Zeolite synthesis using hydrous kaolin

Abstract

Described herein is a method for preparing a zeolite comprising mixing an aluminum source, a sodium source, and water to form a mixture. After mixing, a silicon source is added and mixed. Zeolite crystals or zeolite seeds are then added to form a gel mixture, which is then crystallized at a temperature of about 100 DEG C to about 200 DEG C for about 10 to about 108 hours to obtain zeolite crystals.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent No. 63 / 432,441, filed on December 14, 2022, and U.S. Provisional Patent No. 63 / 539,648, filed on September 21, 2023, the entire contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention generally relates to a method for preparing zeolites. Specifically, the method includes preparing zeolites using a crystallization process. The zeolites can be used to prepare FCC catalytic materials. In another embodiment, the zeolites can be part of an exhaust gas treatment system for treating exhaust gas streams, particularly those from gasoline or diesel engines. Background Art

[0004] Refined products of gasoline, light olefins, and light cycle oils are always more valuable than the bottom distillate fractions. A catalyst composition that can selectively produce one of the valuable fractions is desirable for refiners. Currently, a phosphorus - containing ZSM - 5 additive can selectively crack gasoline - range olefins in an FCC unit to produce light olefins such as ethylene, propylene, and butene. Thus, refineries have widely used ZSM - 5 - containing catalysts to obtain light olefins in FCC petrochemical processes.

[0005] Metal - promoted zeolites (such as copper - exchanged zeolites) are used to facilitate the reaction of ammonia (or ammonia precursors such as urea) with nitrogen oxides (NOx) in the presence of oxygen (selectively preferentially to the competing reaction with oxygen) to form nitrogen and H2O. Thus, the catalytic reaction is generally referred to as selective catalytic reduction (SCR), in which a high degree of nitrogen oxide removal can be achieved using a small amount of a reducing agent. In some embodiments, chabazite (CHA) can be used as a catalyst in such reactions.

[0006] In typical zeolite manufacturing methods, zeolites are crystallized using solutions that typically contain less than 25 wt% solids. These reactions are most often carried out in the form of slurries with a significant amount of water. However, the amount of water can reduce the yield and the operation can be more expensive. Therefore, there is a need to improve the current crystallization process. Summary of the Invention

[0007] It has been found that synthesizing zeolites (such as ZSM-5) using hydrated kaolin as an aluminum source can result in high gel solids of about 25 wt% or higher, which leads to high zeolite productivity. It has also been found that synthesizing zeolites with lower solid content (such as chabazite) using hydrated kaolin as the sole aluminum source can provide a method with high manufacturing efficiency and cost competitiveness. It has been found that hydrated kaolin significantly reduces the viscosity of the gel mixture even at high solid contents (such as 35 wt%), thus allowing the reagents to mix and react fully during crystallization. In addition, using hydrated kaolin is advantageous because its low cost and high product yield make the synthesis method highly efficient and cost-competitive in manufacturing.

[0008] In an embodiment of the present invention, a method for preparing zeolites is provided. The method includes mixing an aluminum source, a sodium source or a potassium source, and water to form a first mixture. The method further includes adding a silicon source to the first mixture and mixing, and then adding zeolite crystals or zeolite seeds to form a gel mixture. The method further includes crystallizing the gel mixture at a temperature of about 150 °C to about 200 °C for about 12 to about 48 hours to obtain zeolite crystals. In some embodiments of the method, the aluminum source is hydrated kaolin.

[0009] Unless otherwise specified, the methods of the present disclosure will be described with reference to using ZSM-5 as the zeolite, but it should be understood that the methods can be applied to various zeolite materials, including but not limited to aluminosilicate zeolites, aluminophosphate zeolites, gallium phosphate zeolites, silicoaluminophosphate zeolites, metal aluminophosphate zeolites (wherein the metal represents a transition metal element), germanosilicate zeolites, borosilicate zeolites, beryllium silicate zeolites, zinc silicate zeolites, and titanium silicate zeolites. In another embodiment, the methods of the present disclosure can be described with reference to using chabazite as the zeolite as stated therein.

[0010] In some embodiments of the method, the sodium source can be sodium silicate. In some embodiments of the method, the potassium source can be potassium silicate. In some embodiments of the method, the silicon source can include an aqueous dispersion of colloidal silica with the solid at or above about 20 wt%. In some embodiments, the silicon source can include but is not limited to sodium silicate, sodium metasilicate, potassium silicate, stabilized silica sol, silica gel, polysilicic acid, tetraethyl orthosilicate, fumed silica, precipitated silica, or a mixture thereof.

[0011] The aluminum source and / or the silicon source may be doped with a suitable dopant. In some embodiments, the dopant may include compounds that include: rare earth metals such as Ce, La, Y, Gd, Eu, Pr, Sm, Ho, Nd, Er, Yb, or Tb; alkali metals and alkaline earth metals such as Mg, Ca, K, Na, and Ba; transition metals such as Zr, Mn, Fe, Ti, Ag, Au, Cu, Ni, Zn, Mo, W, V, and Sn; actinides; noble metals such as Rh, Ru, Pt, and Pd; Group III, IV, or V elements such as Ga, B, In, Ge, and / or P.

[0012] An alkali may be added to the gel mixture to adjust the pH, where the alkali may include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, ammonium hydroxide, magnesium hydroxide, or calcium hydroxide.

[0013] In some embodiments, the hydrated kaolin may have a particle size with D90 (the diameter of 90% of the particles) below 30 μm, below 20 μm, or below 15 μm.

[0014] In some embodiments of the method, the zeolite crystals may be ZSM-5.

[0015] In some embodiments of the method, the hydrated kaolin may have a solids content of about 50 wt% to about 75 wt% solids.

[0016] In some embodiments of the method, the zeolite crystals or zeolite seeds may have a silica to alumina ratio (SAR) of about 20 to about 35.

[0017] In some embodiments, the method may further include post-treating the zeolite crystals by acid washing or ion exchange to remove sodium or potassium. In some embodiments, the acid washing may include using dilute sulfuric acid having a concentration of about 1% to about 20%. In some embodiments, the ion exchange may include using an ammonium nitrate or ammonium sulfate solution.

[0018] In some embodiments of the method, the sodium may be removed such that the amount of sodium oxide in the zeolite crystals is less than about 0.4 wt% or less than about 0.2 wt%.

[0019] In some embodiments, zeolite crystals crystallized in the sodium form may have an XRD crystallinity greater than about 85% and a TSA greater than about 260 m 2 / g.

[0020] In some embodiments of the method, the gel mixture can have an SiO2 / Al2O3 molar ratio of from about 30 to about 42. In some embodiments, the gel mixture can have a Na2O / SiO2 and OH- / Si molar ratio of from about 0.1 to about 0.3. In some embodiments, the gel mixture has an H2O / SiO2 molar ratio of less than about 11.

[0021] In some embodiments of the method, zeolite crystals or zeolite seeds can be included in an amount of from about 0.1 wt% to about 6 wt%.

[0022] In some embodiments of the method, the gel mixture can have a solids content of at least about 25%.

[0023] In some embodiments of the method, crystallization can be achieved by heating the gel mixture in an autoclave. In some embodiments, the crystallized gel mixture can be separated to obtain zeolite crystals.

[0024] In some embodiments of the method, the mixing order of the raw materials can be changed depending on the mixing efficiency.

[0025] In some embodiments of the method, the zeolite crystals can have a particle size with D90 below 25 μm, or below 15 μm.

[0026] In some embodiments of the method, the zeolite seeds can be FCC or FAU seeds.

[0027] In another embodiment of the present disclosure, zeolite crystals are provided. The zeolite crystals comprise ZSM-5 having a SAR of from about 24 to about 40 and a sodium content of less than about 0.4%.

[0028] In yet another embodiment, a method for preparing chabazite (CHA) zeolite is provided. The method includes preparing an aqueous mixture comprising a silica source, the only alumina source, an alkali agent, and an organic structure-directing agent (OSDA) to form a gel mixture. The method further includes crystallizing the gel mixture at a temperature of from about 100 °C to about 200 °C for about 10 to about 108 hours to obtain zeolite crystals. In some embodiments, the only aluminum source can be hydrated kaolin.

[0029] In some embodiments, the method can further include a sodium source. The sodium source can be sodium silicate or potassium silicate. In some embodiments, the silica source can be colloidal silica or fumed silica, wherein the colloidal silica can be an aqueous colloidal silica having a solids content at or above 20 wt.%.

[0030] In some embodiments, the hydrated kaolin may have a particle size with D90 (diameter of 90% of the particles) below 30 μm, below 25 μm, below 15 μm, or below 12 μm.

[0031] In some embodiments, the base agent may be an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide may be sodium hydroxide.

[0032] In some embodiments, the hydrated kaolin may have a solids content of about 50 wt% to about 75 wt% solids. In some embodiments, the hydrated kaolin may have a solids content of at least about 50 wt% solids.

[0033] In some embodiments, the method may further include post-treating the zeolite crystals by acid washing or ion exchange to remove sodium. In some embodiments, the acid washing may include using dilute sulfuric acid that may have a concentration of about 1% to about 20%. In some embodiments, the ion exchange may include using ammonium nitrate or ammonium sulfate solution. In some embodiments, the sodium may be removed such that the amount of sodium oxide in the zeolite crystals may be less than about 0.2 wt%, or less than about 0.02 wt%.

[0034] In some embodiments, the OSDA agent may include a quaternary ammonium salt. In some embodiments, the quaternary ammonium salt may include trimethyladamantyl ammonium hydroxide, trimethylbenzyl ammonium hydroxide, triethylcyclohexyl ammonium hydroxide, or a combination thereof. In certain embodiments, the quaternary ammonium salt may include trimethyladamantyl ammonium hydroxide. In certain embodiments, the quaternary ammonium salt may include trimethylbenzyl ammonium hydroxide. In certain embodiments, the quaternary ammonium salt may include triethylcyclohexyl ammonium hydroxide.

[0035] In some embodiments, the base agent may include NaOH, KOH, F−, quaternary ammonium hydroxide, diquaternary ammonium hydroxide, or a combination thereof. In certain embodiments, the base agent may be NaOH. In certain embodiments, the base agent may be KOH. In certain embodiments, the base agent may be F−. In certain embodiments, the base agent may be quaternary ammonium hydroxide. In certain embodiments, the base agent may be diquaternary ammonium hydroxide.

[0036] In some embodiments, the gel mixture may have a solids content of at least about 15%. In some embodiments, crystallization may be achieved by heating the gel mixture in an autoclave. In some embodiments, the crystallized gel mixture may be separated to obtain zeolite crystals.

[0037] In another embodiment, a method of producing a catalytic article is provided. The method includes coating a substrate with a catalytic coating using a washcoat process. The method further includes drying and calcining the coated substrate at a temperature of about 550 °C for about 1 hour. In some embodiments, the catalytic coating can include chabazite, about 3.0 wt% to about 6.0 wt% copper oxide, about 5 wt% zirconia, and about 5 wt% pseudoboehmite (PB-250) binder.

[0038] In some embodiments, a catalytic article can be produced. The catalytic article can include ion-exchanged chabazite, wherein the chabazite can have a zeolite surface area (ZSA) greater than about 450 m 2 / g.

[0039] In some embodiments, a method of reducing nitrogen oxides (NO x ) can include contacting a gaseous stream containing nitrogen oxides with at least one ion-exchanged chabazite or at least one catalytic article. DETAILED DESCRIPTION

[0040] The present invention advances the art by developing a method for preparing zeolites at a higher solids content (such as above 20 wt%) using hydrated kaolin as an aluminum source. In some embodiments, the art is advanced by a method for preparing zeolites using hydrated kaolin as the sole aluminum source. The hydrated kaolin used herein is a feedstock that has not been further heat-treated or chemically treated prior to use in the methods herein. Thus, the hydrated kaolin used in the methods of the present invention is the lowest cost aluminum source for synthesizing zeolites such as ZSM-5. In other embodiments, the zeolite can be chabazite, beta zeolite, ZSM-11, ZSM-23, or SAPO. The hydrated kaolin is in the form of a fine powder or an aqueous slurry having a solids content of about 50 wt% or more, or about 60 wt% or more, or about 70 wt% or more. The hydrated kaolin in the form of a fine powder or a slurry has a low particle size, with a D90 (diameter of 90% of the particles) below 30 μm, below 20 μm, below 15 μm, or below 12 μm.

[0041] In addition to the aluminum source for forming zeolite, a silica source, or a silica / sodium source is also used. In some embodiments, the silica source can be sodium silicate. The sodium silicate can be selected from N-brand, or silica gel. In other embodiments, the silica source can be colloidal silica or fumed silica, such as Ludox AS-40. In some embodiments, the colloidal silica is an aqueous colloidal silica having solids at or above 20 wt.%. In some embodiments of the method, zeolite crystals or zeolite seeds can be used as seeds to improve product quality. Zeolite crystal particles (such as ZSM-5 particles) can have a particle size with D90 less than about 25 μm, less than about 15 μm, or less than about 12 μm to obtain better product quality.

[0042] The inventors have found that when using hydrated kaolin as the aluminum source, the preparation of zeolite can obtain a high gel solid of at least about 15 wt%, or at least about 25 wt% or higher, which results in a high zeolite productivity (space-time yield, STY). In contrast, current zeolites such as ZSM-5 using other aluminum sources (such as aluminum sol, sodium aluminate, aluminum sulfate, or other organic aluminum salts such as aluminum isopropoxide) need to have a solid content of less than about 20 wt%, or about 5 to about 15 wt%, because these aluminum sources are found to cause extremely high viscosities of the gel mixture at higher solids or may solidify in the gel mixture. By using hydrated kaolin as the aluminum source, even at a relatively high solid content (such as 35 wt%), it significantly reduces the viscosity of the gel mixture, thus allowing the reagents to be fully mixed and react during crystallization.

[0043] It is also found that zeolites made with hydrated kaolin as the sole aluminum source have catalytic properties similar to or better than those of zeolites made with other aluminum sources. In addition, zeolites made with other crude kaolins have lower crystallinity and / or poorer catalytic properties. The hydrated kaolin and the high product production rate make this method have high manufacturing efficiency and be cost-competitive.

[0044] The inventors have also found that after calcining hydrated kaolin at a high temperature to convert it into the metakaolin phase, the fine metakaolin particles can also be used as an aluminum source to obtain a high gel solid of about 25 wt% or higher for the ZSM-5 crystallization process. However, due to the additional costs associated with calcination, hydrated kaolin becomes the best choice for the current high-solid zeolite (such as ZSM-5) crystallization process or other crystallization processes of other zeolites (such as chabazite).

[0045] Various embodiments are described below. It should be noted that the specific embodiments are not intended as an exhaustive description or a limitation on the broader aspects discussed herein. One aspect described in connection with a particular embodiment is not necessarily limited to that embodiment and can be practiced with any other one or more embodiments.

[0046] As used herein, "about" will be understood by one of ordinary skill in the art and will vary somewhat depending on the context in which it is used. If a term is not clear to one of ordinary skill in the art, then in the context in which that term is used, "about" will mean up to plus or minus 10% of that particular term.

[0047] The articles "a / an" and "the" are used herein to refer to one or more than one (i.e., at least one) of the grammatical object of the article. For example, "seed crystal" means one seed crystal or more than one seed crystal.

[0048] All references to wt% or wt. % throughout the specification and claims are to the weight of the component relative to the weight of the entire composition.

[0049] Unless otherwise indicated herein, the recitation of ranges of values herein is merely intended to be a shorthand method of referring individually to each separate value falling within the range, and each separate value is incorporated into the specification as if it were recited individually herein. Unless otherwise indicated herein or clearly contradicted by context, all methods described herein can be performed in any suitable order.

[0050] Any and all examples, or use of exemplary language (e.g., "such as") provided herein are only intended to illustrate certain materials and methods and are not intended to limit the scope. No language in this specification should be construed as indicating that any non-claimed element is essential for the practice of the disclosed materials and methods.

[0051] 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 bind to the zeolite structure. The OSDA can, for example, contain large and / or sterically bulky organic groups. The OSDA can, for example, contain an adamantammonium group. In an embodiment, trimethyladamantammonium can be, but is not limited to, the OSDA in this disclosure.

[0052] The inventors of the present invention have developed a method for preparing zeolites using an aluminum source and a sodium source. In some embodiments, the method for preparing zeolites can use a sole aluminum source and a sodium source. In one embodiment of the present invention, a method for preparing zeolites is provided. The method for preparing zeolites includes mixing an aluminum source, a sodium source, and water to form a first mixture. In other embodiments, the method for preparing zeolites includes mixing a sole aluminum source, a sodium source, and water to form a first mixture. The method includes further adding a silicon source to the first mixture and mixing. In another embodiment, the method can include mixing an aluminum source or a sole aluminum source and at least one of a sodium source, water, and a silicon source. The method further includes adding zeolite crystals or zeolite seeds to form a gel mixture. The method then includes crystallizing the gel mixture at a temperature of about 150 °C to about 200 °C for about 12 to about 48 hours to obtain the prepared zeolite crystals. In another embodiment, the method can include crystallizing the gel mixture at a temperature of about 100 °C to about 200 °C for about 10 to about 108 hours. The aluminum source, or the sole aluminum source, can be hydrated kaolin.

[0053] In an embodiment, a method for preparing high-solid zeolites (i.e., having a solid content of at least 20 wt.%) such as ZSM-5 using an aluminum source and a sodium source is developed. The method includes mixing an aluminum source, a sodium source, and water to form a first mixture. The method further includes adding a silicon source to the first mixture and mixing. The method also includes adding zeolite crystals or zeolite seeds to form a gel mixture. The method then includes crystallizing the gel mixture at a temperature of about 150 °C to about 200 °C for about 12 to about 48 hours to obtain the prepared zeolite crystals. The aluminum source can be hydrated kaolin, and the prepared zeolite can be ZSM-5.

[0054] In another embodiment, a method for preparing chabazite (CHA) zeolites is developed. The method includes preparing an aqueous mixture containing a sole alumina source, a silica source, an alkali agent, and an organic structure-directing agent (OSDA) to form a gel mixture. The method further includes crystallizing the gel mixture at a temperature of about 100 °C to about 200 °C for about 10 to about 108 hours to obtain the prepared zeolite crystals. The sole aluminum source can be hydrated kaolin.

[0055] In some embodiments, crystallization of the gel mixture can be carried out at a temperature of about 100 °C, about 105 °C, about 110 °C, about 115 °C, about 120 °C, about 125 °C, about 130 °C, about 135 °C, about 140 °C, about 145 °C, about 150 °C, about 155 °C, about 160 °C, about 165 °C, about 170 °C, about 175 °C, about 180 °C, about 185 °C, about 190 °C, about 195 °C, or about 200 °C. In other embodiments, crystallization can be carried out at a temperature of about 100 °C to about 200 °C, about 105 °C to about 195 °C, about 110 °C to about 190 °C, about 115 °C to about 185 °C, about 120 °C to about 180 °C, about 125 °C to about 175 °C, about 130 °C to about 170 °C, about 135 °C to about 165 °C, about 140 °C to about 160 °C, or about 145 °C to about 155 °C. In yet another embodiment, crystallization can be carried out at a temperature of at least about 100 °C, at least about 110 °C, at least about 120 °C, at least about 130 °C, at least about 140 °C, or at least about 150 °C.

[0056] In some embodiments, crystallization of the gel mixture can be carried out for about 12 hours, about 14 hours, about 16 hours, about 18 hours, about 20 hours, about 22 hours, about 24 hours, about 26 hours, about 28 hours, about 30 hours, about 32 hours, about 34 hours, about 36 hours, about 38 hours, about 40 hours, about 42 hours, about 44 hours, about 46 hours, about 48 hours, about 54 hours, about 60 hours, about 66 hours, about 72 hours, about 78 hours, about 84 hours, about 90 hours, about 96 hours, about 102 hours, about 108 hours, about 114 hours, or about 120 hours. In some embodiments, crystallization can be carried out for about 10 hours to about 48 hours, about 10 hours to about 120 hours, about 12 hours to about 46 hours, about 14 hours to about 44 hours, about 16 hours to about 42 hours, about 18 hours to about 40 hours, about 18 hours to about 108 hours, about 20 hours to about 38 hours, about 22 hours to about 36 hours, about 24 hours to about 34 hours, about 24 hours to about 100 hours, about 26 hours to about 32 hours, about 28 hours to about 30 hours, about 30 hours to about 94 hours, about 36 hours to about 88 hours, about 42 hours to about 82 hours, about 48 hours to about 76 hours, about 50 hours to about 72 hours, about 52 hours to about 68 hours, or about 54 hours to about 60 hours. Depending on the zeolite being synthesized, the temperature and time of crystallization can be selected to limit the formation of impurities.

[0057] In some embodiments, the hydrated kaolin may have a particle size D90 (diameter of 90% of the particles) of less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, or less than 12 μm. If the particle size is greater than about 30 μm, the chemical properties of the process will be affected and the amount of impurities will increase. If the particle size is too large, the hydrated kaolin may not be a slurry because the particles cannot be suspended in the liquid. Since the hydrated kaolin is a fine particle slurry, it has been found to be a preferred or the sole aluminum source because it is easy to control the particle size of the hydrated kaolin to be effective in the process of the present application. In addition, the hydrated kaolin is a well-dispersed clay with a small particle size.

[0058] In some embodiments, the hydrated kaolin slurry may have a solids content of about 50 wt.% to about 75 wt.%. In other embodiments, the hydrated kaolin may have a solids content of about 55 wt.% to about 72 wt.%, about 60 wt.% to about 72 wt.%, or about 65 wt.% to about 71 wt.%. In other embodiments, the hydrated kaolin slurry may have a solids content of at least about 50 wt.%, at least about 55 wt.%, at least about 60 wt.%, at least about 65 wt.%, at least about 70 wt.%, or about 75 wt%.

[0059] In some embodiments, the sodium source may be sodium silicate, potassium silicate, or a combination thereof. In some embodiments, the silicon source may include colloidal silica, fumed silica, or a combination thereof. In some embodiments, the colloidal silica may be an aqueous dispersion of colloidal silica with the solid at or above 20 wt.%. In some embodiments, the colloidal silica may be included in the aqueous dispersion in an amount of at least about 20 wt.%, at least about 25 wt.%, at least about 30 wt.%, or at least about 35 wt.%.

[0060] The aluminum source and / or the silicon source may be doped with a suitable dopant. In some embodiments, the dopant may include compounds including the following: rare earth metals such as Ce, La, Y, Gd, Eu, Pr, Sm, Ho, Nd, Er, Yb, or Tb; alkali metals and alkaline earth metals such as Mg, Ca, K, Na, and Ba; transition metals such as Zr, Mn, Fe, Ti, Ag, Au, Cu, Ni, Zn, Mo, W, V, and Sn; actinides; noble metals such as Rh, Ru, Pt, and Pd; Group III, IV, or V elements such as Ga, B, In, Ge, and / or P.

[0061] In other embodiments, the zeolite crystals can be zeolite Y (including HY, USY, dealuminated Y, RE-Y, and RE-USY), ZSM-5, ZSM-11, IM-5, MCM-68, ZSM-57, ZSM-23, CIT-5, ZSM-35, MCM-22, MCM-56, MCM-49, UZM-8, EMM-10, ITQ-2, ITQ-30, TNU-9, ZSM-22, ZSM-18, EMM-26, zeolite T, EMC-2, gismondine, beta zeolite, ITQ-13, zeolite A, zeolite L, MCM-35, mordenite, ZSM-12, NU-87, ECR-1, EU-1, ZSM-50, Li-A, Na-Pl, Na-P2, chabazite, SSZ-13, SAPO-34, zeolite RHO, SSZ-35, SAPO-5, ITQ-12, stilbite, CIT-7, ITQ-39, Linde Q, UZM-4, natrolite, IPC-4, ZSM-48, SSZ-61, ITQ-4, ITQ-51, epistilbite, ZSM-4, SUZ-4, SSZ-48, SSZ-23, SAPO-11, SAPO-31, AIPO-18, SAPO-18, SAPO-41, ITQ-7, ITQ-3, SSZ-36, MCM-58. In some embodiments, the zeolite crystals can be ZSM-5 or chabazite.

[0062] In some embodiments, ZSM-5 can have a particle size D90 of less than about 25 μm, less than about 20 μm, or less than about 15 μm, or less than about 12 μm. In some embodiments, chabazite can have a particle size D90 of less than about 25 μm, less than about 20 μm, less than about 15 μm, or less than about 12 μm. In some embodiments, the zeolite crystals can have a silica to alumina ratio (SAR) of about 20 to about 40. In other embodiments, the zeolite crystals can have an SAR of about 20, about 24, about 28, about 30, about 32, about 34, or about 40.

[0063] In some embodiments, the method may further include treating the zeolite crystals with an organic structure-directing agent and / or a base agent to adjust the pH of the gel. The organic structure-directing agent may include: a base agent such as an alkali metal hydroxide, namely caustic soda (NaOH), caustic potash (KOH), sodium hydroxide; or an acid such as sulfuric acid. In another embodiment, the OSDA may be trimethyladamantylammonium. In some embodiments, the OSDA may include a quaternary ammonium salt. In some embodiments, the quaternary ammonium salt may include trimethyladamantylammonium hydroxide, trimethylbenzylammonium hydroxide, triethylcyclohexylammonium hydroxide, or a combination thereof. In certain embodiments, the quaternary ammonium salt may include trimethyladamantylammonium hydroxide. In certain embodiments, the quaternary ammonium salt may include trimethylbenzylammonium hydroxide. In certain embodiments, the quaternary ammonium salt may include triethylcyclohexylammonium hydroxide.

[0064] In some embodiments, the base agent may further include NaOH, KOH, F−, quaternary ammonium hydroxide, diquaternary ammonium hydroxide, or a combination thereof. In certain embodiments, the base agent may be NaOH. In some embodiments, the base agent may be KOH. In some embodiments, the base agent may be F−. In some embodiments, the base agent may be quaternary ammonium hydroxide. In some embodiments, the base agent may be diquaternary ammonium hydroxide.

[0065] In some embodiments, the method may further include post-treating the zeolite crystals by acid washing or ion exchange to remove sodium and / or adjust the pH of the gel. In some embodiments, the acid washing may include using dilute sulfuric acid having a concentration of about 1% to about 20%. In some embodiments, the dilute sulfuric acid may have a concentration of about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, or about 20%. In some embodiments, the ion exchange may include using an ammonium nitrate or ammonium sulfate solution.

[0066] In some embodiments, sodium may be removed. In some embodiments of the method, the amount of sodium oxide in the zeolite crystals may be less than about 1 wt.%, less than about 0.9 wt.%, less than about 0.8 wt.%, less than about 0.7 wt.%, less than about 0.6 wt.%, less than about 0.5 wt.%, less than about 0.4 wt.%, less than about 0.3 wt.%, less than about 0.2 wt.%, or less than about 0.1 wt.%. In certain embodiments, the amount of sodium oxide in the zeolite crystals may be less than about 0.4 wt.% or less than about 0.2 wt.%.

[0067] In some embodiments, the zeolite crystals may have an XRD crystallinity greater than about 85% and a BET surface area greater than about 260 m2 The total surface area (TSA) per g. In some embodiments, the zeolite crystals can have an XRD crystallinity greater than about 85%, greater than about 88%, greater than about 90%, greater than about 92%, or greater than about 95%. In some embodiments, the zeolite crystals crystallized in the sodium form can have a TSA greater than about 260 m 2 / g, about 265 m 2 / g, about 270 m 2 / g, about 275 m 2 / g, about 280 m 2 / g, about 285 m 2 / g, or about 290 m 2 / g of TSA. For example, the zeolite crystals can be ZSM-5 and have an XRD crystallinity greater than about 85% and a TSA greater than about 260 m 2 / g. In some embodiments, the zeolite crystals crystallized in the sodium form can have a TSA greater than about 550 m 2 / g, about 560 m 2 / g, about 570 m 2 / g, about 575 m 2 / g, about 580 m 2 / g of TSA. For example, the zeolite crystals can be chabazite and have an XRD crystallinity greater than about 85% and a TSA greater than about 550 m 2 / g of TSA.

[0068] In some embodiments of the method, the gel mixture can have a SiO2 / Al2O3 molar ratio of about 30 to about 45. In certain embodiments, the gel mixture can have a SiO2 / Al2O3 molar ratio of about 30, about 32, about 34, about 36, about 38, about 40, about 42, or about 45.

[0069] In some embodiments of the method, the gel mixture can have a Na2O / SiO2 and OH- / Si molar ratio of about 0.1 to about 1. In certain embodiments, the gel mixture can have a Na2O / SiO2 and OH- / Si molar ratio of about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.8 or about 1.

[0070] In some embodiments of the method, the gel mixture can have an H2O / SiO2 molar ratio of less than about 14. In other embodiments, the gel mixture can have an H2O / SiO2 molar ratio of from about 5 to about 14, from about 5.5 to about 13.5, from about 5.8 to about 13, from about 6 to about 12, from about 6.5 to about 11.5, from about 7 to about 11, or from about 8 to about 10. In yet another embodiment, the gel mixture can have an H2O / SiO2 molar ratio of less than about 14, less than about 13, less than about 12, less than about 11, less than about 10, less than about 9, less than about 8, or less than about 7.

[0071] In some embodiments of the method, zeolite crystals or zeolite seeds can be included in an amount of from about 0.1 wt.% to about 8 wt.% based on the total weight of the mixture. In other embodiments, zeolite crystals or zeolite seeds can be included in an amount of from about 0.1 wt.% to about 7.5 wt.%, from about 0.5 wt.% to about 7 wt.%, from about 1 wt.% to about 6 wt.%, from about 1.5 wt.% to about 5 wt.%, from about 2 wt.% to about 4 wt.% based on the total weight of the mixture.

[0072] In some embodiments of the method, the gel mixture can have a solids content of at least about 15%. In certain embodiments, the gel mixture can have a solids content of about 15%, 20%, 25%, about 27%, about 30%, about 33%, about 35%, or about 37%.

[0073] In some embodiments of the method, crystallization can be achieved by heating the gel mixture in an autoclave. In some embodiments of the method, after crystallization, the gel mixture can be separated to obtain zeolite crystals.

[0074] In some embodiments, the method includes mixing various raw materials. The raw materials can include an aluminum source, a sodium source, a silicon source, zeolite crystals or zeolite seeds. These raw materials can be mixed in various orders to achieve the desired mixing efficiency. For example, the aluminum source and the sodium source can be mixed first, and then the silicon source can be added. In another example, the aluminum source, the sodium source, and the silicon source can be mixed, and then zeolite crystals or zeolite seeds can be added. In yet another example, the aluminum source, the sodium source, the silicon source, and zeolite crystals or zeolite seeds can be mixed together in a single step.

[0075] In some embodiments of the method, the zeolite seeds can be FCC or FAU seeds.

[0076] In certain embodiments, crystallization can occur in two stages. In the first stage, a gel suspension is prepared by mixing an alumina source, a silica source, and an alkali or sodium hydroxide. The gel suspension is then heated, for example, in an autoclave for a period of time to crystallize. In some embodiments, crystallization can be carried out at a temperature of about 175 °C for about 18 hours. The gel is then cooled and drained. After draining, the solid crystals are separated from the liquid. The collected solid is zeolite crystals in the sodium form.

[0077] It has been found that including zeolite seeds in the method helps to promote the reaction and formation of zeolite crystals in the method of the present disclosure.

[0078] In another embodiment of the present invention, a zeolite crystal is provided. The zeolite crystal can include ZSM-5 having a SAR of about 25 to about 40 and an XRD zeolite crystallinity of more than 95%. In another embodiment, the zeolite crystal can include chabazite having a SAR of about 15 to about 30 and an XRD crystallinity of more than 90%.

[0079] The zeolite crystals of the present disclosure can be used in FCC catalysts or FCC additives, as is known in the art.

[0080] The zeolite crystals of the present disclosure can be used in an exhaust gas treatment system for treating exhaust gas streams, particularly those discharged from gasoline or diesel engines, as is known in the art.

[0081] A method of producing a catalytic article is also provided. The method includes coating a substrate with a catalytic coating using a washcoat process. The method can further include drying and calcining the coated substrate at a temperature of about 550 °C for about 1 hour. In some embodiments, drying and calcining can occur at a temperature of about 450 °C to about 750 °C, 500 °C to about 700 °C, or about 550 °C to about 650 °C. In some embodiments, drying and calcining can be carried out for about 1 hour to about 12 hours, about 2 hours to about 10 hours, or about 4 hours to about 8 hours.

[0082] In some embodiments, the catalytic coating can comprise chabazite, about 3.0 wt% to about 6.0 wt% copper oxide, about 5 wt% zirconia, and about 5 wt% pseudoboehmite binder. In some embodiments, the catalytic coating can comprise copper oxide in an amount of about 1 wt% to about 20 wt%, about 2 wt% to about 15 wt%, about 3 wt% to about 10 wt%, or about 4 wt% to about 8 wt%. In some embodiments, the catalytic coating can comprise zirconia in an amount of about 1 wt% to about 15 wt%, about 2 wt% to about 12 wt%, about 3 wt% to about 10 wt%, or about 4 wt% to about 8 wt%. In some embodiments, the catalytic coating can comprise a pseudoboehmite binder such as PB-250. The pseudoboehmite binder can be included in an amount of about 1 wt% to about 30 wt%, about 2 wt% to about 25 wt%, about 3 wt% to about 20 wt%, about 4 wt% to about 15 wt%, about 5 wt% to about 10 wt%, or about 6 wt% to about 8 wt%.

[0083] In some embodiments, the catalytic article can be produced by any method / process described herein. In some embodiments, the catalytic article can comprise ion-exchanged chabazite, wherein the chabazite has a zeolite surface area (ZSA) greater than about 450 m 2 / g. In some embodiments, the chabazite can have a ZSA greater than about 460 m 2 / g, greater than about 470 m 2 / g, greater than about 480 m 2 / g, greater than about 500 m 2 / g, or greater than about 550 m 2 / g.

[0084] In another embodiment, a method for reducing nitrogen oxides is provided. The method includes contacting a gaseous stream comprising nitrogen oxides with at least one ion-exchanged chabazite as described herein or at least one catalytic article as described herein.

[0085] Examples

[0086] Examples of methods and materials used in some embodiments of this disclosure are presented in Table 1 herein. N-brand is a commercially available sodium silicate. AS-40 is a commercial colloidal silica containing 40 wt% SiO2. The ZSM-5 seed uses a commercially available ZSM-5 material having a sodium oxide content of less than 0.4 wt% and a particle size D90 ≤ 21 microns.

[0087] In this study, different raw materials and solid contents were tested. During this research, the raw materials were mixed and crystallized according to the conditions presented in Table 1. As can be seen from Table 1, it was found that when using hydrated kaolin (HK slurry) with a gel mixture having a high solid content (above 30 wt%), it has properties superior to Comparative Example 1, which represents the current state of the art.

[0088] Table 1

[0089]

[0090] The properties of the HK slurry are presented in Table 2. The HK slurry has a solid content of approximately 70 wt%.

[0091] Table 2

[0092] <![CDATA[Al2O3 wt%]]> <![CDATA[wt% of SiO2]]> D50, μm D90, μm HK Slurry 44.71 51.39 1.82 7.89

[0093] The properties of the as-crystallized zeolite crystals of Comparative Example 1 and Examples 1 - 3 were also collected and presented in Table 3. The high-solid formulations of Examples 1 - 3 have a crystallinity similar to or better than that of the low-solid formulation of Comparative Example 1. After post-treatment with acid washing to remove sodium, all the H-form ZSM-5 materials in Table 3 have TSA > 260 m 2 / g.

[0094] Table 3

[0095]

[0096]

[0097] Additional studies were conducted on the preparation of chabazite zeolite. As understood by those skilled in the art, when the alumina source is from a aluminosilicate crystalline material, a solid content greater than 10 wt% is considered high in the synthesis of chabazite. Hydrated kaolin is the lowest-cost alumina source, while the cost of Na-FAU used in Comparative Example 2 is approximately 20 times higher. The inventors of the present invention have found that using chabazite with 18 wt% solids is successful and has a crystallinity similar to or better than that of the low-solid formulation. Ludox AS-40 is a commercial colloidal silica containing 40 wt% SiO2. Trimethylammonium adamantyl hydroxide was used as the OSDA.

[0098] During this research, the raw materials were mixed and crystallized according to the conditions presented in Table 4. As can be seen from Table 4, it was found that when using hydrated kaolin (HK slurry) with a gel mixture having a high solid content (above 18 wt%), it has properties superior to Comparative Example 2, which represents the current state of the art.

[0099] Table 4

[0100]

[0101] The properties of the as-crystallized zeolite crystals of Comparative Example 2 and Example 4 were also collected and presented in Table 5. The high-solid formulation of Example 4 had a crystallinity similar to or better than that of the low-solid formulation of Comparative Example 2. After post-treatment by ammonium exchange to remove sodium, all of the H-form chabazite materials in Table 5 had a TSA > 530 m 2 / g.

[0102] Table 5

[0103]

[0104] Although certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the broader aspects of the technology as defined in the following claims.

[0105] The embodiments described exemplarily herein can be practiced appropriately without any one or more elements, one or more limitations not specifically disclosed herein. Thus, for example, the terms "comprising", "including", "containing", etc. should be understood broadly and without limitation. In addition, the terms and expressions used herein have been used as descriptive terms and not restrictive terms, and the use of these terms and expressions is not intended to exclude any equivalents of the features shown and described or portions thereof, but it should be recognized that various modifications can be made within the scope of the claimed technology. In addition, the phrase "consisting essentially of" will be understood to include those specifically recited elements and those additional elements that do not materially affect the basic and novel features of the claimed technology. The phrase "consisting of" excludes any unspecified elements.

[0106] This disclosure is not limited to the specific embodiments described in this application. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from its spirit and scope. From the foregoing description, in addition to the methods and compositions recited herein, functionally equivalent methods and compositions within the scope of this disclosure will be apparent to those skilled in the art. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only by the terms of the appended claims and the full scope of the equivalents given by such claims. It should be understood that this disclosure is not limited to specific methods, reagents, compounds, or compositions, which can of course vary. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and are not intended to be restrictive.

[0107] In addition, when describing the features or aspects of the present disclosure in terms of a Markush group, those skilled in the art will recognize that the present disclosure is also thereby described in terms of any single member or subgroup of members of the Markush group.

[0108] As will be understood by those skilled in the art, for any and all purposes, particularly in providing a written description, all ranges disclosed herein also include any and all possible subranges and combinations of subranges thereof. Any listed range can be readily viewed as fully describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, a middle third, and an upper third, etc. As will also be understood by those skilled in the art, all language such as "at most," "at least," "greater than," "less than," etc. includes the recited numbers and refers to ranges that can then be broken down into the subranges as discussed above. Finally, as will be understood by those skilled in the art, a range includes each individual member.

Claims

1. A method for preparing zeolite, the method comprising: Mixing an aluminum source, a sodium source and water to form a first mixture; After mixing, adding a silicon source to the first mixture and mixing; Adding zeolite crystals or zeolite seeds to form a gel mixture; Crystallizing the gel mixture at a temperature of about 150 °C to about 200 °C for about 12 to about 48 hours to obtain zeolite crystals, wherein the aluminum source is hydrated kaolin.

2. The method according to claim 1, wherein The sodium source is sodium silicate.

3. The method according to claim 1, wherein The silicon source comprises aqueous colloidal silica having a solid content at or above 20 wt.%.

4. The method according to claim 1, wherein The hydrated kaolin has a particle size with D90 (diameter of 90% of the particles) below 30 μm, below 20 μm, or below 15 μm.

5. The method according to any one of the preceding claims, wherein, The zeolite crystals are ZSM-5.

6. The method according to any one of the preceding claims, wherein, The hydrated kaolin has a solid content of about 50 wt% to about 75 wt%.

7. The method according to any one of the preceding claims, wherein, The zeolite crystals or zeolite seeds have a silica to alumina ratio (SAR) of about 20 to about 35.

8. The method according to any one of the preceding claims, further comprising post-treating the zeolite crystals by pickling or ion exchange to remove sodium.

9. The method according to claim 8, wherein, The pickling comprises using dilute sulfuric acid having a concentration of about 1% to about 20%.

10. The method according to claim 8, wherein, The ion exchange comprises using ammonium nitrate or ammonium sulfate solution.

11. The method according to any one of claims 8 to 10, wherein Removing the sodium results in an amount of sodium oxide in the zeolite crystals of less than about 0.4 wt%, or less than about 0.2 wt%.

12. The method according to any one of the preceding claims, wherein, These zeolite crystals have an XRD crystallinity greater than about 85% and a TSA greater than about 260 m 2 / g.

13. The method according to any one of the preceding claims, wherein, The gel mixture has a SiO2 / Al2O3 molar ratio of about 30 to about 42.

14. The method according to any one of the preceding claims, wherein The gel mixture has a Na2O / SiO2 and OH- / Si molar ratio of about 0.1 to about 0.

3.

15. The method according to any one of the preceding claims, wherein, The gel mixture has an H2O / SiO2 molar ratio of less than about 11.

16. The method according to claim 1, wherein The zeolite crystals or the zeolite seeds are included in an amount of about 0.1 wt% to about 6 wt%.

17. The method according to any one of the preceding claims, wherein, The gel mixture has a solid content of at least about 25%.

18. The method according to any one of the preceding claims, wherein, The crystallization is achieved by heating the gel mixture in an autoclave.

19. The method according to any one of the preceding claims, wherein, The crystallized gel mixture is separated to obtain zeolite crystals.

20. The method according to claim 16, wherein, The zeolite crystals or the zeolite seeds have a particle size with D90 below 25 μm, or below 15 μm.

21. The method according to claim 1, wherein, The zeolite seeds are FCC or FAU seeds.

22. A zeolite crystal comprising ZSM-5 having an SAR of about 24 to about 40 and a sodium content of less than about 0.4%.

23. A method for preparing chabazite (CHA) zeolite: Preparing an aqueous mixture comprising a silica source, the only aluminum source, an alkali agent and an organic structure-directing agent (OSDA) to form a gel mixture; Crystallizing the gel mixture at a temperature of about 100 °C to about 200 °C for about 10 to about 108 hours to obtain zeolite crystals, wherein the only aluminum source is hydrated kaolin.

24. The method according to claim 23, wherein, The sodium source is sodium silicate or potassium silicate.

25. The method according to claim 23, wherein, The silicon source is colloidal silica or fumed silica, wherein the colloidal silica is aqueous colloidal silica having a solid content at or above 20 wt.%.

26. The method according to claim 23, wherein, The hydrated kaolin has a particle size with D90 (diameter of 90% of the particles) below 30 μm, below 25 μm, below 15 μm, or below 12 μm.

27. The method according to claim 23, wherein, The organic structure-directing agent comprises an alkali agent selected from alkali metal hydroxides.

28. The method according to any one of claims 23-27, wherein The aqueous kaolin has a solids content of from about 50 wt% to about 75 wt% solids.

29. The method according to any one of claims 23-28, wherein, The aqueous kaolin has a solids content of at least about 50 wt% solids.

30. The method according to any one of claims 23-29, further comprising post-treating the zeolite crystals by acid washing or ion exchange to remove sodium.

31. The method according to claim 30, wherein, The acid washing comprises using dilute sulfuric acid having a concentration of from about 1% to about 20%.

32. The method according to claim 30, wherein, The ion exchange comprises using an ammonium nitrate or ammonium sulfate solution.

33. The method according to any one of claims 30 - 32, wherein, Removing the sodium results in an amount of sodium oxide in the zeolite crystals of less than about 0.2 wt% or less than about 0.02 wt%.

34. The method according to claim 23, wherein, The organic structure-directing agent comprises a quaternary ammonium salt.

35. The method according to claim 34, wherein, The quaternary ammonium salt comprises trimethyladamantylammonium hydroxide, trimethylbenzylammonium hydroxide, triethylcyclohexylammonium hydroxide, or a combination thereof.

36. The method according to claim 34, wherein, The quaternary ammonium salt comprises trimethyladamantylammonium hydroxide.

37. The method according to claim 34, wherein, The quaternary ammonium salt comprises trimethylbenzylammonium hydroxide.

38. The method according to claim 34, wherein The quaternary ammonium salt comprises triethylcyclohexylammonium hydroxide.

39. The method according to any one of claims 23-26, wherein, The base agent comprises NaOH, KOH, F-, quaternary ammonium hydroxide, diquaternary ammonium hydroxide, or a combination thereof.

40. The method according to claim 39, wherein, The base agent is NaOH.

41. The method according to claim 39, wherein, The base agent is KOH.

42. The method according to claim 39, wherein The base agent is F-.

43. The method according to claim 39, wherein, The base agent is quaternary ammonium hydroxide.

44. The method according to claim 39, wherein, The base agent is diquaternary ammonium hydroxide.

45. The method according to any one of claims 23-44, wherein, The gel mixture has a solids content of at least about 15%.

46. The method according to any one of claims 23-45, wherein, The crystallization is achieved by heating the gel mixture in an autoclave.

47. The method according to any one of claims 23-46, wherein, The crystallized gel mixture is separated to obtain zeolite crystals.

48. A method of producing a catalytic article, the method comprising: coating a substrate with a catalytic coating using a washcoat process; and drying and calcining the coated substrate at a temperature of about 550 °C for about 1 hour; wherein the catalytic coating comprises chabazite, from about 3.0 wt% to about 6.0 wt% copper oxide, about 5 wt% zirconia, and about 5 wt% pseudoboehmite (PB-250) binder.

49. A catalytic article produced by the method according to claim 48, the catalytic article comprising ion-exchanged chabazite, wherein the chabazite has a zeolite surface area (ZSA) greater than about 450 m 2 / g.

50. A method for reducing nitrogen oxides (NO x ), the method comprising contacting a gaseous stream containing nitrogen oxides with at least one ion-exchanged chabazite as described in claim 23 or at least one catalytic article as described in claim 48.

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