylalkyl groups include, but are not limited to, benzyl, dibenzyl, 2-phenylethan-1-yl, naphthylmethyl, 2-naphthylethan-1-yl, naphthobenzyl, 2-naphthophenylethan-1-yl, etc. The arylalkyl group contains 6 to 20 carbon atoms. For example, the alkyl portion of the arylalkyl group has 1 to 6 carbon atoms and the aryl portion has 5 to 14 carbon atoms.

[0092] It should be understood that the above radical naming rules refer to diradicals. For example, a substituent identified as "alkyl" requires two bonding points and thus includes diradicals such as -CH2CH2-, -CH2CH(CH3)CH 2- etc. This radical naming rule clearly indicates that any alkyl, alkenyl, cycloalkyl, aryl, and arylalkyl radical is a diradical (i.e., alkylene, alkenylene, cycloalkylene, arylene, and arylalkylene, respectively). It should be understood that, unless otherwise specified, the diradical substituents can be bonded in any orientation configuration.

[0093] Non-limiting examples of the bisquaternary ammonium cation according to Formula I include the structures shown in Table 1. [Table 1-1] [Table 1-2] [Table 1-3]

[0094] In some embodiments, the bis-quaternary ammonium cation has a structure as represented in Table 1.

[0095] In some embodiments, the bisquaternary ammonium cation has a structure selected from the group consisting of N1,N1,N1,N3,N3,N3-hexaethylpropane-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbutane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexaethylbutane-1,4-diaminium, (E)-N1,N1,N1,N4,N4,N4-hexamethylbut-2-ene-1,4-diaminium, N1,N1,N1,N5,N5,N5-hexamethylpentane-1,5-diaminium, (E)-N1,N1,N1,N5,N5,N5-hexamethylpent-2-ene-1,5-diaminium, N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium, (E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2-ene-1,6-diaminium, (2E,4E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2,4-diene-1,6-diaminium, N1,N1,N1,N7,N7,N7-hexamethylheptane-1,7-diaminium, N1,N1,N1,N8,N8,N8-hexamethyloctane-1,8-diaminium, N1,N1,N1,N3,N3,N3-hexamethylcyclohexane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbicyclo[2.2.1]heptane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbenzene-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylcyclohexane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.1]heptane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.2]octane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbenzene-1,4-diaminium, 1,1,4,4-tetramethylpiperazine-1,4-diium, 1,1,3,3-tetramethylhexahydropyrimidine-1,3-diium, 1,1'-(1,3-phenylene)bis(N,N,N-trimethylmethanaminium), 1,1'-(1,4-phenylene)bis(N,N,N-trimethylmethanaminium), and combinations thereof.

[0096] In some embodiments, the source of the first OSDA (i.e., the bis-quaternary ammonium cation) is a bis-quaternary ammonium compound comprising a bis-quaternary ammonium cation as described above herein and a counteranion. In some embodiments, the counteranion is selected from the group consisting of OH, Cl, and Br. In some embodiments, the source of the first organic structure-directing agent is N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium dihydroxide (hexamethonium dihydroxide; HMOH) or N1,N1,N1,N8,N8,N8-hexamethyloctane-1,8-diaminium dihydroxide (octamethonium dihydroxide; OMOH).

[0097] In some embodiments, the first OSDA comprises a derivative of the bis-quaternary ammonium cation. Derivatives of the bis-quaternary ammonium cation include compounds resulting from or produced from the bis-quaternary ammonium cation by replacing one atom with another atom or group of atoms, or by removing an atom or group of atoms, or by converting a single bond to a double or triple bond, or by converting a double or triple bond to a single bond. Derivatives of the bis-quaternary ammonium cation can be intentionally added to the zeolite synthesis mixture or can be generated during the synthesis reaction.

[0098] The second OSDA In some embodiments, the second OSDA is a monoquaternary ammonium cation. In some embodiments, the monoquaternary ammonium cation contains from about 4 to about 14 carbon atoms, such as from about 4, 5, 6, 7, 8, 9, or 10 carbon atoms to about 11, 12, 13, or 14 carbon atoms. The monoquaternary ammonium cation can include various structural arrangements, such as acyclic or cyclic structures. In some embodiments, the monoquaternary ammonium cation is acyclic. Non-limiting examples of acyclic monoquaternary ammonium cations include tetramethylammonium and tetraethylammonium. In some embodiments, the monoquaternary ammonium cation is cyclic. Non-limiting examples of cyclic monoquaternary ammonium cations include N,N,N-trimethyladamantan-1-aminium and 1,1-dimethylpiperidin-1-ium.

[0099] In some embodiments, the nitrogen atom of the monoquaternary ammonium cation has four substituents, each of which is independently selected from the group consisting of alkyl, cycloalkyl, alkenyl, aryl, arylalkyl, and combinations thereof as defined above.

[0100] In some embodiments, the monoquaternary ammonium cation has a structure represented by Formula II,

Chemical formula

[0101] In some embodiments, together with the nitrogen to which R3 and R4 are attached, a piperidine ring is formed (i.e., R3 and R4 together are -(CH2)5-). In some embodiments, the piperidine ring is substituted with one or more methyl groups. In some embodiments, the piperidine ring is substituted with methyl groups at the 3- and 5-positions.

[0102] In some embodiments, together with the nitrogen to which R2, R3, and R4 are attached, an azabicyclooctane ring is formed. In some embodiments, the azabicyclooctane ring is substituted with a hydroxyl group. In some embodiments, the azabicyclooctane ring is substituted with a hydroxyl group at the 3-position.

[0103] Non-limiting examples of the mono-quaternary ammonium cation according to Formula II include the structures shown in Table 2.

Table 2-1

Table 2-2

[0104] In some embodiments, the bis-quaternary ammonium cation has a structure as represented in Table 2.

[0105] In some embodiments, the monoquaternary ammonium cation is selected from the group consisting of tetraethylammonium, 2-hydroxy-N,N,N-trimethylethane-1-aminium, N,N,N-trimethylcyclohexanaminium, N,N,N-trimethyladamantan-1-aminium (TMAda), N,N,N-trimethylbicyclo[2.2.1]heptan-2-aminium, N,N,N-trimethylbenzeneaminium, 1,1-dimethylpiperidin-1-ium, 1,1,3,5-tetramethylpiperidin-1-ium, 1-methylquinuclidin-1-ium, 3-hydroxy-1-methylquinuclidin-1-ium, and combinations thereof. In some embodiments, the second organic structure-directing agent is N,N,N-trimethyladamantan-1-aminium (TMAda).

[0106] In some embodiments, the source of the second OSDA (i.e., the monoquaternary ammonium cation) is a monoquaternary ammonium compound comprising a monoquaternary ammonium cation as described above herein and a counteranion. In some embodiments, the counteranion is selected from the group consisting of OH, Cl, and Br. In some embodiments, the source of the second organic structure-directing agent is TMAdaOH.

[0107] In some embodiments, the source of the first organic structure-directing agent is HMOH or OMOH, and the source of the second organic structure-directing agent is TMAdaOH.

[0108] It has previously been shown that only HMOH leads to the synthesis of EUO and *MRE framework zeolites, but it has not been used heretofore for the synthesis of CHA framework zeolites. Surprisingly, according to the present disclosure, it has been found that the use of HMOH or OMOH in the presence of TMAdaOH results in the crystallization of pure CHA phase zeolites.

[0109] The amounts of the first and second OSDA present in the synthesis gel can vary. In some embodiments, the amount of each of the first and second OSDA present can be expressed as a molar ratio to silicon. In some embodiments, the molar ratio of the first OSDA to silicon is from about 0.01 to about 0.2, for example, about 0.01, about 0.02, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07, about 0.08, about 0.09, or from about 0.1 to about 0.11, about 0.12, about 0.13, about 0.14, about 0.15, about 0.16, about 0.17, about 0.18, about 0.19, or about 0.2. In some embodiments, the molar ratio of the second OSDA to silicon is from about 0.02 to about 0.1, for example, about 0.02, about 0.03, about 0.04, about 0.05 to about 0.06, about 0.07, about 0.08, or about 0.09, or about 0.1.

[0110] The ratio of the first organic structure-directing agent to the second organic structure-directing agent can vary. In some embodiments, the molar ratio of the first organic structure-directing agent to the second organic structure-directing agent ranges from about 0.001 to about 1000, for example, about 0.001, about 0.01, about 0.1, about 0.5, or from about 1 to about 10, about 20, about 50, about 100, about 500, or about 1000. In some embodiments, the molar ratio of the first organic structure-directing agent to the second organic structure-directing agent is from about 0.1 to about 10. In some embodiments, the molar ratio of the first organic structure-directing agent to the second organic structure-directing agent is from about 0.5 to about 2.0.

[0111] In some embodiments, the second OSDA includes derivatives of monoquaternary ammonium cations. Derivatives of monoquaternary ammonium cations include compounds resulting from or generated from monoquaternary ammonium cations by replacing one atom with another atom or group of atoms, or by removing an atom or group of atoms, or by converting a single bond to a double or triple bond, or by converting a double or triple bond to a single bond. Derivatives of monoquaternary ammonium cations can be intentionally added to the zeolite synthesis mixture or can be generated during the synthesis reaction.

[0112] Inorganic structure directing agent In some embodiments, the synthesis gel further comprises an inorganic structure directing agent (SDA). When present, the inorganic SDA can vary and in some embodiments can be an alkali metal or alkaline earth metal cation. In some embodiments, the inorganic SDA can be an alkali metal cation such as lithium, sodium, potassium, or cesium. In certain embodiments, the inorganic SDA is a sodium or potassium cation. The source of the inorganic SDA (e.g., the alkali metal cation) can vary. For example, Li + , K + , or Cs + such alkali metal cations can be added in the form of hydroxides or as another suitable salt (e.g., sulfate, chloride, nitrate, etc.). In certain embodiments, the source of the sodium or potassium cation is, respectively, an aqueous solution of sodium hydroxide or potassium hydroxide, e.g., sodium hydroxide (NaOH) or potassium oxide (K2O). In some embodiments, the source of the sodium or potassium cation is sodium sulfate or potassium sulfate.

[0113] The amount of the inorganic structure directing agent present can vary. In particular, hydroxide ions are the only necessary mineralizing agent required in the reaction mixture, and the amount of hydroxide required in the synthesis gel can be provided from the source of the organic structure directing agent. In some embodiments, the alkali metal hydroxide functions as both the inorganic SDA and the source of hydroxide ions and is provided in an amount such that the synthesis gel has a pH within a particular range. For example, in some embodiments, the pH is advantageously basic, e.g., from about 12 to about 13.

[0114] Aluminum source The aluminum source can vary. In some embodiments, the aluminum source is non-zeolitic. In some embodiments, the aluminum source is amorphous. For example, in certain embodiments, the aluminum source can be an amorphous source selected from aluminum salts (such as aluminum triisopropoxide or other alkoxides, aluminum hydroxide, aluminum nitrate, aluminum chloride, aluminum phosphate), aluminum metal, amorphous aluminum oxide, or amorphous aluminosilicate. In other embodiments, the source of aluminum is crystalline, such as crystalline alumina or zeolite.

[0115] In some embodiments, the aluminum source includes zeolite. The zeolite used as the aluminum source can be diverse and will include various zeolite materials known in the art, particularly various aluminosilicate zeolites. In some embodiments, the source of aluminum includes zeolites having an FAU, LTA, LTL, MFI, or BEA crystal framework. In some embodiments, the source of aluminum is zeolite Y in the Na+ form.

[0116] Silicon source The silicon source can also vary. In various embodiments, silicon is provided by one or more of precipitated silica, colloidal silica, silica gel, silicon hydroxide, silicon alkoxide, amorphous silica, aluminosilicate, fumed silica, or silicate, such as an alkali silicate. In some embodiments, the silicon source is colloidal silica. In some embodiments, the silicon source is an alkali metal silicate. In some embodiments, the silicon source is sodium silicate.

[0117] In some embodiments, the amounts of silicon and aluminum present in the synthesis gel are selected such that the calculated SAR of the starting composition is in the range of about 1 to about 100, for example, about 2 to 60. In some embodiments, the SAR of the starting composition is in the range of about 10 to about 35. In some embodiments, the SAR of the starting composition is in the range of about 20 to about 30. Those skilled in the art know that the SAR during synthesis is not necessarily the same as the SAR in the final zeolite, and also know how to select the SAR value during synthesis to obtain the desired SAR in the final zeolite.

[0118] In some embodiments, the OH / Si ratio of the synthesis gel is from about 0.03 to about 1.0, for example, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07, about 0.08, about 0.09, or about 0.1 to about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, or about 1.0.

[0119] Mixing As described above, the method generally includes forming a reaction mixture comprising water, an aluminum source, a silicon source, a source of a first organic structure-directing agent (OSDA), and a second OSDA to form a synthesis gel, and subjecting the synthesis gel to a crystallization process to crystallize the zeolite.

[0120] In some embodiments, the method includes mixing a reaction mixture comprising water, an aluminum source, a silicon source, a source of a first organic structure-directing agent (OSDA), and a source of a second OSDA to form an aluminosilicate-containing solution herein referred to as a "synthesis gel" or "gel". Generally, the synthesis gel has a high solids content (e.g., about 15% or more or about 20% or more).

[0121] The mixing step can be carried out at various temperatures. In some embodiments, the mixing is carried out at room temperature. In some embodiments, the mixing is carried out at an elevated temperature (e.g., a temperature higher than room temperature such as about 25 °C to about 100 °C).

[0122] The mixing process can be carried out at various times. The time for mixing can range from 1 second to about 24 hours. For example, the time can be from about 1 second to about 1 minute, or from about 1 minute, about 5 minutes, about 10 minutes, or about 15 minutes to about 30 minutes, about 45 minutes, or about 1 hour, or from about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, or about 6 hours to about 12 hours, or about 24 hours. In some embodiments, the time is about 2 hours.

[0123] In some embodiments, the mixing can be carried out in separate and distinct steps. Thus, in some embodiments, the method includes a first mixing step that includes adding a source of a first OSDA, a source of a second OSDA, and a source of aluminum to water to form an aluminum-containing aqueous solution and mixing the aqueous solution for a first time.

[0124] The first time can range from 1 second to about 24 hours. For example, the first time can range from about 1 second to about 1 minute, or from about 1 minute, about 5 minutes, about 10 minutes, or about 15 minutes to about 30 minutes, about 45 minutes, or about 1 hour, or from about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, or about 6 hours to about 12 hours, or about 24 hours. In some embodiments, the first time is about 15 minutes.

[0125] The first mixing step can be carried out at various temperatures, and in some embodiments, the mixing is carried out at room temperature. In some embodiments, the mixing is carried out at an elevated temperature (e.g., a temperature higher than room temperature such as about 25°C to about 100°C).

[0126] In some embodiments, the method includes a second mixing step that includes adding a source of silicon to the aluminum-containing aqueous solution and mixing for a second time to form a synthetic gel.

[0127] The second time can range from 1 second to about 24 hours. For example, the second time can be from about 1 second to about 1 minute, or about 1 minute, about 5 minutes, about 10 minutes, or about 15 minutes to about 30 minutes, about 45 minutes, or about 1 hour, or about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, or about 6 hours to about 12 hours, or about 24 hours. In some embodiments, the second time is about 2 hours.

[0128] The second mixing step can be performed at various temperatures. In some embodiments, the mixing is performed at room temperature. In some embodiments, the mixing is performed at an elevated temperature (e.g., a temperature higher than room temperature such as about 25°C to about 100°C).

[0129] In some embodiments, the first and second times are each independently from about 1 second to about 24 hours. In some embodiments, the first time is from about 5 minutes to about 1 hour. In some embodiments, the second time is from about 5 minutes to about 1 hour.

[0130] In some embodiments, the first and second mixing steps are carried out at a temperature of about 20°C to about 100°C. In some embodiments, the first and second mixing steps are carried out at a temperature of about 20°C to about 50°C. In some embodiments, the first and second mixing steps are carried out at a temperature of about 20°C to about 30°C.

[0131] Crystallization Following the mixing of the synthetic gel components, the synthetic gel is then subjected to a crystallization process to crystallize the microporous zeolite. The crystallization conditions are generally selected to promote the formation of a solid precipitate containing zeolite crystals. Typically, the crystallization process involves maintaining the synthetic gel at an elevated temperature for a period of time. Generally, the reaction mixture described herein, when heated with stirring in a pressure vessel, produces the desired microporous zeolite crystalline product. In some embodiments, the crystallization further optionally includes adding zeolite seed crystals to the synthetic gel to facilitate the formation of the desired crystal structure. In some embodiments, the seed crystals have a CHA framework. In some embodiments, the seed crystals are calcined and in the Na + form of a CHA-type zeolite.

[0132] In some embodiments, the time can range from about 24 hours to about 6 days. For example, the time can range from about 24 hours, about 30 hours, or about 36 hours to about 2 days, about 3 days, about 4 days, about 5 days, or about 6 days. In some embodiments, the time is from about 30 hours to about 3 days. In some embodiments, the time is about 3 days. The crystallization process can be carried out at various temperatures at the corresponding autogenous pressure, and in some embodiments, the crystallization process ranges from about 90°C to about 250°C, for example, from about 120°C to about 200°C, or from about 140°C to about 180°C. In some embodiments, the temperature is from about 160°C to about 180°C.

[0133] After cooling the synthetic gel, the precipitate containing the zeolite material is then filtered off and optionally subjected to further processing. Optionally, the product can be centrifuged. Organic additives can be used to aid in the handling and isolation of the solid product. The precipitate can be filtered, for example, as disclosed in U.S. Patent Application Publication No. 2015 / 118150 by Yang et al., which is incorporated herein by reference, and the remaining mother liquor can be discarded or recycled. Spray drying is an optional step in the processing of the product.

[0134] Further processing The zeolite product can 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 450 °C to about 750 °C) over a period of 1 to 10 hours. Following the initial calcination, the zeolite product is predominantly in the alkali metal form (e.g., Na + form).

[0135] The zeolite obtained after calcination can be ion-exchanged to reduce the amount of alkali or, for example, to exchange with ammonium ions. In some embodiments, single or multiple ammonium ion exchanges are used to produce the NH4 + form of the zeolite, which can optionally be further calcined to form the H + form. Ion exchange methods are well known in the art and can be applied without departing from the scope of the claims. Ion exchange can be achieved, for example, by treating with an aqueous ammonium chloride solution.

[0136] Properties of zeolite In some embodiments, the microporous zeolite obtained by the disclosed process has a structure containing cages, and the maximum diameter of the spheres that can be included in the structure containing cages is from about 4.4 Å to about 7.8 Å.

[0137] In some embodiments, the microporous zeolite crystals resulting from crystallization can be from about 50 to about 100% crystalline. In some embodiments, the microporous zeolite crystals resulting from crystallization can be from about 80% to about 99% crystalline or from about 90% to about 97% crystalline. The percent crystallinity can be measured by X-ray diffraction analysis.

[0138] In some embodiments, the small pore zeolite has a crystal framework structure type selected from AEI, AFT, AFX, AFV, AVL, CHA, EAB, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV. In some embodiments, the small pore zeolite has a crystal framework structure type selected from AEI, AFV, AVL, CHA, EAB, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV. In some embodiments, the small pore zeolite has an AEI or CHA crystal framework. In some embodiments, the small pore zeolite has a CHA crystal framework.

[0139] In some embodiments, the small pore zeolite product can be characterized by a silica to alumina molar ratio (SAR). In one embodiment, the molar ratio of silica to alumina in the small pore zeolite ranges from about 6 to about 100. In certain embodiments, the zeolite product has an SAR of about 10 to about 30. In certain embodiments, the small pore zeolite product has an SAR of about 20 to about 30.

[0140] In some embodiments, the small pore zeolite product is characterized by a relatively low mesopore surface area (MSA) combined with a zeolite surface area (ZSA) that provides good catalytic performance. The pore volume and surface area characteristics can be determined by nitrogen adsorption (BET surface area method). In some embodiments, the MSA of the zeolite product is less than about 75 m 2 / g (e.g., about 25 to about 75 m 2 / g) or less than about 25 m 2 / g (e.g., about 5 to about 25 m 2 / g). The ZSA of the zeolite product is typically at least about 450 m 2 / g, or at least about 475 m 2 / g, or at least about 500 m 2 / g, and an exemplary ZSA range is about 450 to about 600 m 2 / g or about 500 to about 600 m 2 / g.

[0141] In some embodiments, the microporous zeolite product also has the H form of the microporous zeolite material treated with a 40 wt% NH4F solution at 50 °C, stirred and sonicated (35 kHz, 90 W) at 350 rpm for 20 minutes, and then dried and calcined at 450 °C for 6 hours, and can also be characterized by a relatively low normalized ZSA loss after treatment with an NH4F solution, such as less than about 60% (or less than about 50%). The NH4F treatment that selectively etches the zeolite material at the grain boundaries, which are the interfaces between the intergrown crystallites and other defective regions, was originally developed by Qin et al. [Qin et.al, Angew.Chem.Int.Ed. 2016 55, 19049] as a means of imparting mesoporosity. Herein, this treatment is used as a means of quantifying the defect density by measuring the relative rate of etching. + In some embodiments, the microporous zeolite products disclosed herein exhibit a controlled aluminum distribution, and the controlled aluminum distribution includes an array of anionic framework Al centers. Such a controlled aluminum distribution can be evidenced by properties associated with the zeolite material. For example, in some embodiments, the microporous zeolites disclosed herein exhibit altered Al positioning and pairing relative to microporous zeolites prepared by a process in which the OSDA is a monoquaternary ammonium cation (e.g., only N,N,N-trimethylcyclohexanammonium or N,N,N-trimethyladamantan-1-ammonium (TMAda)). In some embodiments, the altered Al positioning and pairing can be characterized by an altered equilibrium Cu

[0142] uptake compared to that of zeolites synthesized with only monoquaternary OSDA. Specifically, in some embodiments, the zeolites disclosed herein exhibit a higher Cu +2 uptake than expected based on their SAR. Such differences are due to a higher concentration of Cu +2 under ion exchange conditions. +2 uptake. +2can be shown (e.g., at least about 0.1 M, at least about 0.2 M, at least about 0.25 M, at least about 0.3 M, or at least about 0.4 M of Cu +2 concentration). In some embodiments, the zeolite has a Cu concentration greater than 0.25 M compared to small pore zeolites synthesized using TMAdaOH as the only organic structure directing agent +2 characterized by an altered equilibrium Cu +2 uptake at concentration.

[0143] In some embodiments, prior to calcination, at least a portion of the pores of the small pore zeolite are occupied by bis-quaternary ammonium cations and at least a portion of the pores are occupied by mono-quaternary ammonium cations (i.e., the OSDA used to prepare the small pore zeolite), with each ammonium cation as described hereinabove. In some embodiments, about 1 to about 99% of the pores are occupied by bis-quaternary ammonium cations and about 99 to about 1% of the pores are occupied by mono-quaternary ammonium cations. In some embodiments, about 60 to about 40% of the pores are occupied by bis-quaternary ammonium cations and about 40 to about 60% of the pores are occupied by mono-quaternary ammonium cations. In some embodiments, the bis-quaternary ammonium cation contains about 8 to about 20 carbon atoms. In some embodiments, each nitrogen atom of the bis-quaternary ammonium cation has four substituents, each substituent independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof. In some embodiments, the bis-quaternary ammonium cation has a structure represented by Formula I, [Chemical Formula] wherein each of the substituents R1, R2, and R3 is methyl or ethyl, or optionally, both R3 groups are joined to form a -(CH2) n -bridge, and n is an integer from 1 to 3, X is selected from the group consisting of alkyl, cycloalkyl, alkenyl, aryl, arylalkyl, and combinations thereof, provided that alkyl, cycloalkyl, alkenyl, aryl, arylalkyl are each as defined above.

[0144] In some embodiments, the bisquaternary ammonium cation is N1,N1,N1,N3,N3,N3-hexaethylpropane-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbutane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexaethylbutane-1,4-diaminium, (E)-N1,N1,N1,N4,N4,N4-hexamethylbut-2-ene-1,4-diaminium, N1,N1,N1,N5,N5,N5-hexamethylpentane-1,5-diaminium, (E)-N1,N1,N1,N5,N5,N5-hexamethylpent-2-ene-1,5-diaminium, N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium (hexamethonium), (E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2-ene-1,6-diaminium, (2E,4E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2,4-diene-1,6-diaminium, N1,N1,N1,N7,N7,N7-hexamethylheptane-1,7-diaminium, N1,N1,N1,N8,N8,N8-hexamethyloctane-1,8-diaminium, N1,N1,N1,N3,N3,N3-hexamethylcyclohexane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbicyclo[2.2.1]heptane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbenzene-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylcyclohexane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.1]heptane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.2]octane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbenzene-1,4-diaminium, 1,1,4,4-tetramethylpiperazine-1,4-diium, 1,1,3,3-tetramethylhexahydropyrimidine-1,3-diium, 1,1'-(1,3-phenylene)bis(N,N,N-trimethylmethanaminium), 1,1'-(1,4-phenylene)bis(N,N,N-trimethylmethanaminium), or a combination thereof.In some embodiments, the bis-quaternary ammonium cation is selected from Table 1. In some embodiments, the bis-quaternary ammonium cation is hexamethonium or octamethonium.

[0145] In some embodiments, the mono-quaternary ammonium cation contains from about 4 to about 14 carbon atoms. The nitrogen atom of the mono-quaternary ammonium cation has four substituents, each of which is independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

[0146] In some embodiments, the mono-quaternary ammonium cation has a structure represented by Formula II,

Chemical formula

[0147] In some embodiments, the monoquaternary ammonium cation is tetraethylammonium, 2-hydroxy-N,N,N-trimethylethane-1-aminium, N,N,N-trimethylcyclohexanaminium, N,N,N-trimethyladamantan-1-aminium (TMAda), N,N,N-trimethylbicyclo[2.2.1]heptan-2-aminium, N,N,N-trimethylbenzenaminium, 1,1-dimethylpiperidin-1-ium, 1,1,3,5-tetramethylpiperidin-1-ium, 1-methylquinuclidin-1-ium, 3-hydroxy-1-methylquinuclidin-1-ium, or a combination thereof. In some embodiments, the monoquaternary ammonium cation is selected from Table 2. In some embodiments, the monoquaternary ammonium cation is TMAda. In some embodiments, the bisquaternary ammonium cation is hexamethonium or octamethonium, and the monoquaternary ammonium cation is TMAda.

[0148] The microporous zeolite synthesized by the method of the present invention comprises a carbon to nitrogen ratio, i.e., C / N ratio, in the range of 7 to 15.

[0149] Promoted zeolite In some embodiments, the microporous zeolite material disclosed herein is further treated with a promoter metal to form a metal-promoted (e.g., ion-exchanged) zeolite catalyst. As used herein, the term "promoted" refers to a metal component ("promoter metal") that is intentionally added to the molecular sieve material, as opposed to inherent impurities in the molecular sieve. Thus, a promoter is intentionally added to improve the activity of a catalyst as compared to a catalyst that does not have an intentionally added promoter. The promoter metal is actively involved in promoting a chemical reaction; for example, copper is involved in the conversion of nitrogen oxides and is thus often referred to as an active metal. In order to promote the selective catalytic reduction of nitrogen oxides in the presence of ammonia, in one or more embodiments, suitable metals are independently exchanged into the disclosed zeolite material.

[0150] In some embodiments, the disclosed zeolites are promoted with a promoter metal selected from the group consisting of alkali metals, alkaline earth metals, Group IIIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIIIB, Group IB, and Group IIB transition metals, Group IIIA elements, Group IVA elements, lanthanides, actinides, and combinations thereof. In some embodiments, further, promoter metals that can be used to prepare the promoted zeolites of the disclosed catalyst compositions include, but are not limited to, copper (Cu), cobalt (Co), nickel (Ni), lanthanum (La), manganese (Mn), iron (Fe), vanadium (V), silver (Ag), cerium (Ce), neodymium (Nd), praseodymium (Pr), titanium (Ti), chromium (Cr), zinc (Zn), tin (Sn), niobium (Nb), molybdenum (Mo), hafnium (Hf), yttrium (Y), tungsten (W), and combinations thereof. In some embodiments, the promoter metal is copper or iron. For example, copper or iron can be ion-exchanged to form Cu-chabazite or Fe-chabazite. When copper acetate is used, the copper concentration of the liquid copper solution used in the copper ion exchange is, in certain embodiments, in the range of about 0.01 to about 0.4 moles, more specifically in the range of about 0.05 to about 0.3 moles.

[0151] The promoter metal can be exchanged onto the zeolite by a liquid phase exchange process, where the soluble metal ions exchange with protons or ammonium or sodium ions located within the pores of the zeolite. The exchange can also be carried out by a solid state process, where solid particles of the promoter metal oxide or metal salt are mixed with the zeolite powder and treated under certain temperatures and gas environments, which may or may not contain vapor. The exchange process can also be achieved via an in-situ process during slurry preparation, where fine metal oxide particles are suspended in the zeolite slurry under conditions suitable for solid-liquid interaction. In some embodiments, before exchanging the zeolite materials as disclosed herein with a promoter metal, the zeolite is converted to its H +To obtain the morphology, as is known in the art, it must be exchanged with NH4 + and calcined.

[0152] To further promote the SCR of nitrogen oxides, in some embodiments, the zeolite can be promoted with two or more metals (e.g., copper in combination with one or more other metals). When two or more metals are included in the promoted zeolite-based material, multiple metal precursors (e.g., copper and iron precursors) can be ion-exchanged simultaneously or separately. In certain embodiments, the second metal can be exchanged into the zeolite material first promoted with the first metal (e.g., the second metal can be exchanged into the zeolite material promoted with copper).

[0153] The amount of metal ions exchanged in the metal-promoted zeolite can vary. In one or more embodiments, the promoter metal content calculated as metal oxide, independently, when reported on a volatile-free basis based on the total weight of the corresponding calcined zeolite (including the promoter metal), can range from about 0.01 wt% to about 15 wt%, from about 0.5 wt% to about 12 wt%, or from about 1.0 wt% to about 10 wt%. In some embodiments, the promoter metal content calculated as oxide, when reported on a volatile-free basis based on the total weight of the corresponding calcined zeolite (including the promoter metal), is at least about 0.1 wt%. In certain embodiments, the promoter metal of the zeolite contains Cu, and the Cu content calculated as CuO ranges from about 0.1 wt% to about 20 wt%, for example, from about 0.5 wt% to about 17 wt%, from about 2 wt% to about 15 wt%, or from about 2 wt% to about 10 wt%, in each case based on the total weight of the calcined zeolite reported on a volatile-free basis.

[0154] In some embodiments, the zeolite (including the promoter metal) can be defined by the ratio of the promoter metal to aluminum in the promoted zeolite. For example, in some embodiments, the weight ratio of the promoter metal to aluminum is in the range of about 0.002 to about 0.5. In certain embodiments, the promoter metal of the zeolite comprises Cu, and the atomic ratio of copper to aluminum in the zeolite is from about 0.1 to about 0.5 (e.g., the Cu / Al ratio is from about 0.1 to about 0.5).

[0155] The copper species (e.g., copper oxide, metal, and ion-exchanged copper) that can be present in the zeolite material can be identified by monitoring the perturbed T-O-T bond (Si-O-Al and Si-O-Si) vibrations by diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy. The use of this FTIR technique is shown in the literature, e.g., Giamello et al., J. Catal. 136, 510 - 520 (1992). The structural vibrations of the T-O-T bonds in the zeolite have absorption peaks at 1300 - 1000 cm -1 and 850 - 750 cm -1 for the asymmetric and symmetric vibration modes, respectively. Since the frequency of the asymmetric T-O-T vibration of the oxygen-containing ring is sensitive to the interaction with the cation, when interacting with the cation, the IR band shifts from the normal 1000 - 1300 cm -1 (the position characteristic of the unperturbed ring) to about 850 - 1000 cm -1Shift to. The shifted band appears in the transmission window between two strong bands of T-O-T asymmetric vibration and symmetric vibration. The position of such a shifted band depends on the properties of the cation. Such perturbed T-O-T coupled vibrations are observed when copper ions are exchanged at the cation exchange positions of the zeolite framework structure based on the strong interaction between copper ions and adjacent oxygen atoms in the framework structure. The peak position depends on the state of the compensating cation and the structure of the zeolite framework. In some embodiments, the powder sample of the copper-promoted zeolite disclosed herein exhibits a T-O-T coupling peak measured by DRIFT spectroscopy that is shifted to a higher wavenumber compared to a copper-promoted zeolite prepared by a process in which the OSDA is only a monoquaternary ammonium ion (e.g., N,N,N-trimethylcyclohexanammonium or N,N,N-trimethyladamantan-1-ammonium (TMAda)).

[0156] SCR catalyst composition The present disclosure provides a selective catalytic reduction (SCR) catalyst composition effective for catalyzing the reduction of NO x from engine exhaust gases, such as from a lean burn engine, in the presence of a reducing agent, and the catalyst composition comprises a promoted small pore zeolite disclosed herein.

[0157] In some embodiments, the SCR catalyst composition may further include a binder, such as a ZrO2 binder derived from a suitable precursor such as zirconyl acetate or any other suitable zirconium precursor such as zirconyl nitrate. For example, when the catalyst is exposed to high temperatures of at least about 600 °C, such as about 800 °C or higher and a high steam environment of about 5% or more, the zirconyl acetate binder provides a uniform and intact coating after thermal aging. Other potentially suitable binders include, but are not limited to, alumina and silica. Examples of alumina binders include aluminum oxide, aluminum hydroxide, and aluminum oxyhydroxide. Aluminum salts, and colloidal forms of alumina may be used. Silica binders include various forms of SiO2, including silicates and colloidal silica. The binder composition may include any combination of zirconia, alumina, and silica. Other exemplary binders include boehmite, gamma-alumina, or delta / theta alumina, as well as silica sols. When present, the binder is typically used in an amount of about 1 to 5 wt% of the total washcoat loading. Alternatively, the binder can be zirconia-based or silica-based, such as zirconyl acetate, zirconia sol, or silica sol. When present, the alumina binder is typically in an amount of about 0.05 g / in 3 ~ about 1 g / in 3 of the amount used.

[0158] Catalyst article In another aspect, there is provided an SCR article effective to catalyze the reduction of NO x from engine exhaust gases, such as from a lean burn engine, in the presence of a reducing agent. The SCR article includes a substrate having an inlet end and an outlet end defining a total length, and the SCR catalyst composition disclosed herein disposed on at least a portion of the substrate.

[0159] Substrate In one or more embodiments, the present SCR catalyst composition is disposed on a substrate to form a catalyst article. The catalyst article including the substrate is generally used as part of an exhaust gas treatment system (examples of the catalyst article include, but are not limited to, articles including the SCR compositions disclosed herein). Useful substrates are three-dimensional and have a length, diameter, and volume similar to a cylinder. The shape does not necessarily have to match a cylinder exactly. The length is the axial length defined by an inlet end and an outlet end.

[0160] According to one or more embodiments, the substrate for the disclosed compositions can be composed of any suitable material typically used to prepare automotive catalysts, typically including a metal or ceramic honeycomb structure. The substrate typically provides a plurality of walls to which a washcoat composition is applied and adhered, thereby functioning as a substrate for the catalyst composition.

[0161] The ceramic substrate can be made from any suitable refractory material, such as cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon mullite, lischite, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicate, and the like.

[0162] The substrate can also be a metal, including one or more metals or metal alloys. The metal substrate can include any metal substrate having openings or "punch-outs" in the channel walls. The metallic substrate can be used in various shapes such as pellets, compressed metallic fibers, corrugated sheets, or monolithic forms. Specific examples of metal substrates include heat-resistant base metal alloys, especially those in which iron is a substantial or major component. Such alloys can contain one or more of nickel, chromium, and aluminum, and the total of these metals is advantageously, in each case, at least about 15 weight % (weight percent) of the alloy, based on the weight of the substrate, for example, about 10 to about 25 weight % of chromium, about 1 to about 8 weight % of aluminum, and 0 to about 20 weight % of nickel. Examples of metal substrates include those having straight channels, those having blades protruding along the axial channels to obstruct the gas flow and open the communication of the gas flow between the channels, and those having holes for improving the gas transport between the channels to enable radial gas transport across the blades and the monolith.

[0163] Any suitable substrate for the catalyst articles disclosed herein can be employed, such as a monolithic substrate ("flow-through substrate") of the type having fine parallel gas flow channels extending therethrough from the inlet or outlet face of the substrate so that the passageway is open to the fluid flow therethrough. Another suitable substrate is of the type having a plurality of fine substantially parallel gas flow channels extending along the longitudinal axis of the substrate, typically with each passageway blocked at one end of the substrate body and every other passageway blocked at the opposite end face ("wall flow filter"). Flow-through and wall flow substrates are also taught, for example, in International Application Publication No. WO 2016 / 070090, which is hereby incorporated by reference in its entirety.

[0164] In some embodiments, the catalyst 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. The flow-through substrate and the wall flow filter are further discussed herein below.

[0165] Flow-through substrate In some embodiments, the substrate is a flow-through substrate (e.g., a monolithic substrate including a flow-through honeycomb monolithic substrate). The flow-through substrate has fine and parallel gas flow channels extending from an inlet end to an outlet end of the substrate such that the channels are open to the fluid flow. The channels, which are essentially straight paths from the fluid inlet to the fluid outlet, are defined by walls, and on or in the walls, the catalytic coating is disposed such that the gas flowing through the channels contacts the catalytic material. The flow channels of the flow-through substrate 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. The flow-through substrate can be ceramic or metal as described above.

[0166] The flow-through substrate is, for example, about 50 in 3 ~ about 1200 in 3 in volume, with a cell density (inlet openings) of about 60 cells per square inch (cpsi) to about 500 cpsi or up to 900 cpsi, for example, about 200 to about 400 cpsi, and a wall thickness of about 50 to about 200 microns or about 400 microns.

[0167] Wall flow filter substrate In some embodiments, the substrate is a wall flow filter, which generally has a plurality of fine and substantially parallel gas flow paths extending along the longitudinal axis of the substrate. Typically, each passage is blocked at one end of the substrate body, and every other passage is blocked at the opposite end face. Such a monolithic wall flow filter substrate may include up to about 900 or more flow paths (or "cells") per square inch of cross-section, although far fewer 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 can have a cross-section that is rectangular, square, circular, elliptical, triangular, hexagonal, or other polygonal. The wall flow filter substrate can be ceramic or metal as described above.

[0168] Referring to FIG. 1, an exemplary wall flow filter substrate has a cylindrical shape and a cylindrical outer surface having a diameter D and an axial length L. A cross-sectional view of the monolithic wall flow filter substrate is illustrated in FIG. 2, which shows alternating blocked and open passages (cells). The blocked or closed ends 100 alternate with the open passages 101, with each opposing end being open and blocked, respectively. The filter has an inlet end 102 and an outlet end 103. The arrows across the porous cell walls 104 represent the exhaust gas flow that enters the open cell ends, diffuses through the porous cell walls 104, and exits from the open outlet cell ends. The closed ends 100 impede the 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 surrounded by the cell walls.

[0169] The wall flow filter article substrate can be, for example, about 50 cm 3 , about 100 in 3 , about 200 in 3 , about 300 in 3 , about 400 in 3 , about 500 in 3 , about 600 in 3 , about 700 in 3 , about 800 in 3 , about 900 in 3 , or about 1000 in3 from about 1500 in 3 to about 2000 in 3 to about 2500 in 3 to about 3000 in 3 to about 3500 in 3 to about 4000 in 3 to about 4500 in 3 or to about 5000 in 3 and may have a volume up to. The wall flow filter substrate typically has a wall thickness of from about 50 microns to about 2000 microns, such as from about 50 microns to about 450 microns, or from about 150 microns to about 400 microns.

[0170] The walls of the 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 diameter of at least about 10 microns before applying the functional coating. For example, the wall flow filter article substrate in some embodiments has a porosity of ≧40%, ≧50%, ≧60%, ≧65%, or ≧70%. For example, the wall flow filter article substrate will have a wall porosity from about 50%, about 60%, about 65%, or about 70% to about 75% and an average pore diameter from about 10 microns or about 20 microns to about 30 microns or about 40 microns before applying the catalytic coating. The terms "wall porosity" and "substrate porosity" have the same meaning and are interchangeable. Porosity is the ratio of the void volume (or pore volume) to the total volume of the substrate material. Pore diameter and pore diameter distribution are typically determined by Hg porosimetry measurements.

[0171] Substrate Coating Process To manufacture the SCR catalytic article of the present disclosure, the substrates described herein are coated with the SCR catalyst compositions disclosed herein. The coating is a "catalyst coating composition" or a "catalyst coating". The terms "catalyst composition" and "catalyst coating composition" are synonyms.

[0172] Generally, the catalyst composition is prepared as described herein and coated onto a substrate. This method can include mixing the catalyst composition (or one or more components of the catalyst composition) generally disclosed herein with a solvent (e.g., water) to form a slurry for coating the catalyst substrate. In addition to the catalyst composition, the slurry can optionally contain various additional components. Typical additional components include, but are not limited to, binders as described above herein, e.g., additives for controlling the pH and viscosity of the slurry. Additional components can include hydrocarbon (HC) storage components (e.g., zeolites), associative thickeners, and / or surfactants (including anionic, cationic, nonionic or amphoteric surfactants). A typical pH range for the slurry is from about 3 to about 6. Acidic or basic species can 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 glacial acetic acid.

[0173] The slurry can be milled to reduce the particle size and improve the mixing of the particles and the formation of a homogeneous material. Milling can be accomplished with a ball mill, a continuous mill, or other similar apparatus, and the solids content of the slurry can be, for example, from about 20 to 60 wt%, more specifically from about 20 to 40 wt%. In one embodiment, the milled slurry is characterized by a D 90 particle size of from about 1 to about 40 microns, preferably from 2 to about 20 microns, more preferably from about 4 to about 15 microns.

[0174] The catalyst composition can typically be applied in the form of one or more washcoats containing the SCR catalyst composition components as disclosed herein. The washcoat is formed by preparing a slurry containing a specific solids content (e.g., about 10% to about 60% by weight) of the catalyst composition (or one or more components of the catalyst composition) in a liquid vehicle, and then applying it to a substrate using any washcoating technique known in the art, followed by drying and calcining to provide a coating layer. When multiple coatings are applied, the substrate is dried and / or calcined after each washcoat is applied and / or after the desired number of multiple washcoats are applied. In one or more embodiments, the catalyst material is applied to the substrate as a washcoat.

[0175] After calcination, the catalyst loading obtained by the washcoating technique described above can be determined through calculation of the difference between the coated weight and the uncoated weight of the substrate. As will be apparent to those skilled in the art, the catalyst loading can be modified by changing the rheology of the slurry. In addition, the coating / drying / calcination process for generating the washcoat layer (coating layer) can be repeated as necessary to build the coating to the desired loading level or thickness, meaning that more than one washcoat can be applied.

[0176] Composition of the Coating The catalytic coating can include one or more coating layers, at least one of which contains the catalyst composition or one or more components of the catalyst composition. The catalyst coating can include one or more thin adhesive coating layers disposed on and adhering to at least a portion of the substrate. The entire coating includes individual "coating layers".

[0177] In some embodiments, the catalytic article can include the use of one or more catalyst layers and combinations of one or more catalyst layers. The catalyst material can be present only on the inlet side of the substrate wall, only on the outlet side, on both the inlet and outlet sides, or the wall itself can be wholly or partially composed of the catalyst material. The washcoat can be on the surface of the substrate wall and / or within the pores of the substrate wall, i.e., "within" and / or "on" the substrate wall. Thus, the phrase "washcoat disposed on a substrate" means on any surface, e.g., on the wall surface and / or on the pore surface.

[0178] The washcoat can be applied such that different coating layers can be in direct contact with the substrate. Alternatively, one or more "undercoats" may be present, whereby at least a portion of the catalytic coating layer or coating layers do not contact the substrate directly (rather, they contact the undercoat). One or more "overcoats" may be present such that at least a portion of the coating layer is not directly exposed to the gas flow or atmosphere (rather, it contacts the overcoat).

[0179] Alternatively, the catalytic composition can be present in a top coating layer that covers the bottom coating layer. The catalytic composition can be present in the top and bottom layers. Any one layer can extend over the entire axial length of the substrate. For example, the bottom layer can extend over the entire axial length of the substrate, and the top layer can also extend over the entire axial length of the substrate above the bottom layer. The top and bottom layers can each extend from either the inlet end or the outlet end.

[0180] For example, both the bottom and top coating layers can extend from the same substrate end, the top layer partially or completely overlays the bottom layer, the bottom layer extends over a partial or full length of the substrate, and the top layer extends over a partial or full length of the substrate. Alternatively, the top layer may overlay a part of the bottom layer. For example, the bottom layer can extend over the full length of the substrate, and the top layer can extend from either the inlet end or the outlet end to 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.

[0181] Alternatively, the bottom layer can extend from either the inlet end or the outlet end 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, the top layer can extend from either the inlet end or the outlet end 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 substrate length, and at least a part of the top layer overlays the bottom layer. This "overlay" zone can extend, for example, from about 5% to about 80%, such as about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60, or about 70% of the length of the substrate.

[0182] In some embodiments, the oxidation catalyst composition as disclosed herein disposed on a substrate as disclosed herein includes a first washcoat disposed on at least a part of the length of the catalyst substrate.

[0183] In some embodiments, the first washcoat is disposed directly on the catalyst substrate, and the second washcoat (which may be the same or contain different catalysts or catalyst components) is disposed on at least a portion of the first washcoat. In some embodiments, the second washcoat is disposed directly on the catalyst substrate, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, the first washcoat is disposed directly on the catalyst substrate from the inlet end to a length of about 10% to about 50% of the total length, and the second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, the second washcoat is disposed directly on the catalyst substrate from the inlet end to a length of 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, the first washcoat is disposed directly on the catalyst substrate from the inlet end to a length of about 20% to about 40% of the total length, and the second washcoat extends from the inlet end to the outlet end. In some embodiments, the first washcoat is disposed directly on the catalyst substrate from the outlet end to a length of about 10% to about 50% of the total length, and the second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, the first washcoat is disposed directly on the catalyst substrate from the outlet end to a length of about 20 to about 40% of the total length, and the second washcoat extends from the inlet end to the outlet end. In some embodiments, the second washcoat is disposed directly on the catalyst substrate from the outlet end to a length of 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, the first washcoat is disposed directly on the catalyst substrate covering 100% of the total length, and the second washcoat is disposed on the first washcoat covering 100% of the total length.In some embodiments, the second washcoat is disposed directly on a catalyst substrate covering 100% of the total length, and the first washcoat is disposed on the second washcoat covering 100% of the total length.

[0184] The catalytic coating can advantageously be "zoned", including zoned catalytic layers, i.e., the catalytic coating contains various compositions over the axial length of the substrate. This can be referred to as "laterally zoned". For example, the layer can extend over 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, extending from the inlet end to the outlet end. Another layer can extend over 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, extending from the outlet end to the inlet end. The different coating layers can be adjacent to each other and may not overlap each other. Alternatively, the different layers can overlap a part of each other to provide a third "intermediate" zone. The intermediate zone can extend, for example, over about 5% to about 80% of the substrate length, such as over about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% of the substrate length.

[0185] The zones of the present disclosure are defined by the relationship of the coating layers. There are several possible zoning configurations for different coating layers. For example, an upstream zone and a downstream zone can exist, an upstream zone, an intermediate zone, and a downstream zone can exist, four different zones can exist, etc. When two layers are adjacent and do not overlap, an upstream zone and a downstream zone exist. When two layers overlap to some extent, upstream, downstream, and intermediate zones exist. For example, when a coating layer extends over the entire length of the substrate, a different coating layer extends over a certain length from the outlet end and overlays a part of the first coating layer, an upstream and a downstream zone exist.

[0186] For example, an SCR catalyst article can include an upstream zone including a first washcoat layer and a downstream zone including a second washcoat layer with a different catalyst material or component. Alternatively, the upstream zone can include the second washcoat layer and the downstream zone can include the first washcoat layer.

[0187] In some embodiments, the first washcoat is disposed on the catalyst substrate from the inlet end to a length of about 10% to about 50% of the total length, and the second washcoat is disposed on the catalyst substrate from the outlet end to a length of about 50% to about 90% of the total length. In some embodiments, the first washcoat is disposed on the catalyst substrate from the outlet end to a length of about 10% to about 50% of the total length, and the second washcoat is disposed on the catalyst substrate from the inlet end to a length of about 50% to about 90% of the total length.

[0188] Figures 3a, 3b, and 3c show some possible coating layer configurations having two coating layers. A substrate wall 200 is shown with coating layers 201 (top coat) and 202 (bottom coat) disposed thereon. This is a simplified view and in the case of a porous wall flow substrate, pores and the coating adhering to the pore walls are not shown and the closed ends are not shown. In Figure 3a, coating layers 201 and 202 each extend over the entire length of the substrate and the upper layer 201 overlays the bottom layer 202. The substrate of Figure 3a does not include a zoned coating configuration. Figure 3b illustrates a zoned configuration having a coating layer 202 that extends from the outlet to about 50% of the length of the substrate to form a downstream zone 204 and a coating layer 201 that extends from the inlet to about 50% of the length of the substrate to provide an upstream zone 203. In Figure 3c, the bottom coating layer 202 extends from the outlet to about 50% of the length of the substrate, the upper coating layer 201 extends more than 50% of the length from the inlet, overlays a portion of layer 202, and provides an upstream zone 203, an intermediate overlay zone 205, and a downstream zone 204. Figures 3a, 3b, and 3c can be useful for illustrating an SCR catalyst composition coating on a wall-through substrate or a flow-through substrate.

[0189] 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 SCR catalyst composition disclosed herein, when incorporated into the SCR catalyst articles disclosed herein, is effective to catalyze the reduction of NO x derived from engine exhaust gases such as exhaust from a lean burn engine in the presence of a reducing agent. In some embodiments, the SCR article can be characterized by SCR activity at various temperatures. In some embodiments, effective reduction of NO x occurs at temperatures higher than about 150°C and lower than about 700°C. In some embodiments, effective reduction of NO x occurs at temperatures from about 200°C to about 600°C.

[0190] Exhaust gas treatment system In a further aspect, there is provided a system for treating an exhaust gas stream from an engine, the system being located downstream of and in fluid communication with an engine that generates an exhaust gas stream, such as a lean burn engine. The engine can be, for example, a diesel engine operating under combustion conditions with an excess of air beyond that required for stoichiometric combustion, i.e., lean conditions. In other embodiments, the engine can be a gasoline engine (e.g., a lean burn gasoline engine), or an engine associated with a stationary power source (e.g., a generator or a pump yard). The exhaust gas treatment system generally includes two or more catalytic articles disposed downstream of the engine in fluid communication with the exhaust gas stream. The system can include, for example, a selective catalytic reduction catalyst (SCR) disclosed herein, a diesel oxidation catalyst (DOC), a reductant injector, a soot filter, an ammonia oxidation catalyst (AMOx), or one or more articles including a lean NOx trap (LNT). The article including the reductant injector is a reductant article. The reductant system includes a reductant injector and / or a pump and / or a reservoir, etc. The present treatment system can further include a soot filter and / or an ammonia oxidation catalyst. The soot filter can be uncatalyzed or catalyzed (CSF). For example, the present treatment system can include, from upstream to downstream, an article including DOC, CSF, a urea injector, an SCR article, and an article including AMOx. A lean NOx trap (LNT) may also be included.

[0191] The relative arrangement of the various catalytic components present within the emission treatment system can vary. In the present exhaust gas treatment system and method, the exhaust gas stream enters at an upstream end and exits at a downstream end to be received by an article or treatment system. The inlet end of a 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 an internal combustion engine.

[0192] One exemplary emissions treatment system is illustrated in FIG. 4 depicting a schematic of emissions treatment system 20. As shown, the emissions treatment system can include a plurality of catalyst components in series downstream of an engine 22 such as a lean burn engine. At least one of the catalyst components will be the SCR catalyst of the present invention as described herein. The catalyst compositions of the present invention can be combined with a number of additional catalyst materials and placed at various positions relative to the additional catalyst materials. FIG. 4 illustrates five catalyst components 24, 26, 28, 30, 32 in series, although the total number of catalyst components can vary and the five components are merely an example.

[0193] Without limitation, Table 3 presents various exhaust gas treatment system configurations of one or more embodiments. Note that each catalyst is connected via an exhaust duct 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, which is upstream of catalyst E (if present) to the next catalyst. References to components A - E in the table can be cross - referenced with the same symbols in FIG. 4.

[0194] The LNT catalyst described in Table 3 can be any catalyst conventionally used as a NO x trap and typically includes base metal oxides (such as BaO, MgO, CeO2) and platinum group metals (e.g., Pt and Rh) for the oxidation and reduction of NO by the catalyst. x adsorbent composition.

[0195] The LT - NA catalyst described in Table 3 can be any catalyst capable of adsorbing NO x (e.g., NO or NO2) at low temperatures (<250 °C) and releasing it into the gas stream at high temperatures (>250 °C). The released NO X is generally converted to N2 and H2O on a downstream SCR or SCRoF catalyst. Typically, the LT - NA catalyst includes Pd - promoted zeolite or Pd - promoted refractory metal oxide.

[0196] References to SCR in the table refer to SCR catalysts that may include the SCR catalyst compositions of the present invention. References to SCRoF (i.e., SCR on a filter) refer to particulate or soot filters (e.g., wall flow filters) that can include the SCR catalyst compositions of the present invention. If both SCR and SCRoF are present, one or both can include the SCR catalyst of the present invention, or one of the catalysts can include a conventional SCR catalyst (e.g., a conventional metal-loaded level SCR catalyst).

[0197] References to AMOx in the table refer to ammonia oxidation catalysts that are provided downstream of the catalysts of one or more embodiments of the present invention and can remove any leaked 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 PGM and a top coat having an SCR function.

[0198] As will be recognized by those skilled in the art, in the configurations listed in Table 3, 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 compositions attached at a location near the engine (a direct connection location, CC), and additional catalyst compositions are at a location under the vehicle body (an underfloor location, UF). In one or more embodiments, the exhaust gas treatment system can further comprise a urea injection component. [Table 3]

[0199] Method for treating engine exhaust Another aspect of the present invention relates to a method for treating an exhaust gas stream of a lean burn engine, particularly an engine such as a lean burn gasoline engine or a diesel engine. 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. The present catalyst composition, article, system, and method are suitable for treating exhaust gas streams from internal combustion engines such as gasoline, small diesel, and large diesel engines. The catalyst composition is also suitable for treating emissions from stationary industrial processes, removing harmful or toxic substances from indoor air, or catalysis in chemical reaction processes.

[0200] The article, system, and method are suitable for treating exhaust gas streams from mobile emission sources such as trucks and automobiles. The article, system, and method are also suitable for treating exhaust streams from stationary power sources such as power plants.

[0201] It will be readily apparent to those skilled in the relevant art that suitable modifications and adaptations to the compositions, methods, and uses described herein can be made without departing from the scope of any embodiment or aspects 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 all of the embodiments, aspects, options, examples, and preferences herein. All patents and publications cited herein are incorporated herein by reference for their specific teachings as described, unless a specific incorporation of other specific descriptions is provided.

[0202] The present invention will be described with reference to the following examples. Before describing some exemplary embodiments of the present invention, it should be understood that the present invention is not limited to the details of the configurations or process steps described in the following description. The present invention is capable of other embodiments and can be implemented or executed in various ways.

[0203] Experiment General procedure The surface areas of the mesopores (or matrix) and zeolites (micropores) were determined by N2 adsorption porosimetry using a Micromeritics TriStar 3000 series instrument in accordance with the ISO9277 method. The samples were degassed for a total of 6 hours using a Micromeritics SmartPrep degassing device (heated to 300 °C for 2 hours under a dry nitrogen flow and then held at 300 °C for 4 hours). The nitrogen BET surface area was determined using five partial pressure points from 0.05 to 0.20. The surface areas of the zeolites and matrix were determined using the same five partial pressure points and calculated using the Harkins and Jura t-plot. Pores with diameters greater than 20 Å are considered to contribute to the surface area of the matrix.

[0204] Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) measurements were performed on a Thermo Nicolet FTIR equipped with an MCT detector and a Harrick environmental chamber equipped with a ZnSe window. The sample was ground into a fine powder using a mortar and pestle and filled into a sample cup. The sample powder was first dehydrated at 400 °C for 1 hour while flowing Ar at a flow rate of 40 ml / min and then cooled to 30 °C. The spectrum of the sample was obtained using KBr as a reference.

[0205] Preparation of small-pore zeolite materials In all cases, the same Si and Al sources were used in the gel preparation, and crystallization was carried out at autogenous pressure in a 2 L stirred autoclave. The product was isolated by filtration, dried, and calcined (540 °C, 6 hours) to obtain the product (analyzed by XRD), which was treated with a single or multiple NH4 until the Na2O content reached <500 ppm. +They were subjected to exchange. Table 4 summarizes the gel compositions resulting in zeolite materials of the comparisons (Examples 1-3) and the present invention (Examples 4-6), as well as their corresponding product SARs. All materials were synthesized at 170 °C, and the crystallization time ranged from 30 to 72 hours.

[0206] Examples 1-3 (comparison). In each synthesis, trimethyladamantylammonium hydroxide (TMAdaOH) was the only OSDA used. As shown in Table 4, the gel compositions (Si / Al ratio, OH / Si ratio, H2O to Si ratio) were varied for each example. Na was not added to the gel of Example 3. All crystallizations resulted in products with >90% crystallinity of the CHA phase and a corresponding high micropore surface area (>500 m + 2 / g). The material from Example 2 was calcined and used as seed for Examples 4-7 (the use of CHA seed in the synthesis gel is optional). 2 / g) were obtained.

[0207] Example 4 (comparison). Comparative Example 4 shows an alternative Na-free synthetic approach where the gel and product SAR are different from those of the examples of the present invention. In this synthesis, trimethylcyclohexylammonium hydroxide (TMChAOH) was used as the OSDA. Na was not added to the gel, but some Na was present in the seed zeolite added for crystallization, which accounts for the presence of Na in the product. Tetramethylammonium hydroxide (TMAOH) was added at a ratio of 0.09 with respect to Si and was presumed not to function as a template for CHA zeolite formation since no tetramethylammonium was present in the product. Crystallization resulted in products with >90% crystallinity of the CHA phase and a corresponding high micropore surface area (>500 m + 2 / g). 2 / g) were obtained.

[0208] Examples 5-7 (the present invention). For each synthesis, either hexamethonium dihydroxide (HMOH) or octamethonium dihydroxide (OMOH) was used as the first OSDA source, and TMAdaOH was used as the second OSDA source. In Examples 5 and 7, Na + was not added to the gel, but some Na was present in the seed zeolite added for crystallization, which accounts for the presence of Na in the product. In Example 6, Na + was added to the synthesis gel. Without wishing to be bound by theory, the different Na / Al ratios found in the product zeolite may indicate different aluminum distributions in these zeolite materials compared to Comparative Examples 1-4. Crystallization yielded products with >90% crystallinity of the CHA phase and a corresponding high micropore surface area (>500 m 2 / g).

Table 4

[0209] Without wishing to be bound by theory, the incorporation of a bis-quaternary ammonium compound (HMOH or OMOH), which has a significantly different structure compared to the mono-quaternary TMAdaOH typically used alone in the synthesis of CHA zeolites, indicates that the distribution of Al in the product zeolite is different compared to CHA zeolites synthesized with TMAdaOH alone or with a mixture of two quaternary ammonium compounds.

[0210] To further evaluate the extent of incorporation of each OSDA into the zeolite product, elemental analysis was performed on the washed, as-made products from Examples 4, 5, and 6 of the present invention. TMAdaOH, HMOH, and OMOH have C / N molar ratios of 13, 6, and 7, respectively. The results of the elemental analysis of Examples 4, 5, and 6 show product C / N molar ratios of 10.1, 11, and 11.4, respectively, which indicates that both mono- and bis-quaternary ammonium OSDAs were fairly incorporated into the final product for all materials of the present invention prior to calcination.

[0211] Furthermore, as indicated by the increase in the C / N ratio of Example 4 versus Example 5, the concentration of Na + used can serve to control the extent of bis-quaternary OSDA incorporation (and thus Al distribution) in the CHA product. Specifically, the increase in the C / N ratio shows that the addition of Na + to the synthesis gel used in Example 5 of the present invention decreased the incorporation of bis-quaternary ammonium OSDA (HMOH) into the CHA zeolite product of Example 5.

[0212] Example 8. Cu-exchanged CHA zeolite material The materials from Examples 1, 4, and 5 (each in NH4 + form) were calcined at 450 °C for 6 hours to obtain CHA zeolites in H + form. Each sample was evaluated by Cu-exchange isotherm experiments and FTIR measurements of the Cu-exchanged samples. Cu-exchange was carried out using aqueous copper acetate solutions at different concentrations at 60 °C. The isotherms of Comparative Example 1 and Example 4 showed similar gradients that were significantly different from the isotherm of the material of Example 5 (Figure 5). The uptake at a Cu +2 concentration of 0.1 M (measured as weight % of copper as CuO) followed the expected trend (i.e., materials with higher Al content (lower SAR) showed higher Cu uptake). However, at higher concentrations of Cu 2+(e.g., 0.2 M or higher), Example 5 of the present invention showed significantly higher Cu uptake than predicted based on the product SAR. TMAda + or TMChA + This difference in equilibrium Cu uptake when compared to a comparative CHA zeolite synthesized with only TMAda or TMChA is evidence of the altered Al positioning and pairing in the zeolite product. Since the density and distribution of catalytically active Cu sites in the zeolite depend on the positioning and proximity of aluminum atoms within the zeolite framework structure, this increased Cu uptake suggests the presence of a higher concentration of negatively charged aluminum species arranged in close proximity that effectively balance the positive charge of the copper species.

[0213] Further evidence of the altered Al positioning and pairing in Example 5 was provided by DRIFTS measurements of the T-O-T bond vibrations of this material after Cu exchange (Figure 6). Typically, a peak at about 950 cm -1 is assigned to the perturbed T-O-T bond vibration associated with a single Al site by [CuOH] + . In the case of Example 5, this peak shifted to a higher wave number (960 cm -1 ), indicating that the environment of the [CuOH]+ species in this material is slightly different compared to a comparative zeolite material (e.g., prepared with only TMAda + or TMChA + ).

Claims

1. 1. A method for synthesizing a small pore zeolite, the method comprising: preparing a mixture of water, an aluminum source, a silicon source, a source of a first organic structure directing agent, and a source of a second organic structure directing agent to form a synthesis gel; subjecting the synthesis gel to a crystallization process to crystallize the small pore zeolite; The method of claim 1, wherein the first organic structure directing agent comprises a bisquaternary ammonium cation, a derivative of the bisquaternary ammonium cation, or a combination thereof, and the second organic structure directing agent comprises a monoquaternary ammonium cation, a derivative of the monoquaternary ammonium cation, or a combination thereof.

2. 2. The method of claim 1, wherein the small pore zeolite is a cage-containing structure, the largest possible spheres contained within the cage-containing structure having a diameter of from about 4.4 Å to about 15 Å.

3. The method of claim 1 or 2, wherein the bisquaternary ammonium cation contains from about 8 to about 20 carbon atoms.

4. 4. The method of any one of claims 1 to 3, wherein the small pore zeolite comprises a C / N ratio in the range of 7 to 15.

5. 5. The method of claim 1, wherein each nitrogen atom of the bisquaternary ammonium cation has four substituents, each substituent being independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

6. The bisquaternary ammonium cation has a structure represented by formula I: 【Chemistry 1】 During the ceremony, substituent R １ , R ２ , and R ３ Each of R is methyl or ethyl, or optionally both R ３ The groups are bonded to each other to form a -(CH ２ ) ｎ - bridges, n is an integer from 1 to 3, The method of any one of claims 1 to 5, wherein X is selected from the group consisting of alkyl, cycloalkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

7. The bisquaternary ammonium cation is N1,N1,N1,N3,N3,N3-hexaethylpropane-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbutane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexaethylbutane-1,4-diaminium, (E)-N1,N1,N1,N4,N4,N4-hexamethylbut-2-ene-1,4-diaminium, N1,N1,N1,N5,N5,N5-hexamethylpentane-1,5-diaminium, (E)-N1,N1,N1 , N5,N5,N5-hexamethylpent-2-ene-1,5-diaminium, N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium, (E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2-ene-1,6-diaminium, (2E,4E)-N1,N1,N1,N6,N6,N6-hexamethylhexa-2,4-diene-1,6-diaminium, N1,N1,N1,N7,N7,N7-hexamethylheptane-1,7-diaminium, N1,N1,N1,N8,N8,N 8-Hexamethyloctane-1,8-diaminium, N1,N1,N1,N3,N3,N3-Hexamethylcyclohexane-1,3-diaminium, N1,N1,N1,N3,N3,N3-Hexamethylbicyclo[2.2.1]heptane-1,3-diaminium, N1,N1,N1,N3,N3,N3-Hexamethylbenzene-1,3-diaminium, N1,N1,N1,N4,N4,N4-Hexamethylcyclohexane-1,4-diaminium, N1,N1,N1,N4,N4,N4-Hexamethylbicyclo[2.2.1 ]heptane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.2]octane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbenzene-1,4-diaminium, 1,1,4,4-tetramethylpiperazine-1,4-diium, 1,1,3,3-tetramethylhexahydropyrimidine-1,3-diium, 1,1'-(1,3-phenylene)bis(N,N,N-trimethylmethanaminium), 1,1'-(1,4-phenylene)bis(N,N,The method according to any one of claims 1 to 6, wherein the cation exchanger is selected from the group consisting of N-trimethylmethanaminium, N-trimethylmethanaminium, or a combination thereof.

8. The source of the first organic structure directing agent comprises the bisquaternary ammonium cation and OH － , Cl － , and Br － and a balancing anion selected from the group consisting of:

9. The method of any one of claims 1 to 8, wherein the source of the first organic structure directing agent comprises a hexamethonium or octamethonium cation.

10. 10. The method of any one of claims 1 to 9, wherein the monoquaternary ammonium cation contains from about 4 to about 14 carbon atoms.

11. 11. The method of any one of claims 1 to 10, wherein the nitrogen atom of the monoquaternary ammonium cation bears four substituents, each substituent independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

12. the monoquaternary ammonium cation has a structure represented by Formula II: 【Chemistry 2】 During the ceremony, R １ , R ２ , and R ３ are each methyl or ethyl; R ４ is selected from the group consisting of methyl, ethyl, hydroxyethyl, cyclohexyl, azabicycloheptyl, adamantyl, and phenyl; Or, optionally, R ３ and R ４ together or R ２ , R ３ , and R ４ may be linked together to form a monocyclic or bicyclic ring system, which may optionally be substituted with one or more methyl or OH groups.

13. 13. The method of any one of claims 1 to 12, wherein the monoquaternary ammonium cation is selected from the group consisting of tetraethylammonium, 2-hydroxy-N,N,N-trimethylethane-1-aminium, N,N,N-trimethylcyclohexaneaminium, N,N,N-trimethyladamantan-1-aminium (TMada), N,N,N-trimethylbicyclo[2.2.1]heptane-2-aminium, N,N,N-trimethylbenzeneaminium, 1,1-dimethylpiperidin-1-ium, 1,1,3,5-tetramethylpiperidin-1-ium, 1-methylquinuclidin-1-ium, 3-hydroxy-1-methylquinuclidin-1-ium, or a combination thereof.

14. The source of the second organic structure directing agent comprises a monoquaternary ammonium cation and an OH － , Cl － , and Br － and a balancing anion selected from the group consisting of:

15. The method of any one of claims 1 to 14, wherein the source of the second organic structure directing agent comprises a N,N,N-trimethyladamantan-1-aminium cation.

16. 16. The method of any one of claims 1 to 15, wherein the source of the first organic structure directing agent is hexamethonium dihydroxide (HMOH) or octamethonium dihydroxide (OMOH) and the source of the second organic structure directing agent is N,N,N-trimethyladamantan-1-aminium hydroxide (TMadaOH).

17. 17. The method of any one of claims 1 to 16, wherein the molar ratio of the first organic structure directing agent to the second organic structure directing agent is in the range of about 0.001 to about 1000.

18. 18. The method of any one of claims 1 to 17, wherein the molar ratio of the first organic structure directing agent to the second organic structure directing agent is from about 0.1 to about 10.

19. 19. The method of any one of claims 1 to 18, wherein the molar ratio of the first organic structure directing agent to the second organic structure directing agent is from about 0.5 to about 2.

20. The method of any one of claims 1 to 19, wherein the mixture further comprises an inorganic structure directing agent, the inorganic structure directing agent being an alkali metal cation or an alkaline earth metal cation.

21. 21. The method of claim 20, wherein the alkali metal cation is selected from the group consisting of lithium, sodium, potassium, or cesium.

22. 22. The method of any one of claims 1 to 21, wherein the source of aluminium comprises one or more of an aluminium salt, aluminium metal, aluminium oxide, an aluminosilicate, or a zeolite.

23. 23. The method of any one of claims 1 to 22, wherein the source of aluminum comprises a zeolite having a FAU, LTA, LTL, MFI, or BEA crystalline framework.

24. The aluminum source is Na ＋ 24. The method of claim 1, wherein the zeolite is in the form of zeolite Y.

25. 25. The method of any one of claims 1 to 24, wherein the source of silicon is colloidal silica, a silicon alkoxide compound, an alkali metal silicate, fumed silica, amorphous silica, or an aluminosilicate.

26. 26. The method of any one of claims 1 to 25, wherein the source of silicon is sodium silicate.

27. 27. The method according to any one of claims 1 to 26, wherein the synthesis gel has an OH / Si ratio of about 0.03 to about 1.

0.

28. 28. The method of any one of claims 1 to 27, wherein the crystallization process comprises maintaining the synthesis gel at a temperature of from about 90°C to about 250°C.

29. 29. The method of any one of claims 1 to 28, wherein the crystallization process comprises maintaining the synthesis gel at a temperature of from about 120°C to about 200°C.

30. 30. The method of any one of claims 1 to 29, further comprising filtering the crystals formed during the heating step.

31. 31. The method of any one of claims 1 to 30, further comprising calcining the zeolite at a temperature of from about 450°C to about 750°C.

32. 32. The method of any one of claims 1 to 31, wherein the small pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFT, AFX, AFV, AVL, CHA, EAB, ERI, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV.

33. 33. The method of any one of claims 1 to 32, wherein the small pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFV, AVL, CHA, EAB, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV.

34. 34. The method of any one of claims 1 to 33, wherein the small pore zeolite has an AEI or CHA crystalline framework structure type.

35. 35. The method of any one of claims 1 to 34, wherein the small pore zeolite has a CHA crystalline framework structure type.

36. 36. The method of any one of claims 1 to 35, wherein the small pore zeolite has a silica to alumina ratio (SAR) of from about 6 to about 100.

37. 37. The method of any one of claims 1 to 36, wherein the small pore zeolite has a silica to alumina ratio (SAR) of from about 10 to about 30.

38. 38. The method of any one of claims 1 to 37, wherein the small pore zeolite has an SAR in the range of about 20 to about 30.

39. The small pore zeolite is about 75 m ２ / g, and an MSA of at least about 450 m ２ The method of any one of claims 1 to 38, having a ZSA of 0.1 to 0.25 g.

40. The small pore zeolite has a Cu content of more than 0.25M compared to a small pore zeolite synthesized with only monoquaternary OSDA. ＋２ The altered equilibrium Cu concentration ＋２ 40. The method of any one of claims 1 to 39, characterized by incorporation of a controlled aluminum distribution comprising altered aluminum positioning and pairing sequences.

41. 41. A method according to any one of claims 1 to 40, wherein prior to calcination at least a portion of the pores of the small pore zeolite are occupied by said bisquaternary ammonium cations and at least a portion of the pores are occupied by said monoquaternary ammonium cations.

42. 42. The method of claim 41, wherein from about 1 to about 99% of the pores are occupied by the bisquaternary ammonium cations and from about 99 to about 1% of the pores are occupied by the monoquaternary ammonium cations.

43. 42. The method of claim 41, wherein about 60 to about 40 percent of the pores are occupied by the bisquaternary ammonium cations and about 40 to about 60 percent of the pores are occupied by the monoquaternary ammonium cations.

44. A small pore zeolite prepared according to the method of any one of claims 1 to 43.

45. A small pore zeolite having a controlled aluminum distribution, said controlled aluminum distribution being greater than 0.25M Cu compared to a small pore zeolite synthesized with only a monoquaternary OSDA. ＋２ The altered equilibrium Cu concentration ＋２ Small pore zeolites containing anionic framework Al-centered arrays with altered aluminum positioning and pairing arrangements characterized by the incorporation of

46. A small pore zeolite, wherein at least a portion of the pores of said small pore zeolite are occupied by bisquaternary ammonium cations and at least a portion of the pores are occupied by monoquaternary ammonium cations.

47. 46. ​​The small pore zeolite of claim 45 or 45, wherein the small pore zeolite is a cage-containing structure, the largest possible spheres contained in the cage-containing structure being from about 4.4 Å to about 15 Å.

48. 48. The small pore zeolite of claims 46 or 47, wherein from about 1 to about 99% of the pores are occupied by bisquaternary ammonium cations and from about 99 to about 1% of the pores are occupied by monoquaternary ammonium cations.

49. 49. The small pore zeolite of any one of claims 46 to 48, wherein from about 60 to about 40% of the pores are occupied by bisquaternary ammonium cations and from about 40 to about 60% of the pores are occupied by monoquaternary ammonium cations.

50. 50. The small pore zeolite of any one of claims 46 to 49, wherein the bisquaternary ammonium cation contains from about 8 to about 20 carbon atoms.

51. 51. The small pore zeolite of any one of claims 46 to 50, wherein each nitrogen atom of the bisquaternary ammonium cation bears four substituents, each substituent independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

52. The bisquaternary ammonium cation has a structure represented by formula I: 【Chemistry 3】 During the ceremony, substituent R １ , R ２ , and R ３ Each of R is methyl or ethyl, or optionally both R ３ The groups are bonded to each other to form a -(CH ２ ) ｎ - bridges, n is an integer from 1 to 3, 51. The small pore zeolite of any one of claims 46 to 50, wherein X is selected from the group consisting of alkyl, cycloalkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

53. The bisquaternary ammonium cation is N1,N1,N1,N3,N3,N3-hexaethylpropane-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbutane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexaethylbutane-1,4-diaminium, (E)-N1,N1,N1,N4,N4,N4-hexamethylbut-2-ene-1,4-diaminium, N1,N1,N1,N5,N5,N5-hexamethylpentane-1,5-diaminium, (E)-N1,N1,N1,N5,N 5,N5-hexamethylpent-2-ene-1,5-diaminium, N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium (hexamethonium), (E)-N1,N1,N1,N6,N6,N6-hexamethylhex-2-ene-1,6-diaminium, (2E,4E)-N1,N1,N1,N6,N6,N6-hexamethylhexa-2,4-diene-1,6-diaminium, N1,N1,N1,N7,N7,N7-hexamethylheptane-1,7-diaminium, N1,N1,N1,N8,N8,N 8-Hexamethyloctane-1,8-diaminium (octamethonium), N1,N1,N1,N3,N3,N3-hexamethylcyclohexane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbicyclo[2.2.1]heptane-1,3-diaminium, N1,N1,N1,N3,N3,N3-hexamethylbenzene-1,3-diaminium, N1,N1,N1,N4,N4,N4-hexamethylcyclohexane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[ 2.2.1]heptane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbicyclo[2.2.2]octane-1,4-diaminium, N1,N1,N1,N4,N4,N4-hexamethylbenzene-1,4-diaminium, 1,1,4,4-tetramethylpiperazine-1,4-diium, 1,1,3,3-tetramethylhexahydropyrimidine-1,3-diium, 1,1'-(1,3-phenylene)bis(N,N,N-trimethylmethanaminium), 1,1'-(1,4-phenylene)bis(N,N,N-trimethylmethanaminium), or a combination thereof.

54. 54. The small pore zeolite of any one of claims 46 to 53, wherein the bisquaternary ammonium cation is hexamethonium or octamethonium.

55. 55. The small pore zeolite of any one of claims 46 to 54, wherein the monoquaternary ammonium cation contains from about 4 to about 14 carbon atoms.

56. 56. The small pore zeolite of any one of claims 46 to 55, wherein the nitrogen atom of the monoquaternary ammonium cation bears four substituents, each substituent independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and combinations thereof.

57. the monoquaternary ammonium cation has a structure represented by Formula II: 【Chemistry 4】 During the ceremony, R １ , R ２ , and R ３ are each methyl or ethyl; R ４ is selected from the group consisting of methyl, ethyl, hydroxyethyl, cyclohexyl, azabicycloheptyl, adamantyl, and phenyl; Or, optionally, R ３ and R ４ together or R ２ , R ３ , and R ４ may be linked together to form a monocyclic or bicyclic ring system, which may optionally be substituted with one or more methyl or OH groups.

58. 58. The small pore zeolite of any one of claims 46 to 57, wherein the monoquaternary ammonium cation is tetraethylammonium, 2-hydroxy-N,N,N-trimethylethane-1-aminium, N,N,N-trimethylcyclohexaneaminium, N,N,N-trimethyladamantan-1-aminium (TMada), N,N,N-trimethylbicyclo[2.2.1]heptane-2-aminium, N,N,N-trimethylbenzeneaminium, 1,1-dimethylpiperidin-1-ium, 1,1,3,5-tetramethylpiperidin-1-ium, 1-methylquinuclidin-1-ium, 3-hydroxy-1-methylquinuclidin-1-ium, or a combination thereof.

59. 59. The small pore zeolite according to any one of claims 46 to 58, wherein the monoquaternary ammonium cation is TMAda.

60. 60. The small pore zeolite of any one of claims 46 to 59, wherein the bisquaternary ammonium cation is hexamethonium or octamethonium and the monoquaternary ammonium cation is TMAda.

61. 61. The small pore zeolite of any one of claims 45 to 60, wherein the small pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFT, AFX, AFV, AVL, CHA, EAB, ERI, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV.

62. 62. The small pore zeolite of any one of claims 45 to 61, wherein the small pore zeolite has a crystal framework structure type selected from the group consisting of AEI, AFV, AVL, CHA, EAB, ERI, ITW, KFI, LEV, LTA, MER, SAS, SAT, and SAV.

63. 63. The small pore zeolite of any one of claims 45 to 62, wherein the small pore zeolite has an AEI or CHA crystalline framework structure type.

64. 64. The small pore zeolite of any one of claims 45 to 63, wherein the small pore zeolite has a CHA crystalline framework structure type.

65. 65. The small pore zeolite of any one of claims 45 to 64, wherein the small pore zeolite has a silica to alumina ratio (SAR) of from about 6 to about 100.

66. 66. The small pore zeolite of any one of claims 45 to 65, wherein the small pore zeolite has a silica to alumina ratio (SAR) of from about 10 to about 30.

67. 67. The small pore zeolite of any one of claims 45 to 66, wherein the small pore zeolite has a SAR in the range of from about 20 to about 30.

68. The small pore zeolite is about 75 m ２ / g, and an MSA of at least about 450 m ２ 68. The small pore zeolite of any one of claims 45 to 67, having a ZSA of 0.1 to 0.25 g.

69. Nitrogen oxides (NO ｘ 69. A selective catalytic reduction (SCR) catalyst composition effective for the mitigation of CO2 emissions, the SCR catalyst comprising the zeolite of any one of claims 45 to 68 promoted with a promoter metal.

70. 70. The SCR catalyst composition of claim 69, 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.

71. 71. The SCR catalyst composition of claim 69 or 70, wherein the promoter metal is present in an amount of about 4 to about 6 weight percent.

72. 72. The SCR catalyst composition of any one of claims 70 to 71, wherein the promoter metal is selected from iron, copper, and combinations thereof.

73. Nitrogen oxides (NO ｘ 73. An SCR catalyst article effective for mitigating aggravation of ...

74. 74. The SCR catalyst article of claim 73, wherein the substrate is a honeycomb substrate.

75. 75. The SCR catalyst article of claim 74, wherein the honeycomb substrate is a flow-through substrate or a wall-flow filter.

76. 76. An exhaust gas treatment system comprising the SCR catalyst article of any one of claims 73 to 75 located downstream of and in fluid communication with an engine producing an exhaust gas stream.

77. A method for treating an exhaust gas stream comprising contacting the exhaust gas stream with the SCR catalyst article of any one of claims 73-75 or the exhaust gas treatment system of claim 75.

78. A small pore zeolite comprising an aCHA framework structure having a C / N ratio in the range of 7-15.

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