Method for preparing high-crystallinity hierarchical porous SAPO-20 zeolite molecular sieve by seed method and application thereof

Abstract

This invention relates to the field of zeolite molecular sieve synthesis technology, specifically to a method and application of preparing highly crystalline hierarchical porous SAPO-20 zeolite molecular sieves using a seed crystal method. The method includes the following steps: using boehmite as the aluminum source, 85wt% phosphoric acid aqueous solution as the phosphorus source, and inexpensive water glass as the silicon source, mixing and stirring them sequentially in this order until homogeneous; then adding SAPO-20 as a seed crystal; mixing and stirring until homogeneous; controlling the pH value of the system between 6.6 and 7.8; and carrying out a hydrothermal crystallization reaction at 185-235℃ for 60-108 hours; after removing the product, washing it with water until neutral, drying it, and calcining it at 450℃ for 6 hours to obtain SAPO-20 zeolite molecular sieves with high crystallinity and hierarchical porous structure. This SAPO-20 zeolite molecular sieve is then used as a carrier to support transition metals to prepare a catalyst for the hydrogenation of carbon oxides to alcohols, where the carbon oxides exhibit a high conversion rate.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve synthesis technology, specifically to a method for preparing highly crystalline hierarchical porous SAPO-20 zeolite molecular sieves using the seed crystal method and its application. Background Technology

[0002] SAPO-20 zeolite molecular sieves are SOD-type aluminum phosphate molecular sieves (SAPOs). SAPOs are a type of silica-alumina phosphate with a novel crystal structure obtained by introducing Si atoms into the aluminum phosphate framework. They are isomorphous with AlPO-20 and sodalite, belonging to the cubic crystal system, with a pore size of 9.8 nm (six-membered rings). Their unique framework composition and structural characteristics endow SAPO-20 zeolite molecular sieves with abundant pores, high specific surface area, strong ion exchange properties, and surface acidity. The pentavalent P atoms in the zeolite framework are readily replaced by tetravalent Si during zeolite crystal growth, resulting in a negatively charged silicon-oxygen tetrahedron with significant electron-donating ability. This makes them excellent catalysts, ion exchangers, and adsorbents for separating and purifying molecules.

[0003] Currently, the synthesis of microporous SAPO-20 zeolite molecular sieves mainly involves hydrothermal crystallization, dry gel conversion, and liquid-phase crystallization. Existing technologies require large amounts of expensive small organic molecule templates or amine-based organic templates during the synthesis of SAPO-20. This is not only environmentally unfriendly and costly, but also damages the structure of SAPOs during high-temperature calcination. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing highly crystalline hierarchical porous SAPO-20 zeolite molecular sieves using a seed crystal method, and its applications. This invention uses inexpensive water glass as the silicon source, reducing the synthesis system's dependence on organic template agents. Furthermore, by utilizing the structure-directing effect of SAPO-20 seed crystals, a SAPO-20 molecular sieve with a hierarchical porous structure and high crystallinity is synthesized. The overall synthesis process is simple, reduces equipment corrosion, significantly saves costs, and makes green chemistry more efficient.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A method for preparing highly crystalline hierarchical porous SAPO-20 zeolite molecular sieves using a seed crystal method includes the following steps:

[0007] Using boehmite as the aluminum source, 85wt% phosphoric acid aqueous solution as the phosphorus source, and inexpensive water glass as the silicon source, the materials were mixed and stirred in this order until homogeneous. Then, SAPO-20 was added as a seed crystal. After mixing and stirring until homogeneous, the pH value of the system was controlled between 6.6 and 7.8, and a hydrothermal crystallization reaction was carried out at 185-235℃ for 60-108 hours. After the product was removed, it was washed with water until neutral, dried, and calcined at 450℃ for 6 hours to obtain a highly crystalline hierarchical porous SAPO-20 zeolite molecular sieve.

[0008] The aluminum source, phosphorus source, and silicon source in the system are calculated based on the raw material input amounts of Al2O3, P2O5, and SiO2, and the raw materials are added according to the molar ratio Al2O3:H2O:P2O5:SiO2=(0.8-1.2):63:1.8:1.0.

[0009] Furthermore, the aluminum source, phosphorus source, and silicon source in the system are calculated in terms of raw material input amounts of Al2O3, P2O5, and SiO2, and the raw materials are added according to the molar ratio Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0.

[0010] Furthermore, the amount of seed crystals used is 4wt%-6wt% of the final weight of the SAPO-20 zeolite molecular sieve.

[0011] Preferably, the amount of seed crystals used is 5 wt% of the final weight of the SAPO-20 zeolite molecular sieve.

[0012] Furthermore, the pH value of the system is controlled at 7.0-7.2.

[0013] Furthermore, the hydrothermal crystallization reaction is carried out at a temperature of 205-225°C for a time of 72-84 hours.

[0014] Furthermore, the time for mixing and stirring after adding the seed crystals is 24 hours.

[0015] In another aspect, the present invention provides the application of the highly crystalline hierarchical porous SAPO-20 zeolite molecular sieve prepared by the above preparation method in the reaction of hydrogenation of carbon oxides to prepare alcohols. In application, the SAPO-20 zeolite molecular sieve prepared by the above method is used as a support to support transition metals or their oxides to prepare a catalyst.

[0016] Further, the metal in the transition metal or its oxide is selected from one or more of Zr, Ni, Co, Zn, Cu, and Ce; preferably, the metal in the transition metal or its oxide is selected from a combination of Co and one or more of Zr, Ni, Zn, Cu, and Ce.

[0017] Beneficial technical effects:

[0018] This invention utilizes inexpensive water glass as the silicon source and, guided by SAPO-20 as a seed crystal, directly synthesizes a high-crystallinity, hierarchical porous SAPO-20 zeolite molecular sieve via hydrothermal crystallization. Compared to existing technologies, this significantly reduces the reliance on large amounts of small-molecule organic template agents in traditional synthesis methods, providing an environmentally friendly and low-cost synthetic route, and yielding a high-crystallinity SAPO-20 (S-20) zeolite molecular sieve with a hierarchical porous structure.

[0019] The SAPO-20 zeolite molecular sieve synthesized by the method of this invention has a hierarchical porous structure and high crystallinity. When used as a support to support transition metals to form a catalyst, it can be applied to the reaction of hydrogenation of carbon oxides to alcohols, effectively catalyzing the conversion of carbon oxides to alcohols with a high conversion rate. Attached Figure Description

[0020] Figure 1 SEM image of the highly crystalline hierarchical porous SAPO-20 zeolite molecular sieve prepared by the seed crystal method in Example 1.

[0021] Figure 2 The N2 adsorption-desorption isotherm and pore size distribution curve of the high crystallinity hierarchical porous SAPO-20 zeolite molecular sieve prepared by the seed method in Example 1 are shown.

[0022] Figure 3 XRD patterns of SAPO-20 zeolite molecular sieves synthesized with different Al2O3:P2O5 ratios are shown; where Al2O3:P2O5 = 0.8:1.8 (Example 1), b represents Al2O3:P2O5 = 0.9:1.8 (Example 2), c represents Al2O3:P2O5 = 1.0:1.8 (Example 3), d represents Al2O3:P2O5 = 1.1:1.8 (Example 4), and e represents Al2O3:P2O5 = 1.2:1.8 (Example 5).

[0023] Figure 4 XRD patterns of seed crystals synthesized with different mass fractions are shown; where a represents a mass fraction of 3% (Example 6), b represents a mass fraction of 4% (Example 7), c represents a mass fraction of 5% (Example 8), and d represents a mass fraction of 6% (Example 9).

[0024] Figure 5XRD patterns of SAPO-20 zeolite molecular sieves synthesized at different system pH values ​​are shown; where a represents system pH = 6.6 (Example 10), b represents system pH = 6.8 (Example 11), c represents system pH = 7.0 (Example 12), d represents system pH = 7.2 (Example 13), e represents system pH = 7.4 (Example 14), f represents system pH = 7.6 (Example 15), and g represents system pH = 7.8 (Example 16).

[0025] Figure 6 XRD patterns of SAPO-20 zeolite molecular sieves synthesized at different crystallization reaction temperatures are shown; where a represents 185℃ (Example 17), b represents 195℃ (Example 18), c represents 205℃ (Example 19), d represents 215℃ (Example 20), e represents 225℃ (Example 21), and f represents 235℃ (Example 22).

[0026] Figure 7 XRD patterns of SAPO-20 zeolite molecular sieves synthesized at different hydrothermal crystallization reaction times are shown; where a represents 60 h (Example 23), b represents 72 h (Example 24), c represents 84 h (Example 25), d represents 96 h (Example 26), and e represents 108 h (Example 27).

[0027] Figure 8 The XRD patterns of the hierarchical porous SAPO-20 zeolite molecular sieves prepared in Comparative Examples 1-2 and the high crystallinity hierarchical porous SAPO-20 zeolite molecular sieves prepared by the seed crystal method in Example 25 are shown; where a represents Example 25, b represents Comparative Example 1, and c represents Comparative Example 2.

[0028] Figure 9 The diagram shows the catalytic activity of each catalyst in Application Example 1 for carbon dioxide conversion. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0031] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0032] Solution A used in the following examples was obtained by dissolving 3.0 mL of inexpensive water glass in 5 mL of H2O; the water glass composition was: SiO2: 4.9581 mol / L, Na2O: 1.5357 mol / L, H2O: 51.0692 mol / L.

[0033] In the following examples and comparative examples, the description of "molar ratio of each material Al2O3:H2O:P2O5:SiO2" is as follows: Al2O3 refers to the aluminum source, and the number of moles of the aluminum source is the same as the number of moles of aluminum in the pseudoboehmite; SiO2 refers to the silicon source, and the number of moles of the silicon source is the same as the number of moles of silicon in the water glass; P2O5 refers to the phosphorus source, and the number of moles of the phosphorus source is the same as the number of moles of phosphorus in the phosphoric acid; S-20 represents the seed crystal SAPO-20, which plays a structural guiding role.

[0034] Example 1

[0035] Solution B: Obtained by dissolving 1.6g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0036] 2.8 mL of 85 wt% phosphoric acid aqueous solution was added to solution B and stirred for 30 min. Solution A was then added dropwise, and the mixture was stirred thoroughly for another 30 min. 0.12 g of seed crystal S-20 was added, and the mixture was stirred for 24 h to obtain a mixture. Hydrochloric acid was added dropwise to the mixture to control the pH to 7.0. The resulting mixture was then placed in a high-pressure reactor and subjected to hydrothermal crystallization in an oven at 225 °C for 72 h. After filtration, washing, and drying, the mixture was calcined at 450 °C for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of the materials in the system was Al2O3:H2O:P2O5:SiO2 = 0.8:63:1.8:1.0, and the amount of S-20 used was 4% of the weight of the final product, SAPO-20 zeolite molecular sieve.

[0037] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0038] Example 2

[0039] Solution B: Obtained by dissolving 1.8g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0040] 2.8 mL of 85 wt% phosphoric acid aqueous solution was added to solution B and stirred for 30 min. Solution A was then added dropwise, and the mixture was stirred thoroughly for another 30 min. 0.12 g of seed crystal S-20 was added, and the mixture was stirred for 24 h to obtain a mixture. Hydrochloric acid was added dropwise to the mixture to control the pH to 7.0. The resulting mixture was then placed in a high-pressure reactor and subjected to hydrothermal crystallization in an oven at 225 °C for 72 h. After filtration, washing, and drying, the mixture was calcined at 450 °C for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of the materials in the system was Al2O3:H2O:P2O5:SiO2 = 0.8:63:1.8:1.0, and the amount of S-20 used was 4% of the weight of the final product, SAPO-20 zeolite molecular sieve.

[0041] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0042] Example 3

[0043] Solution B: Obtained by dissolving 2.0 g of high-purity boehmite AlOOH·nH2O in 9.0 mL of H2O;

[0044] 2.8 mL of 85 wt% phosphoric acid aqueous solution was added to solution B and stirred for 30 min. Solution A was then added dropwise, and the mixture was stirred thoroughly for another 30 min. 0.12 g of seed crystal S-20 was added, and the mixture was stirred for 24 h to obtain a mixture. Hydrochloric acid was added dropwise to the mixture to control the pH to 7.0. The resulting mixture was then placed in a high-pressure reactor and subjected to hydrothermal crystallization in an oven at 225 °C for 72 h. After filtration, washing, and drying, the mixture was calcined at 450 °C for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of the materials in the system was Al2O3:H2O:P2O5:SiO2 = 0.8:63:1.8:1.0, and the amount of S-20 used was 4% of the weight of the final product, SAPO-20 zeolite molecular sieve.

[0045] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0046] Experiment Example 4

[0047] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0048] 2.8 mL of 85 wt% phosphoric acid aqueous solution was added to solution B and stirred for 30 min. Solution A was then added dropwise, and the mixture was stirred thoroughly for another 30 min. 0.12 g of seed crystal S-20 was added, and the mixture was stirred for 24 h to obtain a mixture. Hydrochloric acid was added dropwise to the mixture to control the pH to 7.0. The resulting mixture was then placed in a high-pressure reactor and subjected to hydrothermal crystallization in an oven at 225 °C for 72 h. After filtration, washing, and drying, the mixture was calcined at 450 °C for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of the materials in the system was Al2O3:H2O:P2O5:SiO2 = 0.8:63:1.8:1.0, and the amount of S-20 used was 4% of the weight of the final product, SAPO-20 zeolite molecular sieve.

[0049] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0050] Experimental Example 5

[0051] Solution B: Obtained by dissolving 2.4g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0052] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.12 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.0. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.2:63:1.8:1.0, and the amount of S-20 is 4% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0053] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0054] Experimental Example 6

[0055] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0056] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.09 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.0. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 3% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0057] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0058] Experimental Example 7

[0059] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0060] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.12 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.0. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 4% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0061] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0062] Experimental Example 8

[0063] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0064] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.0. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0065] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0066] Experimental Example 9

[0067] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0068] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.18 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.0. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 6% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0069] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0070] Experimental Example 10

[0071] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0072] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 6.6. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0073] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0074] Experimental Example 11

[0075] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0076] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 6.8. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0077] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0078] Experimental Example 12

[0079] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0080] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.0. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0081] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0082] Experimental Example 13

[0083] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0084] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.2. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0085] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0086] Experimental Example 14

[0087] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0088] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.4. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0089] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0090] Experimental Example 15

[0091] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0092] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.6. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0093] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0094] Experimental Example 16

[0095] Solution B: Obtained by dissolving 2.2g of high-purity boehmite AlOOH·nH2O in 9.0mL of H2O;

[0096] Add 3.0 mL of 85 wt% phosphoric acid aqueous solution to solution B, stir for 30 min, then add solution A dropwise, stir thoroughly for another 30 min, add 0.15 g of seed crystal S-20, and stir for another 24 h to obtain a mixture. Add hydrochloric acid dropwise to the mixed solution to control the pH of the system to 7.8. Then, put the obtained mixture into a high-pressure reactor and place it in an oven at 225℃ for hydrothermal crystallization reaction for 72 h. After filtration, washing, and drying, calcine at 450℃ for 6 h to obtain the product SAPO-20 zeolite molecular sieve. The molar ratio of each material in the system is Al2O3:H2O:P2O5:SiO2 = 1.1:63:1.8:1.0, and the amount of S-20 is 5% of the weight of the final product SAPO-20 zeolite molecular sieve.

[0097] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0098] Experiment 17-Experiment 22

[0099] The preparation methods of the products in Examples 17-22 are the same as those in Example 13, except that the hydrothermal crystallization reaction temperature is different.

[0100] The hydrothermal crystallization reaction temperature in Example 17 was 185°C.

[0101] The hydrothermal crystallization reaction temperature in Example 18 was 195°C.

[0102] The hydrothermal crystallization reaction temperature in Example 19 was 205°C.

[0103] The hydrothermal crystallization reaction temperature in Example 20 was 215°C.

[0104] The hydrothermal crystallization reaction temperature in Example 21 was 225°C.

[0105] The hydrothermal crystallization reaction temperature in Example 22 was 235°C.

[0106] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0107] Examples 23-27

[0108] The preparation methods of the products in Examples 23-27 are the same as those in Example 20, except that the hydrothermal crystallization reaction time is different.

[0109] The hydrothermal crystallization reaction time in Example 23 was 60 hours.

[0110] The hydrothermal crystallization reaction time in Example 24 was 72 hours.

[0111] The hydrothermal crystallization reaction time in Example 25 was 84 hours.

[0112] The hydrothermal crystallization reaction time in Example 26 was 96 hours.

[0113] The hydrothermal crystallization reaction time in Example 27 was 108 h.

[0114] The crystallinity of the prepared SAPO-20 zeolite molecular sieve is shown in Table 1.

[0115] Comparative Example 1

[0116] The highly crystalline SAPO-20 zeolite molecular sieve was prepared using the method described in Example 14 of Chinese Patent No. CN113620312B, entitled "A Method for Preparing a Highly Crystalline SAPO-20 Zeolite Molecular Sieves". Specific parameters are shown in Table 1.

[0117] Comparative Example 2

[0118] Example 23 of the Chinese patent (CN114702041B) entitled "A Method for Preparing and Applying a Quasi-Spherical Hierarchical Porous SAPO-20 Zeolite Molecular Sieves" describes the method used to prepare quasi-spherical hierarchical porous SAPO-20 zeolite molecular sieves. Specific parameters are shown in Table 1.

[0119] Crystallinity (%) and nitrogen adsorption were tested in the above examples. Crystallinity was calculated using an X-ray diffractometer with the formula: Crystallinity = (Diffraction peak intensity / Total intensity) * 100%, and data processing was performed using Jade software. Nitrogen adsorption was measured using a physical adsorption analyzer to obtain S... BET The reaction parameters and specific crystallinity data of the above embodiments are shown in Table 1.

[0120] The products of the above examples and comparative examples were subjected to XRD tests and the crystallinity was calculated. The results are shown in Table 1.

[0121] Table 1 shows the preparation parameters and crystallinity of the products from the above examples and comparative examples.

[0122]

[0123]

[0124] Results and Discussion:

[0125] The SEM image of the SAPO-20 zeolite product obtained in Example 1 is shown below. Figure 1 As shown, its N2 adsorption-desorption isotherms and pore size distribution curves are as follows: Figure 2 As shown, the SAPO-20 zeolite product obtained by the method of this invention is spherical with a hierarchical pore distribution and a pore size distribution of 9.8 nm.

[0126] Experiments 1-5 compared whether SAPO-20 zeolite could be synthesized under different Al2O3:P2O5 ratios, as shown in Table 1. Figure 3 XRD patterns show that porous SAPO-20 zeolite can be synthesized hydrothermally within an aluminum-to-phosphorus ratio range of (0.8-1.2):1.8, but the crystallinity is highest when the Al2O3:P2O5 ratio is 1.1:1.8. Therefore, an Al2O3:P2O5 ratio of 1.1:1.8 is favorable for the synthesis of porous SAPO-20.

[0127] Experiments 6-9 compared the optimal mass fraction of S-20 seed crystals for synthesizing SAPO-20 zeolite, as shown in Table 1. Figure 4 The XRD patterns show that highly crystalline porous SAPO-20 zeolite can be synthesized within a seed crystal content range of 4-6% of the product weight, with the best crystallinity at 5% (mass fraction). However, if the seed crystal content is too low, its guiding effect is zero. Therefore, a S-20 content of 5% is optimal.

[0128] Experiments 10-16 compared whether the acidity or alkalinity of the system was favorable for the synthesis of SAPO-20 zeolite, as shown in Table 1. Figure 5 The XRD pattern shows that SAPO-20 zeolite can be synthesized in the pH range of 6.8-7.6, and the crystallinity is highest at around pH 7.2. However, SAPO-20 zeolite cannot be synthesized under excessively acidic or alkaline conditions. Therefore, pH 7.2 is favorable for the synthesis of SAPO-20.

[0129] Experiments 17-22 compared whether SAPO-20 zeolite could be synthesized in the system at different crystallization temperatures, as shown in Table 1. Figure 6 The XRD pattern shows that the crystallinity of SAPO-20 zeolite gradually increases with increasing crystallization temperature. However, at excessively high temperatures, such as above 225℃, the intensity of the characteristic peaks in the XRD pattern drops significantly, and the corresponding crystallinity is also quite low. Therefore, a crystallization temperature of 215℃ is selected as the optimal temperature.

[0130] Example 20 and Experiments 23-27 compare whether SAPO-20 zeolite can be synthesized in the system at different crystallization times, as shown in Table 1. Figure 7 The XRD patterns show that SAPO-20 can be synthesized with crystallization times ranging from 60 to 108 hours. As the crystallization time increases, the crystallinity of SAPO-20 zeolite first increases and then decreases. Therefore, a crystallization time of 84 hours is selected as the optimal time.

[0131] Comparative Examples 1-2 and Experimental Example 25 compared the crystallinity of SAPO-20 zeolite obtained by existing synthesis methods and the optimal synthesis scheme of this invention. The crystallinity is shown in Table 1. Figure 8XRD patterns showed that the crystallinity of SAPO-20 zeolite did not differ significantly under different formulations and material ratios. However, compared with the experimental methods in the literature, the crystallinity of the product obtained by this invention using a small amount of seed crystals under suitable conditions without the need for organic template agents can reach over 99.99%, and the product has a hierarchical porous structure with a pore size distribution of 9.8 nm. The method of this invention does not require organic template agents, which is more conducive to green development.

[0132] Application Example 1

[0133] The highly crystalline hierarchical porous SAPO-20 zeolite molecular sieves from Examples 4 (92.50%), 8 (95.63%), 13 (97.30%), 19 (98.34%), 20 (98.50%), and 25 (99.99%) were applied to the reaction of hydrogenating carbon oxides to prepare alcohols, specifically the reaction of hydrogenating carbon dioxide to methanol.

[0134] Once the crystallinity of SAPO-20 exceeds 98%, its impact on carbon dioxide conversion rate becomes minimal.

[0135] The SAPO-20 zeolite molecular sieve prepared in Example 25 was used as a support for a transition metal catalyst. The specific preparation process was as follows: A certain amount of boehmite was weighed and dissolved in deionized water. After stirring evenly, a certain amount of 85wt% phosphoric acid solution and water glass were added sequentially. After stirring evenly, S-20 seed crystals were added dropwise, and after thorough stirring, a cobalt nitrate solution complexed with EDTA was added. Hydrothermal crystallization was carried out at 215℃ for 84 hours. The system composition was Al2O3:H2O:P2O5:SiO2:CoO=1.1:63:1.0:1.8:0.2. The amount of S-20 used was 5% of the final product weight. The product obtained from the reaction was filtered, washed, and dried, and then calcined at 450℃ for 6 hours to obtain a 5% Co / SAPO-20 (S-20) molecular sieve catalyst.

[0136] In addition, 5% Co / SAPO-20 (S-20), 5% Zn / SAPO-20 (S-20), 5% Cu / SAPO-20 (S-20), 5% Ni / SAPO-20 (S-20), 5% Zr / SAPO-20 (S-20), and 5% Ce / SAPO-20 (S-20) were also prepared according to the aforementioned method.

[0137] The catalytic activity of 5% Co / SAPO-20(S-20), 5% Zn / SAPO-20(S-20), 5% Cu / SAPO-20(S-20), 5% Ni / SAPO-20(S-20), 5% Zr / SAPO-20(S-20), and 5% Ce / SAPO-20(S-20) catalysts for carbon dioxide was tested. The conversion rates of carbon dioxide catalyzed by the catalysts are as follows: Figure 9 As shown. By Figure 9 It can be seen that 5% Co / SAPO-20 (S-20) has the highest CO2 conversion rate and the best selectivity among single metal catalysts.

[0138] Comparative Example 1

[0139] The SAPO-20 zeolite molecular sieve prepared in Example 14 of Chinese Patent CN113620312B, entitled "A Preparation Method of High Crystallinity SAPO-20 Zeolite Molecular Sieves," was used as a support for a transition metal catalyst. The specific preparation process was as follows: A certain amount of boehmite was weighed and dissolved in deionized water. After stirring evenly, a certain amount of 85wt% phosphoric acid solution, water glass, and N,N,N',N'-tetramethyl-1,6-hexanediamine were added sequentially. After thorough stirring, a cobalt nitrate solution complexed with EDTA was added. Hydrothermal crystallization was carried out at 210℃ for 48 hours, with the ratio of Al2O3:H2O:P2O5:SiO2:TMHD:CoO = 0.8:40:1.0:1.0:1.2:0.2. The product obtained from the reaction was filtered, washed, and dried, and then calcined at 450℃ for 6 hours to obtain a 5% Co / SAPO-20 molecular sieve catalyst.

[0140] In addition, 5% Co / SAPO-20, 5% Zn / SAPO-20, 5% Cu / SAPO-20, 5% Ni / SAPO-20, 5% Zr / SAPO-20, and 5% Ce / SAPO-20 were also prepared according to the patented method.

[0141] The catalytic activity of 5% Co / SAPO-20, 5% Zn / SAPO-20, 5% Cu / SAPO-20, 5% Ni / SAPO-20, 5% Zr / SAPO-20, and 5% Ce / SAPO-20 catalysts for carbon dioxide was tested. The conversion rates of carbon dioxide catalyzed by the catalysts were as follows: Figure 9 As shown. By Figure 9 It can be seen that the catalyst loaded with 5% Co exhibits the highest CO2 conversion rate and the best selectivity. However, the CO2 conversion rate of the SAPO-20 zeolite molecular sieve synthesized by the amine template method in Comparative Example 1 is lower than that of the catalyst prepared by supporting transition metals with the seed crystal method of this invention. The SAPO-20 zeolite molecular sieve prepared by the method of this invention shows better catalytic activity after being loaded with transition metals, especially Co.

[0142] This invention uses SAPO-20 as a seed crystal to hydrothermally synthesize a highly crystalline hierarchical porous SAPO-20 as a support to support transition metals to make a catalyst. The catalyst can work continuously for 1000 hours without a significant decrease in catalytic efficiency, and has good industrial application stability and catalytic activity.

[0143] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high crystallinity hierarchical pore SAPO-20 zeolite molecular sieve by a seed crystal method, characterized in that, Includes the following steps: Using boehmite as the aluminum source, 85 wt% phosphoric acid aqueous solution as the phosphorus source, and inexpensive water glass as the silicon source, the materials were mixed and stirred in this order until homogeneous. Then, SAPO-20 was added as a seed crystal. After mixing and stirring until homogeneous, the pH value of the system was controlled between 6.6 and 7.8, and a hydrothermal crystallization reaction was carried out at 185-235℃ for 60-108 h. After the product was removed, it was washed with water until neutral, dried, and calcined at 450℃ for 6 h to obtain a highly crystalline hierarchical porous SAPO-20 zeolite molecular sieve. The aluminum source, phosphorus source, and silicon source in the system are calculated based on the raw material input amounts of Al2O3, P2O5, and SiO2, and the raw materials are added according to the molar ratio Al2O3:H2O:P2O5:SiO2=(0.8-1.2):63:1.8:1.0; The amount of seed crystals used is 4wt%-6wt% of the final weight of the SAPO-20 zeolite molecular sieve.

2. The method for preparing highly crystallinity hierarchical porous SAPO-20 zeolite molecular sieves by seed crystal method according to claim 1, characterized in that, The aluminum source, phosphorus source, and silicon source in the system are calculated based on the raw material input amounts of Al2O3, P2O5, and SiO2, and the raw materials are added according to the molar ratio Al2O3:H2O:P2O5:SiO2=1.1:63:1.8:1.

0.

3. The method for preparing highly crystallinity hierarchical porous SAPO-20 zeolite molecular sieves by seed crystal method according to claim 2, characterized in that, The amount of seed crystals used is 5 wt% of the final weight of the SAPO-20 zeolite molecular sieve.

4. The method for preparing highly crystallinity hierarchical porous SAPO-20 zeolite molecular sieves by seed crystal method according to claim 2, characterized in that, The pH value of the control system is 7.0-7.

2.

5. The method for preparing highly crystallinity hierarchical porous SAPO-20 zeolite molecular sieves by seed crystal method according to claim 2, characterized in that, The hydrothermal crystallization reaction is carried out at a temperature of 205-225℃ for 72-84 hours.

6. The method for preparing highly crystallinity hierarchical porous SAPO-20 zeolite molecular sieves by seed crystal method according to any one of claims 1-5, characterized in that, The time for mixing and homogenizing after adding the seed crystals is 24 h.

7. The application of the highly crystalline hierarchical porous SAPO-20 zeolite molecular sieve prepared by the method according to any one of claims 1-6 in the hydrogenation reaction of carbon oxides to prepare alcohols, characterized in that, In application, the SAPO-20 zeolite molecular sieve prepared by the above method is used as a support to support transition metals or their oxides to prepare catalysts.

8. The application according to claim 7, characterized in that, The metal in the transition metal or its oxide is selected from one or more of Zr, Ni, Co, Zn, Cu, and Ce.

9. The application according to claim 8, characterized in that, The metal in the transition metal or its oxide is selected from one or more combinations of Co and Zr, Ni, Zn, Cu, and Ce.

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