Synthesis of ERI rich zeolitic phase using trimethylcyclohexylammonium cation, its derivatives and mixtures

Abstract

The present invention relates to a process for preparing a zeolite material having an ERI / OFF framework structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetravalent element, which includes preparing a synthesis mixture from a source for X2O3 a source for YO2, and a source for at least one cyclohexylammonium-based organic structure directing agent (OSDA).

Description

SYNTHESIS OF ERI RICH ZEOLITIC PHASE USING TRIMETHYLCYCLOHEXYLAMMONIUM CATION, ITS DERIVATIVES AND MIXTURESField of the invention

[0001] The present invention relates to a process for synthesis of zeolite materials having an ERI / OFF framework structure using a cyclohexylammonium-based organic structure directing agent, the zeolite materials obtainable therefrom, and SCR catalysts comprising the same.Background

[0002] Catalytic articles are essential for modem internal combustion engines to treat exhausts therefrom before emission to air. The exhausts from internal combustion engines typically comprise particulate matter (PM), nitrogen oxides (NOx) such as NO and / or NO2, unbumed hydrocarbons (HC), and carbon monoxide (CO). Control of NOx emissions is always one of the most important topics in automotive field, due to the environmentally negative impact of NOx on ecosystem, animal and plant life.

[0003] One of effective techniques for removal of NOx from internal combustion engine exhausts is selective catalytic reduction (SCR) of NOx with ammonia or a secondary ammonia source. Zeolites having the ERI framework structure are reported to have high performances for the selective catalytic reduction (SCR) of NOx with ammonia, as well as methanol-to-olefins (MTO) reaction with high selectivity for making ethylene.

[0004] One challenge with the synthesis of ERI zeolites is the formation of an intergrowth with the OFF secondary phase. ERI phase is a three dimensional 8 member ring framework, whereas the OFF is a framework with one dimensional 12 member ring pores, thus the property of the intergrowth changes drastically depending on the ratio of ERI to OFF. Among the prior work, for recipes having higher amounts of ERI such as SSZ-98 and UZM-12, the synthesis typically involves very costly templates, causing a difficulty from the manufacturing and / or economic viability perspective.

[0005] There remains a need of more economical and effective processes for preparing zeolite materials having an ERI / OFF framework structure, particularly with high ERI selectivities.Summary of the invention

[0006] It is an object of the present invention to provide a novel process for preparing an ERI / OFF intergrowth zeolite.

[0007] Another object of the present invention is to provide an SCR catalyst based on a zeolite having an ERI-type framework structure, for example a zeolite having an ERI / OFF-type framework structure.

[0008] The objects were achieved by using a cyclohexylammonium-based organic structure directing agent (OSDA) in the zeolite synthesis. It has been surprisingly found that the zeolite having ERI / OFF framework structure with high ERI selectivities can be prepared economically and effectively by using cyclohexylammonium-based as an OSDA.

[0009] This disclosure provides a new pathway for producing an ERI rich phase using cyclohexylammonium-based OSDAs. The templates are more economical compared especially to the templates that are conventionally used to make ERI-rich zeolites. Additionally, the synthesis duration is short (about 60h or less), and is based on conventional hydrothermal synthesis which does not require complicated approaches such as ultrafast synthesis or charge density mismatch. The zeolites having a ERI or ERI / OFF framework structure can be used for catalytic (such as NEE SCR and MTO) and adsorbent purposes.

[0010] Accordingly, in a first example, the present invention relates to a process for preparing a zeolite material having an ERI / OFF framew ork structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetraval ent element, which includes

[0011] (1) preparing a synthesis mixture comprising:

[0012] (A) a source for X2O3,

[0013] (B) a source for YO2, and

[0014] (C) a source for at least one organic structure directing agent (OSDA) comprising a compound according to formula (I),

[0015] wherein Ri to R , independently from each other, are selected from a linear or branched C1-C4 alkyl, and

[0016] R4 to Rs, independently from each other, are H, hydroxyl, or linear or branched Ci-Ce alkyl and

[0017] (2) subjecting the synthesis mixture to crystallization conditions to form an ERI / OFF- type framework structure.

[0018] A second example includes a zeolite material having an ERI / OFF framework structure prepared according to the process of the first example.

[0019] A third example includes a selective catalytic reduction catalyst comprising the zeolite material having an ERI / OFF framework structure prepared according to the process of the first example.

[0020] Another example includes a zeolite material having an ERI / OFF framework structure comprising an amount of an organic structure directing agent within the pores, wherein the organic structure directing agent comprises a compound according to formula (I) ),(I).

[0021] wherein R1 to R3, independently from each other, are selected from a linear or branched C1-C4 alkyl, and

[0022] R4 to R8, independently from each other, are H, hydroxyl, or linear or branched Cl- C6 alkyl;.

[0023] Another example includes a catalyst, an adsorbent, or an ion-exchanger comprising the zeolite material having an ERI / OFF framework structure prepared according to the process set out herein.

[0024] Another example includes an exhaust treatment system comprising a catalyst or an adsorbent as set forth herein.Brief description of the drawings

[0025] Figure 1 shows theoretical x-ray diffraction (XRD) patterns of ERI / OFF intergrowth structures.

[0026] Figure 2 shows XRD patterns for ERI / OFF zeolite synthesized using trimethylcyclohexylammonium cation as an organic template.

[0027] Figures 3 A and 3B show results from SEM observations of ERI / OFF zeolite synthesized using trimethylcyclohexylammonium cation as an organic template.

[0028] Figure 4 shows XRD patterns of ERI / OFF phase obtained using dimethylethylcyclohexylammonium hydroxide as the structure directing agent.

[0029] Figure 5 shows XRD patterns for ERI / OFF zeolite synthesized using trimethylcyclohexylammonium cation as an organic template and NaY as a zeolitic Al source.

[0030] Figure 6 shows XRD patterns for ERI / OFF zeolite synthesized using trimethylcyclohexylammonium cation as an organic template with a starting gel of OH / Si=0.3.

[0031] Figure 7 shows XRD pattern of ERI / OFF phase obtained using tnmelhylbenzylammonium as the structure directing agent.

[0032] Figure 8 shows13C CP-ssNMR spectra for ERI / OFF zeolite synthesized using trimethylcyclohexylammonium cation as an organic template.

[0033] Figure 9 shows13C CP-ssNMR spectra for ERI / OFF zeolite synthesized using dimethylethylcyclohexylammonium cation as an organic template.

[0034] Figure 10 shows NH3-SCR performance of ERI / OFF synthesized in example 1 using TMCh as template Reaction conditions: GHSV: 80 kh’1, 500 ppm NO, 500 ppm NH3, 5% H2O, 10% O2, balance N2.Detailed description of the invention

[0035] The present invention will be described in detail hereinafter. It is to be understood that the present invention may be embodied in many different ways and shall not be construed as limited to the embodiments set forth herein.

[0036] Herein, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. The terms “comprise”, “comprising”, etc. are used interchangeably with “contain”, “containing”, etc. and are to be interpreted in anon-limiting, open manner. That is, e.g., further components or elements may be present. The expressions “consists of’ or “consists essentially of’ or cognates may be embraced within “comprises” or cognates.

[0037] Herein, the term “zeolite material having an ERI / OFF framework structure” generally refers to zeolites having an ERI phase, which is a three dimensional 8 member ring framework, including an OFF intergrowth, which is a framework with one dimensional 12 member ring pores.

[0038] The ERI / OFF framework structure may be more than 95% of the zeolite framework, as determined by X-ray powder diffraction (XRD) analysis. Particularly the zeolite may be at least 98% or at least about 99% ERI / OFF framework structure.

[0039] The term “as -synthesized” as used herein is intended to refer to a zeolite in its form after crystallization, recovery', and drying, prior to removal of the organic structure directing agent.

[0040] The term “calcined form” as used herein is intended to refer to a zeolite in its form upon calcination.

[0041] In the first example, the present invention relates to a process for preparing a zeolite material having an ERI / OFF framework structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetravalent element, which includes

[0042] (1) preparing a synthesis mixture comprising:

[0043] (A) a source for X2O3,

[0044] (B) a source for YO2, and

[0045] (C) a source for at least one organic structure directing agent (OSDA) comprising a compound according to formula (I),(I),

[0046] wherein Ri to R3, independently from each other, are selected from a linear or branched C1-C4 alkyl, and

[0047] R4 to R«. independently from each other, are H, hydroxyl, or linear or branched Ci-Ce alkyl; and

[0048] (2) subjecting the synthesis mixture to crystallization conditions to form an ERI / OFF- type framework structure.

[0049] A second example includes a zeolite material having an ERI / OFF framework structure prepared according to the process of the first example.

[0050] A third example includes a selective catalytic reduction catalyst comprising the zeolite material having an ERI / OFF framework structure prepared according to the process of the first example.

[0051] For example, the cyclohexylammonium-based compound of formula (I) is selected from trimethylcyclohexylammonium (TMCh) and dimethylethylcyclohexylammonium (DMECh) or any combinations thereof.

[0052] The synthesis mixture provided in step (1) comprises a source for X2O3 where X is a trivalent framework element and a source for YO2 where Y is a tetraval ent 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 combinations thereof, with Al being more preferable. 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 combinations thereof, with Si being more preferable. Particularly, X is Al and Y is Si.

[0053] Suitable source for X2O3 may be any known materials useful for providing trivalent framework element during zeolite synthesis. In some embodiments wherein X is Al, suitable examples of the source for AI2O3 may include, a zeolite compound, and / or a non-zeolitic alumina compound, and / or an aluminum salt or a combination thereof. Additional examples include but are not limited to alumina, aluminum hydroxide, aluminates, aluminum alkoxides, aluminum salts, FAU zeolites, LTA zeolites, LTL zeolites, BEA zeolites, MFI zeolites and any combinations thereof, more preferably alumina, aluminum alkoxide, aluminum salts, FAU zeolites and any combinations thereof. Particularly, the source for AI2O3 may be selected from alumina, AIO(OH), A1(OH)3, aluminum tri(Ci-Cs)alkoxide, aluminum halides, aluminum sulfate, aluminum phosphate, aluminum fluorosilicate, FAU zeolites and any combinations 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, CSZ-1, US-Y, ECR-30, LZ-210, Li-LSX, SAPO-37. ZSM-20. ZSM-3, Zeolite X and Zeolite Y, more preferably from the group consisting of faujasite, zeolite X, zeolite Y, US-Y and LZ-210. Zeolite Y, including zeolite NaY, may be particularly mentioned as the source for X2O3.

[0054] Suitable source for YO2 may be any known materials useful for providing tetraval ent framework element during zeolite synthesis. In some embodiments wherein Y is Si, suitable sources for YO2 may include, but are not limited to fumed silica, precipitated silica, silica hydrosols, silica gels, colloidal silica, silicic acid, silicon alkoxides, alkali metal silicates, sodium metasilicate hydrate, sesquisilicate, disilicate, silicic acid esters. FAU zeolites, LTA zeolites, LTL zeolites, BEA zeolites, MFI zeolites and any combinations thereof. Particularly, the source for YO2 may be selected from fumed silica, sodium silicate, potassium silicate. FAU zeolites and any combinations thereof, more preferably fumed silica, FAU zeolites and any combinations thereof. For example, the FAU zeolite may be selected from the group consisting of faujasite, [Ga-Al-Si- 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. more preferably from the group consisting of faujasite, zeolite X, zeolite Y, US-Y, and LZ-210. Particularly, one or more materials selected from the group consisting of fumed silica, precipitated silica, silica hydrosols, silica gels, colloidal silica and zeolite Y may be mentioned as the source for YO2.

[0055] It will be understood that the sources for X2O3 and YO2 may be provided separately (i.e., separate sources) and / or conjointly (i.e., combined source). In the latter case, the sources may be provided by for example a zeolite containing framework elements X and Y. It can be contemplated that the synthesis mixture provided in step (1) may comprise a combined source for X2O3 and YO2 and one or more additional separate sources for X2O3 and / or YO2.

[0056] In some particular embodiments, the synthesis mixture provided in step (1) comprises a source for AI2O3 and a source for SiCh, in form of separate sources or a combined source, or a combination of a combined source and one or two separate sources. Accordingly, an aluminosilicate zeolite having a ERI / OFF-type framework structure, will be obtained from the process according to the present invention.

[0057] The term “aluminosilicate” as used within the context of zeolite is intended to mean the framework constructed primarily of alumina and silica, which may or may not comprise a framework element other than oxygen, aluminum, and silicon.

[0058] In certain illustrative embodiments, the synthesis mixture provided in step (1) comprises an FAU zeolite as the combined source for AI2O3 and SiCh and an additional source for SiCh. Particularly the FAU zeolite is zeolite Y, which may be in Na+-form, H-form or NFU - exchanged form. Zeolite Y having a molar ratio of SiCh to AI2O3 of no more than 40 or no more than 30 is more preferable. The additional source for S1O2 is selected from the group consisting of fumed silica, precipitated silica, silica hydrosols, silica gels and colloidal silica, including mixtures of two or more thereof.

[0059] The synthesis mixture provided in step (1) has a YO2 : X2O3 molar ratio in the range of from 5 to 100, for example from 10 to 60, or from 20 to 50.

[0060] The synthesis mixture provided in step (1) may be a gel having a S1 / AI2 molar ratio (SAR) of 5 to 30. for example from 10 to 20.

[0061] According to the present invention, the source for organic structure directing agent(OSDA) may, or may not, further comprise an OSDA and / or an organic compound other than the cyclohexylammonium-based compound of formula (I) as described herein.

[0062] In some particular embodiments, the source for organic structure directing agent (OSDA) and thus the synthesis mixture provided in step (1) comprises no OSDA other than the cyclohexylammonium-based compound as described herein.

[0063] The synthesis mixture provided in step (1) has a molar ratio of total OSDA (Q) to the source(s) for YO2, calculated as YO2 (Q : YO2), in the range of from 0.01 to 1 .0, for example from 0.02 to 0.5, or from 0.04 to 0.2. When the source for organic structure directing agent comprises the cyclohexylammonium-based compound of formula (I) and an additional OSDA, the cyclohexylammonium-based compound and the additional OSDA (and / or organic compound) may be present in a molar ratio of at least 1 : 1, or at least 2 : 1, for example 3 : 1 or higher, 4 : 1 or higher. 5 : 1 or higher, or 6 : 1 or higher.

[0064] Preferably, the synthesis mixture provided in step (1) has a molar ratio of cyclohexylammonium-based compound to the source(s) for YO2. calculated as YO2, in the range of from 0.01 to 1.0, for example from 0.02 to 0.5, or from 0.04 to 0.2.

[0065] The synthesis mixture provided in step (1) may further comprise at least one solvent, preferably water, more preferably deionized water. The solvent may be comprised in one or more of starting materials of the synthesis mixture, such as the sources for X2O3, YO2 and the organic structure directing agent and thus be carried into the synthesis mixture, and / or may be incorporated into the synthesis mixture separately.

[0066] In some embodiments, the synthesis mixture has a molar ratio of water to the source(s) for YO2, calculated as H2O to YO2, in the range of from 3 to 100, for example 10 to 80. or 10 to 40.

[0067] In some embodiments, the synthesis mixture provided in step (1) may, or may not, further comprise an amount of seed crystals of ERI zeolite. If used, the seed cry stals of the ERI zeolite may be obtained from the process as described herein without using seed crystals, or from any other known processes.

[0068] The synthesis mixture may be subjected to crystallization conditions to form a zeolite having a ERI / OFF framework structure in step (2) with no particular restriction. The crystallization may be carried out at an elevated temperature in the range of from 80 to 250 °C, more preferably from 100 to 200 °C, for a period sufficient for crystallization, for example 0.5 to 12 days, or 1 to6 days. Typically, the crystallization is carried out under autogenous pressure, for example in a pressure tight vessel such as an autoclave. Further, the crystallization may be carried out with or without agitation.

[0069] The ERI zeolite as formed by crystallization may be subjected to a work-up procedure including isolating for example by filtration, optionally washing, and drying to obtain the as- synthesized zeolite. Accordingly, step (2) in the process according to the present invention optionally further comprises the work-up procedure.

[0070] The organic structure directing agent remaining, if any, in the filtrate liquid from the filtration and optionally the washed liquid from the washing may be recycled, and used for further synthesis of the ERI zeolite.

[0071] The as-synthesized zeolite typically comprises the cyclohexylammonium-based compound and comprises the additional OSDA if it is used in the synthesis, as described hereinabove within its structure pores and / or channels.

[0072] In some embodiments, the as -synthesized zeolite from step (2) may be subjected to a calcination procedure. Accordingly, the process according to the present invention further comprises step (3) of calcination of the as-synthesized zeolite.

[0073] In some embodiments, the as-synthesized or the as-calcined zeolite may be subjected to an ion-exchange procedure such that one or more ionic non-framework elements contained in the zeolite are exchanged to H+and / or NFLfi. Accordingly, the process according to the present invention further comprises step (4) exchanging one or more of ionic non-framework elements contained in the zeolite obtained in step (2) or (3) to H+and / or NH4+, preferably NH4+.

[0074] Generally, the zeolite having been exchanged to H+and / or NFU+in step (4) may be subjected to a w ork-up procedure including isolating for example by filtration, optionally washing, and drying, and / or subjected to a calcination procedure. Accordingly, step (4) in the process according to the present invention optionally further comprises the work-up procedure and / or calcination procedure.

[0075] The calcination in step (3) and / or step (4) may be carried out at a temperature in the range of from 300 to 900 °C, for example 350 to 700 °C, or 400 to 650 °C. Particularly, the calcination may be performed in a gas atmosphere having a temperature in the above-describedranges, which may be air, oxygen, nitrogen, or a mixture of two or more thereof. Preferably, the calcination is performed for a period in the range of from 0.5 to 10 hours, for example 3 to 7 hours, or 4 to 6 hours.

[0076] Zeolites having an ERI framework structure, for example zeolites having an ERI / OFF- type framework structure or ER1 / OFF hybrid zeolite materials could be successfully obtained from the process as described in the first aspect, as determined by X-ray powder diffraction (XRD) analysis. As noted in the examples, such zeolites are typically made using potassium (K), sodium (Na), or a combination thereof. It is understood that while K and Na are the alkali cations being used in the examples, it is expected other alkaline cations such as Rb and Cs, as well as alkaline earth metal cations such as Mg, Ca, Sr, for example, may also be used, alone or in combination.

[0077] Accordingly, in the second aspect, the present invention provides a zeolite having an ERI framework structure obtainable and / or obtained from the process as described in the first aspect.

[0078] The ERI zeolite, for example the zeolite having a ERI / OFF-lype framework structure or the ERI / OFF hybrid zeolite material, has a YO2 : X2O3 molar ratio (Si / AE or S AR) of YO2 (e.g., silica) to X2O3 (e.g., alumina) of 5 or more, wherein the molar ratio is preferably comprised in the range of from 5 to 200, or from 5 to 50, or from 5 to 35, or from 5 to 25. According to the present invention, the YO2 : X2O3 molar ratio preferably refers to the zeolite in its calcined form, more preferably in its calcined H-form.

[0079] The ERI zeolite, for example the zeolite having a ERI / OFF-lype framework structure or the ERI / OFF hybrid zeolite material, has a C / N ratio in the range of 7 to 15, for example from 8-10.

[0080] The zeolite having a ERI-type framework structure according to the present invention typically has an average crystal size of 100 microns (pm) or less, for example in the range of from 50 pm or less. The average cry stal size may be determined via scanning electron microscopy (SEM). Particularly, the average crystal size was determined via SEM by measuring the crystal sizes for at least 30 different crystals selected at random from multiple images covering different areas of the sample.

[0081] It has been found that the zeolite having an ERI-type framework structure according to the present invention has a crystal morphology with hexagonal pillared primary crystals, as observed via SEM. Herein, the hexagonal pillared is used to describe the morphology of the crystals of the zeolite having a ERI-type framework structure.

[0082] In the third aspect, the present invention further provides a metal -promoted zeolite having an ERI-type framework structure, for example a metal-promoted zeolite having an ERI / OFF-type framework structure, which comprises the zeolite obtained and / or obtainable by the process according to the present invention and a promoter metal.

[0083] The term ‘‘promoter metal” as used herein refers to a non-framework metal capable of improving the catalytic activity’ of a zeolite. The “non-framework metal” is intended to mean that the metal does not participate in constituting the zeolite framework structure. The promoter metal may reside within the zeolite and / or on at least a portion of the zeolite surface.

[0084] Herein, the promoter metal is particularly present within the zeolite having an ERI-ty pe framework structure (e g., the zeolite having an ERI / OFF-type framework structure), and / or on at least a portion of the surface thereof.

[0085] The zeolite having an ERI-type framework structure is the zeolite as obtained and / or obtainable by the process described in the first aspect and / or the ERI zeolite as described in the second aspect. Any general and particular descriptions with respect to the process in the first aspect or with respect to the ERI zeolite in the second aspect are incorporated here by reference.

[0086] The promoter metal may be any metals known useful for improving catalytic performance of zeolites in the application of selective catalytic reduction (SCR) of NOx. Generally, the promoter metal may be selected from transition metals, for example precious 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. alkali earth metals such as Ca and Mg, and Sb, Sn and Bi. and any' combinations thereof.

[0087] In some embodiments, the metal-promoted zeolite having an ERI-ty pe framework structure compnses Cu and / or Fe as the promoter metal. In some particular embodiments, the metal-promoted zeolite comprises Cu as the promoter metal.

[0088] The promoter metal may be present in the metal-promoted zeolite having an ERI-type framework structure at an amount of 0. 1 to 10 % by weight, preferably 0.5 to 10 % by weight, onan oxide basis, based on the total weight of the promoter metal and the zeolite having an ERI-type framework structure. In some particular embodiments wherein copper, iron or the combination thereof is used as the promoter metal, the promoter metal is preferably present in the metal- promoted zeolite having an ERI-ty pe framework structure at an amount of 1 to 8 % by weight, more preferably 2 to 6 % by weight, on an oxide basis, based on the total weight of the promoter metal and the zeolite having an ERI-type framework structure.

[0089] Alternatively, the promoter metal may be present in the metal-promoted zeolite having an ERI-type framework structure at an amount in the range of from 0.01 to 2 moles, for example 0.03 to 1.8 moles, 0.05 to 1.5 moles, 0.08 to 1.2 moles, 0.1 to 1.0 moles, 0.15 to 0.8 moles, per mole of the trivalent framework element (e.g., Al) of the zeolite having an ERI-type framework structure. In some particular embodiments wherein copper, iron or the combination thereof is used as the promoter metal, the amount of the promoter metal is 0. 1 to 1.0 moles, preferably 0. 15 to 0.8 moles, more preferably 0.2 to 0.6 moles, most preferably 0.3 to 0.5 moles, per mole of the trivalent framework element (e.g.. Al) of the zeolite having an ERI-type framework structure.

[0090] In some preferable embodiments, the present invention provides a metal-promoted zeolite having an ERI-type framework structure, which comprises

[0091] - an aluminosilicate zeolite having a ERI-type framework structure, which has a molar ratio of silica to alumina (SAR) in the range of from 5 to 25, or from 10 to 20, and

[0092] - a promoter metal selected from Cu, Fe or a combination thereof, particularly Cu,

[0093] wherein the promoter metal is present at an amount of 0.2 to 0.6 moles, preferably 0.3 to 0.5 moles per mole of framework aluminum of the zeolite.

[0094] The promoter metal may be incorporated into the zeolite having an ERI-type framework structure via any known processes, for example ion exchange and impregnation. For example, the promoter metal may be incorporated into the zeolite having an ERI-type framework structure by mixing the zeolite into a solution of a soluble precursor of the promoter metal. The zeolite upon ion-exchanging with the promoter metal typically in form of cation may be conventionally washed, dried and calcined. Useful soluble precursors of the promoter metal may be for example salts of the promoter metal, complexes of the promoter metal and a combination thereof. Alternatively, the promoter metal may be incorporated into the zeolite having an ERI-typeframework structure in situ during the preparation of catalytic articles such as extrudate or coated monolith as described hereinbelow.

[0095] In the fourth aspect, the present invention relates to use of the zeolite having an ERI- type framework structure obtained and / or obtainable by the process as described in the first aspect in catalysts for selective catalytic reduction (SCR) of nitrogen oxides. Further, the present invention relates to use of the metal -promoted zeolite having an ERI-type framework as described in the third aspect for selective catalytic reduction (SCR) of NOx.

[0096] For the SCR applications, the zeolite having an ERI-type framework structure, preferably the metal -promoted ones as described hereinabove, may be applied in form of an extrudate or in form of a washcoat on a monolithic substrate.

[0097] Accordingly, in the fifth aspect, the present invention provides a catalytic article in form of an extrudate comprising an SCR catalyst composition or in 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 having an ERI-type framework structure as described in the third aspect.

[0098] The term “extrudate” generally refers to shaped body formed by extrusion. According to the present invention, the extrudate comprising the metal -promoted zeolite having an ERI-type framework structure typically has a honeycomb structure.

[0099] The term “washcoat’ ’ has its usual meaning in the art, that is a thin, adherent coating of a catalytic or other material applied to a substrate.

[0100] The term “substrate” generally refers to a monolithic material onto which a catalytic coating is disposed, for example monolithic honeycomb substrate, particularly flow-through monolithic substrate and wall-flow monolithic substrate.

[0101] The zeolite having an ERI-type framework structure or the metal -promoted zeolite having an ERI-ty pe framew ork structure may be processed into the catalytic article by any known processes with no particular restriction.

[0102] In the sixth aspect, the present invention relates to an exhaust gas treatment system compnsing an internal combustion engine and an exhaust gas conduit in fluid communication withthe internal combustion engine, wherein the catalytic article as described herein is present in the exhaust gas conduit.

[0103] In addition thereto, the present invention further relates to a method for selective catalytic reduction of nitrogen oxides, which includes contacting a gas stream comprising nitrogen oxides (NOx) with a metal -promoted zeolite having an ERI-type framework structure as described in the third aspect, or with the catalytic article as described in the fifth aspect.

[0104] In the seventh aspect, the present invention relates to a zeolite material having an ERI / OFF framework structure having peak features in the 25-30 ppm range and in the 70-80 ppm range in13C ssNMR spectra.

[0105] The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back -references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as ‘'The ... according to any one of embodiments 1 to 4”, every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e., the wording of this term is to be understood by the skilled person as being synonymous to “The ... according to any one of embodiments 1. 2, 3, and 4”. Further, it is explicitly noted that the following set of embodiments is not the set of claims determining the extent of protection, but represents a suitably structured part of the description directed to general and preferred aspects of the present invention.Embodiments

[0106] Not A first embodiment includes a process for preparing a zeolite material having an ERI / OFF framework structure comprising X2O3 and YO2, wherein X is a tri valent element and Y is a tetravalent element, which includes

[0107] (1) preparing a synthesis mixture comprising:

[0108] (A) a source for X2O3.

[0109] (B) a source for YO2, and

[0110] (C) a source for at least one organic structure directing agent (OSDA) comprising a compound according to formula (I),

[0111] wherein R1 to R3, independently from each other, are selected from a linear or branched C1-C4 alkyl, and

[0112] R4 to R8, independently from each other, are H, hydroxyl, or linear or branched Cl- C6 alkyl; and

[0113] (2) subjecting the synthesis mixture to crystallization conditions to form a CHA-type framework structure.

[0114] A further embodiment includes the process of the first embodiment, wherein at least two of Rl, R2 and R3 are methyl.

[0115] A further embodiment includes the process of the first embodiment, wherein each of Rl. R2 and R3 is methyl.

[0116] A further embodiment includes the process of the first embodiment, wherein at least one of Rl, R2 and R3 is ethyl.

[0117] A further embodiment includes the process of the first embodiment, wherein Y is selected from Si, Sn, Ti, Zr, Ge, and mixtures thereof.

[0118] A further embodiment includes the process of the first embodiment, wherein X is selected from the group consisting of Al, B, In, Ga and any combinations thereof

[0119] A further embodiment includes the process of the first embodiment, wherein the source for X2O3 is a zeolite compound, a non-zeolitic alumina compound, an aluminum salt or a combination thereof.

[0120] A further embodiment includes the process of the first embodiment, wherein the zeolitic material has a crystal size of 100pm or less.

[0121] A further embodiment includes the process of the first embodiment, wherein the zeolite material comprises a C / N ratio in the range of 7 to 15.

[0122] A further embodiment includes the process of the first embodiment, wherein the source for at least one organic structure directing agent (OSDA) further comprising at least one organic compound.

[0123] A further embodiment includes the process of the first embodiment, wherein the zeolite material has a Si / A12 molar ratio (SAR) of 5 to 25.

[0124] A further embodiment includes the process of the first embodiment, wherein the synthesis mixture is a gel having a Si / A12 molar ratio (SAR) of 5 to 30.

[0125] A second embodiment includes a zeolite material having an ERI / OFF framework structure prepared according to the process of the first embodiment.

[0126] A third embodiment includes a selective catalytic reduction catalyst comprising the zeolite material having an ERI / OFF framework structure prepared according to the process of the first embodiment.

[0127] The invention will be further illustrated by following Examples, which set forth particularly advantageous embodiments. While the Examples are provided to illustrate the present invention, they are not intended to limit the present invention.Examples

[0128] Scanning electron microscopy (SEM) measurements were performed by a scanning electron microscope (Hitachi SU5000).

[0129] X-ray powder diffraction (XRD) patterns were measured with PANalytical X'pert3Powder Diffractometer (40kV, 40 mA) using CuKa (X=1.5406 A) radiation to collect data in Bragg-Brentano geometry.

[0130] Reference Example 1

[0131] The theoretical powder patterns of the ERI / OFF intergrowths with different ERI contents are shown in Figure 1. As shown in Figure 1, the intensity of the peak at 20 = 9.7° can be used as an indicator for the relative amount of ERI to OFF phase, and was used to assess the products produced from different preparations.

[0132] Example 1 : Syntheses of ERI / OFF phase using trimethylcyclohexylammonium template

[0133] To DI water, KOH (45 wt%), NaOH (50 wt%), trimethylcyclohexylammonium hydroxide (20 wt%) were mixed. Then, aluminum isopropoxide was added to the solution and stirred for dissolution. After this, sodium silicate (Modulus: 3.4) and sulfuric acid were added. The final composition of the gel is set forth in Table 1 :

[0134] Hydrothermal synthesis was conducted for 60h at 150°C using vertical stirring apparatus. After synthesis, sample was collected by filtration, washed with DI water and dried at 80°C.

[0135] The product characterization results are shown in Figure 2. A clear notable feature is that materials produced with trimethylcyclohexylammonium template possess a high selectivity to ERI phase, as confirmed from the sharp peak at 20=9.7 degrees.

[0136] Morphology' of the product from SEM observations, BET specific surface area and micropore volume from physisorption, and elemental composition from ICP and CHN are shown in Figures 3 A and 3B. The product consisted of hexagonal pillared primary cry stals with sizes of several microns. BET specific surface area came out to be 419 m2 / g with micropore volume of 0.18 cm3 / g.

[0137] Product R / Si and R / (Si+Al) calculated from ICP and CHN analyses were found to be 0.053 and 0.044, indicating that ERI / OFF phase can be prepared with less amount of template than ty pical CHA zeolites (R / Si~0.08). The difference could be due to the larger cages that ERI structure possess (14 T atoms / cage) compared to CHA zeolite (cha cage: 12 T atoms / cage). At the same time, C / N molar ratio from CHN analysis came out to be 8.8 showing that indeed the trimethy cyclohexylammonium cation (C / N=9) is templating this ERI-rich phase.

[0138] For catalytic testing purposes the material was first calcined in air at 540°C for 6 h, then ion-exchanged using 0.25 M NH4NO3 solution at 80°C for 1 h. To desorb off NH4 species, calcination was conducted at 450°C for 6 h.The ion-exchange and 450°C calcination process was conducted twice to remove most of the sodium. Potassium within the zeolite was found to bedifficult to be removed. See, F. H. Alshafei et al., J. CataL 404 (2021) 620-633. The elemental composition of the product after two ion-exchange steps is shown in Table 2, showing that most of the Na was effectively removed. After the last calcination, the material was impregnated with copper nitrate solution to 2.2 wt% CuO / (CuO+zeolite), mixed with Zr acetate binder, then finally calcined at 550°C for 1 h. The testing results for the fresh sample is show n in Figure 10.

[0139] 13C CP-ssNMR result is shown in Figure 8. Features ascribed to trimethylcyclohexylammonium cations were observed in the spectra, showing that this template is indeed acting to form ERI / OFF structure.

[0140] Example 2. Syntheses of ERI / OFF phase using dimethylethylcyclohexylammonium template

[0141] To DI water, KOH (45 wt%), NaOH (50 wt%), dimethylethylcyclohexylammonium hydroxide (20 wt%) were mixed. Then, aluminum isopropoxide was added to the solution and stirred for dissolution. After this, sodium silicate (Modulus: 3.4) and sulfuric acid were added. The final composition of the gel was as set forth in Table 3:

[0142] Hydrothermal synthesis was conducted for 60h at 150°C using vertical stirring apparatus. After synthesis, sample was collected by filtration, w ashed with DI water and dried at 80°C.

[0143] The XRD patterns of the product obtained using diethylmethylcyclohexylammonium hydroxide as templates is shown in Figure 4. As in the case with trimethylcyclohexylammonium template, a sharp peak at 20=9.7 degrees was observed, showing that the product is ERFOFF phase with much presence of ERI phase within.

[0144] 13C CP-ssNMR result is shown in Figure 9. Features ascribed to trimethylcyclohexylammonium cations were observed in the spectra, showing that this template is indeed acting to form ERI / OFF structure.

[0145] Example 3. Syntheses of ERI / OFF phase using trimethylcyclohexylammonium template and zeolitic Al source

[0146] To DI water, KOH (45 wt%), NaOH (50 wt%), K2SO4, Na2SO4, trimethylcyclohexylammonium hydroxide (20 wt%) were mixed. Then, NaY zeolite (CVB100) was added to the solution and stirred. After this, precipitated silica (HiSil233) was added and mixed for 15 min. The final composition of the gel was as set forth in Table 4:

[0147] Hydrothermal synthesis was conducted for 60h at 150°C using vertical stirring apparatus. After synthesis, sample was collected by filtration, washed with DI water and dried at 80°C.

[0148] The XRD patterns of the product obtained using trimethylcyclohexylammonium template and NaY as a zeolitic Al source is shown in Error! Reference source not found.. As in the case with trimethylcyclohexylammonium template, a sharp peak at 20=9.7 degrees was observ ed, showing that the product is ERI / OFF phase with much presence of ERI phase within.

[0149] Example 4. Syntheses of ERI / OFF phase using trimethylcyclohexylammonium template with OH / Si=0.3

[0150] To DI water, KOH (45 wt%). NaOH (50 wt%), trimethylcyclohexylammonium hydroxide (20 wt%) were mixed. Then, aluminum isopropoxide was added to the solution andstirred for dissolution. After this, sodium silicate (Modulus: 3.4) and sulfuric acid were added. The final composition of the gel was as set forth in Table 5:

[0151] Hydrothermal synthesis was conducted for 60h at 150°C using vertical stirring apparatus. After synthesis, sample was collected by filtration, washed with DI water and dried at 80°C.

[0152] The product characterization results are shown in Figure . As mentioned in other examples, the materials produced with trimethylcyclohexylammonium template possessed a higher selectivity to ERI phase, as confirmed from the sharp peak at 20=9.7 degrees.

[0153] Comparative example 1. Syntheses of ERI / OFF phase using trimethylbenzylammonium template

[0154] As a comparative example, synthesis was conducted using trimethylbenzy lammonium as a template having similar molecular structure with trimethylcyclohexylammonium template. This template has been used in an external patent (US3699139 B2) for making an ERI / OFF intergrowth.

[0155] To DI water, KOH (45 wt%), NaOH (50 wt%), trimethyl benzyl ammonium chloride were mixed. Then, aluminum isopropoxide was added to the solution and stirred for dissolution. After this, sodium silicate (Modulus: 3.4) and sulfuric acid were added. The final composition of the gel was as set forth in Table 6:

[0156] Hydrothermal synthesis was conducted for 60h at 150°C using vertical stirring apparatus. After synthesis, sample was collected by filtration, washed with DI water and dried at 80°C.

[0157] When trimethylbenzylammonium template was used, the peak at 20=9.7 degrees was very weak and broadened from the XRD patterns (Figure ). As from Figure 1, this signifies that the product is rich with OFF phase, the counterpart of ERI in this system. As such, the subtle difference in the organic structure plays a significant role for deciding the relative concentrations of ERI / OFF within the intergrowth, also exemplifying the uniqueness of TMCh and DMECh as ERI selective structure directing agent.

[0158] 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 of skill 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. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

We Claim:

1. A process for preparing a zeolite material having an ERI / OFF framework structure comprising X2O3 and YO2, wherein X is a trivalent element and Y is a tetravalent element, which includes(1) preparing a synthesis mixture comprising:(A) a source for X2O3.(B) a source for YO2, and(C) a source for at least one organic structure directing agent (OSDA) comprising a compound according to formula (I),wherein R1 to R3, independently from each other, are selected from a linear or branched C1-C4 alkyl, andR4 to R8. independently from each other, are H. hydroxyl, or linear or branched C1-C6 alkyl; and(2) subjecting the synthesis mixture to crystallization conditions to form an ERI / OFF-type framework structure.

2. The process of claim 1, wherein at least two of Rl, R2 and R3 are methyl.

3. The process of claim 1, wherein each of Rl, R2 and R3 is methyl.

4. The process of claim 1, wherein at least one of Rl, R2 and R3 is ethyl.

5. The process of claim 1, wherein Y is selected from Si, Sn, Ti, Zr, Ge, and mixtures thereof.

6. The process of claim 1, wherein X is selected from the group consisting of Al. B, In, Ga and any combinations thereof.

7. The process of claim 1 , wherein the source for X2O3 is a zeolite compound, a non-zeolitic alumina compound, an aluminum salt or a combination thereof.

8. The process of claim 1, wherein the zeolitic material has a crystal size of 100 pm or less.

9. The process of claim 1, wherein the zeolite material comprises a C / N ratio of about 7 to about 15.

10. The process of claim 1, wherein a second organic structure directing agent (OSDA) is added to the synthesis mixture.

11. The process of claim 1, wherein the zeolite material has a Si / A12 molar ratio (SAR) of 5 to 25.

12. The process of claim 1, wherein the synthesis mixture is a gel having a Si / A12 molar ratio (SAR) of 5 to 30.

13. The process of claim 1, wherein the compound of formula (I) is selected from trimethylcyclohexylammonium (TMCh) and dimethylethylcyclohexylammonium (DMECh) or any combinations thereof.

14. A zeolite material having an ERI / OFF framework structure prepared according to the process of claim 1.

15. A zeolite material having an ERI / OFF framework structure comprising an amount of an organic structure directing agent within the pores, wherein the organic structure directing agent comprises a compound according to formula (I) ),wherein R1 to R3, independently from each other, are selected from a linear or branched C1-C4 alkyl, andR4 to R8, independently from each other, are H, hydroxyl, or linear or branched C1-C6 alkyl;.

16. A catalyst, an adsorbent, or an ion-exchanger comprising the zeolite material having an ERI / OFF framework structure prepared according to the process of claim 1.

17. An exhaust treatment system comprising a catalyst or an adsorbent according to claim 1.

18. A selective catalytic reduction catalyst comprising the zeolite material having an ERI / OFF framework structure prepared according to the process of claim 1.

19. A zeolite material having an ERI / OFF framework structure containing at least one organic structure directing agent (OSDA) comprising a compound according to formula (I) in claim 1.

20. A zeolite material having an ERI / OFF framework structure having peak features of about 25-30 ppm and of about 70-80 ppm in 13C MAS NMR spectra.

Images