Process for preparing molecular sieves using 1, 1-diethyl-2, 6-dimethylpiperidine-1-onium and molecular sieves prepared therefrom

Abstract

Disclosed herein is a process for preparing a molecular sieve wherein the process comprises forming a synthetic gel comprising an aluminum source, a silicon source, an organic structure directing agent, water, an alkali source, and optionally a seed crystal; and heating the synthetic gel to obtain the molecular sieve, wherein the organic structure directing agent comprises a 1, 1-diethyl-2, 6-dimethylpiperidine-1-onium cation, and the molecular sieve comprises a framework type that is not AEI. Also disclosed are molecular sieves prepared according to the disclosed methods, selective catalytic reduction catalysts comprising the disclosed molecular sieves, and methods for selective catalytic reduction using the disclosed selective catalytic reduction catalysts.

Description

[0001] Disclosed herein is a method for preparing a molecular sieve, wherein the method comprises forming a synthesis gel, the synthesis gel comprising an aluminum source, a silicon source, an organic structure directing agent, water, an alkali source and optional seed crystals; and heating the synthesis gel to obtain the molecular sieve; wherein the organic structure directing agent comprises a 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation, and the molecular sieve comprises a framework type that is not AEI. Also disclosed are a molecular sieve prepared according to the disclosed method, a selective catalytic reduction catalyst comprising the disclosed molecular sieve, and a method for selective catalytic reduction using the disclosed selective catalytic reduction catalyst.

[0002] Internal combustion engines, combustion devices and nitric acid production plants emit nitrogen oxides (NO x ) gas mixture, producing air pollution that may cause environmental health hazards, such as smog and acid rain. Various methods can be used to reduce NO x Related air pollution, including the catalytic reduction of nitrogen oxides. For example, carbon monoxide, hydrogen or lower hydrocarbons can be used as non-selective NO x Alternatively, ammonia or an ammonia precursor (such as, for example, urea) can be used as a selective NO reduction agent in a process known as selective catalytic reduction (SCR). x Reductant in the reduction process. In SCR, a high degree of nitrogen oxide removal can be achieved using a small amount of reductant.

[0003] Molecular sieves have been used as catalysts for SCR and other reactions including, for example, methanol to olefins (MTO). Molecular sieves are catalysts with typical pore sizes in the range of to Aluminosilicate materials with a substantially regular porous structure that can be used as catalysts within the range of. Illustratively, certain molecular sieves with 8-ring pore openings and double six-ring secondary building blocks have been used as SCR catalysts. An example of a molecular sieve framework is chabazite (CHA), a small-pore molecular sieve structure with 8-ring pore openings accessible through its 3-dimensional porosity. The double 6-ring building blocks give the chabazite a cage-like structure through the connection of 4 rings. AEI and AFX type molecular sieves are alternative non-limiting examples of small-pore cage-like molecular sieves that can also be used in catalysts (including catalysts for the selective reduction of nitrogen oxides).

[0004] Novel synthetic routes and molecular sieve morphologies can produce molecular sieves with improved performance in SCR and / or other applications. The choice of molecular sieve synthesis route can affect the structure, stability and / or activity of the resulting molecular sieve. Illustratively, the defect density in the molecular sieve framework can affect the hydrothermal stability and / or catalytic activity of the molecular sieve.

[0005] Selective catalytic reduction catalysts are often exposed to high temperature hydrothermal conditions. Under harsh hydrothermal conditions, the activity of transition metal ion-exchanged molecular sieves may decrease.

[0006] Therefore, there is a need for molecular sieves having, for example, enhanced selective catalytic reduction and improved methods for making the same.

[0007] A method for preparing a molecular sieve is disclosed, wherein the method comprises: forming a synthesis gel, the synthesis gel comprising an aluminum source, a silicon source, an organic structure directing agent, water, an alkali source and optional seed crystals; and heating the synthesis gel to obtain the molecular sieve; wherein the organic structure directing agent comprises a 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation, and the molecular sieve comprises a framework type other than AEI. As used herein, the expression "the molecular sieve comprises a framework type other than AEI" means that the zeolite may be mainly a framework other than AEI, such as CHA, but may appropriately contain a small amount of AEI. For example, a molecular sieve comprising a framework type other than AEI may contain 0% to 10% AEI, or more preferably 0% to 5% AEI, as determined by the peak area of ​​XRD.

[0008] In some embodiments, the aluminum source is selected from molecular sieve Y (faujasite), formula Al(OR) 3 Compounds, aluminum oxide, aluminum hydroxide and combinations thereof; and wherein R is selected from C 2 To C 5 Alkyl group.

[0009] In some embodiments, the silicon source is selected from the group consisting of molecular sieve Y (faujasite), sodium silicate, colloidal silica, fumed silica, precipitated silica, and combinations thereof.

[0010] In some embodiments, the organic structure directing agent comprises 1,1-diethyl-2,6-dimethylpiperidin-1-ium hydroxide.

[0011] In some embodiments, the alkalinity source comprises at least one element selected from sodium and potassium.

[0012] In some embodiments, the heating step is performed at a temperature in the range of 100°C to 200°C for a duration in the range of 30 minutes to 100 hours.

[0013] In some embodiments, the molecular sieve comprises a CHA framework type.

[0014] In some embodiments, the molecular sieve has a degree of crystallinity in the range of 50% to 100%.

[0015] In some embodiments, the molecular sieve comprises 50% to 100% CHA framework type based on total crystalline phase intensity as determined by x-ray diffraction.

[0016] In some embodiments, the synthesis gel comprises seed crystals, and the seed crystals comprise a CHA framework type.

[0017] In some embodiments, the synthetic gel has one or more of the following properties: SiO 2 :Al 2 O 3 ratio is in the range of 15 to 50, the Na:Si ratio is in the range of 0.1 to 1, the ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, the OH:Si ratio is in the range of 0.1 to 1, and H 2 The O:Si ratio is in the range of 5-50.

[0018] In some embodiments, the molecular sieve has an average crystal diameter in the range of 0.1 μm to 2 μm as determined by scanning electron microscopy.

[0019] In some embodiments, the organic structure directing agent comprises a trimethyladamantanium cation.

[0020] In some embodiments, the molecular sieve is a Na-form molecular sieve, and the method further comprises one or more steps selected from the following: ion exchanging the Na-form molecular sieve with an aqueous ammonia solution to obtain NH 4 + Form molecular sieve; calcining the NH at a temperature in the range of 200°C to 800°C 4 + form molecular sieve for a duration in the range of 30 minutes to 12 hours to obtain an H form molecular sieve; ion exchanging and / or impregnating the H form molecular sieve with a transition metal M to obtain an M form molecular sieve; calcining the M form molecular sieve at a temperature in the range of 200° C. to 800° C. for a duration in the range of 30 minutes to 12 hours.

[0021] In some embodiments, the transition metal M is selected from iron, copper, and combinations thereof.

[0022] Molecular sieves prepared according to the disclosed methods are disclosed.

[0023] Disclosed is a CHA molecular sieve containing 1,1-diethyl-2,6-dimethylpiperidin-1-ium.

[0024] In some embodiments, the molecular sieve has at least one property selected from the following: a molar ratio of silica to alumina in the range of 5 to 50, a surface area of ​​the molecular sieve in the range of 450 m 2 / g to 650m 2 / g, and the substrate surface area is 5m 2 / g to 50m 2 / g range.

[0025] Disclosed is a selective catalytic reduction catalyst comprising a Cu-form molecular sieve prepared according to the disclosed method.

[0026] A method for the selective catalytic reduction of nitrogen oxides in an exhaust gas is disclosed, wherein the method comprises contacting the exhaust gas with a disclosed selective catalytic reduction catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Scanning electron microscope images of exemplary embodiments of the present disclosure are depicted.

[0028] Figure 2 An x-ray diffraction pattern of an exemplary embodiment of the present disclosure is depicted.

[0029] Figure 3 An x-ray diffraction pattern of an exemplary embodiment of the present disclosure is depicted.

[0030] Figure 4 The selective catalytic reduction activity of exemplary embodiments of the present disclosure is depicted.

[0031] Figure 5 The selective catalytic reduction activity of exemplary embodiments of the present disclosure is depicted.

[0032] Fig. 6A A SEM image of Example L is depicted.

[0033] Figure 6B Another SEM image of Example L is depicted.

[0034] Figure 7 Depicted is the x-ray diffraction pattern of Example L after calcination.

[0035] definition :

[0036] As used herein, unless otherwise specified, "a" or "an" entity refers to one or more of that entity, for example, "a compound" refers to one or more compounds or at least one compound. Therefore, the terms "a" (or "an"), "one or more" and "at least one" are used interchangeably herein.

[0037] As used herein, the term "material" refers to elements, components, and / or substances that make up something or can be made into something.

[0038] As used herein, the term "calcining" refers to heating a solid to an elevated temperature (ie, above ambient temperature) in air or oxygen, such as, for example, to remove impurities or volatile materials from the solid.

[0039] As used herein, the term "aluminum source" refers to a material containing aluminum and / or aluminum ions, such as, for example, aluminum salts, aluminum isopropoxide, and / or aluminum hydroxide.

[0040] As used herein, the term "catalyst" or "catalyst composition" refers to a molecule or material that facilitates a reaction.

[0041] As used herein, the term "copper source" refers to a material comprising copper and / or copper ions, such as, for example, a copper salt and / or a copper complex, such as, for example, copper-tetraethylenepentamine.

[0042] As used herein, the term "ion exchange treatment" refers to a process in which one or more ions are incorporated into and / or removed from a molecular sieve. As a non-limiting example, the molecular sieve may be subjected to a copper ion exchange treatment by, for example, mixing the molecular sieve with a material containing copper (such as, for example, CuO) and a solution (such as, for example, an aqueous zirconium acetate solution).

[0043] As used herein, the term "molecular sieve" refers to a material having a substantially regular porous structure. In some embodiments, the molecular sieve is capable of selectively sorting molecules based on size exclusion. In some embodiments, the molecular sieve is a zeolite.

[0044] As used herein, molecular sieves, such as zeolite framework types, are classified by the Structure Commission of the International Zeolite Association according to the rules of the IUPAC Commission on Zeolite Nomenclature. According to this classification, zeolite framework types are assigned three-letter codes and are described in Atlas of Zeolite Framework Types, 5th Edition, Elsevier, London, England (2001).

[0045] As used herein, the term "organic structure directing agent" refers to an organic compound that can affect the morphology and / or structure of a molecular sieve. For example, the organic structure directing agent can be an ionic organic molecule that can be incorporated into the structure of the molecular sieve. The organic structure directing agent can, for example, contain a large and / or sterically bulky organic group. The organic structure directing agent can, for example, contain an adamantane ammonium group. Trimethyl adamantane ammonium is a non-limiting example of an organic structure directing agent.

[0046] As used herein, the term "reducing agent" refers to an agent capable of reducing NO at elevated temperatures (i.e., above ambient temperature). xNon-limiting examples of reducing agents include ammonia, urea, and fuel.

[0047] As used herein, the term "selective catalytic reduction" (SCR) refers to a catalytic process that reduces nitrogen oxides using a reductant.

[0048] As used herein, the term "silicon dioxide source" refers to a material comprising silicon and / or silicon oxides such as, for example, colloidal silica, silicates, sodium silicate, and / or Ludox AS-40.

[0049] As used herein, the term "pore" with respect to the size of a material refers to a material having a pore size smaller than The hole opening (such as, for example, to The material of the hole opening).

[0050] As used herein, the term "heat treating" refers to the process of subjecting a composition to an elevated temperature (ie, above ambient temperature) for a sustained period of time.

[0051] As used herein, the term "zeolite" refers to an aluminosilicate material having a substantially regular porous structure. The zeolites of the present disclosure may have many different framework structures having a substantially regular porous structure of molecular size. In some embodiments, the zeolites of the present disclosure have a substantially regular porous structure composed of corner-sharing TO 4 The open 3D framework structure of tetrahedron composition, wherein T is Al or Si. In some embodiments, the non-framework cations of the charge of the balance anion framework are loosely associated with the framework oxygen, and the remaining pore volume is filled with water molecules. In some embodiments, the non-framework cations are exchangeable. In some embodiments, the water molecules are removable.

[0052] The structure of the molecular sieve of the present disclosure can be analyzed using common techniques in the art, such as, for example, x-ray diffraction (XRD). As a non-limiting example, the degree of crystallinity of the molecular sieve of the present disclosure can be determined by XRD analysis.

[0053] As used herein, "phase crystallinity" refers to the weight percent of a specified crystalline phase based on the total weight of the molecular sieve.

[0054] As used herein, "1,1-diethyl-2,6-dimethylpiperidin-1-ium" refers to a cation having the following structure.

[0055]

[0056] 1,1-Diethyl-2,6-dimethylpiperidin-1-ium

[0057] Method for preparing molecular sieves :

[0058] A method for preparing a molecular sieve is disclosed, wherein the method comprises: forming a synthesis gel, the synthesis gel comprising an aluminum source, a silicon source, an organic structure directing agent, water, an alkali source and optional seed crystals; and heating the synthesis gel to obtain the molecular sieve; wherein the organic structure directing agent comprises a 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation, and the molecular sieve comprises a framework type that is not AEI.

[0059] In some embodiments, the aluminum source is selected from molecular sieve Y (faujasite), formula Al(OR) 3 Compounds, aluminum oxide, aluminum hydroxide and combinations thereof; and wherein R is selected from C 2 To C 5 Alkyl group.

[0060] In some embodiments, the silicon source is selected from the group consisting of molecular sieve Y (faujasite), sodium silicate, colloidal silica, fumed silica, precipitated silica, and combinations thereof.

[0061] In some embodiments, the Si source and the Al source can be the same or different.

[0062] In some embodiments, the organic structure directing agent comprises 1,1-diethyl-2,6-dimethylpiperidin-1-ium hydroxide.

[0063] In some embodiments, the alkalinity source comprises at least one element selected from sodium and potassium.

[0064] In some embodiments, the synthesis gel comprises seed crystals, and the seed crystals comprise a CHA framework type.

[0065] In some embodiments, the heating step is performed at a temperature in the range of 100°C to 200°C for a duration in the range of 30 minutes to 100 hours.

[0066] In some embodiments, the synthetic gel has one or more of the following properties: SiO 2 :Al 2 O 3 ratio is in the range of 15 to 50, the Na:Si ratio is in the range of 0.1 to 1, the ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, the OH:Si ratio is in the range of 0.1 to 1, and H 2 The O:Si ratio is in the range of 5-50.

[0067] In some embodiments, the synthetic gel has two or more of the following properties: SiO 2 :Al 2 O 3ratio is in the range of 15 to 50, the Na:Si ratio is in the range of 0.1 to 1, the ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, the OH:Si ratio is in the range of 0.1 to 1, and H 2 The O:Si ratio is in the range of 5-50.

[0068] In some embodiments, the synthetic gel has three or more of the following properties: SiO 2 :Al 2 O 3 ratio is in the range of 15 to 50, the Na:Si ratio is in the range of 0.1 to 1, the ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, the OH:Si ratio is in the range of 0.1 to 1, and H 2 The O:Si ratio is in the range of 5-50.

[0069] In some embodiments, the synthetic gel has four or more of the following properties: SiO 2 :Al 2 O 3 ratio is in the range of 15 to 50, the Na:Si ratio is in the range of 0.1 to 1, the ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, the OH:Si ratio is in the range of 0.1 to 1, and H 2 The O:Si ratio is in the range of 5-50.

[0070] In some embodiments, the synthetic gel has the following properties: SiO 2 :Al 2 O 3 ratio is in the range of 15 to 50, the Na:Si ratio is in the range of 0.1 to 1, the ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, the OH:Si ratio is in the range of 0.1 to 1, and H 2 The O:Si ratio is in the range of 5-50.

[0071] In some embodiments, the organic structure directing agent comprises a trimethyladamantanium cation.

[0072] In some embodiments, the method further comprises one or more steps selected from the following: ion exchange the Na form molecular sieve with an aqueous ammonia solution to obtain NH 4 + Form molecular sieve; calcining the NH at a temperature in the range of 200°C to 800°C 4+ form molecular sieve for a duration in the range of 30 minutes to 12 hours to obtain an H form molecular sieve; ion exchanging and / or impregnating the H form molecular sieve with a transition metal M to obtain an M form molecular sieve; calcining the M form molecular sieve at a temperature in the range of 200° C. to 800° C. for a duration in the range of 30 minutes to 12 hours; treating the Na form molecular sieve with an acid exchange or acid treatment to obtain an H form molecular sieve; and ion exchanging the Na form molecular sieve to obtain the M form molecular sieve.

[0073] In some embodiments, the method further comprises two or more steps selected from the following: ion exchanging the Na form molecular sieve with an aqueous ammonia solution to obtain NH 4 + Form molecular sieve; calcining the NH at a temperature in the range of 200°C to 800°C 4 + form molecular sieve for a duration in the range of 30 minutes to 12 hours to obtain the H form molecular sieve; ion exchanging and / or impregnating the H form molecular sieve with a transition metal M to obtain the M form molecular sieve; and calcining the M form molecular sieve at a temperature in the range of 200° C. to 800° C. for a duration in the range of 30 minutes to 12 hours.

[0074] In some embodiments, the method further comprises three or more steps selected from the following: ion exchange of the Na form molecular sieve with an aqueous ammonia solution to obtain NH 4 + Form molecular sieve; calcining the NH at a temperature in the range of 200°C to 800°C 4 + form molecular sieve for a duration in the range of 30 minutes to 12 hours to obtain the H form molecular sieve; ion exchanging and / or impregnating the H form molecular sieve with a transition metal M to obtain the M form molecular sieve; and calcining the M form molecular sieve at a temperature in the range of 200° C. to 800° C. for a duration in the range of 30 minutes to 12 hours.

[0075] In some embodiments, the method further comprises: exchanging the Na-form molecular sieve with an aqueous ammonia solution to obtain NH 4 + Form molecular sieve; calcining the NH at a temperature in the range of 200°C to 800°C 4 +form molecular sieve for a duration in the range of 30 minutes to 12 hours to obtain the H form molecular sieve; ion exchanging and / or impregnating the H form molecular sieve with a transition metal M to obtain the M form molecular sieve; and calcining the M form molecular sieve at a temperature in the range of 200° C. to 800° C. for a duration in the range of 30 minutes to 12 hours.

[0076] In some embodiments, the transition metal M is selected from iron, copper, and combinations thereof.

[0077] In some embodiments, the synthesis gel is heated to a temperature in the range of 90°C to 200°C for a reaction time in the range of 0.1 hours to 160 hours. In some embodiments, the synthesis gel is heated to a temperature in the range of 120°C to 200°C for a reaction time in the range of 1 hour to 160 hours. In some embodiments, the synthesis gel is heated to a temperature in the range of 140°C to 190°C for a reaction time in the range of 10 hours to 160 hours. In some embodiments, the synthesis gel is heated to a temperature in the range of 140°C to 190°C for a reaction time in the range of 20 hours to 100 hours.

[0078] In some embodiments, the synthesis gel further comprises at least one additional component selected from the group consisting of sodium hydroxide, sulfuric acid, sodium sulfate, and combinations thereof.

[0079] Molecular sieve :

[0080] Disclosed is a CHA molecular sieve containing 1,1-diethyl-2,6-dimethylpiperidin-1-ium.

[0081] Molecular sieves prepared according to the disclosed methods are disclosed.

[0082] In some embodiments, the molecular sieve comprises a CHA framework type.

[0083] In some embodiments, the molecular sieve has a degree of crystallinity in the range of 50% to 100%. In some embodiments, the molecular sieve has a degree of crystallinity in the range of 60% to 100%. In some embodiments, the molecular sieve has a degree of crystallinity in the range of 70% to 95%. In some embodiments, the molecular sieve has a degree of crystallinity in the range of 80% to 95%.

[0084] In some embodiments, the molecular sieve comprises 50% to 100% of the CHA framework type in terms of total crystalline phase intensity as determined by x-ray diffraction. In some embodiments, the molecular sieve comprises 50% to 98% of the CHA framework type in terms of total crystalline phase intensity as determined by x-ray diffraction. In some embodiments, the molecular sieve comprises 50% to 95% of the CHA framework type in terms of total crystalline phase intensity as determined by x-ray diffraction. In some embodiments, the molecular sieve comprises 70% to 100% of the CHA framework type in terms of total crystalline phase intensity as determined by x-ray diffraction. In some embodiments, the molecular sieve comprises 80% to 98% of the CHA framework type in terms of total crystalline phase intensity as determined by x-ray diffraction. In some embodiments, the molecular sieve comprises 80% to 95% of the CHA framework type in terms of total crystalline phase intensity as determined by x-ray diffraction.

[0085] In some embodiments, the molecular sieve has an average crystal diameter in the range of 0.1 μm to 2 μm as determined by scanning electron microscopy.

[0086] In some embodiments, the molecular sieve is a Na form molecular sieve. In some embodiments, the molecular sieve is NH 4 + In some embodiments, the molecular sieve is an H-form molecular sieve. In some embodiments, the molecular sieve is an M-form molecular sieve, wherein M is one or more transition metals. In some embodiments, the molecular sieve is a Cu-form molecular sieve. In some embodiments, the molecular sieve is an Fe-form molecular sieve.

[0087] In some embodiments, the molecular sieve has at least one property selected from the following: a molar ratio of silica to alumina in the range of 5 to 50, a surface area of ​​the molecular sieve in the range of 450 m 2 / g to 650m 2 / g, and the substrate surface area is 5m 2 / g to 50m 2 / g range.

[0088] In some embodiments, the molecular sieve has two or more properties selected from the following: a molar ratio of silica to alumina in the range of 5 to 50, a molecular sieve surface area in the range of 450 m 2 / g to 650m 2 / g, and the substrate surface area is 5m 2 / g to 50m 2 / g range.

[0089] In some embodiments, the molecular sieve has the following properties: a molar ratio of silica to alumina in the range of 5 to 50, a surface area of ​​the molecular sieve in the range of 450 m 2 / g to 650m 2 / g, and the substrate surface area is 5m 2 / g to 50m 2 / g range.

[0090] In some embodiments, the molecular sieve has a 2 / g to 1000m 2 In some embodiments, the molecular sieve has a surface area in the range of 400 m / g. 2 / g to 800m 2 In some embodiments, the molecular sieve has a surface area in the range of 500 m / g. 2 / g to 600m 2 / g range of molecular sieve surface area.

[0091] In some embodiments, the molecular sieve has a 2 / g to 100m 2 In some embodiments, the molecular sieve has a substrate surface area in the range of 1 m 2 / g to 50m 2 In some embodiments, the molecular sieve has a substrate surface area in the range of 1 m 2 / g to 40m 2 In some embodiments, the molecular sieve has a substrate surface area in the range of 1 m 2 / g to 20m 2 In some embodiments, the molecular sieve has a substrate surface area in the range of 1 m 2 / g to 19m 2 In some embodiments, the molecular sieve has a substrate surface area in the range of 5 m 2 / g to 19m 2 / g range of substrate surface area.

[0092] In some embodiments, the molecular sieve has a primary phase crystallinity greater than 90%. In some embodiments, the molecular sieve has a chabazite crystallinity greater than 90%. In some embodiments, the molecular sieve has a secondary phase crystallinity less than 50%. In some embodiments, the molecular sieve has a secondary phase crystallinity less than 10%. In some embodiments, the molecular sieve has a mordenite crystallinity less than 50%. In some embodiments, the molecular sieve has a mordenite crystallinity less than 10%. In some embodiments, the molecular sieve has an amorphous phase less than 50%. In some embodiments, the molecular sieve has an amorphous phase less than 10%. In some embodiments, the molecular sieve has a primary phase crystallinity greater than 50% and a secondary phase crystallinity in the range of 1% to 50%. In some embodiments, the molecular sieve has a primary phase crystallinity greater than 80% and a secondary phase crystallinity in the range of 1% to 20%. In some embodiments, the molecular sieve has a primary phase crystallinity greater than 90% and a secondary phase crystallinity in the range of 1% to 10%. In some embodiments, the molecular sieve has greater than 50% chabazite and mordenite in the range of 1% to 50%. In some embodiments, the molecular sieve has greater than 80% chabazite and mordenite in the range of 1% to 20%. In some embodiments, the molecular sieve has greater than 90% chabazite and mordenite in the range of 1% to 10%. In some embodiments, the molecular sieve has greater than 80% chabazite and mordenite in the range of 1% to 20%. In some embodiments, the molecular sieve has greater than 90% chabazite and mordenite in the range of 0% to 10%.

[0093] In some embodiments, the molecular sieve is a Cu-form molecular sieve. In some embodiments, the Cu-form molecular sieve is calculated as CuO and based on the gross weight of the molecular sieve, and the Cu-form molecular sieve includes copper in an amount in the range of 0.1 wt % to 20 wt %. In some embodiments, the Cu-form molecular sieve is calculated as CuO and based on the gross weight of the molecular sieve, and the Cu-form molecular sieve includes copper in an amount in the range of 0.1 wt % to 10 wt %. In some embodiments, the Cu-form molecular sieve is calculated as CuO and based on the gross weight of the molecular sieve, and the Cu-form molecular sieve includes copper in an amount in the range of 0.1 wt % to 5 wt %. In some embodiments, the Cu-form molecular sieve is calculated as CuO and based on the gross weight of the molecular sieve, and the Cu-form molecular sieve includes copper in an amount in the range of 1 wt % to 5 wt %. In some embodiments, the Cu-form molecular sieve is calculated as CuO and based on the gross weight of the molecular sieve, and the Cu-form molecular sieve includes copper in an amount in the range of 2 wt % to 5 wt %.

[0094] In some embodiments, the molecular sieve has less than 20% extra-framework aluminum based on the total aluminum content.

[0095] Catalyst substrate :

[0096] The molecular sieve of the present disclosure can be deposited on a substrate. The substrate can be any material commonly used to prepare a catalyst, such as, for example, a substrate having a ceramic or metal honeycomb structure. Any suitable substrate can be used, such as, for example, a monolithic substrate (referred to as a honeycomb flow-through substrate) having a thin parallel gas flow path, which extends from the inlet face or outlet face of the substrate through the substrate, so that the path is open to the fluid flow through the substrate. The path from its fluid inlet to its fluid outlet, which can be substantially a straight path, can be defined by a wall, and the molecular sieve is deposited on these walls as a washcoat so that the gas flowing through the path contacts the molecular sieve. The flow path of the monolithic substrate can be a thin-walled channel, which can have any suitable cross-sectional shape and size, such as, for example, a trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical or circular cross section. Such structures can contain 60 to 400 or more gas inlet openings (i.e., pores) per square inch of cross section.

[0097] The substrate can also be a wall-flow filter substrate, in which the channels are alternately blocked, thereby allowing the gaseous stream to enter the channel from one direction (inlet direction), flow through the channel wall, and then leave the channel from another direction (outlet direction). The molecular sieve of the present disclosure can be coated on a flow-through or wall-flow filter. If a wall-flow substrate is utilized, the resulting system can be capable of removing particulate matter together with gaseous pollutants (such as, for example, nitrogen oxides). The wall-flow filter substrate can be made of materials known in the art (such as, for example, cordierite, aluminum titanate, or silicon carbide). It should be understood that the loading of the molecular sieve on the wall-flow substrate will depend on the substrate properties such as porosity and wall thickness, and will generally be lower than the loading on the flow-through substrate.

[0098] The ceramic substrate may be made of any suitable refractory material such as, for example, cordierite, cordierite-alumina, silicon nitride, zircon-mullite, spodumene, alumina-silica magnesia, zirconium silicate, sillimanite, magnesium silicate, zircon, petalite, alpha-alumina, or aluminosilicate.

[0099] The substrate that can be used for the molecular sieve of the present disclosure can also be metallic in nature and be composed of one or more metals or metal alloys. The metal substrate can be adopted in various shapes (such as, for example, corrugated sheets or monolithic forms). Suitable metal carriers include heat-resistant metals and metal alloys, such as, for example, titanium and stainless steel and other alloys in which iron is a substantial component or a major component. Such alloys can contain one or more nickel, chromium and / or aluminum, and the total amount of these metals can advantageously account for at least 15% by weight of the alloy, such as 10% by weight-25% by weight of chromium, 3% by weight-8% by weight of aluminum and up to 20% by weight of nickel. The alloy may also contain a small amount or trace amount of one or more other metals, such as, for example, manganese, copper, vanadium or titanium. The surface or metal substrate can be oxidized at high temperatures (such as, for example, 1000° C. and higher temperatures) to improve corrosion resistance by forming an oxide layer on the surface of the substrate. High temperature induced oxidation can enhance the adhesion of refractory metal oxide carriers and catalytically promoted metal components to the substrate.

[0100] Selective Catalytic Reduction Catalyst :

[0101] A selective catalytic reduction catalyst is disclosed that includes the disclosed molecular sieve disposed on a substrate.

[0102] In some embodiments, the molecular sieve is a Cu form molecular sieve.

[0103] Methods of treating waste gas :

[0104] A method for the selective catalytic reduction of nitrogen oxides in an exhaust gas is disclosed, wherein the method comprises contacting the exhaust gas with a selective catalytic reduction catalyst disclosed herein.

[0105] Non-limiting exemplary embodiments :

[0106] Without limitation, exemplary disclosed embodiments include:

[0107] 1. A method for preparing a molecular sieve, wherein the method comprises: forming a synthesis gel, the synthesis gel comprising an aluminum source, a silicon source, an organic structure directing agent, water, an alkali source and / or an alkaline earth metal source and optional seed crystals; and heating the synthesis gel to obtain the molecular sieve; wherein the organic structure directing agent comprises a 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation, and the molecular sieve comprises a framework type that is not AEI.

[0108] 2. The method according to embodiment 1, wherein the aluminum source is selected from zeolites, Al(OR) 3 Compounds, aluminum oxide, aluminum hydroxide and combinations thereof; and wherein R is selected from C 2 To C 5 Alkyl group.

[0109] 3. The method according to embodiment 1 or 2, wherein the silicon source is selected from zeolite, sodium silicate, colloidal silica, fumed silica, precipitated silica and combinations thereof.

[0110] 4. The method according to any one of embodiments 1 to 3, wherein the organic structure directing agent comprises 1,1-diethyl-2,6-dimethylpiperidin-1-ium hydroxide.

[0111] 5. The process according to any one of embodiments 1 to 4, wherein the synthesis gel comprises the alkali source and the alkali source comprises at least one base selected from sodium and potassium.

[0112] 6. The method according to any one of embodiments 1 to 5, wherein the heating step is at 100°C

[0113] The treatment is carried out at a temperature in the range of 30 minutes to 100 hours.

[0114] 7. The method according to any one of embodiments 1 to 6, wherein the molecular sieve comprises a CHA framework type.

[0115] 8. The method according to any one of embodiments 1 to 7, wherein the molecular sieve has a degree of crystallinity in the range of 50% to 100%.

[0116] 9. The method according to any one of embodiments 1 to 8, wherein the molecular sieve comprises 50% to 100% CHA framework type based on total crystalline phase intensity as determined by x-ray diffraction.

[0117] 10. The method according to any one of embodiments 1 to 9, wherein the synthesis gel comprises the seed crystal, and the seed crystal comprises a CHA framework type.

[0118] 11. The method according to any one of embodiments 1 to 10, wherein the synthesis gel has one or more of the following properties: SiO 2 :Al 2 O 3 ratio is in the range of 10 to 50, the M:Si ratio is in the range of 0.1 to 1, the ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, the OH:Si ratio is in the range of 0.1 to 1, and H 2 The O:Si ratio is in the range of 5 to 50; wherein M is an alkali metal and / or an alkaline earth metal.

[0119] 12. The method according to any one of embodiments 1 to 11, wherein the molecular sieve has an average crystal diameter in the range of 0.1 μm to 2 μm as determined by scanning electron microscopy.

[0120] 13. The method according to any one of embodiments 1 to 12, wherein the organic structure directing agent comprises a trimethyladamantanium cation.

[0121] 14. The method according to any one of embodiments 1 to 13, wherein the molecular sieve is a Na-form molecular sieve and the method further comprises one or more steps selected from the following: ion-exchanging the Na-form molecular sieve with an aqueous ammonia solution to obtain NH 4+ Form molecular sieve; calcining the NH at a temperature in the range of 200°C to 800°C 4+ form molecular sieve for a duration ranging from 30 minutes to 12 hours to obtain the H form molecular sieve;

[0122] The H form molecular sieve is ion exchanged and / or impregnated with a transition metal M to obtain the M form molecular sieve; the M form molecular sieve is calcined at a temperature in the range of 200°C to 800°C for a duration in the range of 30 minutes to 12 hours; the Na form molecular sieve is treated with acid exchange or acid treatment to obtain the H form molecular sieve; and the Na form molecular sieve is ion exchanged to obtain the M form molecular sieve.

[0123] 15. The method according to embodiment 14, wherein the transition metal M is selected from iron, copper and combinations thereof.

[0124] 16. A molecular sieve prepared according to the method of any one of embodiments 1 to 15.

[0125] 17. The molecular sieve according to embodiment 16, wherein the molecular sieve has at least one property selected from the following: a molar ratio of silica to alumina in the range of 5 to 50, a zeolite surface area in the range of 450 m 2 / g to 650m 2 / g range, and the substrate surface area is

[0126] 5m 2 / g to 50m 2 / g range.

[0127] 18. A selective catalytic reduction catalyst comprising a Cu-form molecular sieve prepared according to the method of embodiment 14 or 15.

[0128] 19. A method for the selective catalytic reduction of nitrogen oxides in exhaust gas, wherein the method comprises contacting the exhaust gas with the selective catalytic reduction catalyst according to embodiment 18.

[0129] 20. A CHA zeolite comprising 1,1-diethyl-2,6-dimethylpiperidin-1-ium.

[0130] 21. The method according to any one of embodiments 1 to 15, wherein the aluminum source is zeolite Y

[0131] (Faujasite).

[0132] 22. The method according to any one of embodiments 1 to 15, wherein the silicon source is zeolite Y

[0133] (Faujasite).

[0134] Claims or specific embodiments that include "or" or "and / or" between at least one member of the group are considered satisfied if one, more than one, or all of the group members are present in, used in, or otherwise related to a given product or method, unless indicated to the contrary or otherwise obvious from the context. The present disclosure includes embodiments in which exactly one member of the group is present in, used in, or otherwise related to a given product or method. The present disclosure includes embodiments in which more than one or all of the group members are present in, used in, or otherwise related to a given product or method.

[0135] In addition, the present disclosure encompasses all variations, combinations and arrangements, wherein at least one limitation, element, clause and descriptive term from at least one of the listed claims is introduced into another claim. For example, any claim subordinate to another claim can be modified to include at least one limitation found in any other claim subordinate to the same basic claim. In the case where an element exists in a list (such as, for example, in Markush (Markush) group format), each subgroup of the element is also disclosed, and any element can be removed from the group. It should be understood that, in general, in the case where the present disclosure or the various aspects of the present disclosure are referred to as including specific elements and / or features, the embodiments of the present disclosure or the various aspects of the present disclosure are made up of or substantially made up of such elements and / or features. For simplicity, these embodiments are not specifically described herein. When a range is given, endpoints are also included. In addition, unless otherwise stated or clearly seen from the context and the understanding of those of ordinary skill in the art, otherwise in different embodiments of the present disclosure, the value expressed as a range can be assumed to be any specific value or sub-range within the range, unless the context clearly indicates otherwise.

[0136] Those skilled in the art will recognize or be able to ascertain, using no more than routine experimentation, many equivalents to the specific embodiments of the disclosure described herein. Such equivalents are intended to be encompassed by the following claims. Example

[0137] The following examples are intended to be illustrative, and are not meant to limit the scope of the present disclosure in any way.

[0138] abbreviation

[0139] % Percent

[0140] wt.% weight percentage

[0141] SiO 2 Silicon dioxide

[0142] Al 2 O 3 Alumina

[0143] Na 2 O Sodium Oxide

[0144] H 2 O Water

[0145] FAU Molecular Sieve Y (Faujasite)

[0146] Sodium form of Na-FAU molecular sieve Y (faujasite)

[0147] NH 4+ Ammonium ion

[0148] CuO Copper(II) oxide

[0149] N 2 Dinitrogen

[0150] NO Nitrous oxide

[0151] NO 2 Nitrogen dioxide

[0152] NOx Nitrogen Oxides

[0153] EF-Al Frame Aluminum

[0154] MSA matrix surface area

[0155] ZSA Molecular Sieve Surface Area

[0156] SAR Silica to Alumina Ratio

[0157] XRD X-ray diffraction

[0158] The following is an exemplary method for preparing an exemplary molecular sieve.

[0159] Procedure for determining percent crystallinity

[0160] The sample was ground using a mortar and pestle, and then loaded into a flat rack for analysis. The PANalytical MPD X'Pert Pro diffraction system was used to collect data in the Bragg-Brentano geometry. CuKα radiation was used in the analysis, with the generator set to 45 kV and 40 mA. The optical path consisted of: 1 / 8 divergence slit, 0.04 radian Soller slit, 15 mm mask, 1 / 4 ° antiscatter slit, 1 / 8 ° antiscatter slit, 0.04 radian Soller slit, Ni filter, and X'Celerator linear position sensitive detector.

[0161] Data were collected from 3° to 70° 2θ using a step length of 0.0167° 2θ and a counting time of 60 s per step. Phase identification was performed using JadePlus 9 analytical X-ray diffraction software. The phase present was identified by searching / matching the PDF-4 / full file database from ICDD (which is the International Diffraction Data Center). Rietveld refinement was performed using Bruker AXS Topas software to determine the percentage of the crystalline phase present.

[0162] Characterization of Molecular Sieve

[0163] Pore ​​volume and surface area characteristics were determined by nitrogen adsorption (BET surface area method). Mesopore and zeolite (micropore) surface areas were measured on a Micromeritics Tristar 3000 series instrument via N adsorption according to ISO 9277. 2 - Determined by adsorptive porosimetry.

[0164] For N 2 Procedure for physical adsorption: Zeolite BET surface area analysis and nitrogen pore size distribution were analyzed on a Micromeritics TriStar 3000 series instrument. The samples were degassed on a Micromeritics SmartPrep degasser for a total of 6 hours (2 hour ramp to 300° C. under dry nitrogen flow, then 4 hours at 300° C.). Nitrogen BET surface area was determined using 5 partial pressure points between 0.08 and 0.20. Nitrogen pore size (BJH) was determined using 33 desorption points.

[0165] The same 5 partial pressure points were used to determine and calculate the zeolite and matrix surface areas using the Harkins and Jura t plots. The diameter of the pores is believed to contribute to the matrix surface area (MSA).

[0166] Synthesis of molecular sieves

[0167] The molecular sieve is prepared by forming a synthesis gel comprising an aluminum source, a silicon source, an organic structure directing agent, water, an alkali source and optional seed crystals; and heating the synthesis gel to obtain the molecular sieve. Tables 1 and 2 provide the raw material details, gel composition and crystallization conditions of the various example materials described. For materials B, G, H and L, sodium hydroxide and sodium sulfate are both sodium sources in the synthesis so that the specified OH / Si ratio and Na / Si ratio are obtained. For material F, potassium hydroxide is the only potassium source in the synthesis gel.

[0168] Table 1:

[0169]

[0170]

[0171] Table 2 :

[0172]

[0173] In Table 2, "Am" indicates amorphous, and "Un" indicates an unknown phase.

[0174] Molecular sieve

[0175] The properties of the prepared molecular sieves are described in Table 2.

[0176] Comparing material A with materials C to F, the formation of a CHA phase was observed when 1,1-diethyl-2,6-dimethylpiperidin-1-ium hydroxide (DEDMPOH) was used. In the absence of TMAdaOH, a different zeolite phase (AEI) was synthesized as seen from materials C and D, regardless of whether CHA zeolite seeds were used in these examples. In the absence of DEDMPOH, a small amount of CHA phase was observed in the product of material E. Due to the different OH / Si ratios of materials E and A, material F shows OH - The alternative source of ions (KOH) did not aid in the synthesis of CHA zeolite in this example. The lack of AEI zeolite formation in Material A suggests that DEDMPOH is more effective in directing the synthesis of CHA zeolite formation using both TMAdaOH and DEDMPOH. + The structural directing role of the cation is slightly altered.

[0177] The zeolite synthesized in Material A contained C and N in a ratio of 11.7, indicating that both OSDA cations were incorporated in the product material. This is reported in Table 2 as Product R 1 / R 2 ratios and calculated from elemental analysis data.

[0178] Material B describes another route to obtain CHA zeolite containing two OSDA cations. In this example, it seems that the use of CHA seeds helps to obtain CHA zeolite as a product, because material G does not show any formation of CHA zeolite. Interestingly, the product R of material B 1 / R 2 The ratio (Table 2) is higher than that of gel R 1 / R 2 ratio (Table 1), which is opposite to that observed for Material A.

[0179] Figure 1 Depicted are SEM images of materials A, B, H and I. These materials have similar morphology when viewed by this technique. Fig. 6A and 6B A SEM image of material L is depicted.

[0180] Although CHA zeolite materials A and B are prepared by synthesis using zeolitic aluminum sources, it is believed that similar processes using non-zeolitic aluminum sources will also produce CHA molecular sieves.

[0181] Selective Catalytic Reduction Catalyst

[0182] The SCR catalyst was prepared using materials A, B, H and I as follows:

[0183] Ion exchange of Na-form zeolite : All samples were subjected to ammonium exchange to remove the base present in the pores, and then subsequently calcined (450° C. for 6 h) to obtain the corresponding H-form materials.

[0184] Impregnation with Cu and forming the catalyst : H-form zeolite powder was impregnated with an aqueous copper (II) nitrate solution by incipient wetness impregnation and stored in a sealed container at 50°C for 20 h. It was then dried and calcined at 450°C for 5 h to obtain Cu-loaded zeolite.

[0185] Catalyst formation : By using Zr acetate as a binder (5 wt% ZrO 2 ), the Cu-loaded zeolite was slurried and then dried under stirring to prepare the test sample. It was then calcined at 550°C for 1 hour. The obtained product was crushed and then aged at 650°C for 50 hours in a 10% steam / air mixture flow or at 820°C for 16 hours in a 10% steam / air mixture flow (as specified).

[0186] Figure 7 XRD data for example Example L after calcination is shown.

[0187] Selective catalytic reduction of nitrogen oxides

[0188] The SCR measurements were carried out in a fixed bed reactor according to the following conditions, where 120 mg of the respective test sample were loaded to about 1 mL bed volume together with corundum of the same sieved fraction as diluent.

[0189] 1. Gas feed: 500ppm NO, 500ppm NH3, 5% H 2 O, 10% O 2 and the remainder N 2 , where the gas hourly space velocity (GHSV) is 80,000h -1 (for samples aged at 820°C for 16 h) and 120,000 h -1 (For samples aged at 650°C for 50h);

[0190] 2. Temperature: Run 1: 200°C, 400°C, 575°C (the first run is for slight degreening)

[0191] 3. Operation 2: 175°C, 200°C, 225°C, 250°C, 500°C, 550°C, 575°C.

[0192] The samples aged at 650°C for 50 h were then subjected to simulated sulfur aging and regeneration as follows.

[0193] 1. Each catalyst sample was placed downstream of a 2" piece of DOC (diesel oxidation catalyst) so that the gas flow first contacted the DOC before reaching the catalyst being evaluated.

[0194] 2. In this configuration, the catalyst sample was heated to 400°C (heating rate was 10°C / min)

[0195] In the presence of airflow (8% H 2 O, 7% CO 2 , 10% O 2 and the remainder N 2 , where GHSV is 10,000h -1 ) was maintained at this temperature for 1 h.

[0196] 3. Switch the gas feed to 35ppm SO 2 , 8% H 2 O, 7% CO 2 , 10% O 2 and the remainder N 2 , where GHSV is 10,000h -1 (i.e. SO 2 "On" in feed for 96 h).

[0197] 4. “Shut off” SO in the gas feed 2 The sample was cooled to room temperature

[0198] 5. For regeneration, the sample was heated to 550 °C (heating rate 10 °C / min) and in the presence of air flow (8% H 2 O, 7% CO 2 , 10% O 2 and the remainder N 2 , where GHSV is 20,000h -1 ) Maintain at this temperature for 30 min

[0199] 6. The samples were then cooled to room temperature and then subjected to SCR performance measurements following the above procedure.

[0200] Figure 4 The SCR performance of material A and material H at similar Cu / Al ratios after aging at 650°C for 50 h was compared. It can be observed that the SCR performance of Cu-loaded material A shows higher NO x In addition, for material A, the undesirable by-product N produced in this process 2 The amount of O is lower at 350 °C or higher. Finally, the performance of material A after S aging and regeneration is better than that of material H ( Figure 4C) is significantly higher, which highlights the excellent durability of the catalyst prepared using material A.

[0201] Figure 5 The SCR performance of material A and material I at similar CuO loading after aging at 820°C for 16 h was compared. It can be observed that the SCR performance of Cu-loaded material A shows higher NO than that of material I across the measured temperature range. x Although material I has a higher SAR, this may result in a higher hydrothermal stability of the material, indicating that DEDMP can be used as an OSDA to synthesize CHA zeolite materials with excellent stability and activity. In addition, for material A, the undesirable byproduct N 2 The amount of O is low at 350°C or lower.

Claims

1. A method for preparing a molecular sieve, wherein the method include: forming a synthesis gel comprising: an aluminum source, a silicon source, an organic structure directing agent, water, an alkali source and / or an alkaline earth metal source, and optionally seed crystals; as well as heating the synthesis gel to obtain the molecular sieve; wherein the organic structure directing agent comprises a 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation, and the molecular sieve comprises a framework type that is not AEI.

2. The method according to claim 1, wherein (a) the molecular sieve is a small pore zeolite; and / or (b) the aluminum source is selected from zeolite, formula Al(OR) 3 Compounds, aluminum oxide, aluminum hydroxide and combinations thereof; and wherein R is selected from C 2 To C 5 an alkyl group; and / or (c) the silicon source is selected from zeolite, sodium silicate, colloidal silica, fumed silica, precipitated silica and combinations thereof; and / or (d) The organic structure directing agent comprises 1,1-diethyl-2,6-dimethylpiperidin-1-ium hydroxide.

3. A process according to claim 1 or 2, wherein the molecular sieve has a degree of crystallinity in the range of 50% to 100%.

4. The method according to any one of claims 1 to 3, wherein the synthesis gel comprises the alkali source and the alkali source comprises at least one alkali selected from sodium and potassium.

5. The method according to any one of claims 1 to 4, wherein the heating step is performed at a temperature in the range of 100°C to 200°C for a duration in the range of 30 minutes to 100 hours.

6. The process according to any one of claims 1 to 5, wherein the molecular sieve comprises a CHA framework type, and / or wherein the molecular sieve comprises 50% to 100% CHA framework type in terms of total crystalline phase intensity as determined by x-ray diffraction.

7. The method according to any one of claims 1 to 10, wherein the synthesis gel comprises the seed crystals, and the seed crystals comprise a CHA framework type, and / or wherein the synthesis gel has one or more of the following properties: SiO 2 :Al 2 O 3 The ratio is in the range of 10 to 50. The M:Si ratio is in the range of 0.1 to 1, The ratio of 1,1-diethyl-2,6-dimethylpiperidin-1-ium cation to Si is in the range of 0.01 to 0.3, The OH:Si ratio is in the range of 0.1 to 1, and H 2 O:Si ratio in the range of 5 to 50; wherein M is an alkali metal and / or an alkaline earth metal.

8. The process according to any one of claims 1 to 7, wherein the molecular sieve has an average crystal diameter in the range of 0.1 μm to 2 μm as determined by scanning electron microscopy.

9. The method of any one of claims 1 to 8, wherein the organic structure directing agent comprises a trimethyladamantanium cation.

10. The method according to any one of claims 1 to 9, wherein the molecular sieve is a Na-form molecular sieve, and the method further comprises one or more steps selected from the following: The Na form molecular sieve is ion exchanged with an aqueous ammonia solution to obtain NH 4 + Form molecular sieve, The NH is calcined at a temperature ranging from 200°C to 800°C. 4 + form molecular sieve, for a duration ranging from 30 minutes to 12 hours to obtain the H form molecular sieve, Ion exchange and / or impregnation of the H-form molecular sieve with a transition metal M to obtain an M-form molecular sieve, calcining the M-form molecular sieve at a temperature in the range of 200°C to 800°C for a duration in the range of 30 minutes to 12 hours, and The Na-form molecular sieve is treated with acid exchange or acid treatment to obtain the H-form molecular sieve, and The Na-form molecular sieve is ion exchanged to obtain the M-form molecular sieve, optionally wherein the transition metal M is selected from iron, copper and combinations thereof.

11. A molecular sieve prepared according to the method of any one of claims 1 to 10.

12. The molecular sieve according to claim 11, wherein the molecular sieve has at least one property selected from the following, optionally at least two properties: The molar ratio of silica to alumina is in the range of 5 to 50, The surface area of ​​zeolite is 450m 2 / g to 650m 2 / g, and The substrate surface area is 5m 2 / g to 50m 2 / g range.

13. A selective catalytic reduction catalyst, comprising the Cu-form molecular sieve prepared according to the method of claim 10.

14. A method for the selective catalytic reduction of nitrogen oxides in an exhaust gas, wherein the method comprises contacting the exhaust gas with the selective catalytic reduction catalyst according to claim 13.

15. A CHA zeolite comprising 1,1-diethyl-2,6-dimethylpiperidin-1-ium.

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