Synthesis of molecular sieve SSZ-122 without using organic templates

Abstract

Provided is an organic template-free synthesis process for synthesizing aluminosilicate molecular sieve SSZ-122, comprising: (1) preparing a reaction mixture comprising (a) a source of silicon atoms, (b) a source of aluminum atoms, (c) a source of alkali metal [M], (d) a source of hydroxide ions, (e) water, and (f) seed crystals; and (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve.

Description

[Technical field]

[0001] The present disclosure relates to a process for preparing molecular sieve SSZ-122. [Background technology]

[0002] Molecular sieves are a commercially important class of materials having specific chemical compositions with a characteristic crystal structure with defined pore structure revealed by a characteristic X-ray diffraction (XRD) pattern, which defines the cavities and pores characteristic of that particular type of molecular sieve.

[0003] Molecular sieves are classified by the International Zeolite Society Structure Commission according to the rules of the IUPAC Commission on Zeolite Nomenclature, according to which framework-type zeolites and other crystalline microporous molecular sieves with established unique structures are assigned unique three-letter codes, as described, for example, in "Atlas of Zeolite Framework Types" by Ch. Baerlocher, LBMcCusker and DH Olson (Elsevier, Sixth Revised Edition, 2007).

[0004] BOG framework molecular sieves have a three-dimensional channel system of 10- and 12-membered rings. Materials with the BOG framework include boggsite, ITQ-47, and SSZ-122.

[0005] The composition and characteristic X-ray diffraction pattern of the molecular sieve SSZ-122 are disclosed in U.S. Patent Application Publication No. 2022 / 0024775, which also describes the synthesis of the molecular sieve in the presence of an organic template containing a 1-adamantyl-3-propylimidazolium cation.

[0006] In accordance with the present disclosure, it has been discovered that SSZ-122 can be synthesized in the absence of an organic template. Summary of the Invention

[0007] In one embodiment, there is provided an organic template-free synthesis process for synthesizing an aluminosilicate molecular sieve having an SSZ-122 framework structure, the process comprising: (1) preparing a reaction mixture comprising (a) a source of silicon atoms, (b) a source of aluminum atoms, (c) a source of alkali metal [M], (d) a source of hydroxide ions, (e) water, and (f) seed crystals; and (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve.

[0008] In another embodiment, there is provided an organic template-free synthetic aluminosilicate molecular sieve having a framework structure of SSZ-122, the molecular sieve optionally comprising an alkali metal [M], and the molecular sieve is not calcined. [Brief description of the drawings]

[0009] [Figure 1] 1 shows the powder X-ray diffraction (XRD) pattern of the as-synthesized SSZ-122 material according to Example 1.

[0010] [Diagram 2] 1 shows a scanning electron microscope (SEM) image of the as-synthesized SSZ-122 material according to Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] definition The term "organic template" as used in this disclosure designates any conceivable organic material suitable for the synthesis of templated molecular sieve materials, preferably molecular sieve materials having a BOG-type framework structure, even more preferably SSZ-122. Such organic templates include 1-adamantyl-3-propylirimidazolium cation.

[0012] Within the meaning of the present disclosure, a synthesis process that does not use an "organic template" refers to a synthesis process in which the materials used therein are substantially free of organic template materials, in which "substantially" as used in the present disclosure with respect to the amount of one or more organic templates contained in one or more materials used in the synthesis process refers to an amount of one or more organic templates of 0.001% by weight or less, for example, 0.0005% by weight or less, or 0.00001% by weight or less, or 0.000005% by weight or less, or even 0.000001% by weight or less. The amount of one or more organic templates may also be expressed as "impurities" or "trace amounts" within the meaning of the present disclosure, even if they are present in any one of the materials used in the synthesis process. It is further noted that the terms "organic template" and "organic structure directing agent" are used interchangeably in the present disclosure.

[0013] The term "BOG" refers to the topological type of BOG recognized by the International Zeolite Society Structure Committee.

[0014] The term "SiO2 / Al2O3 molar ratio" is sometimes abbreviated as "SAR."

[0015] Reaction mixture Molecular sieve SSZ-122 can be synthesized by (1) preparing a reaction mixture containing (a) a source of silicon atoms, (b) a source of aluminum atoms, (c) a source of alkali metal [M], (d) a source of hydroxide ions, (e) water, and (f) seed crystals, and (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve.

[0016] The reaction mixture may have a composition, in terms of molar ratios, within the ranges set forth in Table 1. [Table 1]

[0017] Examples of sources of silicon atoms include colloidal suspensions of silica, precipitated silica, fumed silica, alkali metal silicates, tetraalkyl orthosilicates (eg, tetraethyl orthosilicate), and mixtures thereof.

[0018] Examples of aluminum atom sources include hydrated alumina, aluminum hydroxide, alkali metal aluminates, aluminum alkoxides, and water-soluble aluminum salts (eg, aluminum nitrate), and mixtures thereof.

[0019] Sources of combined silicon and aluminum atoms, such as aluminosilicate zeolites (e.g., Y-type zeolites), can also be used. The aluminosilicate zeolites can be used as the sole or major source of silicon and aluminum. The term "major" means more than 50 mol%, suitably more than 75 mol%, preferably more than 90 mol%.

[0020] The alkali metal [M] may be selected from lithium, sodium, potassium, rubidium, and cesium, but more preferably the alkali metal is sodium and / or potassium, and even more preferably the alkali metal is sodium.

[0021] Generally, any conceivable hydroxide ion source can be used, said source preferably comprising a metal hydroxide, in particular a hydroxide of an alkali metal [M], preferably sodium hydroxide and / or potassium hydroxide, even more preferably sodium hydroxide.

[0022] According to the process of the present disclosure, in step (1), a seed crystal is provided, the seed crystal comprising a molecular sieve material having a BOG-type framework structure. In general, the seed crystal can comprise any molecular sieve material having a BOG-type framework structure, provided that the molecular sieve material having a BOG-type framework structure is crystallized in step (2). In some embodiments, the seed crystal comprises a molecular sieve selected from the group consisting of boggsite, ITQ-47, SSZ-122, and mixtures thereof, and even more preferably, the seed crystal preferably comprises SSZ-122.

[0023] Any suitable amount of seed crystals can be provided to the mixture according to step (1), provided that the molecular sieve material having a BOG-type framework structure is crystallized in step (2). Generally, the amount of seed crystals included in the reaction mixture according to step (1) ranges from 0.01 to 30 wt. % (e.g., 0.1 to 20 wt. %, or 0.5 to 10 wt. %) based on 100 wt. % of SiO2 in the silicon atom source.

[0024] According to the present process, the reaction mixture prepared in step (1) and crystallized in step (2) does not contain any organic structure directing agent, particularly specific tetraalkylammonium salts and / or related organic templates, such as 1-adamantyl-3-propylimidazolium salts, specifically used in the synthesis of molecular sieve materials with BOG-type framework structure, beyond impurities. Such impurities may be caused, for example, by organic structure directing agents still present in the seed crystals used in the present process. However, the organic templates contained in the seed crystal materials may not participate in the crystallization process, since they are trapped in the seed crystal framework and may not act as structure directing agents within the meaning of the present disclosure.

[0025] The reaction mixture components can be supplied by multiple sources. Similarly, two or more reaction mixture components can be provided by a single source.

[0026] The reaction mixture may be prepared by any conceivable means, but mixing by agitation is preferred, preferably by stirring. The reaction mixture may be prepared in batch, continuous, or semi-continuous mode.

[0027] The reaction mixture may be in the form of a solution, a colloidal dispersion (colloidal sol), a gel, or a paste, with a gel being preferred.

[0028] Crystallization and post-synthesis treatment Crystallization of the molecular sieve can be carried out in a suitable reaction vessel, such as a polypropylene jar or a Teflon-lined or stainless steel autoclave, placed in a convection oven maintained at a temperature of about 100 to about 200° C. under static or stirred conditions for a period of time sufficient to cause crystallization (e.g., about 1 to 21 days, or 1 to 14 days, or 1 to 10 days).

[0029] After the desired molecular sieve crystals are formed, the solid product is separated from the reaction mixture by standard separation techniques, such as filtration or centrifugation. The recovered crystals are washed with water and then dried for a few seconds to a few minutes (e.g., 5 seconds to 10 minutes for air flow drying) or for a few hours (e.g., 4 to 24 hours for oven drying at 75°C to 150°C) to obtain the as-synthesized molecular sieve crystals. The drying step may be performed at atmospheric pressure or under vacuum.

[0030] The molecular sieve crystallized in step (2) may optionally be subjected to at least one step of an ion exchange procedure. The term "ion exchange" according to the present disclosure generally refers to non-framework ionic elements and / or molecules contained in the molecular sieve material. In some embodiments, the non-framework ionic elements include alkali metals [M], preferably contained in the molecular sieve.

[0031] In general, any conceivable ion exchange procedure with all possible ionic elements and / or molecules can be carried out on the molecular sieve, except for the organic structure directing agents used specifically in the synthesis of molecular sieve materials having a BOG-type framework structure. In some embodiments, the ionic elements include H + , NH4 + At least one cation and / or cationic element is used which may be selected from the group consisting of Sc, Zr, Cr, Mo, W, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, and mixtures thereof.

[0032] It is preferred that the process of the present disclosure does not use a calcination step. Typically, the calcination step involves heating the molecular sieve material crystallized according to step (2) at a temperature above 500°C. In some embodiments, the molecular sieve crystallized according to step (2) is not subjected in a subsequent step to a temperature above 450°C, or 350°C, or 300°C, or 250°C, or even 200°C.

[0033] Molecular sieve characterization The product obtained by the process described herein is a synthetic aluminosilicate molecular sieve having the framework structure of SSZ-122.

[0034] Within the meaning of this disclosure, an "organic template-free" molecular sieve refers to a molecular sieve that is substantially free of organic template material, where "substantially" as used herein with respect to the amount of one or more organic templates contained in the molecular sieve refers to an amount of one or more organic templates of 0.001% by weight or less, such as 0.0005% by weight or less, or 0.00001% by weight or less, or 0.000005% by weight or less, or even 0.000001% by weight or less, which amount of one or more organic templates, if any, may be expressed as "impurities" or "trace amounts" within the meaning of this disclosure in the molecular sieve.

[0035] According to the present disclosure, the molecular sieve does not contain any organic structure directing agent specifically used in the synthesis of molecular sieve materials having a BOG-type framework structure, in particular certain tetraalkylammonium salts and / or related organic templates, such as 1-adamantyl-3-propylimidazolium salts, beyond impurities, which may be due, for example, to organic structure directing agents still present in the seed crystals used in the process.

[0036] The organic template-free molecular sieve can have a SiO2 / Al2O3 molar ratio of at least 10 (e.g., 10-100, or 10-60, or 15-100, or 15-60, or 15-40, or 20-100, or 20-60, or 20-40, or 25-100, or 25-60, or 25-40).

[0037] In embodiments where the organic template-free zeolitic material comprises an alkali metal [M] as a non-framework element, the M:SiO2 molar ratio can range from greater than 0 to 0.1. In embodiments, the molecular sieve comprises sodium and / or potassium as a non-framework element.

[0038] In some embodiments, at least a portion of the alkali metal [M] optionally present in the molecular sieve is replaced by at least one cation and / or cationic element. The cation and / or cationic element is H + , NH4 + , Sc, Zr, Cr, Mo, W, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, and mixtures thereof.

[0039] The powder XRD spectrum of the molecular sieve product obtained by this process is consistent with other materials having a BOG-type framework structure. Powder XRD patterns representative of BOG-type framework molecular sieves can be found in "Collection of Simulated XRD Powder Patterns for Zeolites" by MMJ Treacy and JB Higgins (Elsevier, Fifth Revised Edition, 2007). The powder XRD patterns presented herein were characterized by standard techniques. The radiation was copper K-alpha / doublet. EXAMPLES

[0040] The following illustrative examples are intended to be non-limiting.

[0041] Example 1 Synthesis of SSZ-122 0.90 g of 50% NaOH solution, 5.00 g of deionized water, and 0.096 g of Reheis F-2000 hydrated alumina (53% Al2O3, 47% H2O) were mixed in a Teflon liner. The resulting gel was stirred until the alumina was completely dissolved. 5.00 g of 30% LUDOX® HS-30 colloidal silica was then added to the solution. The gel was stirred until homogeneous. 0.15 g of as-synthesized SSZ-122 seeds were then added to the solution and the gel was further stirred. The liner was then capped and placed in a Parr steel autoclave reactor. The autoclave was then placed in a heated oven at 135° C. for 10 days. The solid product was collected from the cooled reactor by centrifugation, washed with deionized water, and dried at 95° C.

[0042] The resulting product was analyzed by powder XRD and SEM. The powder XRD of the product is shown in Figure 1 and indicates that the material is pure SSZ-122 molecular sieve. The SEM image is shown in Figure 2 and shows uniform crystalline regions.

[0043] According to ICP elemental analysis, the product had a SiO2 / Al2O3 molar ratio of 26.3.

[0044] Example 2 Synthesis of SSZ-122 0.80 g of 50% NaOH solution, 5.07 g of deionized water, and 0.06 g of Reheis F-2000 hydrated alumina (53% Al2O3, 47% H2O) were mixed in a Teflon liner. The resulting gel was stirred until the alumina was completely dissolved. 5.00 g of 30% LUDOX® HS-30 colloidal silica was then added to the solution. The gel was stirred until homogeneous. 0.15 g of as-synthesized SSZ-122 seeds were then added to the solution and the gel was further stirred. The liner was then capped and placed in a Parr steel autoclave reactor. The autoclave was then placed in a heated oven at 135° C. for 10 days. The solid product was collected from the cooled reactor by centrifugation, washed with deionized water, and dried at 95° C.

[0045] The resulting zeolite product was identified as pure SSZ-122 molecular sieve by powder XRD and SEM.

[0046] According to ICP elemental analysis, the product had a SiO2 / Al2O3 molar ratio of 34.8.

[0047] Example 3 Synthesis of SSZ-122 0.39 g of 50% NaOH solution, 8.51 g of deionized water, and 1.00 g of CBV720 Y-type zeolite (SAR=30) powder were mixed in a Teflon liner. 0.10 g of as-synthesized SSZ-122 seeds were then added to the solution. The resulting gel was stirred until homogeneous. The liner was then capped and placed in a Parr steel autoclave reactor. The autoclave was then placed in a heated oven at 135° C. for 7 days. The solid product was collected from the cooled reactor by centrifugation, washed with deionized water, and dried at 95° C.

[0048] The resulting zeolite product was identified as pure SSZ-122 molecular sieve by powder XRD and SEM.

[0049] According to ICP elemental analysis, the product had a SiO2 / Al2O3 molar ratio of 23.7.

[0050] Example 4 Firing The as-synthesized product of Example 1 was calcined in a muffle furnace under air flow heated to 540° C. at a rate of 1° C. / min, held at 540° C. for 5 hours, cooled and then analyzed by powder XRD. The powder XRD pattern showed that the material remained stable after calcination.

[0051] Example 5 Ammonium ion exchange The calcined material of Example 4 was treated with 10 mL (per gram of zeolite) of 1N ammonium nitrate solution for 2 hours at 90° C. The solution was cooled, decanted, and the same process was repeated.

[0052] The dried product (NH4-SSZ-122) was subjected to micropore volumetric analysis by BET using N as the adsorbate. The molecular sieve had a pore size of 0.19 cm 3 The micropore volume was 1.0 g / g.

Claims

1. 1. An organic template-free synthesis process for synthesizing an aluminosilicate molecular sieve having an SSZ-122 framework structure, comprising: (1) (a) a silicon atom source; (b) an aluminum atom source; (c) a source of an alkali metal or alkaline earth metal [M]; (d) a hydroxide ion source; (e) water, and (f) Seed crystal preparing a reaction mixture comprising: (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve. The process comprising: the seed crystals comprise molecular sieve SSZ-122; The process wherein the amount of seed crystals in the reaction mixture according to step (1) ranges from 0.01 to 30 wt %, based on 100 wt % of SiO 2 in the silicon atom source.

2. 10. The process of claim 1, wherein the reaction mixture has the following composition, in terms of molar ratio: 【Table 1】

3. 10. The process of claim 1, wherein the reaction mixture has the following composition, in terms of molar ratio: 【Table 2】

4. 10. The process of claim 1, wherein the silicon atom source comprises a colloidal suspension of silica, precipitated silica, fumed silica, an alkali metal silicate, a tetraalkyl orthosilicate, or a mixture thereof.

5. 10. The process of claim 1, wherein the aluminum atom source comprises hydrated alumina, aluminum hydroxide, alkali metal aluminate, aluminum alkoxide, water-soluble aluminum salt, or mixtures thereof.

6. 2. The process of claim 1, wherein the source of both the silicon atoms and the aluminum atoms is a Y-type zeolite.

7. 2. The process of claim 1, wherein the alkali metal [M] is selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, or mixtures thereof.

8. 2. The process of claim 1, wherein the alkali metal [M] comprises sodium, potassium, or a mixture thereof.

9. 2. The process of claim 1, wherein the crystallization conditions according to step (2) comprise a temperature of 100° C. to 200° C. and a crystallization time of about 1 day to 21 days.

10. The process of claim 1 , wherein the organic template-free synthesis does not include a calcination step.

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