Synthesis of aluminosilicate molecular sieves with SWY framework topology

Abstract

A method for synthesizing an aluminosilicate molecular sieve with SWY framework topology via an interzeolite conversion is described. The method includes (1) preparing a reaction mixture containing an aluminosilicate zeolite with FAU framework topology, a structure directing agent comprising 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cation, a source of alkali metal cations, a source of hydroxide ions, and water, and (2) heating the reaction mixture to obtain an aluminosilicate molecular sieve with SWY framework topology.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 384,627, filed November 22, 2022, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a method for preparing aluminosilicate molecular sieves having a SWY framework topology. [Background technology]

[0003] Molecular sieves are crystalline microporous materials formed by corner-sharing TO4 tetrahedra (T=Si, Al, P, Ge, B, Ti, Sn, etc.) interconnected by oxygen atoms, forming pores and cavities of uniform size and shape precisely defined by their crystalline structure. Molecular sieves have important commercial applications as adsorbents, ion exchangers, and catalysts.

[0004] Molecular sieves are classified by the International Zeolite Association (IZA) according to the rules of the IUPAC Commission on Molecular Sieve Nomenclature. Once a new framework topology is established, a three-letter code is assigned. This code defines the atomic structure of the framework, from which an unambiguous X-ray diffraction pattern can be written.

[0005] SWY framework topology molecular sieves are members of the ABC-6 family of zeotype structures. SWY framework topology materials exhibit a 12-layer stacking sequence, AABAABAACAAC, containing parallel rows of can cages and double six-membered ring (d6r) units, and parallel rows of gme and larger swy cages, with the latter two types of cages connected through eight-membered ring windows. Examples of molecular sieves with SWY framework topology include STA-20 and STA-30. SWY molecular sieves have shown attractive properties as catalysts or catalyst components for methanol-to-olefins (MTO) processes and selective catalytic reduction (SCR) of nitrogen oxides.

[0006] The composition and characteristic X-ray diffraction pattern of aluminophosphate STA-20 are disclosed in U.S. Pat. No. 10,213,776, which also describes the synthesis of the molecular sieve in the presence of an alkylamine (e.g., trimethylamine) and 1,6-(1,4-diazabicyclo[2.2.2]octane)hexyl (diDABCO-C6) cation as a structure directing agent.

[0007] A. Turrina and P.A. Wright et al. (Chem. Mater. 2021, 33, 5242-5256) disclose the aluminosilicate STA-30 and its synthesis in the presence of 1,8-(1,4-diazabicyclo[2.2.2]octane)octyl (diDABCO-C8) and potassium cations as structure-directing agents.

[0008] In accordance with the present disclosure, it has been discovered that aluminosilicate molecular sieves with SWY framework topology can be synthesized from high-silica FAU zeolite via interzeolite conversion in the presence of a structure directing agent comprising 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cation. Summary of the Invention

[0009] In one aspect, the present disclosure relates to a method for synthesizing an aluminosilicate molecular sieve with a SWY framework topology, the method comprising: (1) preparing a reaction mixture comprising: (a) an aluminosilicate zeolite with a FAU framework topology; (b) a structure directing agent comprising a 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cation; (c) an alkali metal cation source; (d) a hydroxide ion source; and (e) water; and (2) heating the reaction mixture to obtain an aluminosilicate molecular sieve with a SWY framework topology.

[0010] In another aspect, the present disclosure relates to an aluminosilicate molecular sieve of SWY framework topology, which in its as-synthesized form contains 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cations in its pore structure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows a scanning electron microscope (SEM) image of the as-synthesized SWY material of Example 1.

[0012] [Figure 2] FIG. 2 shows the powder X-ray diffraction (XRD) patterns of the as-synthesized SWY material (lower pattern) and the calcined SWY material (upper pattern) of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0013] definition The term "SWY" refers to the SWY topology or framework as recognized by the International Zeolite Association (IZA) Structure Commission.

[0014] The term "FAU" refers to the FAU-type topology or framework as recognized by the IZA Structure Commission, and the term "FAU zeolite" means an aluminosilicate whose primary crystalline phase is FAU.

[0015] The "as-synthesized" (or "as-made") aluminosilicate molecular sieves of the present disclosure (i.e., before any optional heat treatment or other treatment to remove the structure directing agent from the pores) typically contain within their pores a structure directing agent that was one of the components of the reaction mixture. Aluminosilicate molecular sieves of the present disclosure from which some or all of the structure directing agent has been removed (e.g., via heat treatment or other treatment to remove the structure directing agent from the pores) are at least partially calcined or "as-calcined" materials.

[0016] Reaction mixture Generally, aluminosilicate molecular sieves with SWY framework topology can be synthesized by (1) preparing a reaction mixture containing (a) an aluminosilicate zeolite with FAU framework topology, (b) a structure directing agent [Q] comprising 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cations, (c) a source of alkali metal cations [M], (d) a source of hydroxide ions [OH], and (e) water, and (2) heating the reaction mixture to obtain the aluminosilicate molecular sieve with SWY framework topology.

[0017] The reaction mixture may have a composition, in terms of molar ratios, within the ranges shown in Table 1. [Table 1]

[0018] The FAU framework topology aluminosilicate zeolite may be a single type of aluminosilicate FAU zeolite or a mixture of two or more aluminosilicate FAU zeolites. The aluminosilicate FAU zeolite may be zeolite Y. The aluminosilicate FAU zeolite may be two or more zeolite Ys with different SiO / AlO molar ratios.

[0019] The reaction mixture contains one or more sources of alkali cations [M]. The alkali metal is preferably selected from the group consisting of sodium, potassium, lithium, rubidium, and mixtures thereof, preferably sodium and / or potassium, more preferably potassium. If present, the sodium source may be sodium hydroxide, sodium aluminate, sodium silicate, sodium aluminate, or a sodium salt such as NaCl, NaBr, or sodium nitrate. If present, the potassium source may be potassium hydroxide, potassium aluminate, potassium silicate, or a potassium salt such as KCl, KBr, or potassium nitrate. If present, the lithium source may be lithium hydroxide or a lithium salt such as LiCl, LiBr, LiI, lithium nitrate, or lithium sulfate. If present, the rubidium source may be rubidium hydroxide or a rubidium salt such as RbCl, RbBr, RbI, or rubidium nitrate.

[0020] The structure directing agent [Q] comprises a 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cation represented by the following structure (1): [ka]

[0021] The structure directing agent [Q] may be present in any suitable form, for example as a halide such as iodide or bromide, or as a hydroxide, for example in its hydroxide form.

[0022] The synthesis mixture contains at least one hydroxide ion [OH]. For example, the hydroxide ion may be present as a counterion to the structure directing agent [Q]. A suitable hydroxide ion source may be selected from the group consisting of alkali metal hydroxides, ammonium hydroxide, and mixtures thereof; for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, ammonium hydroxide, and mixtures thereof; more often, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, and mixtures thereof; and most often, sodium hydroxide and / or potassium hydroxide.

[0023] The reaction mixture can further include seed crystals of a crystalline molecular sieve material, such as a crystalline molecular sieve with a SWY framework topology. The amount of seed crystals is not particularly limited, but is typically in the range of 0.1 to 10 wt.%, based on 100 wt.% of SiO2 in the framework structure of the aluminosilicate FAU zeolite, and preferably in the range of 0.5 to 5 wt.%, based on 100 wt.% of SiO2 in the framework structure of the aluminosilicate FAU zeolite.

[0024] The reaction mixture can be prepared by any conceivable means, but mixing by agitation, preferably stirring, is preferred. The reaction mixture can be prepared in batch mode, continuous mode, or semi-continuous mode.

[0025] 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.

[0026] Crystallization and post-synthesis treatment The reaction mixture is then subjected to suitable crystallization conditions to form the aluminosilicate SWY molecular sieve. Crystallization can be carried out under static or stirred conditions in a suitable reaction vessel, such as, for example, a Teflon®-lined or stainless steel autoclave placed in a convection oven maintained at a suitable temperature. Preferably, crystallization is carried out under autogenous pressure, preferably in an autoclave.

[0027] Crystallization is typically carried out at a temperature between 100°C and 200°C (e.g., 120°C and 170°C) for a time sufficient for crystallization to occur at the temperature used. For example, at higher temperatures, crystallization times can be shortened. For example, crystallization conditions can include heating for a period of 1 to 20 days (e.g., at least 1 day or at least 3 days up to 15 or 10 days). Crystallization times can be established by methods known in the art, for example, by sampling the synthesis mixture at various time points and determining the yield and X-ray crystallinity of the precipitated solid.

[0028] Typically, the aluminosilicate SWY molecular sieve is formed in solution and can be recovered by standard means such as centrifugation or filtration. The separated aluminosilicate molecular sieve product can be washed, recovered by centrifugation or filtration, and dried.

[0029] As a result of the crystallization process, the recovered as-synthesized crystalline molecular sieve product contains within its pore structure at least a portion of the structure directing agent used in the synthesis.

[0030] The recovered as-synthesized molecular sieve can be further subjected to heat treatment, ozone treatment, or other treatment to remove all or a portion of the structure directing agent used in its synthesis. Heat treatment (e.g., calcination) of the as-synthesized aluminosilicate molecular sieve typically involves exposing the material in a furnace under an atmosphere selected from air, nitrogen, ozone, or a mixture thereof to a temperature high enough to remove some or all of the structure directing agent. Heat treatment can be carried out at temperatures ranging from 300°C to 800°C (e.g., 400°C to 650°C) for a time ranging from 1 hour to 10 hours (e.g., 3 hours to 6 hours).

[0031] The aluminosilicate SWY molecular sieve can also be subjected to an ion exchange treatment, for example, with an aqueous solution of an ammonium salt (e.g., ammonium nitrate, ammonium chloride, and ammonium acetate) to remove residual alkali metal cations and replace them with protons to produce the acidic form of the molecular sieve. To the desired extent, the original cations of the as-synthesized material, such as alkali metal cations, can be replaced by ion exchange with other cations. Preferred replacement cations include hydrogen ions, hydrogen precursors (e.g., ammonium ions), and mixtures thereof. The ion exchange step can be performed after drying the as-prepared molecular sieve. The ion exchange step can be performed either before or after the calcination step.

[0032] Molecular sieve characterization The SWY molecular sieve synthesized by the methods described herein can have a SiO2 / Al2O3 molar ratio of 10 to 50 (e.g., 15 to 40, or 20 to 35). The silica to alumina molar ratio of the zeolite can be determined by conventional analysis.

[0033] The synthesis methods described herein can produce aluminosilicate SWY crystals of high purity, preferably phase pure. As used herein, the term "phase pure" means that the aluminosilicate SWY molecular sieve composition can comprise at least 95 wt. % (e.g., at least 97 wt. % or at least 99 wt. %) molecular sieve having SWY topology, based on the total weight of the composition, as measured by powder XRD or NMR, or other known methods for such measurements. The remainder of the composition is non-SWY material, which may include amorphous material, a different crystalline phase, a different framework type (e.g., undissolved FAU), or a combination thereof.

[0034] The crystals of the aluminosilicate SWY molecular sieve produced according to the methods described herein may be uniform, have little or no twinning and / or multiple twinning, or may form aggregates.

[0035] Aluminosilicate SWY molecular sieve crystals produced according to the methods described herein can have an average crystal size of 0.1-10 μm (e.g., 0.1-3 μm, 0.5-5 μm, or 1-3 μm). Crystal size is based on individual crystals (including twins), but does not include aggregates of crystals. Crystal size is the length of the longest diagonal of a three-dimensional crystal. Direct measurement of crystal size can be performed using microscopy techniques such as SEM and TEM. For example, SEM measurements involve examination of the morphology of the material at high magnification (e.g., 1000x-10,000x). SEM can be performed by scattering a representative portion of the molecular sieve powder on a suitable mount so that individual particles are fairly evenly spread across the field of view at 1000x-10,000x magnification. From this population, examine a statistically significant sample of random individual crystals (e.g., 50–200) and measure and record the longest diagonal of each individual crystal. Particles that are clearly large polycrystalline aggregates should not be included in the measurements. Based on these measurements, calculate the arithmetic mean of the crystal size for the sample. [Example]

[0036] Example The following illustrative examples are intended to be non-limiting.

[0037] Example 1 0.70 g of 45% KOH solution, 3.94 g of deionized water, 3.39 g of 13.80% 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium hydroxide solution, and 1.00 g of Zeolyst CBV720Y zeolite (SiO2 / Al2O3 molar ratio = 30) powder were mixed together in a Teflon liner. 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 an oven heated to 150°C under static conditions for 6 days. The solid product was recovered from the cooled reactor by centrifugation, washed with deionized water, and dried at 95°C.

[0038] An SEM image of the as-synthesized product is shown in Figure 1.

[0039] The as-synthesized product was then calcined in a muffle furnace under a flow of air 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.

[0040] The powder XRD patterns of the as-synthesized and calcined products are graphically shown in Figure 2, confirming that the synthesized material possesses the SWY structure.

[0041] The calcined material 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.

[0042] The dried ammonium-exchanged product was subjected to micropore volume analysis by the BET method using N2 as the adsorbate. The molecular sieve was 0.30 cm 3 / g micropore volume.

[0043] Example 2 0.60 g of 45% KOH solution, 6.17 g of deionized water, 5.09 g of 13.80% 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium hydroxide solution, and 1.50 g of Zeolyst CBV720Y zeolite powder were mixed together in a Teflon liner. The gel was stirred until homogeneous. The liner was then capped and placed in a Parr steel autoclave reactor. The autoclave was then placed in an oven heated to 150°C for 11 days. The solid product was recovered from the cooled reactor by centrifugation, washed with deionized water, and dried at 95°C.

[0044] Analysis by powder XRD showed the product to be phase-pure SWY molecular sieve.

[0045] Example 3 1.36 g of 45% KOH solution, 7.94 g of deionized water, 2.54 g of 13.80% 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium hydroxide solution, and 1.50 g of Zeolyst CBV720Y zeolite powder were mixed together in a Teflon liner. The gel was stirred until homogeneous. The liner was then capped and placed in a Parr steel autoclave reactor. The autoclave was then placed in an oven heated to 150°C for 5 days. The solid product was recovered from the cooled reactor by centrifugation, washed with deionized water, and dried at 95°C.

[0046] Analysis by powder XRD showed the product to be phase-pure SWY molecular sieve.

[0047] Example 4 0.80 g of 45% KOH solution, 3.89 g of deionized water, 3.39 g of 13.80% 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium hydroxide solution, and 1.00 g of Zeolyst CBV760Y-zeolite (SiO2 / Al2O3 molar ratio = 60) powder were mixed together in a Teflon liner. The gel was stirred until homogeneous. The liner was then capped and placed in a Parr steel autoclave reactor. The autoclave was then placed in an oven heated to 150°C for 6 days. The solid product was recovered from the cooled reactor by centrifugation, washed with deionized water, and dried at 95°C.

[0048] Analysis by powder XRD showed the product to be phase-pure SWY molecular sieve.

Claims

1. A method for synthesizing aluminosilicate molecular sieves for a SWY framework topology, （１） (a) Aluminosilicate zeolite in FAU framework topology, (b) A structure-directing agent [Q] containing a 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cation, (c) Alkali metal cation [M] source, (d) hydroxide ion [OH] source, and (e) Prepare a reaction mixture containing water, (2) The method comprising heating the reaction mixture to obtain an aluminosilicate molecular sieve in a SWY framework topology, The method wherein the reaction mixture has the following composition in terms of molar ratio: Table 1A

2. The method according to claim 1, wherein the reaction mixture has the following composition in terms of molar ratio: Table 1B

3. The method according to claim 1, wherein the aluminosilicate zeolite in the FAU framework topology is zeolite Y.

4. The method according to claim 1, wherein the alkali metal includes potassium.

5. The method according to claim 1, wherein the heating is performed at a temperature in the range of 100°C to 200°C.

6. The method according to claim 1, wherein the heating is performed under self-generated pressure.

7. The method according to claim 1, further comprising firing the aluminosilicate molecular sieves of the SWY framework topology.

8. The method according to claim 1, further comprising ion-exchange of the aluminosilicate molecular sieve in the SWY framework topology.

9. An aluminosilicate molecular sieve in a SWY framework topology, wherein, in its as-synthesized form, it contains a 1-methyl-1-[7-(trimethylammonio)heptyl]piperidinium cation in its pore structure.

10. The aluminosilicate molecular sieve according to claim 9, wherein SiO ２ / Al ２ O ３ The aluminosilicate molecular sieve having a molar ratio of 10 to 50.

11. The aluminosilicate molecular sieve according to claim 9, wherein SiO ２ / Al ２ O ３ The aluminosilicate molecular sieve having a molar ratio of 20 to 35.

12. The aluminosilicate molecular sieve according to claim 9, wherein the aluminosilicate molecular sieve has a phase purity of at least 95% by weight.

Images