Synthesis of CHA zeolite material, CHA zeolite material obtainable therefrom, and SCR catalyst containing the same

Abstract

The present invention provides a process for preparing a zeolite having a CHA-type framework structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetravalent element, comprising: (1) (A) a source of X2O3; (B) a source of YO2; and (C) a diquaternary ammonium cation of formula (I) or formula (R1R2R3)N as claimed in the claims. + (CH2) n N + The present invention relates to a process comprising: (1) preparing a synthesis mixture containing a source of an organic structure directing agent (OSDA) comprising a combination of diquaternary ammonium cations of (R4R5R6)(I); and (2) subjecting the synthesis mixture to crystallization conditions to form a zeolite having a CHA-type framework structure. The present invention also relates to a zeolite having a CHA-type framework structure obtained from the process, and to the use of the zeolite in a catalyst for the selective catalytic reduction of nitrogen oxides.

Description

[Technical Field]

[0001] The present invention relates to a process for synthesizing a zeolitic material having a CHA-type framework structure, to a zeolitic material obtainable therefrom, and to an SCR catalyst containing the same. [Background technology]

[0002] Catalytic articles are essential for modern internal combustion engines to treat exhaust gases before they are released into the atmosphere. Exhaust gases from internal combustion engines typically contain particulate matter (PM), nitrogen oxides (NOx), such as NO and / or NO2, unburned hydrocarbons (HC), and carbon monoxide (CO). Control of NOx emissions has always been one of the most important topics in the automotive field due to the adverse environmental impacts of NOx on ecosystems, animal, and plant life.

[0003] One of the effective technologies for removing NOx from the exhaust gas of an internal combustion engine is selective catalytic reduction (SCR) of NOx with ammonia or a second ammonia source. Recently, small-pore zeolites have been proposed for the selective catalytic reduction of NOx, among which CHA-type zeolites have been widely studied and found to be one of the most promising SCR catalysts, especially when the zeolite is exchanged with a metal promoter such as Cu or Fe.

[0004] Chabazite is a type of naturally occurring zeolite, and also has a synthetic CHA form. A well-known synthetic CHA-type zeolite is a crystalline CHA material called SSZ-13, as reported in U.S. Pat. No. 4,544,538. SSZ-13 was prepared under crystallization conditions using a structure-directing agent containing an N-alkyl-3-quinuclidinol cation, an N,N,N-trialkyl-1-adamantammonium cation, an N,N,N-trialkyl-2-exoaminonorbornane cation, or a mixture thereof. The synthesis of CHA-type zeolites using other structure-directing agents has also been developed, as reported, for example, in the following non-patent and patent publications:

[0005] Itakura Masaya et al. in Chemistry Letters, 2008, Vol. 37, No. 9, pages 908 to 909, describe a process for synthesizing CHA zeolite using benzyltrimethylammonium hydroxide as a structure directing agent.

[0006] US Patent Application Publication No. 2010 / 254895(A1) discloses a process for preparing CHA-type zeolites using a cationic 1,4-diazabicyclo[2.2.2]octane structure directing agent in combination with at least one cationic cyclic nitrogen-containing structure directing agent.

[0007] WO 2020 / 039074(A1) describes a compound of the formula [NR 1 R 2 R 3 R 4 ](where R 1 , R 2 , R 3 and R4 is independently a C1-C4-alkyl group optionally substituted with one or more hydroxy groups.

[0008] Biaohua Chen et al. in Environmental Science & Technology, 2014, 48, pages 13909 to 13916, describe a process for synthesizing SSZ-13 using choline chloride as a structure-directing agent.

[0009] WO 2013 / 035054 A1 discloses a process for preparing zeolitic materials having a CHA-type framework structure, which uses an N,N-dimethylammonium organic template containing N,N-dimethylpiperidinium.

[0010] There remains a need for additional processes for preparing zeolitic materials having a CHA-type framework structure, particularly processes that can provide CHA-type zeolitic materials with improved catalytic performance for the selective catalytic reduction of NOx. Summary of the Invention

[0011] An object of the present invention is to provide a novel process for preparing zeolite materials having a CHA-type framework structure. Another object of the present invention is to provide an SCR catalyst based on a zeolite having a CHA-type framework structure, which has improved catalytic performance for selective catalytic reduction of NOx.

[0012] This objective was achieved by using a linear diquat organic structure directing agent (OSDA) in zeolite synthesis. Surprisingly, it was found that zeolites with a CHA-type framework structure prepared with the linear diquat organic structure directing agent possess desirable activity combined with excellent stability, especially with respect to aging at high temperatures, e.g., above 800°C.

[0013] Thus, in a first aspect, the present invention provides a process for preparing a zeolitic material having a CHA-type framework structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetravalent element, (1) (A) A source of X2O3, (B) A source of YO2, and (C) a source of organic structure directing agent (OSDA) comprising a diquaternary ammonium cation of formula (I) or a combination of diquaternary ammonium cations of formula (I), (R1R2R3)N + (CH2) n N + (R4R5R6)(I) During the ceremony, R1, R2, R3, R4, R5, and R6 are each independently selected from C1 to C 10 alkyl, and n is an integer in the range of 3 to 10, or During the ceremony, One of R1, R2, and R3 is C1-C 10 alkyl, and the other two are linked together to form a C4-C6 alkylene; One of R4, R5, and R6 is C1 to C 10 alkyl, the other two being linked together to form a C4-C6 alkylene; and preparing a synthesis mixture comprising a source of organic structure directing agent (OSDA), wherein n is an integer ranging from 3 to 10; (2) subjecting the synthesis mixture to crystallization conditions to form a CHA-type framework structure.

[0014] In a second aspect, the present invention relates to a zeolite having a CHA-type framework structure obtained and / or obtainable by the process described herein.

[0015] In a third aspect, the present invention relates to a metal-promoted zeolite having a CHA-type framework structure, the metal-promoted zeolite comprising a zeolite obtained and / or obtainable by the process described herein, and a promoter metal.

[0016] In a fourth aspect, the present invention relates to the use of a zeolite having a CHA-type framework structure according to the second aspect or the use of a metal-promoted zeolite according to the third aspect in a catalyst for selective catalytic reduction (SCR) of NOx.

[0017] In a fifth aspect, the present invention relates to a catalyst article in the form of an extrudate comprising an SCR catalyst composition or in the form of a monolith comprising a washcoat containing an SCR catalyst composition on a substrate, wherein the SCR catalyst composition comprises a metal-promoted zeolite having a CHA-type framework structure as described herein.

[0018] In a sixth aspect, the present invention relates to an exhaust gas treatment system comprising an internal combustion engine and an exhaust gas conduit in fluid communication with the internal combustion engine, wherein a catalytic article as described herein is present in the exhaust gas conduit. [Brief explanation of the drawings]

[0019] [Figure 1A] 1 shows SEM images of zeolites (Zeolite A, B, and C) from Examples 2, 3, and 4, respectively. [Figure 1B] 1 shows SEM images of zeolites (Zeolite A, B, and C) from Examples 2, 3, and 4, respectively. [Figure 1C] 1 shows SEM images of zeolites (Zeolite A, B, and C) from Examples 2, 3, and 4, respectively. [Figure 2] 1 shows the XRD patterns of zeolites (Zeolites A, B, and C) from Examples 2, 3, and 4, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail herein below. It should be understood that the present invention can be embodied in many different ways and should not be construed as limited to the embodiments set forth herein.

[0021] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Terms such as "comprise," "comprising," and the like are used interchangeably with "contain," "containing," and the like, and are to be interpreted in an open and non-restrictive manner; that is, for example, additional components or elements may be present. The phrases "consists of" or "consists essentially of" or cognates can be encompassed by "comprises" or cognates.

[0022] As used herein, the terms "zeolite having a CHA-type framework structure," "CHA-type zeolite," "CHA zeolite," and the like are intended to refer to molecular sieve materials that exhibit an XRD pattern of a CHA-type framework structure and are hereinafter used interchangeably. These terms are also intended to include any form of zeolite, such as as-synthesized, calcined, NH-exchanged, H-exchanged, and metal-substituted forms.

[0023] As used herein, the term "as-synthesized" is intended to refer to the zeolite in its form after crystallization and drying, prior to removal of the organic structure directing agent.

[0024] As used herein, the term "calcined form" is intended to refer to the zeolite in its form as calcined.

[0025] In a first aspect, the present invention provides a process for preparing a zeolite having a CHA-type framework structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetravalent element; (1) (A) A source of X2O3, (B) A source of YO2, and (C) a source of organic structure directing agent (OSDA) comprising a diquaternary ammonium cation of formula (I) or a combination of diquaternary ammonium cations of formula (I), (R1R2R3)N + (CH2) n N + (R4R5R6)(I) During the ceremony, R1, R2, R3, R4, R5, and R6 are each independently selected from C1 to C 10 alkyl, and n is an integer in the range of 3 to 10, or During the ceremony, One of R1, R2, and R3 is C1-C 10 alkyl, and the other two are linked together to form a C4-C6 alkylene; One of R4, R5, and R6 is C1 to C 10 alkyl, the other two being linked together to form a C4-C6 alkylene; and preparing a synthesis mixture comprising a source of organic structure directing agent (OSDA), wherein n is an integer ranging from 3 to 10; (2) subjecting the synthesis mixture to crystallization conditions to form a zeolite having a CHA-type framework structure.

[0026] The synthesis mixture provided in step (1) includes a source of X2O3 (wherein X is a trivalent framework element) and a source of YO2 (wherein Y is a tetravalent framework element). X may be any conventional trivalent framework element. Preferably, X is selected from the group consisting of Al, B, In, Ga, and any combination thereof, with Al being more preferred. Also, Y may be any conventional tetravalent framework element. Preferably, Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and any combination thereof, with Si being more preferred. In particular, X is Al and Y is Si.

[0027] Suitable sources of X2O3 may be any known material useful for providing trivalent framework elements during zeolite synthesis. In some embodiments where X is Al, suitable examples of sources of Al2O3 include, but are not limited to, alumina, aluminum hydroxide, aluminate, aluminum alkoxide, aluminum salt, FAU zeolite, LTA zeolite, LTL zeolite, BEA zeolite, MFI zeolite, and any combination thereof, more preferably alumina, aluminum alkoxide, aluminum salt, FAU zeolite, and any combination thereof. In particular, sources of Al2O3 may be selected from alumina, AlO(OH), Al(OH)3, aluminum tri(C1-C5)alkoxide, aluminum halide, aluminum sulfate, aluminum phosphate, aluminum fluorosilicate, FAU zeolite, and any combination thereof. For example, the FAU zeolite may be selected from the group consisting of faujasite, [Al-Ge-O]-FAU, [Al-Ge-O]-FAU, [Ga-Al-Si-O]-FAU, [Ga-Ge-O]-FAU, [Ga-Si-O]-FAU, CSZ-1, US-Y, ECR-30, LZ-210, Li-LSX, SAPO-37, ZSM-20, ZSM-3, zeolite X, and zeolite Y, and more preferably from the group consisting of faujasite, zeolite X, zeolite Y, US-Y, and LZ-210. Zeolite Y may be particularly mentioned as a source of X2O3.

[0028] Suitable sources of YO may be any known material useful for providing tetravalent framework elements during zeolite synthesis. In some embodiments where Y is Si, suitable sources of YO may include, but are not limited to, fumed silica, precipitated silica, silica hydrosol, silica gel, colloidal silica, silicic acid, silicon alkoxides, alkali metal silicates, sodium metasilicate hydrate, sesquisilicates, disilicates, silicate esters, FAU zeolite, LTA zeolite, LTL zeolite, BEA zeolite, MFI zeolite, and any combination thereof. In particular, the source of YO may be selected from fumed silica, sodium silicate, potassium silicate, FAU zeolite, and any combination thereof, more preferably fumed silica, FAU zeolite, and any combination thereof. For example, the FAU zeolite may be selected from the group consisting of faujasite, [Al-Ge-O]-FAU, [Al-Ge-O]-FAU, [Ga-Al-Si-O]-FAU, [Ga-Ge-O]-FAU, [Ga-Si-O]-FAU, CSZ-1, US-Y, ECR-30, LZ-210, Li-LSX, SAPO-37, ZSM-20, ZSM-3, zeolite X, and zeolite Y, and more preferably from the group consisting of faujasite, zeolite X, zeolite Y, US-Y, and LZ-210. In particular, one or more materials selected from the group consisting of fumed silica, precipitated silica, silica hydrosol, silica gel, colloidal silica, and zeolite Y may be mentioned as a source of YO.

[0029] It is understood that the source of X2O3 and the source of YO2 can be provided separately (i.e., separate sources) and / or together (i.e., a combined source). In the latter case, the source may be provided, for example, by a zeolite containing framework elements X and Y. It can be contemplated that the synthesis mixture provided in step (1) may include a combined source of X2O3 and YO2 and one or more additional separate sources of X2O3 and / or YO2.

[0030] In some particular embodiments, the synthesis mixture provided in step (1) comprises a source of Al2O3 and a source of SiO2, either in the form of separate sources or in a combined source. Thus, the process according to the invention results in an aluminosilicate zeolite having a CHA-type framework structure.

[0031] The term "aluminosilicate," when used within the context of zeolites, is intended to mean a framework composed primarily of alumina and silica, which may or may not include framework elements other than oxygen, aluminum, and silicon.

[0032] In certain illustrative embodiments, the synthesis mixture provided in step (1) includes FAU zeolite as a combined source of AlO and SiO, and as an additional source of SiO. In particular, FAU zeolite is a zeolite containing Na + form, H form, or NH4 + Zeolite Y, which may be in an exchanged form. More preferred is zeolite Y having a molar ratio of SiO to AlO of not more than 40 or not more than 30. Additional sources of SiO are selected from the group consisting of fumed silica, precipitated silica, silica hydrosol, silica gel, and colloidal silica, including mixtures of two or more thereof.

[0033] The synthesis mixture provided in step (1) has a YO2:X2O3 molar ratio in the range of 5-100, for example, 10-60, or 15-30.

[0034] A suitable source of organic structure directing agents (OSDAs) may be compounds containing a diquaternary ammonium cation of formula (I) as described herein, in particular compounds containing a diquaternary ammonium cation of formula (I) wherein R1, R2, R3, R4, R5, and R6 are each independently selected from C1-C6 alkyl, and n is an integer ranging from 3 to 10.

[0035] Preferably, the source of organic structure directing agent is a compound containing a diquaternary ammonium cation of formula (I): (R1R2R3)N + (CH2) n N + (R4R5R6)(I) During the ceremony, R1, R2, R3, R4, R5, and R6 are the same and are selected from C1-C6 alkyl; n is 4 to 7, or A combination thereof is selected.

[0036] More preferably, the source of organic structure directing agent is selected from compounds containing a diquaternary ammonium cation of formula (I), wherein each of R1, R2, R3, R4, R5, and R6 is methyl, ethyl, or propyl, preferably ethyl, and n is 5, 6, or 7, or combinations thereof.

[0037] Most preferably, the source of organic structure directing agent is a compound containing a diquaternary ammonium cation of formula (Ia): (C2H5)3N + (CH2) n N + (C2H5)3(Ia) During the ceremony, n is 5, 6, or 7; or A combination thereof is selected.

[0038] In some particular embodiments, the organic structure directing agent is N,N,N,N',N',N'-hexaethyl-1,5-pentanediammonium (Et6-diquat-5), i.e., a diquaternary ammonium cation of formula (I) where R1, R2, R3, R4, R5, and R6 are each ethyl and n is 5, or a diquaternary ammonium cation of formula (Ia) where n is 5.

[0039] Suitable compounds containing diquaternary ammonium cations of formula (I) or (Ia) may be in the form of a salt. There are no particular limitations on the counterion, i.e., the anion of the salt, which may be a halide such as fluoride, chloride, or bromide, a hydroxide, a sulfate, a nitrate, a carboxylate such as acetate, or any combination thereof. In particular, the anion may be selected from the group consisting of chloride, bromide, hydroxide, sulfate, or any combination thereof. Preferably, the compound containing a diquaternary ammonium cation is a hydroxide, chloride, or bromide, particularly a hydroxide of the diquaternary ammonium cation of formula (I) or (Ia) described above.

[0040] According to the present invention, the organic structure directing agent (OSDA) may or may not contain cations other than the diquaternary ammonium cations of formula (I) or formula (Ia) described herein. In some particular embodiments, the organic structure directing agent (OSDA), and thus the synthesis mixture provided in step (1), does not contain any cations of the OSDA other than the diquaternary ammonium cations of formula (I) or formula (Ia) described herein.

[0041] Preferably, the synthesis mixture provided in step (1) has a molar ratio of diquaternary ammonium cation (Q) to the source of YO (Q:YO), calculated as YO, in the range of 0.01 to 1.0, for example, 0.05 to 0.5, or 0.08 to 0.2.

[0042] The synthesis mixture provided in step (1) may further comprise a source of alkali metal and / or alkaline earth metal cations (AM), preferably alkali metal cations. The alkali metal is preferably selected from the group consisting of Li, Na, K, Cs, and any combination thereof, more preferably Na and / or K, and most preferably Na. The alkaline earth metal is preferably selected from the group consisting of Mg, Ca, Sr, and Ba, and any combination thereof. Suitable sources of alkali metal and / or alkaline earth metal cations (AM) are typically halides, such as fluorides, chlorides, and bromides, hydroxides, sulfates, and carboxylates, such as acetates, of alkali metals and / or alkaline earth metals, or any combination thereof. Preferably, the source of alkali metal and / or alkaline earth metal cations (AM) includes chlorides, bromides, hydroxides, or sulfates of alkali metals and / or alkaline earth metals, or any combination thereof. More preferably, hydroxides of alkali metals are used in the synthesis mixture.

[0043] The alkali metal and / or alkaline earth metal cation (AM) may be present in the synthesis mixture in a molar ratio to the source of YO2, calculated as AM to YO2, ranging from 0.01 to 1.0, such as 0.03 to 0.5, or 0.05 to 0.3.

[0044] The synthesis mixture provided in step (1) contains an anion OH - A useful source of OH may also be included. - The source of the anion OH may be, for example, a metal hydroxide such as an alkali metal hydroxide or a quaternary ammonium hydroxide. - may be derived from one or more of a source of alkali metal and / or alkaline earth metal cations (AM) and a source of organic structure directing agent.

[0045] OH - The anion is OH for YO2 -The YO2 source may be present in the synthesis mixture in a molar ratio of 0.1 to 2.0, for example, 0.1 to 1.0, or 0.2 to 0.5, calculated as

[0046] The synthesis mixture provided in step (1) may further comprise at least one solvent, preferably water, more preferably deionized water. The solvent may be carried into the synthesis mixture by being included in one or more of the starting materials of the synthesis mixture, such as X2O3, YO2, and a source of organic structure directing agent, and / or may be separately incorporated into the synthesis mixture.

[0047] In some embodiments, the synthesis mixture has a molar ratio of water to source of YO2, calculated as H2O to YO2, ranging from 3 to 100, eg, 10 to 80, or 10 to 40.

[0048] In some exemplary embodiments, the synthesis mixture provided in step (1) has the molar composition shown in Table 1 below.

[0049] [Table 1] 1) The amounts of the X2O3 source and the YO2 source are calculated as the respective oxides.

[0050] In some embodiments, the synthesis mixture provided in step (1) may further comprise a quantity of CHA zeolite seed crystals, which may be obtained from the processes described herein without the use of seed crystals or from any other known process.

[0051] In step (2), the synthesis mixture may be subjected to crystallization conditions, without particular limitation, to form a zeolite having a CHA-type framework structure. Crystallization may be carried out at an elevated temperature in the range of 80 to 250°C, more preferably 100 to 200°C, for a period sufficient for crystallization, e.g., 0.5 to 12 days or 1 to 6 days. Typically, crystallization is carried out under autogenous pressure, e.g., in a pressure vessel such as an autoclave. Furthermore, crystallization may be carried out with or without stirring.

[0052] The CHA zeolite formed by crystallization may be subjected to a post-treatment procedure, including isolation, for example by filtration, optionally washing, and drying, to obtain the as-synthesized CHA zeolite. Thus, step (2) in the process according to the present invention optionally further comprises a post-treatment procedure.

[0053] Any organic structure directing agent remaining in the filtrate from the filtration and optionally in the wash from the washing can be recycled and used in further synthesis of CHA zeolite.

[0054] As-synthesized CHA zeolites typically contain the above-mentioned diquaternary ammonium cations within their structural pores and / or channels.

[0055] In some embodiments, the as-synthesized CHA zeolite from step (2) may be subjected to a calcination procedure. Thus, the process according to the present invention further comprises step (3) of calcining the as-synthesized CHA zeolite.

[0056] In some embodiments, the as-synthesized or calcined CHA zeolite has a structure in which one or more of the ionic non-framework elements contained in the zeolite is H. + and / or NH4 + The process according to the invention may therefore be carried out by exchanging one or more of the ionic non-framework elements contained in the zeolite obtained in step (2) or (3) with H + and / or NH4 +, preferably NH4 + (4) further includes exchanging

[0057] Generally, in step (4), H + and / or NH4 + The exchanged zeolite may be subjected to a post-treatment procedure, including, for example, isolation by filtration, optionally washing, and drying, and / or may be subjected to a calcination procedure. Thus, step (4) in the process according to the invention optionally further comprises a post-treatment procedure and / or a calcination procedure.

[0058] The calcination in step (3) and / or step (4) may be carried out at a temperature in the range of 300 to 900°C, for example, 350 to 700°C or 400 to 650°C. In particular, the calcination may be carried out under a gas atmosphere having a temperature in the above range, which may be air, oxygen, nitrogen, or a mixture of two or more thereof. Preferably, the calcination is carried out for a period in the range of 0.5 to 10 hours, for example, 3 to 7 hours or 4 to 6 hours.

[0059] It was possible to successfully obtain zeolites with a CHA-type framework structure from the process described in the first embodiment, as determined by X-ray powder diffraction (XRD) analysis.

[0060] Thus, in a second aspect, the present invention provides a zeolite having a CHA-type framework structure obtainable and / or obtainable from a process according to the first aspect.

[0061] Zeolites having a CHA-type framework structure have a YO2:X2O3 molar ratio (SAR) of YO2 (e.g., silica) to X2O3 (e.g., alumina) of 2 or greater, the molar ratio preferably being in the range of 4 to 200, more preferably 6 to 100, more preferably 8 to 50, more preferably 10 to 35, more preferably 15 to 30, and most preferably 18 to 25. According to the present invention, the YO2:X2O3 molar ratio refers to a zeolite having a CHA-type framework structure, preferably in its calcined form, more preferably in its calcined H form.

[0062] Zeolites having a CHA-type framework structure according to the present invention typically have an average crystal size of at least 200 nm, e.g., in the range of 0.2 to 6 μm. The average crystal size can be determined by scanning electron microscopy (SEM). Specifically, the average crystal size was determined via SEM by measuring the crystal size of at least 30 different crystals randomly selected from multiple images covering different regions of the sample.

[0063] It has been surprisingly found that zeolites having a CHA-type framework structure according to the present invention have a crystalline morphology with a mosaic-pattern texture on the crystal surface as observed via SEM. As used herein, the term mosaic-pattern is used to describe the surface morphology of zeolite crystals having a CHA-type framework structure and is intended to refer to a surface pattern made up of irregularly shaped platelets with irregularly shaped interstices between them.

[0064] The zeolites having a CHA-type framework structure according to the present invention preferably have a phase purity of at least 90% as determined by X-ray powder diffraction (XRD) analysis, i.e., at least 90% of the zeolite framework is CHA-type. More preferably, the zeolites having a CHA-type framework structure have a phase purity of at least 95%, or even more preferably at least 98% or at least about 99%. Correspondingly, the zeolites having a CHA-type framework structure may contain some other frameworks as intergrowths in small amounts, for example, less than 10%, preferably less than 5%, even more preferably less than 2% or less than 1%.

[0065] It has surprisingly been found that zeolites having a CHA-type framework structure obtained from the process described in the first aspect exhibit significantly higher stability towards ageing at temperatures above 800°C in selective catalytic reduction (SCR) applications of NOx compared to catalysts comprising zeolites having the same framework type but prepared by other methods.

[0066] Thus, in a third aspect, the present invention further provides a metal-promoted zeolite having a CHA-type framework structure, comprising a zeolite obtained and / or obtainable by a process according to the present invention and a promoter metal.

[0067] As used herein, the term "promoter metal" refers to a non-framework metal that can improve the catalytic activity of a zeolite. "Non-framework metal" is intended to mean that the metal does not participate in the formation of the zeolite framework structure. The promoter metal may be present within the zeolite and / or on at least a portion of the zeolite surface.

[0068] In this specification, the promoter metal is present in at least a portion of the interior and / or surface of the zeolite, particularly having a CHA-type framework structure.

[0069] The zeolite having a CHA-type framework structure is a zeolite obtained and / or obtainable by the process according to the first aspect and / or a zeolite according to the second aspect. Any general and specific description of the process according to the first aspect or the zeolite having a CHA-type framework structure according to the second aspect is incorporated herein by reference.

[0070] The promoter metal may be any metal known to be useful for improving the catalytic performance of zeolites in NOx selective catalytic reduction (SCR) applications. Generally, the promoter metal may be selected from transition metals, such as noble metals such as Au, Ag, and platinum group metals, base metals such as Cr, Zr, Nb, Mo, Fe, Mn, W, V, Ti, Co, Ni, Cu, and Zn, alkaline earth metals such as Ca and Mg, and Sb, Sn, and Bi, and any combination thereof.

[0071] In some embodiments, the metal-promoted zeolite having a CHA-type framework structure comprises Cu and / or Fe as the promoter metal, hi some particular embodiments, the metal-promoted zeolite comprises Cu as the promoter metal.

[0072] The promoter metal may be present in the metal-promoted zeolite having a CHA-type framework structure in an amount of 0.1 to 10 wt. %, preferably 0.5 to 10 wt. %, on an oxide basis, based on the total weight of the promoter metal and the zeolite having a CHA-type framework structure. In some specific embodiments in which copper, iron, or a combination thereof is used as the promoter metal, the promoter metal is preferably present in the metal-promoted zeolite having a CHA-type framework structure in an amount of 1 to 8 wt. %, more preferably 2 to 6 wt. %, on an oxide basis, based on the total weight of the promoter metal and the zeolite having a CHA-type framework structure.

[0073] Alternatively, the promoter metal may be present in the metal-promoted zeolite having a CHA-type framework structure in an amount ranging from 0.01 to 2 moles, e.g., 0.03 to 1.8 moles, 0.05 to 1.5 moles, 0.08 to 1.2 moles, 0.1 to 1.0 moles, or 0.13 to 0.8 moles per mole of trivalent framework element (e.g., Al) of the zeolite having a CHA-type framework structure. In some specific embodiments in which copper, iron, or a combination thereof is used as the promoter metal, the amount of promoter metal is 0.1 to 1.0 moles, preferably 0.15 to 0.8 moles, more preferably 0.2 to 0.6 moles, and most preferably 0.3 to 0.5 moles per mole of trivalent framework element (e.g., Al) of the zeolite having a CHA-type framework structure.

[0074] In some preferred embodiments, the metal-promoted zeolite having a CHA-type framework structure is an aluminosilicate zeolite having a CHA-type framework structure and a silica to alumina molar ratio (SAR) in the range of -10 to 35; a promoter metal selected from Cu, Fe, or a combination thereof, in particular Cu; The promoter metal is present in an amount of 0.2 to 0.6 moles, preferably 0.3 to 0.5 moles, per mole of framework aluminum of the zeolite.

[0075] In some more preferred embodiments, the metal-promoted zeolite having a CHA-type framework structure according to the present invention is an aluminosilicate zeolite having a CHA-type framework structure and a silica to alumina molar ratio (SAR) of 15 to 30, more preferably 18 to 25; a promoter metal which is Cu; Cu is present in an amount of 0.2 to 0.6 moles per mole of framework aluminum of the zeolite.

[0076] In an exemplary embodiment, the metal-promoted zeolite having a CHA-type framework structure according to the present invention comprises: an aluminosilicate zeolite having a CHA-type framework structure and a silica to alumina molar ratio (SAR) of -18 to 25; a promoter metal which is Cu; Cu is present in an amount of 0.3 to 0.5 moles per mole of framework aluminum of the zeolite.

[0077] Preferably, the metal-promoted zeolite having a CHA-type framework structure according to the present invention exhibits a 120,000 h sintering time during steam aging with 10% H2O at 820°C in a test gas stream consisting of 500 vppm NO, 500 vppm NH3, 5 vol% H2O, 10 vol% O2, and the balance N2. -1At a gas hourly space velocity (GHSV) of 1000 sq. ft., the metal-promoted zeolite having a CHA-type framework structure of the present invention exhibits a NOx conversion of at least 50% at 200°C and at least 60% at 575°C when determined under the same conditions as above. Preferably, the metal-promoted zeolite having a CHA-type framework structure of the present invention exhibits a NOx conversion of at least 65% at 200°C and at least 75% at 575°C when determined under the same conditions as above. More preferably, the metal-promoted zeolite having a CHA-type framework structure of the present invention exhibits a NOx conversion of at least 70% at 200°C and at least 80% at 575°C when determined under the same conditions as above.

[0078] The promoter metal can be incorporated into a zeolite having a CHA-type framework structure by any known process, such as ion exchange and impregnation. For example, the promoter metal can be incorporated into a zeolite having a CHA-type framework structure by mixing the zeolite in a solution of a soluble precursor of the promoter metal. The zeolite ion-exchanged with the promoter metal, typically in the form of a cation, can be washed, dried, and calcined as conventional. Useful soluble precursors of the promoter metal can be, for example, promoter metal salts, promoter metal complexes, and combinations thereof. Alternatively, the promoter metal can be incorporated into a zeolite having a CHA-type framework structure in situ during the preparation of a catalyst article, such as an extrudate or coated monolith, as described below.

[0079] In a fourth aspect, the present invention relates to the use of a zeolite having a CHA-type framework structure obtained and / or obtainable by the process according to the first aspect in a catalyst for selective catalytic reduction (SCR) of nitrogen oxides. Furthermore, the present invention relates to the use of a metal-promoted zeolite having a CHA-type framework according to the third aspect for selective catalytic reduction (SCR) of NOx.

[0080] For SCR applications, zeolites having a CHA-type framework structure, preferably the metal-promoted zeolites described above, can be applied in the form of extrudates or in the form of a washcoat on a monolithic substrate.

[0081] Accordingly, in a fifth aspect, the present invention provides a catalyst article in the form of an extrudate comprising an SCR catalyst composition or in the form of a monolith comprising a washcoat containing an SCR catalyst composition on a substrate, wherein the SCR catalyst composition comprises a metal-promoted zeolite having a CHA-type framework structure as described in the third aspect.

[0082] The term "extrudate" generally refers to a shaped body formed by extrusion. According to the present invention, extrudates comprising a zeolite having a CHA-type framework structure and a promoter metal typically have a honeycomb structure.

[0083] The term "washcoat" has its ordinary meaning in the art: a thin, adherent coating of catalytic or other material applied to a substrate.

[0084] The term "substrate" generally refers to a monolithic material, such as a monolithic honeycomb substrate, particularly a flow-through monolithic substrate and a wall-flow monolithic substrate, on which a catalytic coating is disposed.

[0085] The zeolite having a CHA-type framework structure and the promoter metal can be processed into a catalyst article by any known process without particular limitation.

[0086] In a further aspect, the present invention relates to an exhaust gas treatment system comprising an internal combustion engine and an exhaust gas conduit in fluid communication with the internal combustion engine, wherein a catalytic article as described herein is present in the exhaust gas conduit.

[0087] Additionally, the present invention further relates to a method for the selective catalytic reduction of nitrogen oxides (NOx), comprising contacting a gas stream comprising nitrogen oxides with a metal-promoted zeolite comprising a promoter metal as defined in the third aspect, or with a catalyst article as defined in the fifth aspect.

[0088] The present invention is further illustrated by the following series of embodiments and combinations of embodiments resulting from dependencies and reverse references as indicated. In particular, it should be noted that where a range of embodiments is mentioned, for example, in the context of terms such as "described in any one of embodiments 1 to 4," all embodiments within this range are expressly disclosed to those skilled in the art, i.e., this expression would be understood by those skilled in the art to be synonymous with "described in any one of embodiments 1, 2, 3, and 4." Furthermore, it should be clearly noted that the following series of embodiments represents a suitably structured portion of the description directed to general and preferred aspects of the present invention, rather than a series of claims determining the scope of protection.

[0089] Embodiment 1. A process for preparing a zeolite having a CHA-type framework structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetravalent element, (1) (A) A source of X2O3, (B) A source of YO2, and (C) a source of organic structure directing agent (OSDA) comprising a diquaternary ammonium cation of formula (I) or a combination of diquaternary ammonium cations of formula (I), (R1R2R3)N + (CH2) n N + (R4R5R6)(I) During the ceremony, R1, R2, R3, R4, R5, and R6 are each independently selected from C1 to C 10 alkyl, and n is an integer in the range of 3 to 10, or During the ceremony, One of R1, R2, and R3 is C1-C 10 alkyl, and the other two are linked together to form a C4-C6 alkylene; One of R4, R5, and R6 is C1 to C 10alkyl, the other two being linked together to form a C4-C6 alkylene; and preparing a synthesis mixture comprising a source of organic structure directing agent (OSDA), wherein n is an integer ranging from 3 to 10; (2) subjecting the synthesis mixture to crystallization conditions to form a zeolite having a CHA-type framework structure. 2. The process of embodiment 1, wherein in formula (I), R1, R2, R3, R4, R5, and R6 are each independently selected from C1 to C6 alkyl, and n is an integer ranging from 3 to 10. 3. The process of embodiment 2, wherein in formula (I), R1, R2, R3, R4, R5, and R6 are the same and selected from C1 to C6 alkyl, and n is 4 to 7. 4. The process of embodiment 3, wherein in formula (I), each of R1, R2, R3, R4, R5, and R6 is methyl, ethyl, or propyl, and n is 5, 6, or 7. 5. The process of embodiment 4, wherein in formula (I), each of R1, R2, R3, R4, R5, and R6 is ethyl. 6. The process of embodiment 5, wherein in formula (I), each of R1, R2, R3, R4, R5, and R6 is ethyl, and n is 5. 7. The process of any one of embodiments 1 to 6, wherein the synthesis mixture has a molar ratio of diquaternary ammonium cation to source of YO2, calculated as YO2, in the range of 0.01 to 1.0, for example, 0.05 to 0.5, or 0.08 to 0.2. 8. The process of any one of embodiments 1-7, wherein X is selected from the group consisting of Al, B, In, Ga, and any combination thereof, and Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and any combination thereof. 9. The process of embodiment 8, wherein X is Al and Y is Si. 10. The process of any one of embodiments 1 to 9, wherein the source of X2O3 and the source of YO2 comprise a FAU zeolite, in particular zeolite Y, more preferably zeolite Y having a molar ratio of XO2 to YO2O3 of 40 or less, preferably 30 or less. 11. The process according to any of the preceding embodiments, wherein the synthesis mixture has a molar ratio of the source of YO2, calculated as YO2, to the source of X2O3, calculated as X2O3, in the range of 5 to 100, for example, 10 to 60, or 15 to 30. 12. The process according to any one of the preceding embodiments, wherein the synthesis mixture comprises a source of alkali metal and / or alkaline earth metal cations and has a ratio of alkali metal and / or alkaline earth metal cations to the source of YO, calculated as AM to YO, in the range of 0.01 to 1.0, for example 0.03 to 0.5, or 0.05 to 0.3. 13. The synthesis mixture contains the anion OH - and a source of OH relative to YO - the anion OH, calculated as - 13. The process of any one of embodiments 1 to 12, wherein the molar ratio of YO to the source of YO is: 14. The process of any one of embodiments 1 to 13, wherein the organic structure directing agent does not contain any cations other than the diquaternary ammonium cation of formula (I). 15. A zeolite having a CHA-type framework structure obtained and / or obtainable by a process according to any of embodiments 1 to 14. 16. The zeolite according to embodiment 15, having a YO2:X2O3 molar ratio of 2 or greater, preferably in the range of 4 to 200, more preferably 6 to 100, more preferably 8 to 50, more preferably 10 to 35, more preferably 15 to 30, and most preferably 18 to 25. 17. The zeolite of embodiment 15 or 16, having a crystalline morphology with a mosaic-patterned texture of the crystal surface as observed via SEM. 18. A metal-promoted zeolite having a CHA-type framework structure, comprising the zeolite of any one of embodiments 15 to 17 and a promoter metal. 19. The metal-promoted zeolite according to embodiment 18, wherein the promoter metal is selected from transition metals, alkaline earth metals, Sb, Sn, and Bi, and any combination thereof, and preferably comprises Cu and / or Fe, preferably Cu. 20. The metal-promoted zeolite of embodiment 19, wherein the promoter metal consists of Cu and / or Fe, preferably Cu. 21. The metal-promoted zeolite of embodiment 20, wherein the promoter metal is present in the metal-promoted zeolite in an amount in the range from 0.1 to 1.0 moles, preferably from 0.15 to 0.8 moles, more preferably from 0.2 to 0.6 moles, and most preferably from 0.3 to 0.5 moles. 22. Steam aging with 10% H2O at 820°C for 120,000 hours in a test gas stream consisting of 500 vppm NO, 500 vppm NH3, 5% by volume H2O, 10% by volume O2, and the balance N2. -1 22. The metal-promoted zeolite of any of embodiments 18 to 21, exhibiting a NOx conversion of at least 50% at 200°C and at least 60% at 575°C, at a gas hourly space velocity (GHSV) of 1000 sq. m / s. 23. The metal-promoted zeolite of embodiment 22, which upon steam aging with 10% HO at 820°C, exhibits a NOx conversion of at least 65% at 200°C and at least 75% at 575°C, preferably at least 70% at 200°C and at least 80% at 575°C. 24. A catalyst article in the form of an extrudate comprising an SCR catalyst composition or in the form of a monolith comprising a washcoat containing an SCR catalyst composition on a substrate, wherein the SCR catalyst composition comprises the metal-promoted zeolite of any of embodiments 18-23. 25. An exhaust gas treatment system comprising an internal combustion engine and an exhaust gas conduit in fluid communication with the internal combustion engine, wherein the catalytic article of embodiment 24 is present in the exhaust gas conduit. 26. Use of a zeolite having a CHA-type framework structure according to any one of embodiments 15 to 17 or a metal-promoted zeolite according to any one of embodiments 18 to 23 in a catalyst for the selective catalytic reduction of nitrogen oxides. 27. A method for selective catalytic reduction of nitrogen oxides (NOx), comprising contacting a gas stream containing nitrogen oxides with the metal-promoted zeolite of any of embodiments 18-23 or the catalytic article of embodiment 24.

[0090] The present invention will be further illustrated by the following examples which describe particularly advantageous embodiments. The examples are provided to illustrate the invention but are not intended to limit the invention. [Example]

[0091] Scanning electron microscopy (SEM) measurements were carried out by a scanning electron microscope (Hitachi SU5000).

[0092] X-ray powder diffraction (XRD) patterns were obtained using PANalytical X'pert 3 Data were collected in Bragg-Brentano geometry using a Powder Diffractometer (40 kV, 40 mA) with CuKα (λ=1.5406 Å) radiation.

[0093] Example 1 Preparation of CHA Zeolite Seeds 814.6 g of an aqueous solution of 1-methyl-1-n-propylpiperidinium hydroxide (12.6 wt %) was mixed with 2814.3 g of DI water, followed by the addition of 110.8 g of sodium hydroxide (99%, solids). After the sodium hydroxide was dissolved, 44.9 g of zeolite HY (SAR = 7.2, manufactured by Shandong Duoyou) and 567.6 g of Ludox® AS-40 colloidal silica were added. After stirring at room temperature for 30 minutes, the synthesis mixture was transferred to an autoclave equipped with a Teflon liner for crystallization. Crystallization was carried out under static conditions at 150°C for 5 days. After cooling to room temperature, the zeolite product was collected by filtration and dried overnight at 120°C.

[0094] The as-synthesized zeolite was calcined at 550°C for 6 hours to remove the organic structure directing agent. The calcined zeolite was crushed and ion-exchanged in 10 wt% aqueous NH4Cl solution at a solid / liquid ratio of 1:10. The ion-exchange process was carried out at 80°C for 2 hours, collected by filtration, washed with DI water, and dried at 110°C overnight. The ion-exchange procedure was repeated once, and the dried product was calcined at 450°C for 6 hours to obtain the calcined H-form zeolite.

[0095] The zeolite has a SiO2 / Al2O3 molar ratio (SAR) of 14.2 as determined by XRF in the calcined H form. The XRD pattern confirmed that the zeolite has a typical CHA-type framework.

[0096] Example 2 Preparation of CHA Zeolite (Zeolite A, Calcined H Form) with N,N,N,N',N',N'-Hexaethyl-1,5-pentanediammonium Dihydroxide (Et6-Diquat-5 Dihydroxide) 260 g of an aqueous solution of Et6-diquat-5 dihydroxide (20 wt%) was mixed with 194.3 g of DI water, followed by the addition of 3.2 g of sodium hydroxide (99%, solid). After the sodium hydroxide was dissolved, 112.4 g of zeolite HY (SAR = 22, manufactured by Qilu Huaxin) was added. After stirring at room temperature for 30 minutes, 0.4 g of CHA seeds were added, and the synthesis mixture was transferred to an autoclave equipped with a Teflon liner for crystallization. Crystallization was carried out under static conditions at 180 °C for 2 days. After cooling to room temperature, the zeolite product was collected by filtration and dried at 120 °C overnight.

[0097] The as-synthesized zeolite was calcined at 550°C for 6 hours to remove the organic structure directing agent. The calcined zeolite was crushed and ion-exchanged in 10 wt% aqueous NH4Cl solution at a solid / liquid ratio of 1:10. The ion-exchange process was carried out at 80°C for 2 hours, collected by filtration, washed with DI water, and dried at 110°C overnight. The ion-exchange procedure was repeated once, and the dried product was calcined at 450°C for 6 hours to obtain the calcined H-form zeolite.

[0098] The zeolite has a SiO2 / Al2O3 molar ratio (SAR) of 22 as measured in the calcined H form by XRF.

[0099] The zeolite crystal morphology observed from the SEM image (15.0 KV, 6.1 mm × 30.0 K) and XRD pattern is shown in Figure 1A and Figure 2, respectively. The XRD pattern confirmed that the zeolite had a typical CHA-type framework. Furthermore, the SEM image clearly showed a mosaic-pattern texture on the surface of the zeolite crystals.

[0100] Example 3 Preparation of CHA Zeolite (Zeolite B, Calcined H Form) with N,N,N,N',N',N'-Hexaethyl-1,5-pentanediammonium Dihydroxide (Et6-Diquat-5 Dihydroxide) 173.4 g of an aqueous solution of Et6-diquat-5 dihydroxide (20 wt %) was mixed with 208.3 g of DI water, followed by the addition of 7.1 g of sodium hydroxide (99%, solid). After the sodium hydroxide was dissolved, 35.8 g of zeolite HY (SAR = 7.2, manufactured by Shandong Duoyou) and 114.3 g of Ludox® AS-40 colloidal silica were added. After stirring for 30 minutes at room temperature, 2.4 g of CHA seeds were added, and the synthesis mixture was transferred to an autoclave equipped with a Teflon liner for crystallization. Crystallization was carried out under static conditions at 180°C for 2 days. After cooling to room temperature, the zeolite product was collected by filtration and dried overnight at 120°C.

[0101] The as-synthesized zeolite was calcined at 550°C for 6 hours to remove the organic structure directing agent. The calcined zeolite was crushed and ion-exchanged in 10 wt% aqueous NH4Cl solution at a solid / liquid ratio of 1:10. The ion-exchange process was carried out at 80°C for 2 hours, collected by filtration, washed with DI water, and dried at 110°C overnight. The ion-exchange procedure was repeated once, and the dried product was calcined at 450°C for 6 hours to obtain the calcined H-form zeolite.

[0102] The zeolite has a SiO2 / Al2O3 molar ratio (SAR) of 20 as measured in the calcined H form by XRF.

[0103] The crystalline morphology of the zeolite observed from the SEM image (15.0 KV, 8.2 mm × 50.0 K) and XRD pattern is shown in Figure 1B and Figure 2, respectively. The XRD pattern confirmed that the zeolite had a typical CHA-type framework. Furthermore, the SEM image clearly showed a mosaic-pattern texture on the surface of the zeolite crystals.

[0104] Example 4 Preparation of CHA Zeolite with N,N,N-trimethyl-1-adamantylammonium Hydroxide (Zeolite C, Calcined H Form) To a solution of 0.5 g of sodium hydroxide (99%, solid) in 35 g of DI water, 95 g of sodium silicate, 3 g of sodium sulfate (99%, solid), and then 9 g of zeolite Na-Y (SAR = 5.1, CBV 100 from Zeolyst) were added. Then, 16 g of an aqueous solution of N,N,N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH, 20 wt%) was added and stirred at room temperature for 30 minutes. The synthesis mixture was then transferred to an autoclave equipped with a Teflon liner for crystallization. Crystallization was carried out under static conditions at 140 °C for 3 days. After cooling to room temperature, the zeolite product was collected by filtration and dried at 120 °C overnight.

[0105] The as-synthesized zeolite was calcined at 550°C for 6 hours to remove the organic structure directing agent. The calcined zeolite was crushed and ion-exchanged in 10 wt% aqueous NH4Cl solution at a solid / liquid ratio of 1:10. The ion-exchange process was carried out at 80°C for 2 hours, collected by filtration, washed with DI water, and dried at 110°C overnight. The ion-exchange procedure was repeated once, and the dried product was calcined at 450°C for 6 hours to obtain calcined H-type zeolite.

[0106] The zeolite has a SiO2 / Al2O3 molar ratio (SAR) of 11 as measured in the calcined H form by XRF.

[0107] The crystalline morphology of the zeolite observed from the SEM image (15.0 KV, 5.3 mm × 5.00 K) and XRD pattern is shown in Figure 1C and Figure 2, respectively. The XRD pattern confirmed that the zeolite had a typical CHA-type framework. However, the SEM image did not reveal any mosaic texture on the surface of the zeolite crystals.

[0108] Example 5 Preparation of Cu-loaded CHA zeolite material (SCR catalyst) The as-obtained calcined H-form zeolite powder was impregnated with an aqueous solution of copper(II) nitrate by incipient wetness impregnation and maintained in a sealed vessel at 50° C. for 20 h. The resulting solid was dried and calcined in a furnace at 450° C. for 5 h in air to obtain Cu-promoted CHA zeolite.

[0109] Cu-promoted CHA zeolites prepared according to the general procedure above are summarized in Table 2 below.

[0110] [Table 2]

[0111] Example 6 Catalyst Performance Test To test the SCR performance, each of the Cu-loaded zeolite materials was slurried with an aqueous Zr acetate solution, then dried under stirring in air at ambient temperature and calcined at 550°C for 1 hour to obtain a product containing 5 wt% ZrO as a binder based on the amount of product. The product was crushed, and the 250-500 micron powder fraction was aged at 650°C for 50 hours or at 820°C for 16 hours in a 10% by volume steam / air flow to obtain the test samples.

[0112] Selective catalytic reduction (SCR) tests were carried out in a fixed bed reactor packed with 80 mg of test sample in a bed volume of approximately 1 mL together with corundum of the same sieve fraction as a diluent, according to the following conditions:

[0113] Gas feed: 500 vppm NO, 500 vppm NH, 5% by volume H, 10% by volume O, and balance N, gas hourly space velocity (GHSV) 120,000 h -1 ; Temperature: Run 1 - 200, 400, 575°C (first run for degreening) Run 2 - 175, 200, 225, 250, 500, 550, 575°C.

[0114] NOx conversions measured from Run 2 at 200°C and 575°C are reported as test results and are summarized in Table 3 below.

[0115] [Table 3]

[0116] Catalysts comprising Cu-promoted CHA zeolites according to the present invention have been found to be effective in selective catalytic reduction (SCR) of nitrogen oxides.

[0117] Surprisingly, upon aging at 650°C, inventive catalyst A.2 (Example 2), based on CHA zeolite A prepared with diquaternary ammonium cation OSDA, shows higher NOx conversion compared to comparative catalyst D.1 (Example 4), based on CHA zeolite D with the same Cu / Al ratio but prepared with conventional TMAdaOH OSDA.

[0118] Furthermore, upon aging at 820°C, inventive catalysts A.1-A.4 exhibit significantly improved NOx conversion compared to comparative catalyst D.1. Upon aging at 820°C, the inventive catalysts provide NOx conversions of greater than 70%, and even up to 79%, at 200°C, and greater than 80%, and even up to 91%, at 575°C, compared to zero NOx conversion for the corresponding comparative catalysts. The relatively high SCR activity of the inventive catalysts after aging at 820°C reflects the high stability of CHA zeolite at extremely high temperatures.

[0119] Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Therefore, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. X ２ O ３ and Y.O. ２ 1. A process for preparing a zeolite having a CHA-type framework structure comprising: (A) X ２ O ３ Source of, (B)YO ２ Sources of, and (C) a source of organic structure directing agent (OSDA) comprising a diquaternary ammonium cation of formula (I) or a combination of diquaternary ammonium cations of formula (I), (R １ R ２ R ３ )N ＋ (CH ２ ) ｎ N ＋ (R ４ R ５ R ６ )(I) During the ceremony, R １ , R ２ , R ３ , R ４ , R ５ , and R ６ However, independently of each other, C １ ~C １０ alkyl, and n is an integer ranging from 3 to 10, or During the ceremony, R １ , R ２ , and R ３ One of them is C １ ~C １０ alkyl, and the other two are linked together to form C ４ ~C ６ Forming an alkylene R ４ , R ５ , and R ６ One of them is C １ ~C １０ alkyl, and the other two are linked together to form C ４ ~C ６ forming an alkylene, and preparing a synthesis mixture including a source of organic structure directing agent (OSDA), where n is an integer ranging from 3 to 10; (2) subjecting said synthesis mixture to crystallization conditions to form a zeolite having a CHA-type framework structure.

2. In formula (I), R １ , R ２ , R ３ , R ４ , R ５ , and R ６ However, independently of each other, C １ ~C ６ 2. The process of claim 1, wherein n is selected from alkyl, n is an integer ranging from 3 to 10.

3. In formula (I), R １ , R ２ , R ３ , R ４ , R ５ , and R ６ are the same, and C １ ~C ６ 3. The process of claim 2, wherein n is selected from alkyl and n is 4 to 7.

4. In formula (I), R １ , R ２ , R ３ , R ４ , R ５ , and R ６ 4. The process of claim 3, wherein each of is methyl, ethyl, or propyl, preferably ethyl, and n is 5, 6, or 7.

5. In formula (I), R １ , R ２ , R ３ , R ４ , R ５ , and R ６ 5. The process of claim 4, wherein each of is ethyl and n is 5.

6. The synthesis mixture has a YO of the diquaternary ammonium cation in the range of 0.01 to 1.0, for example, 0.05 to 0.5, or 0.08 to 0.

2. ２ The YO calculated as ２ The process of any one of claims 1 to 5, wherein the molar ratio of the source of

7. 7. The process of any one of claims 1 to 6, wherein X is selected from the group consisting of Al, B, In, Ga, and any combination thereof, and Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and any combination thereof.

8. 8. The process of claim 7, wherein X is Al and Y is Si.

9. The X ２ O ３ and the source of said YO ２ is a source of FAU zeolite, especially zeolite Y, more preferably XO of 40 or less, preferably 30 or less. ２ Y ２ O ３ 9. The process of claim 1, wherein the zeolite Y has a molar ratio of:

10. The synthetic mixture contains YO in the range of 5 to 100, for example, 10 to 60, or 15 to 30. ２ The YO calculated as ２ of the source of X ２ O ３ The X calculated as ２ O ３ The process of any one of claims 1 to 9, wherein the molar ratio of the source of

11. the synthesis mixture comprises a source of alkali metal and / or alkaline earth metal cations, and YO ２ The YO of the alkali metal and / or alkaline earth metal cations is in the range of 0.01 to 1.0, for example, 0.03 to 0.5, or 0.05 to 0.3, calculated as AM relative to ２ The process of any one of claims 1 to 10, wherein the ratio of the source of

12. The synthesis mixture contains the anion OH － and a source of YO ２ OH － the anion OH in the range of 0.1 to 2.0, for example 0.1 to 1.0, or 0.2 to 0.5, calculated as － The above YO ２ The process of any one of claims 1 to 11, wherein the molar ratio of the source of

13. 13. The process of any one of claims 1 to 12, wherein the organic structure directing agent does not contain any cations other than the diquaternary ammonium cation of formula (I).

14. A zeolite having a CHA-type framework structure obtained and / or obtainable by a process according to any one of claims 1 to 13.

15. Preferably, 2 or more YOs in the range of 4 to 200, more preferably 6 to 100, more preferably 8 to 50, more preferably 10 to 35, more preferably 15 to 30, and most preferably 18 to 25. ２ :X ２ O ３ 15. The zeolite of claim 14 having a molar ratio of

16. 16. The zeolite of claim 14 or 15, having a crystalline morphology with a mosaic-pattern texture of the crystal surface as observed via SEM.

17. A metal-promoted zeolite having a CHA-type framework structure, comprising the zeolite of any one of claims 14 to 16 and a promoter metal.

18. 18. The metal-promoted zeolite of claim 17, wherein the promoter metal is selected from transition metals, alkaline earth metals, Sb, Sn, and Bi, and any combination thereof, preferably comprising Cu and / or Fe, preferably Cu.

19. 19. A metal-promoted zeolite according to claim 17 or 18, wherein the promoter metal consists of Cu and / or Fe, preferably Cu.

20. 20. The metal-promoted zeolite of claim 19, wherein the promoter metal is present in the metal-promoted zeolite in an amount in the range of from 0.1 to 1.0 molar, preferably from 0.15 to 0.8 molar, more preferably from 0.2 to 0.6 molar, and most preferably from 0.3 to 0.5 molar.

21. 820°C, 10% H ２ During steam aging with O, 500 vppm NO, 500 vppm NH ３ , 5 vol% H ２ O, 10% by volume O ２ , and the remaining N ２ 120,000h in a test gas flow consisting of －１ 21. The metal-promoted zeolite of any one of claims 17 to 20, which exhibits a NOx conversion of at least 50% at 200°C and at least 60% at 575°C, at a gas hourly space velocity (GHSV) of 1000 MPa.

22. 820°C, 10% H ２ 22. The metal-promoted zeolite of claim 21, which upon steam aging with O exhibits a NOx conversion of at least 65% at 200°C and at least 75% at 575°C, preferably at least 70% at 200°C and at least 80% at 575°C.

23. 23. A catalyst article in the form of an extrudate comprising an SCR catalyst composition or in the form of a monolith comprising a washcoat containing an SCR catalyst composition on a substrate, wherein the SCR catalyst composition comprises the metal-promoted zeolite of any one of claims 17 to 22.

24. 24. An exhaust gas treatment system comprising an internal combustion engine and an exhaust gas conduit in fluid communication with said internal combustion engine, wherein the catalytic article of claim 23 is present in said exhaust gas conduit.

25. Use of a zeolite having a CHA-type framework structure according to any one of claims 14 to 16 or a metal-promoted zeolite according to any one of claims 17 to 22 in a catalyst for the selective catalytic reduction of nitrogen oxides.

26. 24. A process for the selective catalytic reduction of nitrogen oxides (NOx), comprising contacting a gas stream containing nitrogen oxides with the metal-promoted zeolite of any one of claims 17 to 22 or the catalytic article of claim 23.

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