Enhanced hydrothermal stability of zeolites for selective catalytic reduction applications

Abstract

Disclosed herein are processes for forming a chabazite-type zeolite having an intermediate mordenite phase to produce a zeolite having enhanced hydrothermal stability, methods of making the zeolite having enhanced hydrothermal stability, zeolites having enhanced hydrothermal stability, catalytic articles comprising zeolites having enhanced hydrothermal stability, and methods of making the zeolite having enhanced hydrothermal stability. And a method of reducing nitrogen oxides (NOx) using the catalytic article.

Description

[0001] The present disclosure relates to procedures for preparing chabazite-type zeolites from conventional zeolitic or non-zeolitic alumina and silica sources, which produce zeolites with enhanced hydrothermal stability and improved selective catalytic reduction (SCR) performance. In the disclosed procedures, mordenite (MOR) is observed as an intermediate phase.

[0002] Zeolites are aluminosilicate crystalline materials having substantially uniform and ordered pore sizes, the diameters of which are typically in the range of about 3 angstroms to about 10 angstroms, depending on the type of zeolite and the type and amount of cations included in the zeolite lattice. Both synthetic and natural zeolites and their use in promoting certain reactions are well known in the art. For example, metal-promoted zeolites (such as copper-exchanged zeolites) are used to selectively promote the reaction of ammonia (or an ammonia precursor, such as urea) with nitrogen oxides (NOx) in the presence of oxygen in preference to competing reactions with oxygen. x ) to form nitrogen and H 2 O. Therefore, the catalyzed reaction is often referred to as selective catalytic reduction (SCR), where a high degree of nitrogen oxide removal can be achieved using a small amount of reducing agent.

[0003] One particular zeolite that has been found to be useful as a catalyst is chabazite (CHA). Methods for its preparation are known in the art. For example, U.S. Pat. No. 4,544,538 to Zones discloses the synthetic preparation of a high silica form (Si / Al ratio of about 15 to 30) of chabazite known as SSZ-13. The chabazite is prepared using an organotemplated (N,N,N-trimethyl-1-adamantanammonium) hydrothermal synthesis at high temperature (about 150°C) and autogenous pressure.

[0004] Conventional zeolite synthesis methods rely on the use of non-zeolite alumina sources to synthesize the target zeolite product. On the other hand, inter-zeolite conversion requires the use of zeolite (e.g., FAU, LTA, etc.) as a source of alumina to synthesize the target zeolite product. The zeolite synthesis approach can affect the structure, stability and / or activity of the resulting zeolite. For example, the distribution of aluminum (Al) atoms in the zeolite framework can affect the hydrothermal stability and / or catalytic activity of the zeolite. Hydrothermal stability is generally improved with reducing the framework alumina content (i.e., increasing the silica to alumina ratio (SAR)), but the latter also limits the amount of catalytically active Cu and Fe sites.

[0005] Light-duty diesel (LDD) applications, in which SCR catalysts are often exposed to high temperature hydrothermal conditions, such as those associated with soot filter regeneration, place special demands on the hydrothermal stability of zeolites. It has been found that under harsh hydrothermal conditions, the activity of copper (Cu) or iron (Fe) exchanged SCR chabazites (CHA) begins to decline. Reducing the SAR framework can increase the amount of catalytically active Cu / Fe sites. Therefore, enhancing the hydrothermal stability of lower SAR frameworks would provide an effective strategy for improving LDD performance.

[0006] US2021 / 171357 A1 relates to a method for synthesizing a zeolite having a chabazite (CHA) crystalline framework, the method comprising the steps of: forming a reaction mixture comprising at least one alumina source comprising a zeolite, at least one silica source and at least one organic structure directing agent, the reaction mixture having a molar ratio of OH greater than 1:1. - wherein M is the number of moles of alkali metal and R is the number of moles of organic structure directing agent; and crystallizing the reaction mixture to form a product zeolite having the CHA crystalline framework, wherein the product zeolite has a CHA crystalline framework having a molecular weight of less than about 25 m / s. 2 / g of mesopore surface area (MSA).

[0007] L. Xie et al., "Excellent Performance of One-Pot synthesized Cu-SSZ-13 Catalyst for the Selective Catalytic Reduction of NOx with NH3," ENVIRONMENTAL SCIENCE TECHNOLOGY, Vol. 48, No. 1, January 7, 2014, pp. 566-572, relates to Cu-SSZ-13 samples prepared by a one-pot synthesis method.

[0008] Therefore, there is a need for new zeolites having altered aluminum distribution and / or altered defect density (such as lower silanol density), and new methods of producing the new zeolites while maintaining hydrothermal stability, such as for LDD SCR applications.

[0009] The present disclosure relates to a method for producing a zeolite having a CHA crystalline framework that minimizes the structural defect density of the CHA zeolite, which in turn enhances the hydrothermal stability and catalytic performance of the product zeolite. Also provided is the use of the zeolite to prepare a catalytic article. Such a catalytic article can be used to treat exhaust gas streams, such as those from gasoline or diesel engines. Applicants have found that the catalytic articles made by the methods disclosed herein exhibit excellent hydrothermal stability and high catalytic activity over a wide temperature range.

[0010] In the process of the present disclosure, different (zeolitic / non-zeolitic) alumina sources are used to form an intermediate MOR zeolite phase. The CHA zeolites of the present disclosure synthesized from the MOR mesophase appear to be more durable and exhibit improved SCR catalytic activity compared to zeolites prepared using procedures in which the MOR mesophase is not formed.

[0011] Applicants surprisingly discovered that by changing the crystallization gel composition and procedure, the starting reagent zeolite Y (faujasite) can be converted to a mordenite (MOR) phase before forming a CHA phase, and the resulting CHA zeolite has better hydrothermal stability and enhanced LDD performance, such as improved SCR activity after hydrothermal aging, compared to CHA zeolite formed using conventional procedures. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to provide an understanding of the embodiments of the present disclosure, reference is made to the accompanying drawings, which are exemplary and should not be construed as limiting the present disclosure.

[0013] Figure 1 is a diagram showing the crystallographic phase transition of chabazite (CHA) prepared by conventional procedures and CHA produced by embodiments of the present disclosure, in which an intermediate mordenite (MOR) phase is formed.

[0014] Figure 2 is a graph showing the sonic velocity profile during the crystallization process of exemplary zeolites 3 and 4 of the present disclosure.

[0015] Figure 3 is a graph showing the X-ray diffraction (XRD) pattern of an exemplary zeolite 4 taken at 66 hours and containing 23% MOR.

[0016] Figure 4 is a graph showing the MOR percentages for exemplary zeolite 4 taken at 64 hours to 88 hours.

[0017] Figure 5 is a graph showing X-ray diffraction (XRD) patterns of exemplary zeolite 4 taken at 64 hours to 88 hours.

[0018] Figure 6 is a graph showing the particle size distribution (PSD) of an exemplary zeolite 4 taken at 64 hours to 88 hours.

[0019] Figure 7 is a graph showing the selective catalyst reduction (SCR) performance of catalysts resulting from embodiments of the present disclosure (comparative zeolites 1 and 2 and exemplary zeolites 3 and 4).

[0020] Figure 8 is a graph showing the selective catalyst reduction (SCR) performance of catalysts resulting from embodiments of the present disclosure (comparative zeolite 1 and exemplary zeolites 6 and 7).

[0021] The present disclosure will now be described more fully. However, the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0022] 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.

[0023] As used herein, "about" refers to small fluctuations. For example, the term "about" can refer to less than or equal to ±5%, such as less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.2%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Values ​​modified by the term "about" also include specific values. For example, "about 5.0" includes 5.0.

[0024] As used herein, the term "material" refers to an element, component, or substance that makes up or can be made into something.

[0025] As used herein, the term "substantially" refers to a property having a statistical occurrence greater than about 75% (eg, greater than about 90%).

[0026] 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.

[0027] As used herein, the term "alumina source" refers to a material containing aluminum and / or aluminum ions, such as, for example, aluminum salts, aluminum isopropoxide, and / or aluminum hydroxide.

[0028] As used herein, the term "catalyst" or "catalyst composition" refers to a molecule or material that facilitates a reaction.

[0029] 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.

[0030] As used herein, the term "ion exchange treatment" refers to the process of incorporating one or more ions into and / or removing them from a zeolite. As a non-limiting example, the zeolite may be subjected to a copper ion exchange treatment by, for example, mixing the zeolite with a material containing copper (such as, for example, CuO) and a solution (such as, for example, an aqueous zirconium acetate solution).

[0031] 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.

[0032] As used herein, the term "organic structure directing agent" (OSDA) refers to an organic compound that can affect the morphology and / or structure of a zeolite. For example, an OSDA can be an ionic organic molecule that can be incorporated into the zeolite structure. The OSDA can, for example, contain large and / or sterically bulky organic groups. The OSDA can, for example, contain adamantane ammonium groups. Trimethyladamantanium is a non-limiting example of an OSDA.

[0033] As used herein, the term "reductant" or "reducing agent" refers to a substance capable of reducing NO at elevated temperatures (i.e., above ambient temperature). x In some embodiments, the reducing agent is ammonia. In some embodiments, the reducing agent is an ammonia precursor, such as urea, and the reducing agent is a nitrogen reducing agent. In some embodiments, the reducing agent includes a fuel. In some embodiments, the reducing agent includes diesel fuel and its fractions and any hydrocarbons and oxygenated hydrocarbons collectively referred to as HC reducing agents.

[0034] As used herein, the term "selective catalytic reduction" (SCR) refers to the use of a reducing agent to reduce nitrogen oxides (NO x ) catalytic process.

[0035] 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.

[0036] As used herein, the term "zeolite" refers to an aluminosilicate material having a framework structure consisting of a substantially regular porous structure. In some embodiments of the present disclosure, the zeolite includes at least two different types of framework structures. In some embodiments of the present disclosure, the zeolite includes substantially one framework structure. In some embodiments, a zeolite having substantially one framework structure is referred to as a "phase pure" zeolite. In some embodiments, the non-framework cations that balance the charge of the 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.

[0037] The structure of the zeolite of the present disclosure can be analyzed using common techniques in the art, such as, for example, x-ray diffraction (XRD) and N2 physical adsorption. As a non-limiting example, the degree of crystallinity of the zeolite of the present disclosure can be determined by XRD analysis.

[0038] The catalytic articles of the present disclosure find use in treating exhaust gas streams, such as those originating from diesel engines.In use, the exhaust gas stream is contacted with a catalytic article prepared according to an embodiment of the present disclosure.

[0039] As discussed below, the catalytic article has excellent NO over a wide operating temperature range. x Therefore, the catalytic product can be used as an SCR catalyst.

[0040] The term "SCR catalyst" is used herein in a broad sense to refer to selective catalytic reduction, in which a catalyzed reaction of nitrogen oxides with a reductant occurs to reduce the nitrogen oxides.

[0041] This disclosure outlines methods for synthesizing CHA from conventional non-zeolitic or zeolitic alumina and silica sources that result in products with improved light duty diesel (LDD) properties.

[0042] In some embodiments, a method for preparing a CHA zeolite having an intermediate unstable MOR phase is provided. In some embodiments, the method comprises step (a): preparing an aqueous mixture comprising a silica source, an alumina source, a mineralizer, and an organic structure directing agent (OSDA) to form an aqueous gel, the mineralizer being typically a strong base or an organic base. In some embodiments, the method further comprises step (b): heating the gel at about 100°C to about 200°C for about 15 hours to about 90 hours, about 16 hours to about 80 hours, about 20 hours to about 70 hours, about 25 hours to about 60 hours, about 28 hours to about 50 hours, or about 30 hours to about 40 hours to form an intermediate phase comprising mordenite (MOR) crystals. In some embodiments, the gel is heated at an autogenous pressure corresponding to the vapor pressure of water. In some embodiments, the method further comprises step (c): heating the mesophase at about 100° C. to about 200° C. for about 15 hours to about 90 hours, about 16 hours to about 80 hours, about 20 hours to about 70 hours, about 25 hours to about 60 hours, about 28 hours to about 50 hours, or about 30 hours to about 40 hours to obtain a phase pure CHA zeolite. In some embodiments, the mesophase is heated at an autogenous pressure corresponding to the vapor pressure of water.

[0043] In some embodiments, the silica source is selected from colloidal silica, precipitated silica, fumed silica, sodium silicate, zeolite silica, and combinations thereof. In some embodiments, the silica source is colloidal silica. In some embodiments, the silica source is precipitated silica. In some embodiments, the silica source is fumed silica. In some embodiments, the silica source is zeolite silica. In some embodiments, the silica source is sodium silicate. In some embodiments of the method, the silica source includes a SiO2 / Na2O weight % ratio of about 1 to about 4. In some embodiments, the silica source includes a SiO2 / Na2O weight % ratio of about 1. In some embodiments, the silica source includes a SiO2 / Na2O weight % ratio of about 2. In some embodiments, the silica source includes a SiO2 / Na2O weight % ratio of about 3. In some embodiments, the silica source includes a SiO2 / Na2O weight % ratio of about 3.3. In some embodiments, the silica source comprises a SiO2 / Na2O weight % ratio of about 4.0. In some embodiments, the silica source has a solid content greater than about 20 weight %. In some embodiments, the silica source has a solid content greater than about 25 weight %. In some embodiments, the silica source has a solid content greater than about 30 weight %. In some embodiments, the silica source has a solid content greater than about 35 weight %. In some embodiments, the silica source has a solid content of about 37 weight %. In some embodiments, the molar ratio of silica to alumina (SAR) in the gel is at least about 30. In some embodiments, the molar ratio of silica to alumina (SAR) in the gel is at least about 35.

[0044] In some embodiments, the alumina source is selected from aluminum isopropoxide, aluminum sulfate, zeolite alumina, alumina, aluminum hydroxide, and combinations thereof. In some embodiments, the alumina source is aluminum isopropoxide. In some embodiments, the alumina source is aluminum sulfate. In some embodiments, the alumina source is a combination of aluminum isopropoxide and aluminum sulfate. In some embodiments, the alumina source is zeolite alumina. In some embodiments, the alumina source is alumina. In some embodiments, the alumina source is aluminum hydroxide.

[0045] In some embodiments, the method further comprises adding a zeolite initiator. In some embodiments, the zeolite initiator is referred to as NaY seed crystals. In some embodiments, the zeolite initiator is referred to as FAU seed crystals. In some embodiments, the zeolite initiator comprises a mixture of sodium aluminate, sodium silicate and sodium hydroxide. In some embodiments, the zeolite initiator has a SiO2 / Al2O3 molar ratio of about 65. In some embodiments, the zeolite initiator has a SiO2 / Na2O molar ratio of about 1.7. In some embodiments, the zeolite initiator has a H2O / SiO2 molar ratio of about 10.3. In some embodiments, the aqueous gel of step (a) further comprises a zeolite initiator having a SiO2 / Al2O3 molar ratio of about 65, a SiO2 / Na2O molar ratio of about 1.7, and a H2O / SiO2 molar ratio of about 10.3.

[0046] In some embodiments, the mineralizer is selected from the group consisting of - (Fluoride) ions and / or OH - In some embodiments, the mineralizer is selected from alkaline hydroxides and fluorides. In some embodiments, the mineralizer is selected from alkaline hydroxides. In some embodiments, the mineralizer is selected from fluorides. In some embodiments, the mineralizer is NaOH. In some embodiments, the mineralizer is KOH. In some embodiments, the mineralizer is F - ions. In some embodiments, the mineralizer is a quaternary ammonium hydroxide. In some embodiments, the mineralizer is a combination of NaOH and KOH. In some embodiments, the mineralizer is a combination of NaOH and F - In some embodiments, the mineralizer is a combination of NaOH and a quaternary ammonium hydroxide. In some embodiments, the mineralizer is a combination of KOH and F - In some embodiments, the mineralizer is a combination of KOH and a quaternary ammonium hydroxide. In some embodiments, the mineralizer is F - ions and quaternary ammonium hydroxides.

[0047] In some embodiments, OSDA is selected from quaternary ammonium salts. In some embodiments, OSDA is trimethyladamantyl ammonium hydroxide. In some embodiments, OSDA is trimethylbenzylammonium hydroxide. In some embodiments, OSDA is triethylcyclohexylammonium hydroxide. In some embodiments, OSDA is a combination of trimethyladamantyl ammonium hydroxide and trimethylbenzylammonium hydroxide. In some embodiments, OSDA is a combination of trimethyladamantyl ammonium hydroxide and triethylcyclohexyl ammonium hydroxide. In some embodiments, OSDA is a combination of trimethylbenzylammonium hydroxide and triethylcyclohexyl ammonium hydroxide.

[0048] In some embodiments, the gel is heated at about 100°C. In some embodiments, the gel is heated at about 110°C. In some embodiments, the gel is heated at about 120°C. In some embodiments, the gel is heated at about 130°C. In some embodiments, the gel is heated at about 140°C. In some embodiments, the gel is heated at about 150°C. In some embodiments, the gel is heated at about 160°C. In some embodiments, the gel is heated at about 170°C. In some embodiments, the gel is heated at about 180°C. In some embodiments, the gel is heated at about 190°C. In some embodiments, the gel is heated at about 200°C. In some embodiments, the gel is heated for about 15 hours to 90 hours. In some embodiments, the gel is heated for about 16 hours to about 80 hours. In some embodiments, the gel is heated for 20 hours to 70 hours. In some embodiments, the gel is heated for about 25 hours to 60 hours. In some embodiments, the gel is heated for about 28 hours to 50 hours. In some embodiments, the gel is heated for about 30 hours. In some embodiments, the gel is heated for about 31 hours. In some embodiments, the gel is heated for about 32 hours. In some embodiments, the gel is heated for about 33 hours. In some embodiments, the gel is heated for about 34 hours. In some embodiments, the gel is heated for about 35 hours. In some embodiments, the gel is heated for about 36 hours. In some embodiments, the gel is heated for about 37 hours. In some embodiments, the gel is heated for about 38 hours. In some embodiments, the gel is heated for about 39 hours. In some embodiments, the gel is heated for about 40 hours. In some embodiments, the gel is heated from room temperature to the first target temperature for about 2 hours to about 4 hours. In some embodiments, the gel is heated to about 160°C for about 5 hours to about 20 hours. In some embodiments, the gel is heated at a temperature of about 140°C for about 30 hours to about 80 hours.

[0049] In some embodiments, the mesophase is heated at about 100°C. In some embodiments, the mesophase is heated at about 110°C. In some embodiments, the mesophase is heated at about 120°C. In some embodiments, the mesophase is heated at about 130°C. In some embodiments, the mesophase is heated at about 140°C. In some embodiments, the mesophase is heated at about 150°C. In some embodiments, the mesophase is heated at about 160°C. In some embodiments, the mesophase is heated at about 170°C. In some embodiments, the mesophase is heated at about 180°C. In some embodiments, the mesophase is heated at about 190°C. In some embodiments, the mesophase is heated at about 200°C. In some embodiments, the mesophase is heated for about 30 hours. In some embodiments, the mesophase is heated for about 31 hours. In some embodiments, the mesophase is heated for about 15 hours to 90 hours. In some embodiments, the mesophase is heated for about 16 hours to about 80 hours. In some embodiments, the mesophase is heated for 20 hours to 70 hours. In some embodiments, the mesophase is heated for about 25 hours to 60 hours. In some embodiments, the mesophase is heated for about 28 hours to 50 hours. In some embodiments, the mesophase is heated for about 32 hours. In some embodiments, the mesophase is heated for about 33 hours. In some embodiments, the mesophase is heated for about 34 hours. In some embodiments, the mesophase is heated for about 35 hours. In some embodiments, the mesophase is heated for about 36 hours. In some embodiments, the mesophase is heated for about 37 hours. In some embodiments, the mesophase is heated for about 38 hours. In some embodiments, the mesophase is heated for about 39 hours. In some embodiments, the mesophase is heated for about 40 hours.

[0050] In some embodiments, based on complete aluminum conversion, the SiO2 yield is greater than about 50%. In some embodiments, the SiO2 yield of the zeolite is about 50%. In some embodiments, the SiO2 yield of the zeolite is about 51%. In some embodiments, the SiO2 yield of the zeolite is about 52%. In some embodiments, the SiO2 yield of the zeolite is about 53%. In some embodiments, the SiO2 yield of the zeolite is about 54%. In some embodiments, the SiO2 yield of the zeolite is about 55%. In some embodiments, the SiO2 yield of the zeolite is about 56%. In some embodiments, the SiO2 yield of the zeolite is about 57%. In some embodiments, the SiO2 yield of the zeolite is about 58%. In some embodiments, the SiO2 yield of the zeolite is about 59%. In some embodiments, the SiO2 yield of the zeolite is about 60%. In some embodiments, the SiO2 yield of the zeolite is about 61%. In some embodiments, the SiO2 yield of the zeolite is about 62%. In some embodiments, the SiO2 yield of the zeolite is about 63%. In some embodiments, the SiO2 yield of the zeolite is about 64%. In some embodiments, the SiO2 yield of the zeolite is about 65%.

[0051] In some embodiments, the phase pure CHA zeolite has a molecular weight of less than about 40 m 2 / g of matrix surface area (MSA). In some embodiments, the phase pure CHA zeolite has a surface area between about 10 m 2 / g and about 25m 2 In some embodiments, the phase-pure CHA zeolite has an MSA of about 10 m / s. 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 11 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 12 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 13 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 14 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 15 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 16 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 17 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 18 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 19m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 20 m2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 21 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 22 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 23 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 24 m 2 / g of MSA. In some embodiments, the phase-pure CHA zeolite has about 25 m 2 / g MSA. MSA can be calculated using the t-plot method.

[0052] In some embodiments, the phase pure CHA zeolite has a silica to alumina ratio (SAR) greater than about 15.0. In some embodiments, the phase pure CHA zeolite has a SAR greater than about 15.5. In some embodiments, the phase pure CHA zeolite has a SAR greater than about 16.0. In some embodiments, the phase pure CHA zeolite has a SAR greater than about 16.5. In some embodiments, the phase pure CHA zeolite has a SAR greater than about 17.0. In some embodiments, the phase pure CHA zeolite has a SAR greater than about 17.5. In some embodiments, the phase pure CHA zeolite has a SAR greater than about 18.0. In some embodiments, the phase pure CHA zeolite has a SAR greater than about 18.5. In some embodiments, the phase pure CHA zeolite has a SAR of about 19.0. In some embodiments, the phase pure CHA zeolite has a SAR of about 19.5. In some embodiments, the phase pure CHA zeolite has a SAR of about 20. In some embodiments, the phase pure CHA zeolite has a SAR of about 20.5. In some embodiments, the phase pure CHA zeolite has a SAR of about 21.0. In some embodiments, the phase pure CHA zeolite has a SAR of about 21.5. In some embodiments, the phase pure CHA zeolite has a SAR of about 21.7. In some embodiments, incorporating gel silica into the zeolite material produces a zeolite having a SAR significantly lower than the SAR of the starting gel silica.

[0053] In some embodiments, the CHA zeolite has a molecular weight of less than about 40 m 2 / g of substrate surface area (MSA). In some embodiments, the MSA is less than about 25 m 2 / g. In some embodiments, MSA is about 24m 2 / g. In some embodiments, MSA is about 23m 2 / g. In some embodiments, MSA is about 22m 2 / g. In some embodiments, MSA is about 21m2 / g. In some embodiments, MSA is about 20m 2 / g. In some embodiments, MSA is about 19m 2 / g. In some embodiments, MSA is about 18m 2 / g. In some embodiments, MSA is about 17m 2 / g. In some embodiments, MSA is about 16m 2 / g. In some embodiments, the MSA is about 15m 2 / g. In some embodiments, MSA is about 14m 2 / g. In some embodiments, MSA is about 13m 2 / g. In some embodiments, MSA is about 12m 2 / g. In some embodiments, MSA is about 11m 2 / g. In some embodiments, MSA is about 10m 2 / g.

[0054] In some embodiments, the CHA zeolite has a substantially larger CHA framework. In some embodiments, the CHA zeolite has a CHA framework greater than about 75%. In some embodiments, the CHA zeolite has a CHA framework greater than about 80%. In some embodiments, the CHA zeolite has a CHA framework greater than about 85%. In some embodiments, the CHA zeolite has a CHA framework greater than about 90%. In some embodiments, the CHA zeolite has a CHA framework greater than about 95%. In some embodiments, the CHA zeolite has a MOR framework less than about 25%. In some embodiments, the CHA zeolite has a MOR framework less than about 20%. In some embodiments, the CHA zeolite has a MOR framework less than about 15%. In some embodiments, the CHA zeolite has a MOR framework less than about 10%. In some embodiments, the CHA zeolite has a MOR framework less than about 5%.

[0055] In some embodiments, the sonic velocity profile of each step of the method for producing CHA zeolite is measured. In some embodiments, the sonic velocity is measured as an ultrasonic measurement result in m / s. In some embodiments, the ultrasonic measurement result of the gel of step (a) is greater than about 1000m / s. In some embodiments, the ultrasonic measurement result of the mesophase of step (b) is about 5m / s to about 15m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the mesophase of step (b) is about 5m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the mesophase of step (b) is about 9m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the mesophase of step (b) is about 11m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the mesophase of step (b) is about 13m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the mesophase of step (b) is about 15 m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the CHA zeolite of step (c) is about 7 m / s to about 17 m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the CHA zeolite of step (c) is about 7 m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the CHA zeolite of step (c) is about 9 m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the CHA zeolite of step (c) is about 11 m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the CHA zeolite of step (c) is about 13 m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the CHA zeolite of step (c) is about 15 m / s higher than the ultrasonic measurement result of the gel of step (a). In some embodiments, the ultrasonic measurement result of the CHA zeolite of step (c) is 17 m / s higher than the ultrasonic measurement result of the gel of step (a).

[0056] In some embodiments, the method of preparing CHA zeolite includes further isolating the phase-pure CHA zeolite by filtration. In some embodiments, the isolated phase-pure zeolite is dried and calcined to produce Na +In some embodiments, the calcination is carried out at a temperature greater than about 500°C, preferably in a range of about 500°C to about 550°C. In some embodiments, the calcination is carried out at about 500°C. In some embodiments, the calcination is carried out at about 510°C. In some embodiments, the calcination is carried out at about 520°C. In some embodiments, the calcination is carried out at about 530°C. In some embodiments, the calcination is carried out at about 540°C. In some embodiments, the calcination is carried out at about 550°C. In some embodiments, the calcination is carried out for more than about 5 hours. In some embodiments, the calcination is carried out for about 6 hours. In some embodiments, the calcination is carried out for about 7 hours.

[0057] In some embodiments, the calcined CHA zeolite is subjected to NH + In some embodiments, NH4 + The form has a Na2O content of less than about 500 ppm.

[0058] In some embodiments, Cu ions are introduced into NH4 + In some embodiments, calcining NH4 + Form to produce H + form. In some embodiments, calcination is carried out at greater than about 400°C. In some embodiments, calcination is carried out at about 410°C. In some embodiments, calcination is carried out at about 420°C. In some embodiments, calcination is carried out at about 430°C. In some embodiments, calcination is carried out at about 440°C. In some embodiments, calcination is carried out at about 450°C. In some embodiments, calcination is carried out for more than about 5 hours. In some embodiments, calcination is carried out for about 6 hours. In some embodiments, calcination is carried out for about 7 hours.

[0059] In some embodiments, by introducing Cu ions into H +In some embodiments, the zeolite catalyst is formed in a CHA zeolite of the form. In some embodiments, the zeolite catalyst has a copper loading ranging from about 3.0% by weight to about 6.0% by weight. In some embodiments, the zeolite catalyst has a copper loading ranging from about 3.5% by weight to about 5.5% by weight. In some embodiments, the zeolite catalyst has a copper loading ranging from about 4.0% by weight to about 5.0% by weight. In some embodiments, the zeolite catalyst has a copper loading ranging from about 4.7% by weight to about 5.0% by weight. In some embodiments, the zeolite catalyst has a copper loading of about 3.0% by weight. In some embodiments, the zeolite catalyst has a copper loading of about 3.5% by weight. In some embodiments, the zeolite catalyst has a copper loading of about 4.0% by weight. In some embodiments, the zeolite catalyst has a copper loading of about 4.5% by weight. In some embodiments, the zeolite catalyst has a copper loading of about 4.8% by weight. In some embodiments, the zeolite catalyst has a copper loading of about 4.9% by weight. In some embodiments, the zeolite catalyst has a copper loading of about 5.0 wt %. In some embodiments, the zeolite catalyst has a copper loading of about 5.5 wt %. In some embodiments, the zeolite catalyst has a copper loading of about 6.0 wt %. In some embodiments, the copper loading is expressed as CuO content.

[0060] In some embodiments, the zeolite has a silica to alumina ratio (SAR) ranging from about 20 to about 22. In some embodiments, the zeolite has a SAR of about 20. In some embodiments, the zeolite has a SAR of about 21. In some embodiments, the zeolite has a SAR of about 22. Another aspect of the present disclosure is a method of producing a catalytic article. In some embodiments, the method includes applying a catalytic coating to a substrate via a washcoat process. In some embodiments, the method also includes drying and calcining the coated substrate at a temperature greater than about 500°C, preferably for about 1 hour or longer, more preferably drying and calcining the coated substrate at a temperature of about 550°C for about 1 hour. In some embodiments, the catalytic coating comprises a CHA zeolite as described in the present disclosure, the CHA zeolite having a copper loading ranging from about 4.7 wt% to about 5.0 wt%. In some embodiments, the catalytic coating also comprises about 5% zirconium oxide. In some embodiments, the catalytic coating also comprises about 5% pseudo-boehmite (PB-250) binder.

[0061] In another aspect of the present disclosure, a catalytic article comprising a copper-exchanged CHA zeolite is provided. In some embodiments, the CHA zeolite of the present disclosure has a CHA content greater than about 450 m 2 In some embodiments, the CHA zeolites of the present disclosure have a zeolite surface area (ZSA) of less than about 40 m 2 / g of matrix surface area (MSA). The total surface area of ​​the zeolite can be determined by the BET method. The matrix or mesopore surface area (MSA) can be calculated using the t-plot method. The ZSA can then be calculated by subtracting the MSA from the total surface area. The ZSA relates to a copper-loaded zeolite. In another aspect of the present disclosure, a copper-exchanged CHA zeolite is provided, which is obtained or obtainable by the above method.

[0062] Another aspect of the present disclosure provides a method for reducing nitrogen oxides (NO x ). In some embodiments, the method includes contacting a gaseous stream containing nitrogen oxides with at least one copper-exchanged CHA zeolite of the present disclosure. In some embodiments, the method includes contacting a gaseous stream containing nitrogen oxides with at least one catalytic product of the present disclosure. In some embodiments, the method of reducing nitrogen oxides is carried out at a temperature ranging from about 200°C to about 550°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 200°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 250°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 300°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 350°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 400°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 450°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 500°C. In some embodiments, the method of reducing nitrogen oxides is carried out at about 550°C.

[0063] The zeolite 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 thin parallel gas flow passages extending from the inlet or outlet face of the substrate through the substrate, so that the passage is open to the fluid flow through the substrate. A passage that can be substantially a straight path from its fluid inlet to its fluid outlet can be defined by a wall, and the zeolite is deposited on these walls as a washcoat so that the gas flowing through the passage contacts the zeolite. The flow passage 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 about 60 to about 400 or more gas inlet openings (i.e., pores) per square inch of cross section.

[0064] 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 zeolite disclosed herein 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 along 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 zeolite on a wall-flow substrate will depend on substrate properties such as porosity and wall thickness, and will generally be lower than the loading on a flow-through substrate.

[0065] The ceramic substrate may be made of any suitable refractory material such as, for example, cordierite, cordierite-alumina, silicon nitride, zircon-mullite, spodumene, alumina-magnesium silicate, zirconium silicate, sillimanite, magnesium silicate, zircon, petalite, alpha-alumina or aluminosilicate, etc.

[0066] The substrates that can be used for the zeolites of the present disclosure can also be metallic in nature and consist 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 supports 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 may contain one or more of nickel, chromium and / or aluminum, and the total amount of these metals may account for at least about 15% by weight of the alloy, such as about 10% to 25% by weight of chromium, about 3% to about 8% by weight of aluminum, and up to about 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 may be oxidized at high temperatures (such as, for example, about 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 supports and catalytically promoted metal components to the substrate.

[0067] Before describing exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of construction or process steps set forth in the following examples and is capable of other embodiments and of being practiced or carried out in various ways. Example

[0068] Example 1

[0069] The gel compositions and crystallization conditions that produced comparative zeolites 1 and 2 and exemplary zeolites 3 and 4 are summarized in Table 1 below, and the properties of the resulting products are presented in Table 2 below.

[0070] Table 1. Gel composition and crystallization conditions

[0071] composition Comparison with Zeolite 1 Comparison with Zeolite 2 Exemplary Zeolite 3 Exemplary Zeolite 4 Al source <![CDATA[Al(i-C3H7O)3]]> Na-FAU Na-FAU Na-FAU Si Source Colloidal Silica Na silicate Na silicate Na silicate OSDA TMA TMA TMA TMA <![CDATA[SiO2 / Al2O3]]> 20 29.19 29.19 29.19 Na / Si 0.13 0.82 0.82 0.82 R / Si 0.071 0.091 0.091 0.091 OH / Si 0.2 0.509 0.509 0.509 <![CDATA[H2O / Si]]> 11 21.60 32.05 32.05 T(℃) 170 140 140 140 Time under T (h) 30 30 88 80 solid(%) 22 12.4 9.1 9.1

[0072] Table 2. Properties of zeolite products

[0073]

[0074] For CHA crystallization, trimethyladamantyl ammonium hydroxide (TMAdaOH) was used as an organic structure directing agent (OSDA).

[0075] For comparative zeolite 1, NaOH was used as the mineralizer and the only Na + Source, and aluminum isopropoxide and colloidal silica (40 wt. % SiO2) were used as Si source and Al source, respectively. For comparative zeolite 2 and exemplary zeolites 3 and 4 (as well as for zeolites E, F, H and I described in Table 7 below), sodium silicate solution (SiO2 / Na2O=2.6, 37% solid content) and Na-FAU (SiO2 / Al2O3=5.1) were used as Si source and Al source, respectively.

[0076] Supplementing gel Na with Na2SO4 + content to achieve the desired Na / Si ratio. In addition, the excess OH is neutralized by using H2SO4 - To obtain the desired OH / Si ratio. Assuming that the Na + With OH - The ratio between them is 1:1 to calculate OH - / SiO2 ratio.

[0077] In all cases, crystallization was carried out under autogenous pressure in 10 L to 110 L stirred autoclaves. During crystallization, the sound velocity of the reactor slurry was measured in situ and continuously using an ultrasonic measuring instrument, the Sensotech LiquiSonic immersion sensor 24-24. This measurement method is based on the determination of the propagation velocity of ultrasonic waves in a liquid medium.

[0078] Reactor slurry samples were taken at various times during the crystallization. In-process samples and final products were separated by filtration, dried and calcined (560°C, 6h) to yield Na + Form, the Na + The forms were characterized by XRD and N2 physical adsorption. Phase identification analysis was performed using Panalytical HighScore version 4.5 software and ICDD PDF 4+2019 version 4.1903 powder diffraction file database. Rietveld refinement was performed using Topas 4.2 to determine the MOR percentage. After calcination, single or multiple NH4 + Exchange until the Na2O content reaches <500ppm. NH4+ Calcination (450℃, 6h) to produce H + Form. Also for H + Copper loading was performed on the zeolite (via in situ solid state exchange).

[0079] All crystallizations yielded products with >90% primary phase crystallinity and correspondingly high ZSA (>500 m 2 For Comparative Zeolite 1, the gel silica to alumina ratio (SAR) was similar to the product SAR, based on a silica yield of >90% (based on complete aluminum conversion). In Comparative Zeolite 2 and Exemplary Zeolites 3 and 4, the silica yield varied between 55% and 58%, and was consistent with the large difference between the gel SAR and the product SAR.

[0080] The comparative zeolites and exemplary zeolites also exhibit important structural differences during crystallization. First, the MSA of comparative zeolites 1 and 2 ranges from 20 m 2 / g to 50m 2 / g, while exemplary zeolites 3 and 4 showed <15m 2 In addition, compared with the corresponding comparative zeolites 1 and 2 having similar SAR, the H of exemplary zeolites 3 and 4 is + The form contains 30% to 50% less extra-framework aluminum. In the prepared form and NH4 + Dealumination typically occurs during formal calcination, and the tendency to retain framework Al during these high temperature treatments may also be relevant to hydrothermal stability. Comparison of silanol defect density measurements in zeolites 1 and 2 compared to exemplary zeolite 3 also highlights structural differences in the zeolite products obtained. 1 The density of Si—OH / g zeolite determined from H MAS NMR measurement was 0.21 mmol / g, 0.38 mmol / g, and 0.09 mmol / g zeolite, respectively.

[0081] The silanol measurements were performed as follows. The samples were loaded into glass tubes with an outer diameter of 6 mm. They were then heated in a vacuum furnace with the following temperature regime: heating from room temperature to 120°C in 2 h, maintained at 120°C for 2 h, heating from 120°C to 400°C in 3 h, maintained at 400°C for 12 h, and then finally cooled while maintaining the vacuum. During this process, a temperature of <10 -2 The sample was then repacked into a 3.2 mm bottom-closed ZrO2 rotor under dry N2 gas to avoid any contact with air. The run was performed at 600 MHz, 15 kHz MAS, 90° pulse, 20 μs dead time delay, 20 ms FID acquisition, 30 s recycle delay and 32 scans. 1H MAS NMR.

[0082] Most importantly, exemplary zeolites 3 and 4 undergo a MOR phase (e.g. Figure 1 and Figure 2 The speed of sound is also very closely related to the phase transition ( Figure 2 ).

[0083] A set of intermediate in-process samples were taken during the crystallization process of Exemplary Zeolite 3. Exemplary Zeolite 4 is an in-process sample of Exemplary Zeolite 3 taken at 80 hours, which still contained 7% MOR. As crystallization time progressed, the MOR percentage decreased, while the CHA percentage increased, as shown in FIG. Figure 3 , Figure 4 and Figure 5 The particle size distribution also responds well to the MOR percentage, where the second peak decreases and the first peak increases as the MOR decreases ( Figure 6 ).

[0084] Differences in the synthetic routes can be used to minimize the defect density, which in turn leads to enhanced hydrothermal stability and improved SCR catalytic performance, such as Figure 7 shown.

[0085] Example 2

[0086] Comparative zeolite 1 (also described above in Example 1) having a silica to alumina molar ratio (SAR) of 18 was prepared using NaOH as the mineralizer and aluminum isopropoxide (AIP) and colloidal silica (40 wt% SiO2) as silica and alumina sources, respectively.

[0087] For the gels in Exemplary Zeolite 6 and Exemplary Zeolite 7, sodium silicate (having a SiO2 / Na2O wt% ratio of 3.3 and a solids content of 37 wt%) and aluminum isopropoxide were used as the primary silica and alumina sources, respectively.

[0088] The gel compositions of Comparative Zeolite 1, Exemplary Zeolite 6, and Exemplary Zeolite 7 are summarized in Table 3 below.

[0089] Table 3. Molar composition of gel

[0090]

[0091]

[0092] In exemplary zeolite 7, a portion of the sodium silicate and aluminum isopropoxide (10% based on total silica) is replaced with a zeolite initiator commonly used to crystallize Y-type zeolites. This material, which contains a SiO2 / Al2O3 molar ratio of 65, a SiO2 / Na2O molar ratio of 1.7, and a H2O / SiO2 molar ratio of 10.3, is referred to as "FAU seeds". The zeolite initiator is also interchangeably referred to as "NaY seeds" and is known to those skilled in the art as "NaY seeds".

[0093] The Na / Si ratio and OH / Si ratio of the gel were adjusted by adding Na2SO4 and H2SO4, respectively. For all crystallizations, trimethyladamantyl ammonium hydroxide (TMAdaOH) was used as an organic structure directing agent (OSDA). Further details of the gel composition and crystallization conditions are summarized in Table 4.

[0094] Table 4. Gel composition and crystallization conditions for comparative zeolite 1 and exemplary CHA zeolites 6 and 7.

[0095]

[0096] Initial crystallization experiments were conducted in 300 mL stirred autoclaves for 15 h and 36 h (comparative zeolite 1) and 36 h and 72 h (exemplary zeolites 6 and 7). An amorphous / CHA phase mixture was observed after 15 h of crystallization of the comparative zeolite 1 gel, and a completely crystalline phase of pure CHA was observed after 30 h.

[0097] For exemplary zeolites 6 and 7, a phase mixture of MOR and CHA was observed at an intermediate crystallization time (36 h), which eventually converted to phase pure CHA at 72 h. Taken together, these results indicate that for comparative zeolite 1, CHA crystallized directly from an amorphous gel, while for exemplary zeolites 6 and 7, an unstable MOR intermediate phase was formed.

[0098] A larger amount of material for SCR testing was prepared in a 2 L stirred autoclave. The products were isolated by filtration, dried and calcined (540 °C, 6 h) to yield Na + Form, the Na + The forms were characterized by XRD and N2 physical adsorption.

[0099] Procedure for XRD characterization: Grind the sample using a mortar and pestle and then load the sample into a flat-mount sample holder. Data collection was performed using a PANalytical MPD X'Pert Pro diffraction system. A copper anode tube (wavelength: ) was operated at 45 kV and 40 mA. A Bragg-Brentano configuration was employed and data were collected from 3° to 80° 2θ with a step size of 0.016° and a counting time of 60 s / step.

[0100] Pore ​​volume and surface area characteristics can be determined by nitrogen adsorption (BET surface area method).Mesopore and zeolite (micropore) surface areas were determined via N2-adsorption porosimetry on a Micromeritics Tristar 3000 series instrument according to the ISO 9277 method.

[0101] Procedure for N2 physisorption: 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.

[0102] 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 pores are believed to contribute to the matrix surface area.

[0103] After calcination, NH4 + exchange, resulting in a Na2O content of <500ppm. + Calcination (450℃, 6h) to produce H + Table 5 summarizes the Na + The properties of these phase-pure CHA products in form.

[0104] Table 5. Product properties comparing zeolite 1 and exemplary zeolites 6 and 7

[0105]

[0106] Assuming complete conversion of the gel alumina to the zeolitic material, the silica yield per crystallization can be calculated from the corresponding gel SAR and product SAR. For comparative zeolite 1, this yield is over 90%, and for exemplary zeolites 6 and 7, this yield is about 60%. It should also be noted that although all CHA materials exhibit the zeolitic surface area characteristic of highly crystalline CHA (>500 m 2 / g), but exemplary zeolites 6 and 7 possess significantly lower matrix surface areas than comparative zeolite 1.

[0107] In order to prepare SCR catalysts from the above materials, Cu ions were introduced into H +The catalytic coating containing Cu-CHA, zirconia and pseudo-boehmite (PB-250) binder was placed on a porous ceramic monolith with a cell density of 400 cpsi and a wall thickness of 6 mils via a wash coating process. The coated monolith was dried at 110° C. to 150° C. and calcined at about 550° C. for 1 hour. The coating process provided 2.1 g / in 3 The catalyst loading was 5% zirconia and 5% alumina binder. The coated monoliths were hydrothermally aged at 800°C for 16 hours or at 850°C for 16 hours in the presence of 10% H2O / air, as specified. For aging at 650°C for 50 hours, the cores were exposed to a gas (composition: 10% O2, 10% H2O, balance nitrogen) flow rate of 3 liters per minute.

[0108] In a laboratory reactor, the temperature was increased from 200°C to 550°C at a temperature ramp of 5°C / min in a gas mixture of 500 ppm NO, 500 ppm NH3, 10% O2, 5% H2O, and the balance N2 for 80,000 h under pseudo-steady-state conditions. -1 The space velocity based on the volume of gas per hour is measured for materials aged at 800℃ / 16h and 850℃ / 16h (such as Figure 8 and Table 8) of NO x Conversion. For materials aged at 650°C / 50h (except Comparative Material J), in a reactor, in a gas mixture of 1000ppm NO, 1050ppm NH3, 10% O2, 8% CO2, 7% H2O, balance N2, at discrete temperature points when the catalyst is heated after allowing time sufficient to obtain steady state (heat and gas composition), at steady state conditions for 60000h. -1 The space velocity based on the gas volume per hour, measured on the coated core (subjected to the hydrothermal aging treatment specified previously) is NO x Conversion. In a gas mixture of 1000 ppm NO, 1050 ppm NH3, 10% O2, 6% H2O, balance N2, at discrete temperature points when the catalyst is heated after allowing enough time to obtain steady state (heat and gas composition), at steady state conditions, at 120,000 h -1 Comparative Sample J after 650°C / 50h aging was tested at a space velocity based on gas volume per hour. The % recovery after sulfidation-desulfurization treatment was measured on cores subjected to 650°C / 50h aging before these treatments under the same conditions as the cores subjected to sulfidation treatment and then to desulfurization treatment (Table 8).x =0.7), 10% O2, 10% H2O, balance N2 flowing gas at 400°C for 8 hours, totaling about 40 g / L total S exposure. For the desulfurization treatment, the cured cores were maintained at 550°C for 0.5 hours under a flowing gas composition of 10% O2, 10% H2O, balance N2.

[0109] Despite having similar SAR and copper loading, the catalysts prepared from exemplary zeolites 6 and 7 exhibit superior NO conversion at 200°C and 550°C compared to the catalyst prepared from comparative zeolite 1.

[0110] Furthermore, exemplary zeolite 7, in which the gel producing CHA was composed in part of FAU seeds, exhibited higher NO conversion at 550°C compared to the catalyst prepared from exemplary zeolite 6 (sodium silicate only).

[0111] These results indicate that catalysts prepared from the disclosed CHA materials (e.g., exemplary zeolites 6 and 7) possess superior hydrothermal stability and improved SCR activity (NOx conversion) after hydrothermal aging compared to catalysts obtained by conventional procedures (e.g., comparative zeolite 1).

[0112] Example 3

[0113] The following exemplary zeolites were made using non-zeolitic Al sources, as shown in Tables 6 and 7 below.

[0114] Table 6. Synthesis details of inventive examples and comparative examples

[0115]

[0116] ^Na-FAU and K-LTL denote FAU and LTL zeolites; formulations using FAU seeds are described in U.S. Pat. No. 6,908,60 B2.

[0117] & Crystallization was performed using a stepwise temperature protocol: ramp from 25 °C to 160 °C over 8 h; hold at 160 °C for 10 h; cool to 140 °C over 2 h; hold at 140 °C for 50 h

[0118] Table 7: Product details of comparative zeolites and exemplary zeolites A to L

[0119] Material Mutually Moderate MOR observed SAR Na / Al Example / Comparison A CHA Yes (30 hours) 19.9 0.86 Exemplary B CHA Yes (30 hours) 21.4 0.83 Exemplary C CHA Yes (15 hours) 21.0 0.65 Exemplary D CHA Yes (30 hours) 18.4 0.46 Exemplary E CHA Yes (30 hours) 17.4 0.51 Exemplary F CHA no 17.0 0.70 contrast G CHA No (30 hours) 16.6 - contrast H CHA no 19.5 0.83 contrast I CHA no 18.3 0.84 contrast J CHA no 18.3 0.84 contrast K CHA no 17.6 0.73 contrast L CHA no 11.4 - contrast

[0120] The zeolite initiator listed in Table 6 as FAU seed is identical to the zeolite initiator described as NaY seed in U.S. Patent No. 6,908,603B2. When measuring the XRD spectrum of the material, no crystallization peak is observed, which indicates a lack of any crystallinity. Similar gel compositions are used in the synthesis of zeolites A to K, wherein sulfuric acid is added as required to adjust the OH / Si ratio. Due to all the comparison zeolites shown in Table 6 (except zeolite K; that is, F to J and L) being prepared using a zeolite Al source, these zeolites are synthesized via inter-zeolite conversion. SEM images (not shown) are obtained for all zeolites prepared.

[0121] The SCR performance of the Cu-containing CHA catalyst is measured as the percentage of nitrogen oxides (NOx) reduced at a certain temperature in the feed stream. For simplicity, the comparative SCR performance normalized to a specific reference material (as indicated) after different simulated aging schemes is shown in Table 8 below. The last column of Table 8 shows the SCR performance recovered on the catalyst after desulfurization treatment at 550°C, that is, the SCR performance after desulfurization normalized to the SCR performance before the catalyst was exposed to sulfur. A higher degree of performance recovery indicates that the catalysts are more stable and more active because they are not affected by exposure to sulfur oxides. It is clear from these examples that the exemplary zeolites of the present disclosure synthesized after the formation of the MOR intermediate phase exhibit favorable characteristics as SCR catalysts relative to similar materials made with similar raw materials and gel conditions without the presence of an intermediate MOR phase.

[0122] Table 8. SCR performance data for comparative zeolites and exemplary zeolites A to L

[0123]

[0124] Implementation

[0125] The invention is further illustrated by the following set of embodiments and combinations of embodiments obtained from the indicated dependencies and back-references. In particular, it should be noted that in each case where the scope of an embodiment is mentioned, for example in the context of a term such as "a method according to any one of embodiments 1 to 4", each embodiment within this scope is meant to be explicitly disclosed to the skilled person, i.e. the wording of this term should be understood by the skilled person as being synonymous with "a method according to any one of embodiments 1, 2, 3 and 4". In addition, it should be explicitly pointed out that the following set of embodiments represents a properly structured part of a general description of preferred aspects of the invention and therefore properly supports but does not represent the claims of the invention.

[0126] 1. A method for preparing chabazite (CHA) zeolite, the method comprising the following steps:

[0127] (a) preparing an aqueous mixture comprising a silica source, an alumina source, a mineralizer and an organic structure directing agent (OSDA) to form a gel;

[0128] (b) heating the gel at about 100° C. to about 200° C. to form a mesophase comprising mordenite (MOR) crystals; and

[0129] (c) further heating the mesophase at about 100°C to about 200°C to obtain a CHA zeolite, wherein the CHA zeolite preferably has a substantially larger CHA framework.

[0130] 2. The method according to embodiment 1, wherein the CHA zeolite comprises less than about 10% MOR crystals.

[0131] 3. The method according to embodiment 1 or 2, wherein the CHA zeolite does not contain MOR crystals.

[0132] 4. The method of any one of embodiments 1 to 3, wherein step (b) is maintained for less than about 100 hours.

[0133] 5. The method according to any one of embodiments 1 to 4, wherein step (b) is maintained for about 15 hours to 90 hours, preferably about 16 to about 80 hours, more preferably 20 hours to 70 hours, more preferably about 25 hours to 60 hours, more preferably about 28 hours to 50 hours, more preferably about 30 hours to about 40 hours.

[0134] 6. The method according to any one of embodiments 1 to 5, wherein step (c) is maintained for about 15 hours to 90 hours, preferably about 16 to about 80 hours, more preferably 20 hours to 70 hours, more preferably about 25 hours to 60 hours, more preferably about 28 hours to 50 hours, more preferably about 30 hours to about 40 hours.

[0135] 7. The method according to any one of embodiments 1 to 6, wherein the CHA zeolite has a molecular weight of less than about 40 m 2 / g of matrix surface area (MSA).

[0136] 8. The method according to any one of embodiments 1 to 7, wherein the CHA zeolite has a molecular weight of less than about 25 m 2 / g of matrix surface area (MSA).

[0137] 9. The method according to any one of embodiments 1 to 8, wherein the CHA zeolite has a molecular weight of less than about 22 m 2 / g of matrix surface area (MSA).

[0138] 10. The method according to any one of embodiments 1 to 9, wherein the CHA zeolite has a molecular weight of less than about 15 m 2 / g of matrix surface area (MSA).

[0139] 11. The method according to any one of embodiments 1 to 10, wherein the CHA zeolite has a 2 / g of matrix surface area (MSA).

[0140] 12. The method according to any one of embodiments 1 to 11, wherein the CHA zeolite has a silica to alumina ratio (SAR) greater than about 15.

[0141] 13. The method according to any one of embodiments 1 to 12, wherein the CHA zeolite has a silica to alumina ratio (SAR) greater than about 18.5.

[0142] 14. The method according to any one of embodiments 1 to 13, wherein the CHA zeolite has a silica to alumina ratio (SAR) greater than about 20.0.

[0143] 15. The method according to any one of embodiments 1 to 14, wherein the CHA zeolite has a silica to alumina ratio (SAR) of about 20.1.

[0144] 16. The method according to any one of embodiments 1 to 14, wherein the CHA zeolite has a silica to alumina ratio (SAR) of about 21.7.

[0145] 17. The method according to any one of embodiments 1 to 16, wherein the alumina source is selected from aluminum isopropoxide, aluminum sulfate, zeolites, aluminum oxides, aluminum hydroxides, kaolin clay, and combinations thereof.

[0146] 18. The method according to any one of embodiments 1 to 17, wherein the alumina source is aluminum isopropoxide.

[0147] 19. The method according to any one of embodiments 1 to 17, wherein the alumina source is aluminum sulfate.

[0148] 20. The method according to any one of embodiments 1 to 17, wherein the alumina source is a zeolite, such as Al-FAU or Al-LTL.

[0149] 21. The method according to any one of embodiments 1 to 17, wherein the aluminum oxide source is aluminum oxide.

[0150] 22. The method according to any one of embodiments 1 to 17, wherein the alumina source is aluminum hydroxide.

[0151] 23. The method according to any one of embodiments 1 to 17, wherein the alumina source is kaolin clay.

[0152] 24. The method according to any one of embodiments 1 to 23, wherein the mineralizer is selected from alkaline hydroxides, fluorides, F - , quaternary ammonium hydroxides, diquaternary ammonium hydroxides and combinations thereof.

[0153] 25. The method according to any one of embodiments 1 to 24, wherein the mineralizer is chosen from alkaline hydroxides.

[0154] 26. The method according to any one of embodiments 1 to 24, wherein the mineralizer is chosen from fluorides.

[0155] 27. The method according to any one of embodiments 1 to 24, wherein the mineralizer is NaOH.

[0156] 28. The method according to any one of embodiments 1 to 24, wherein the mineralizer is KOH.

[0157] 29. The method according to any one of embodiments 1 to 24, wherein the mineralizer is F - .

[0158] 30. The method according to any one of embodiments 1 to 24, wherein the mineralizer is a quaternary ammonium hydroxide.

[0159] 31. The method according to any one of embodiments 1 to 24, wherein the mineralizer is a diquaternary ammonium hydroxide.

[0160] 32. The method according to any one of embodiments 1 to 31, wherein the OSDA is selected from quaternary ammonium salts.

[0161] 33. A method according to embodiment 32, wherein the quaternary ammonium salt is selected from trimethyladamantylammonium hydroxide, trimethylbenzylammonium hydroxide, triethylcyclohexylammonium hydroxide and combinations thereof, preferably wherein the quaternary ammonium salt is selected from trimethyladamantylammonium hydroxide, trimethylbenzylammonium hydroxide, triethylcyclohexylammonium hydroxide and combinations thereof.

[0162] 34. The method of embodiment 33, wherein the quaternary ammonium salt is trimethyladamantyl ammonium hydroxide.

[0163] 35. The method of embodiment 33, wherein the quaternary ammonium salt is trimethylbenzylammonium hydroxide.

[0164] 36. The method of embodiment 33, wherein the quaternary ammonium salt is triethylcyclohexylammonium hydroxide.

[0165] 37. The method according to any one of embodiments 1 to 36, wherein the silica source is selected from colloidal silica, precipitated silica, fumed silica, sodium silicate, zeolite silica, silica from kaolin clay, and combinations thereof.

[0166] 38. The method according to any one of embodiments 1 to 37, wherein the silica source is colloidal silica.

[0167] 39. The method according to any one of embodiments 1 to 37, wherein the silica source is precipitated silica.

[0168] 40. The method according to any one of embodiments 1 to 37, wherein the silica source is fumed silica.

[0169] 41. The method according to any one of embodiments 1 to 37, wherein the silica source is sodium silicate.

[0170] 42. The method according to any one of embodiments 1 to 37, wherein the silica source is zeolitic silica.

[0171] 43. The method according to any one of embodiments 1 to 37, wherein the silica source is silica from kaolin clay.

[0172] 44. The method of any one of embodiments 1 to 43, wherein the silica source comprises a SiO2 / Na2O weight % ratio of about 1.

[0173] 45. The method according to any one of embodiments 1 to 43, wherein the silica source comprises a SiO2 / Na2O weight % ratio of about 2.

[0174] 46. ​​The method according to any one of embodiments 1 to 43, wherein the sodium silicate comprises a SiO2 / Na2O weight % ratio of about 3.

[0175] 47. The method according to any one of embodiments 1 to 43, wherein the sodium silicate comprises a SiO2 / Na2O weight % ratio of about 3.3.

[0176] 48. The method according to any one of embodiments 1 to 43, wherein the sodium silicate comprises a SiO2 / Na2O weight % ratio of about 4.

[0177] 49. The method of any one of embodiments 1 to 48, wherein the silica source has a solids content greater than about 20 wt%.

[0178] 50. The method according to any one of embodiments 1 to 49, wherein the silica source has a solids content greater than about 30 wt%.

[0179] 51. The method according to any one of embodiments 1 to 50, wherein the silica source has a solids content of about 37% by weight.

[0180] 52. The method according to any one of embodiments 1 to 51, wherein the molar ratio of silica to alumina (SAR) in the gel is at least about 30.

[0181] 53. The method according to any one of embodiments 1 to 51, wherein the molar ratio of silica to alumina (SAR) in the gel is at least about 35.

[0182] 54. The method according to any one of embodiments 1 to 53, wherein the gel is heated at about 100°C to about 200°C.

[0183] 55. The method of any one of embodiments 1 to 54, wherein the gel is heated for about 35 hours to about 38 hours.

[0184] 56. The method of any one of embodiments 1 to 55, wherein the gel is heated for about 36 hours.

[0185] 57. The method of any one of embodiments 1 to 56, wherein the mesophase is heated at about 100°C to about 200°C.

[0186] 58. The method of any one of embodiments 1 to 57, wherein the mesophase is heated for about 35 hours to about 38 hours.

[0187] 59. The method of any one of embodiments 1 to 58, wherein the mesophase is heated for about 36 hours.

[0188] 60. The method according to any one of embodiments 1 to 59, wherein the aqueous gel of step (a) further comprises a zeolite initiator.

[0189] 61. A method according to embodiment 60, wherein the zeolite initiator has a SiO2 / Al2O3 molar ratio of about 65.

[0190] 62. The method of embodiment 60, wherein the zeolite initiator has a SiO2 / Na2O molar ratio of about 1.7.

[0191] 63. The method of embodiment 60, wherein the zeolite initiator has a H2O / SiO2 molar ratio of about 10.3.

[0192] 64. A method according to embodiment 60, wherein the zeolite initiator has a SiO2 / Al2O3 molar ratio of about 65, a SiO2 / Na2O ratio of about 1.7, and a H2O / SiO2 molar ratio of about 10.3.

[0193] 65. The method of any one of embodiments 1 to 64, wherein the SiO2 yield of the zeolite is between about 50% and about 65% based on complete aluminum conversion.

[0194] 66. The method of any one of embodiments 1 to 64, wherein the SiO2 yield of the zeolite is between about 55% and about 64% based on complete aluminum conversion.

[0195] 67. The method of any one of embodiments 1 to 66, comprising a sound velocity profile, wherein the ultrasonic measurement of the gel of step (a) is greater than about 1000 m / s.

[0196] 68. A method according to any one of embodiments 1 to 66, the method comprising a sound velocity profile, wherein the ultrasonic measurement result of the intermediate phase of step (b) is about 5 m / s to about 15 m / s higher than the ultrasonic measurement result of the gel of step (a).

[0197] 69. The method of any one of embodiments 1 to 66, comprising a sonic velocity profile wherein the ultrasonic measurement of the CHA zeolite of step (c) is about 7 m / s to about 17 m / s higher than the ultrasonic measurement of the gel of step (a).

[0198] 70. A method according to any one of embodiments 1 to 66, the method includes a sonic velocity profile, wherein the ultrasonic measurement result of the gel of step (a) is greater than about 1000 m / s; the ultrasonic measurement result of the intermediate phase of step (b) is about 5 m / s to about 15 m / s higher than the ultrasonic measurement result of the gel of step (a); and the ultrasonic measurement result of the CHA zeolite of step (c) is about 7 m / s to about 17 m / s higher than the ultrasonic measurement result of the gel of step (a).

[0199] 71. The method according to any one of embodiments 1 to 70, wherein the method further comprises isolating the CHA zeolite by filtration.

[0200] 72. The method according to embodiment 71, wherein the separated phase-pure zeolite is dried and calcined to produce Na + form.

[0201] 73. The method according to embodiment 72, wherein the calcination is carried out at greater than about 500°C.

[0202] 74. The method according to embodiment 72 or 73, wherein the calcination is carried out at a temperature between about 500°C and about 550°C.

[0203] 75. The method according to any one of embodiments 72 to 74, wherein the calcination is carried out for greater than about 5 hours.

[0204] 76. The method according to any one of embodiments 72 to 75, wherein the calcination is carried out for about 7 hours.

[0205] 77. The method according to any one of embodiments 72 to 76, wherein the calcined zeolite is subjected to NH4 + Exchange to become NH4 + Form zeolite.

[0206] 78. The method according to embodiment 77, wherein the NH4 + The form has a Na2O content of less than about 500 ppm.

[0207] 79. The method according to any one of embodiments 77 or 78, wherein the Cu ions are introduced into the NH + The zeolite catalyst is formed by forming CHA zeolite.

[0208] 80. The method according to embodiment 77 or 78, wherein the NH4 + Form to produce H + form.

[0209] 81. The method according to embodiment 80, wherein the calcination is carried out at greater than about 400°C.

[0210] 82. The method according to embodiment 80 or 81, wherein the calcination is carried out at a temperature ranging between about 400°C and about 450°C.

[0211] 83. The method according to any one of embodiments 80 to 82, wherein the calcination is carried out at about 450°C.

[0212] 84. The method according to any one of embodiments 80 to 83, wherein the calcination is carried out for greater than about 5 hours.

[0213] 85. The method according to any one of embodiments 80 to 84, wherein the calcination is performed for about 6 hours.

[0214] 86. The method of any one of embodiments 80 to 85, wherein the H + The zeolite catalyst is formed by forming CHA zeolite.

[0215] 87. The method of embodiment 79 or 86, wherein the copper-exchanged CHA zeolite has a copper loading of about 3.0 wt. % to about 6.0 wt. %.

[0216] 88. The method of embodiment 79 or 86, wherein the copper-exchanged CHA zeolite has a copper loading of about 3.0 wt%.

[0217] 89. The method of embodiment 79 or 86, wherein the copper-exchanged CHA zeolite has a copper loading of about 4.0 wt%.

[0218] 90. The method according to embodiment 79 or 86, wherein the copper loading of the zeolite catalyst is about 4.8 wt%.

[0219] 91. The method of embodiment 79 or 86, wherein the copper-exchanged CHA zeolite has a copper loading of about 5.0 wt%.

[0220] 92. The method of embodiment 79 or 86, wherein the copper-exchanged CHA zeolite has a copper loading of about 6.0 wt%.

[0221] 93. A method according to any one of embodiments 1 to 92, wherein the CHA zeolite has greater than about 75% CHA framework, preferably greater than about 80% CHA framework, preferably greater than about 85% CHA framework, more preferably greater than about 90% CHA framework, more preferably greater than about 95% CHA framework.

[0222] 94. A method according to any one of embodiments 1 to 93, wherein the CHA zeolite has less than about 25% MOR framework, preferably less than about 20% MOR framework, more preferably less than about 15% MOR framework, more preferably less than about 10% MOR framework, more preferably less than about 5% MOR framework.

[0223] 95. The method according to embodiments 1 to 94, comprising:

[0224] (a) preparing an aqueous mixture comprising a silica source, an alumina source, a mineralizer, a zeolite initiator and an organic structure directing agent (OSDA) to form a gel;

[0225] wherein the silica source is selected from the group consisting of colloidal silica, precipitated silica, fumed silica, sodium silicate, zeolite silica, silica from kaolin clay, and combinations thereof;

[0226] wherein the alumina source is selected from zeolites, the zeolites being selected from the group consisting of Al-FAU and Al-LTL;

[0227] The mineralizer is selected from alkaline hydroxides, fluorides, - , quaternary ammonium hydroxides, diquaternary ammonium hydroxides and combinations thereof;

[0228] wherein the OSDA is selected from quaternary ammonium salts;

[0229] wherein the zeolite initiator has one or more of a SiO2 / Al2O3 molar ratio of 65, a SiO2 / Na2O molar ratio of 1.7, and a H2O / SiO2 molar ratio of 10.3;

[0230] (b) heating the gel at 100° C. to 200° C. to form a mesophase comprising mordenite (MOR) crystals; and

[0231] (c) further heating the mesophase at 100°C to 200°C to obtain a CHA zeolite having greater than about 75% CHA framework and less than 25% MOR framework.

[0232] 96. A copper-exchanged CHA zeolite, wherein the zeolite has a 2 / g of zeolite surface area (ZSA).

[0233] 97. A copper-exchanged CHA zeolite obtained or obtainable by the method according to any one of claims 1 to 95.

[0234] 98. The copper-exchanged CHA zeolite of embodiment 96 or 97, wherein the zeolite has a silica to alumina ratio (SAR) of about 15 to about 22.

[0235] 99. The copper-exchanged CHA zeolite of embodiment 96 or 97, wherein the zeolite has a SAR of about 17.

[0236] 100. The copper-exchanged CHA zeolite of embodiment 96 or 97, wherein the zeolite has a SAR of about 21.

[0237] 101. A method of producing a catalytic article, the method comprising the steps of:

[0238] (a) applying a catalytic coating to a substrate via a washcoat process; and

[0239] (b) drying and calcining the coated substrate at greater than about 500° C., preferably for about 1 hour or more, more preferably for about 1 hour;

[0240] Wherein the catalytic coating comprises the CHA zeolite according to Embodiment 1, about 5% zirconium oxide and about 5% pseudo-boehmite (PB-250) binder, the CHA zeolite having a CuO loading of about 3.0 wt % to about 6.0 wt %.

[0241] 102. The method of embodiment 101, wherein the coating step provides about 2.1 g / in 3 of catalyst loading.

[0242] 103. The method of embodiment 102, wherein the catalyst loading further comprises about 5% to about 10% zirconium oxide and about 5% to about 10% alumina binder.

[0243] 104. The method of any one of embodiments 101 to 103, wherein the catalytic article has a cell density of about 400 cpsi.

[0244] 105. The method of any one of embodiments 101 to 104, wherein the catalytic article has a wall thickness of about 6 mm.

[0245] 106. A catalytic article comprising a copper-exchanged CHA zeolite produced according to the method of any one of embodiments 101 to 105, wherein the zeolite has a carbon content greater than about 450 m 2 / g of zeolite surface area (ZSA).

[0246] 107. A method for reducing nitrogen oxides (NO x ) method, the method comprising contacting a gaseous stream containing nitrogen oxides with at least one copper-exchanged CHA zeolite according to any one of Embodiments 97 to 100 or at least one catalytic article according to Embodiment 106 at a temperature ranging from about 200°C to about 550°C.

[0247] 108. The method according to embodiment 107, wherein the method comprises using ammonia or an ammonia precursor to selectively reduce NO x .

[0248] 109. The method according to embodiment 108, wherein NO x The selective reduction is carried out at a temperature ranging from about 200°C to about 550°C.

[0249] 110. The method according to any one of embodiments 107 to 109, wherein NO x The reduction at about 200°C is greater than about 60%.

[0250] 111. The method according to any one of embodiments 105 to 107, wherein NO xThe reduction at about 200°C was greater than about 63%.

[0251] 112. The method according to any one of embodiments 107 to 109, wherein NO x The reduction at about 550°C was greater than about 75%.

[0252] 113. The method of any one of embodiments 107 to 112, wherein the reduction of NOx at about 200°C is greater than about 65%, and the reduction of NOx at about 550°C is greater than about 75%.

[0253] 114. The method according to any one of embodiments 107 to 113, wherein the reduction of NOx is maintained after hydrothermal aging of the zeolite.

[0254] 115. The method according to embodiment 114, wherein the hydrothermal aging is carried out at about 800°C for about 16 hours in the presence of about 10% H2O / air.

[0255] 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.

[0256] 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 claims.

Claims

1. A method for preparing chabazite (CHA) zeolite, the method comprising: (a) preparing an aqueous mixture comprising a silica source, an alumina source, a mineralizer and an organic structure directing agent (OSDA) to form a gel; (b) heating the gel at about 100° C. to about 200° C. to form a mesophase comprising mordenite (MOR) crystals; and (c) further heating the mesophase at about 100°C to about 200°C to obtain a CHA zeolite, wherein the CHA zeolite preferably has a substantially larger CHA framework.

2. The method of claim 1, wherein the CHA zeolite has a carbon content of less than about 40 m 2 / g of matrix surface area (MSA).

3. The method of claim 1 or 2, wherein step (b) is maintained for less than about 100 hours.

4. The process of any one of claims 1 to 3, wherein the zeolite has a SiO2 yield greater than about 50% based on complete aluminum conversion.

5. The process of any one of claims 1 to 4, wherein the CHA zeolite has a silica to alumina ratio (SAR) greater than about 15.

6. The method according to any one of claims 1 to 5, wherein the alumina source is selected from the group consisting of aluminum isopropoxide, aluminum sulfate, zeolite, aluminum oxide, aluminum hydroxide, kaolin clay, and combinations thereof.

7. The method according to any one of claims 1 to 6, wherein the mineralizer is selected from the group consisting of alkaline hydroxides, fluorides, F - , quaternary ammonium hydroxides, diquaternary ammonium hydroxides and combinations thereof.

8. The method according to any one of claims 1 to 7, wherein the OSDA is selected from quaternary ammonium salts.

9. The method of any one of claims 1 to 8, wherein the silica source is selected from the group consisting of colloidal silica, precipitated silica, fumed silica, sodium silicate, zeolite silica, silica from kaolin clay, and combinations thereof.

10. The method of any one of claims 1 to 9, wherein the silica source comprises a SiO2 / Na2O weight % ratio of about 1 to about 4 and a solids content greater than about 20 weight %.

11. The method of any one of claims 1 to 10, wherein the silica to alumina molar ratio (SAR) in the gel is at least about 30.

12. The method according to any one of claims 8 to 11, wherein the quaternary ammonium salt is selected from trimethyladamantyl ammonium salt, trimethylbenzylammonium salt, triethylcyclohexylammonium salt and combinations thereof.

13. The method of any one of claims 1 to 12, comprising a sonic velocity profile wherein the ultrasonic measurement of the gel of step (a) is greater than about 1000 m / s; the ultrasonic measurement of the mesophase of step (b) is about 5 m / s to about 15 m / s higher than the ultrasonic measurement of the gel of step (a); and the ultrasonic measurement of the CHA zeolite of step (c) is about 7 m / s to about 17 m / s higher than the ultrasonic measurement of the gel of step (a).

14. The method according to any one of claims 1 to 13, further comprising the following steps: (d) Implementation of NH4 + Exchange to form NH4 + Form zeolite; (e) optionally calcining the NH4 + Zeolite produces H + form zeolite; and (f) Introducing Cu ions into the H + Form zeolite or the NH4 + to form a zeolite catalyst.

15. The method of any one of claims 1 to 14, wherein the aqueous gel of step (a) further comprises a zeolite initiator, wherein the zeolite initiator has one or more of a SiO2 / Al2O3 molar ratio of about 65, a SiO2 / Na2O molar ratio of about 1.7, and a H2O / SiO2 molar ratio of about 10.

3.

16. The method according to any one of claims 1 to 15, comprising: (a) preparing an aqueous mixture comprising a silica source, an alumina source, a mineralizer, a zeolite initiator and an organic structure directing agent (OSDA) to form a gel; wherein the silica source is selected from the group consisting of colloidal silica, precipitated silica, fumed silica, sodium silicate, zeolite silica, silica from kaolin clay, and combinations thereof; wherein the alumina source is selected from zeolites, and the zeolites are selected from the group consisting of Al-FAU and Al-LTL; The mineralizer is selected from alkaline hydroxides, fluorides, - , quaternary ammonium hydroxides, diquaternary ammonium hydroxides and combinations thereof; wherein the OSDA is selected from quaternary ammonium salts; wherein the zeolite initiator has one or more of a SiO2 / Al2O3 molar ratio of 65, a SiO2 / Na2O molar ratio of 1.7, and a H2O / SiO2 molar ratio of 10.3; (b) heating the gel at 100° C. to 200° C. to form a mesophase comprising mordenite (MOR) crystals; and (c) further heating the mesophase at 100°C to 200°C to obtain a CHA zeolite having greater than about 75% CHA framework and less than 25% MOR framework.

17. A copper-exchanged CHA zeolite wherein the zeolite has a 2 / g of zeolite surface area (ZSA).

18. A copper-exchanged CHA zeolite obtained or obtainable by the method according to any one of claims 1 to 16.

19. The copper-exchanged CHA zeolite of claim 17 or 18, wherein the zeolite has a copper loading ranging from about 3.0 wt% to about 6.0 wt%.

20. A method of producing a catalytic article, the method comprising: (a) applying a catalytic coating to a substrate via a wash coating process; as well as (b) drying and calcining the coated substrate at a temperature greater than about 500° C.; wherein the catalytic coating comprises the CHA zeolite of claim 1, about 5% zirconium oxide and about 5% pseudo-boehmite (PB-250) binder, the CHA zeolite having a copper loading ranging from about 3.0 wt % to about 6.0 wt %.

21. A catalytic article produced according to the method of claim 20, comprising a copper-exchanged CHA zeolite, wherein the zeolite has a carbon content greater than about 450 m 2 / g of zeolite surface area (ZSA).

22. A method for reducing nitrogen oxides (NO x ) comprising contacting a gaseous stream containing nitrogen oxides with at least one copper-exchanged CHA zeolite according to claims 17 to 19 or at least one catalytic article according to claim 21.

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