13x molecular sieve and method for making same

Abstract

The application provides a 13X molecular sieve and a preparation method thereof. The preparation method comprises the following steps: S1) mixing a silicon source gel system and an aluminum source gel system to obtain a mixed gel system; S2) sequentially performing first crystallization treatment and second crystallization treatment on the mixed gel system to obtain a crystallization product; and S3) performing third crystallization treatment on the crystallization product after aging treatment, so as to obtain the 13X molecular sieve. The application can solve the problem of poor performance of the molecular sieve in the prior art and is suitable for the field of molecular sieve preparation.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve preparation, and more specifically, to a 13X molecular sieve and its preparation method. Background Technology

[0002] Molecular sieves are aluminosilicate materials with uniform pore size and regular crystal structure. They possess abundant pore systems, large specific surface areas, and good thermal stability, making them excellent industrial materials for removing oxygen-containing compounds from olefins, catalytic cracking reactions, and adsorbing harmful gases. Among them, 13X molecular sieves, with their highly ordered microporous structure, possess the ability to precisely screen molecules. The micropores in 13X molecular sieves can selectively adsorb molecules based on their size and shape, effectively separating specific molecules and playing a crucial role in the separation and purification processes of the chemical industry.

[0003] In the gas separation industry, 13X molecular sieves can efficiently extract specific components such as oxygen, nitrogen, or carbon dioxide from mixed gases. Their relatively large specific surface area provides numerous active sites for adsorption, thereby enhancing the adsorption performance of the molecular sieve. This allows 13X molecular sieves to adsorb more substances per unit volume, significantly improving processing speed and efficiency, which is particularly important in applications such as liquid or gas purification, as catalyst carriers, and as storage media.

[0004] These properties of 13X molecular sieves not only hold great potential in traditional fields such as chemical, oil and gas processing, but also demonstrate broad application prospects in emerging fields such as environmental protection, clean energy, and bioscience. For example, in treating industrial waste gases, 13X molecular sieves can remove harmful gases and volatile organic compounds (VOCs); in the production of pharmaceuticals and fine chemicals, they help improve product purity and production efficiency.

[0005] Existing methods for preparing X-type molecular sieves include using silica sol as a silicon source and employing specific directing agents. A molecular sieve mother liquor is prepared by mixing water glass, sodium hydroxide, aluminum hydroxide, or sodium aluminate, followed by the addition of a directing agent, aging, the addition of a weakly polar dispersant, and microwave-assisted crystallization to finally obtain submicron X-type molecular sieves. However, these methods suffer from low silicon source utilization, difficulty in controlling the size and morphology of the prepared 13X molecular sieve products, and insufficient dispersibility, resulting in poor performance of the final 13X molecular sieves that fails to meet the demands of increasingly sophisticated industrial applications. Summary of the Invention

[0006] The main objective of this invention is to provide a 13X molecular sieve and its preparation method to solve the problem of poor performance of 13X molecular sieves in the prior art.

[0007] To achieve the above objectives, according to a first aspect of the present invention, a method for preparing 13X molecular sieve is provided, the method comprising: S1) mixing a silicon source gel system and an aluminum source gel system to obtain a mixed gel system; S2) subjecting the mixed gel system to a first crystallization treatment and a second crystallization treatment in sequence to obtain a crystallized product; S3) aging the crystallized product and then subjecting it to a third crystallization treatment to obtain 13X molecular sieve.

[0008] Further, the method for preparing the silicon source gel system includes: mixing a silicon source and a first solvent to obtain a silicon source gel system; preferably, the silicon source includes one or more of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, or silica fume; preferably, the concentration of the silicon source in the silicon source gel system is 50wt% to 99wt%; preferably, the first solvent includes water and / or ethanol.

[0009] Further, the method for preparing the aluminum source gel system includes: mixing an aluminum source and a second solvent to obtain an aluminum source gel system; preferably, the aluminum source includes one or more of sodium aluminate, boehmite, aluminum sulfate, or aluminum nitrate; preferably, the concentration of the aluminum source in the aluminum source gel system is 17wt% to 99wt%; preferably, the second solvent includes water and / or ethanol.

[0010] Further, S1) includes: dropping the aluminum source gel system into the silicon source gel system and stirring to obtain a mixed gel system; preferably, the stirring temperature is 20-100℃ and the stirring time is 0.1-24h.

[0011] Furthermore, the pH of the mixed gel system is 8.5–12.5.

[0012] Further, in S2), the temperature of the first crystallization treatment is 20–60°C, and the time is 4–24 h; the temperature of the second crystallization treatment is 80–120°C, and the time is 6–48 h; preferably, the temperature of the second crystallization treatment is 20°C higher than the temperature of the first crystallization treatment; preferably, the second crystallization treatment is performed immediately after the first crystallization treatment of the mixed gel system; preferably, the molar ratio of each component in the crystallization product is: SiO2:Al2O3 = 0.01–6:1, Na2O:SiO2 = 0.01–4.0:1, H2O:SiO2 = 1.0–50.0:1.

[0013] Further, in S3), the aging treatment includes: mixing the crystallized product with the directing agent and aging it; preferably, the aging temperature is 20-100°C and the time is 0.1-24h; preferably, the directing agent includes polyvinyl alcohol and / or polyvinylpyrrolidone; preferably, the mass ratio of the crystallized product to the directing agent is 1:0.01-0.1.

[0014] Furthermore, in S3), the temperature of the third crystallization treatment is 60–105°C, and the time is 0.1–36 h.

[0015] Furthermore, the 13X molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3 cm³. 3 / g~0.5cm 3 / g, specific surface area 700m² 2 / g~950m 2 / g.

[0016] In a second typical embodiment of this application, a 13X molecular sieve prepared using any of the above-described methods is provided. This 13X molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3 cm³. 3 / g~0.5cm 3 / g, specific surface area 700m² 2 / g~950m 2 / g.

[0017] By applying the technical solution of this invention, a two-stage crystallization process is performed on a mixed gel system containing aluminum and silicon sources to control the crystal form, remove most of the impurities in the seed crystals, and obtain a crystallized product. After aging the crystallized product, a third crystallization process is performed to further introduce microporous and mesoporous structures, increase the pore capacity, and further increase the adsorption sites inside the 13X molecular sieve, thereby improving the overall performance of the final 13X molecular sieve. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0019] As mentioned in the background section, existing methods for preparing 13X molecular sieves suffer from low silicon source utilization, difficulty in controlling the size and morphology of the obtained 13X molecular sieve products, and insufficient dispersibility. This results in poor performance of the final 13X molecular sieve, failing to meet the demands of increasingly sophisticated industrial applications. Therefore, in this application, the inventors attempt to provide a novel method for preparing 13X molecular sieves. This method utilizes a three-stage crystallization process to prepare 13X molecular sieves, achieving high silicon source conversion and producing a 13X molecular sieve product with a large specific surface area, high pore volume, uniform micropore and mesopore distribution, and controllable morphology. Compared to existing 13X methods, this method offers superior performance. Therefore, this application proposes a series of protective solutions.

[0020] In a first typical embodiment of this application, a method for preparing 13X molecular sieve is provided. The method includes: S1) mixing a silicon source gel system and an aluminum source gel system to obtain a mixed gel system; S2) subjecting the mixed gel system to a first crystallization treatment and a second crystallization treatment in sequence; S3) aging the crystallized product and then subjecting it to a third crystallization treatment to obtain 13X molecular sieve.

[0021] In the existing technology for preparing molecular sieves, the crystallization process often adopts a single-stage crystallization method, which results in low silicon source utilization, difficulty in controlling the size and morphology of the molecular sieve products, and ultimately poor performance of the molecular sieves, making it difficult to meet the ever-growing industrial demands.

[0022] In the above preparation method, segmented crystallization, namely a first crystallization treatment and a second crystallization treatment, makes the crystal form controllable and removes most of the seed crystal impurities. After aging, a third crystallization treatment is performed to further incorporate microporous and mesoporous pore structures into the molecular sieve, improving the silicon source conversion rate, increasing the specific surface area and pore capacity, and increasing the number of adsorption sites. Finally, a 13X molecular sieve with a smooth crystal surface free of impurities and improved performance compared to existing technologies is obtained, giving it a wider range of applications in shape-selective adsorption and catalysis.

[0023] In a preferred embodiment, the method for preparing the silicon source gel system includes: mixing a silicon source and a first solvent to obtain a silicon source gel system; preferably, the silicon source includes one or more of silica sol, tetraethyl orthosilicate, coarse-porous silica gel (i.e., type C silica gel, with the chemical formula mSiO2·nH2O), silicon powder, or silica fume; preferably, the concentration of the silicon source in the silicon source gel system is 50wt% to 99wt%, including but not limited to 50, 60, 70, 80, 90, or 99wt%; preferably, the first solvent includes water and / or ethanol.

[0024] In a preferred embodiment, the method for obtaining the aluminum source gel system includes: mixing an aluminum source and a second solvent to obtain the aluminum source gel system; preferably, the aluminum source includes one or more of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate; preferably, the concentration of the aluminum source in the aluminum source gel system is 17wt% to 99wt%, including but not limited to 17, 18, 19, 20, 30, 40, 50, 60, 70, 80, 90, or 99wt%; preferably, the second solvent includes water and / or ethanol.

[0025] In a preferred embodiment, the method for preparing the aluminum-source gel system includes: dropping the aluminum-source gel system into the silicon-source gel system and stirring to obtain a mixed gel system; preferably, the stirring temperature is 20-100°C, including but not limited to 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, and the stirring time is 0.1-24h, including but not limited to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, and 24h.

[0026] In a preferred embodiment, the pH of the mixed gel system is 8.5 to 12.5, including but not limited to 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12 or 12.5.

[0027] This application achieves precise control over the ratio of silicon and aluminum sources to the first and second solvents, the stirring time, and the pH of the subsequent mixed gel system. This facilitates faster crystallization of the subsequent two-stage crystallization process, shortens the crystallization time, and forms a crystallized product with controllable morphology, which is beneficial for the subsequent formation of the 13X molecular sieve of this application.

[0028] In a preferred embodiment, in S2), the temperature of the first crystallization treatment is 20–60°C, including but not limited to 20°C, 30°C, 40°C, 50°C, and 60°C, and the time is 4–24 hours, including but not limited to 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 hours; the temperature of the second crystallization treatment is 80–120°C, including but not limited to 80°C, 90°C, 100°C, 110°C, and 120°C, and the time is… The time is 6 to 48 hours, including but not limited to 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 36, or 48 hours; preferably, the temperature of the second crystallization treatment is 20°C higher than the temperature of the first crystallization treatment; preferably, the second crystallization treatment is performed immediately after the first crystallization treatment of the mixed gel system; preferably, the molar ratio of each component in the crystallization product is: SiO2:Al2O3 = 0.01 to 6:1, including but not limited to 0.01:1, 0. 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 2:1, 3:1, 4:1, 5:1, or 6:1; Na2O:SiO2 = 0.01–4.0:1, including but not limited to 0.01:1, 0.02:1, 0.03:1, 0.0 4:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 2:1, 3:1 or 4:1, H2O:SiO2 = 1.0 to 50.0:1, including but not limited to 1:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1 or 50:1.

[0029] This application employs a two-stage crystallization process with a temperature difference in the mixed gel system. By setting the temperature difference, the adjustment of the silicon-to-aluminum ratio becomes more flexible, which is beneficial for the subsequent formation of 13X molecular sieves with controllable morphology and size and a wide silicon-to-aluminum ratio, while removing most impurities from the seed crystals. Furthermore, by precisely controlling the temperature and time of the two-stage crystallization process, the growth rate and final size of the crystals can be controlled, which is beneficial for improving the overall performance of the final 13X molecular sieve. Moreover, controlling the molar ratio of each component in the crystallization product within the aforementioned range is conducive to the formation of 13X molecular sieves with specific crystal forms.

[0030] In a preferred embodiment, in step S3), the aging process includes: mixing the crystallized product with a directing agent and aging it; preferably, the aging temperature is 20–100°C, including but not limited to 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, and the time is 0.1–24 hours, including but not limited to 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. The aging process involves aging at 16, 17, 18, 19, 20, 21, 22, 23, or 24 hours. Preferably, the directing agent comprises polyethylene and / or polyvinylpyrrolidone. Preferably, the mass ratio of the directing agent to the crystallized product is 1:0.01 to 0.1, including but not limited to 1:0.01, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, or 0.1:1. Polyvinylpyrrolidone and polyvinyl alcohol can act as structure directing agents and crystal growth regulators. Under the conditions described above, mixing them with the crystallized product for aging further assists crystallization, optimizes the crystal form, and improves the structural stability of the final 13X molecular sieve.

[0031] Limiting the aging temperature and time to the above range facilitates the subsequent third crystallization process, and also helps to further remove impurities from the seed crystals, improve the quality of the seed crystals, and make the particle size distribution within the seed crystals more uniform.

[0032] In a preferred embodiment, in S3), the temperature of the third crystallization treatment is 60-105°C, including but not limited to 60°C, 70°C, 80°C, 90°C, 100°C, 101°C, 102°C, 103°C, 104°C, or 105°C, and the time is 0.1-36h, including but not limited to 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, or 36h.

[0033] This application adds a third crystallization treatment after performing two-stage crystallization and aging treatment on a mixed gel system containing aluminum and silicon sources. This process incorporates microporous and mesoporous pore structures into the molecular sieve, further improving the silicon source conversion rate, increasing the specific surface area and pore capacity. This is beneficial for increasing the adsorption sites of the prepared 13X molecular sieve, thereby improving its adsorption performance and broadening its application in the field of shape-selective adsorption.

[0034] In a preferred embodiment, the 13X molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3 cm³. 3 / g~0.5cm 3 / g, specific surface area 700m² 2 / g~950m 2 / g.

[0035] In a second typical embodiment of this application, a 13X molecular sieve prepared using any of the above-described methods is provided. This 13X molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3 cm³. 3 / g~0.5cm 3 / g, specific surface area 700m² 2 / g~950m 2 / g. The 13X molecular sieve prepared using the method described in this application, through a three-stage crystallization treatment, improves the controllability of the seed crystals and introduces the pore volume energy within the mesoporous molecular sieve crystals to enhance the flow and diffusion performance of guest molecules within the molecular sieve. Furthermore, the 13X molecular sieve of this application exhibits uniform morphology dispersion, a large specific surface area, and a large pore volume, demonstrating good selectivity and significantly reducing the carbon deposition rate of the molecular sieve. Compared with existing 13X molecular sieves, its performance is improved, showing promising application prospects in the field of shape-selective adsorption and meeting industrial needs.

[0036] The beneficial effects of this application will be explained in more detail below with reference to specific embodiments.

[0037] Example 1

[0038] 1. Dissolve 21.0g of silica sol (30% by mass) in 36.0g of deionized water and pretreat at 25°C for 1 hour in a sealed reactor to obtain a silica-based gel system; dissolve 24g of aluminum sulfate in 18.0g of deionized water and stir at 25°C for 1 hour to obtain an aluminum-based gel system; slowly add the aluminum-based gel system dropwise to the silica-based gel system (the addition is completed in 0.8 hours), and continue stirring at 60°C for 8 hours to obtain a mixed gel system;

[0039] 2. Dissolve 6.74g of sodium hydroxide in 36g of deionized water dispersion and add it to the mixed gel system until the pH value is 12. Then place it in a hydrothermal reactor for two-stage crystallization treatment. The first crystallization treatment temperature is 40℃ and the time is 12 hours. The second crystallization treatment temperature is 95℃ and the time is 24 hours to obtain 13X crystallized product (where the molar ratio of each component is: SiO2:Al2O3=1.5:1, Na2O:SiO2=1.6:1, H2O:SiO2=32:1).

[0040] 3. Mix the crystallized product with 1g of polyvinylpyrrolidone, and then continue to stir and age at 60℃ for 12h. After that, place it in a hydrothermal reactor for a third crystallization treatment at 98℃ for 24h. Filter and wash the obtained product until the pH reaches 7, and dry it at 90℃ to obtain 13X molecular sieve.

[0041] Example 2

[0042] 1. Dissolve 1g of silicon powder in 18g of deionized water and pretreat at 25°C for 1 hour in a sealed reactor to obtain a silicon-based gel system. Simultaneously, dissolve 12g of aluminum nitrate in 18.0g of deionized water and stir at 35°C for 1 hour to prepare an aluminum-based gel system. Slowly add the prepared aluminum-based gel system dropwise to the silicon-based gel system (dropwise addition completed in 0.6 hours), and continue stirring at 50°C for 6 hours to obtain a mixed gel system.

[0043] 2. Dissolve 2g of sodium hydroxide in 36g of deionized water to obtain a dispersion, and add it to the mixed gel system until the pH value is 11.8. Then transfer it to a hydrothermal reactor for two-stage crystallization treatment: the first crystallization treatment temperature is 50℃ and the time is 14 hours; the second crystallization treatment temperature is 100℃ and the time is 18 hours to obtain 13X crystallized product (where the molar ratio of each component is: SiO2:Al2O3=0.6:1, Na2O:SiO2=3:1, H2O:SiO2=20:1);

[0044] 3. Mix the crystallized product with 1g of polyvinyl alcohol, and then continue to stir and age at 60℃ for 12h. After that, place it in a hydrothermal reactor for a third crystallization treatment at 95℃ for 24h. Filter and wash the obtained product until the pH reaches 7, and dry it at 90℃ to obtain 13X molecular sieve.

[0045] Example 3

[0046] 1. Dissolve 0.17g of silicon powder in 6g of deionized water and pretreat at 25°C for 1 hour in a sealed reactor to obtain a silicon-based gel system. Simultaneously, dissolve 12g of aluminum nitrate in 18.0g of deionized water and stir at 35°C for 1 hour to prepare an aluminum-based gel system. Slowly add the aluminum-based gel system to the silicon-based gel system (dropping at a rate of 1 hour to complete the addition) and stir at 100°C for 24 hours to obtain a mixed gel system.

[0047] 2. Dissolve 0.9g of sodium hydroxide in 6g of deionized water to prepare a dispersion, and add it to the mixed gel system until the pH value is 12.5 to obtain a gel slurry solution. Then, transfer it to a hydrothermal reactor for two-stage crystallization treatment. The first crystallization treatment temperature is 60℃ and the time is 24 hours. The second crystallization treatment temperature is 120℃ and the time is 48 hours to obtain 13X crystallized product (where the molar ratio of each component is: SiO2:Al2O3=0.1:1, Na2O:SiO2=4:1, H2O:SiO2=1:1).

[0048] 3. Mix the crystallized product with 1g of polyvinyl alcohol, and then continue to stir and age at 60℃ for 12h. After that, place it in a hydrothermal reactor and crystallize at 105℃ for 20h for a third crystallization treatment. Filter and wash the obtained product until the pH is 7, and dry it at 90℃ to obtain 13X molecular sieve.

[0049] Example 4

[0050] 1. Mix 14.6-5.0 g of tetraethyl orthosilicate with 36 g of deionized water at a 1:1 volume ratio. Pretreat the mixture in a sealed reactor at 25°C for 1 hour to obtain a silicon-based gel system. Simultaneously, dissolve 12 g of aluminum nitrate in 18.0 g of deionized water and stir at 35°C for 1 hour to obtain an aluminum-based gel system. Then, gradually add the aluminum-based gel system dropwise to the silicon-based gel system (dropping rate completed in 0.5 hours) and mix and stir at 20°C for 0.1 hours to prepare a mixed gel system.

[0051] 2. Dissolve 0.56g of sodium hydroxide in 6g of deionized water as a dispersion, and slowly pour it into the mixed gel system until the pH value is 8.5 to obtain a gel slurry solution. Then, transfer it to a hydrothermal reactor for two-stage crystallization. The first crystallization treatment is carried out at a temperature of 20℃ for 4 hours; the second crystallization treatment is carried out at a temperature of 80℃ for 6 hours to obtain 13X crystallized product (where the molar ratio of each component is: SiO2:Al2O3=2.5:1, Na2O:SiO2=0.1:1, H2O:SiO2=40:1).

[0052] 3. Mix the crystallized product with 1g of polyvinyl alcohol, and then continue to stir and age at 70℃ for 15h. After that, place it in a hydrothermal reactor and crystallize at 115℃ for 16h for a third crystallization treatment. Filter and wash the obtained product until the pH is 7, and dry it at 90℃ to obtain 13X molecular sieve.

[0053] Example 5

[0054] The difference from Example 1 is that the pH of the mixed gel system is 13.5, while the rest of the steps are the same as in Example 1.

[0055] Example 6

[0056] The difference from Example 1 is that the pH of the mixed gel system is 7, while the rest of the steps are the same as in Example 1.

[0057] Example 7

[0058] The difference from Example 1 is that the first crystallization treatment temperature is 70°C and the time is 3 hours, and the second crystallization treatment temperature is 130°C and the time is 5 hours. The remaining steps are the same as in Example 1.

[0059] Example 8

[0060] The difference from Example 1 is that the first crystallization treatment temperature is 15°C and the time is 26 hours, and the second crystallization treatment temperature is 70°C and the time is 50 hours. The remaining steps are the same as in Example 1.

[0061] Example 9

[0062] The difference from Example 1 is that the third crystallization treatment temperature is 110°C and the time is 0.05h, while the remaining steps are the same as in Example 1.

[0063] Example 10

[0064] The difference from Example 1 is that the third crystallization treatment temperature is 50°C and the time is 38 hours, while the remaining steps are the same as in Example 1.

[0065] Comparative Example 1

[0066] The difference from Example 1 is that after obtaining the gel system, aging and a first crystallization treatment are performed, but the second and third crystallization treatments are not performed. The remaining steps are the same as in Example 1.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that after obtaining the gel system, after the first crystallization treatment, an aging treatment and a second crystallization treatment are performed, but the third crystallization treatment is not performed. The remaining steps are the same as in Example 1.

[0069] The BET (Brunauer-Emmett-Teller) specific surface area, pore volume, BJH (Barrett-Joyner-Halenda) adsorption average pore size, and silicon source conversion rate of 13X molecular sieves prepared in Examples 1-10 and Comparative Examples 1-2 of this application are described. It should be noted that in Table 1, micropores refer to pores with a diameter <2 nm, and mesopores refer to pores with a diameter of 2-50 nm.

[0070] Table 1

[0071]

[0072]

[0073] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: This application prepares 13X molecular sieves by precisely controlling the temperature, time and pH during the crystallization process and setting up multi-stage crystallization treatment, which results in high silicon source conversion rate, entry into the microporous and mesoporous structure, increased surface area and pore volume, further increasing the adsorption sites inside the molecular sieve, and improving the flow and diffusion performance of the guest inside the molecular sieve. The 13X molecular sieve obtained by this application has better comprehensive performance than the prior art and can meet the ever-developing industrial needs.

[0074] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing 13X molecular sieve, characterized in that, The preparation method includes: S1) Mix the silicon source gel system and the aluminum source gel system to obtain a mixed gel system; S2) The mixed gel system is subjected to a first crystallization treatment and a second crystallization treatment in sequence to obtain a crystallized product; S3) After aging the crystallized product, a third crystallization process is performed to obtain the 13X molecular sieve; The pH of the mixed gel system is 8.5~12.5; The temperature of the first crystallization treatment is 20~60℃, and the time is 4~24h; The second crystallization treatment is performed at a temperature of 80~120℃ for 6~48 hours. The aging process is carried out at a temperature of 20~100℃ for a time of 0.1~24h. The third crystallization treatment is performed at a temperature of 60~105℃ for a time of 0.1~36h. The method for preparing the silicon-source gel system includes: The silicon source and the first solvent are mixed to obtain the silicon source gel system; The silicon source includes one or more of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, or precipitated silica. The first solvent includes water and / or ethanol; The method for preparing the aluminum source gel system includes: The aluminum source and the second solvent are mixed to obtain the aluminum source gel system; The second solvent includes water and / or ethanol.

2. The preparation method according to claim 1, characterized in that, The concentration of silicon source in the silicon source gel system is 50wt%~99wt%.

3. The preparation method according to claim 1, characterized in that, The concentration of aluminum source in the aluminum source gel system is 17wt%~99wt%.

4. The preparation method according to claim 1, characterized in that, S1) includes: dropping the aluminum source gel system into the silicon source gel system and stirring to obtain the mixed gel system.

5. The preparation method according to claim 4, characterized in that, The stirring temperature is 20~100℃, and the stirring time is 0.1~24h.

6. The preparation method according to claim 1, characterized in that, The temperature of the second crystallization treatment is 20°C higher than that of the first crystallization treatment.

7. The preparation method according to claim 6, characterized in that, The mixed gel system undergoes the second crystallization treatment immediately after the first crystallization treatment.

8. The preparation method according to claim 1, characterized in that, The molar ratios of the components in the crystallized product are: SiO2:Al2O3 = 0.01~6:1, Na2O:SiO2 = 0.01~4.0:1, H2O:SiO2 = 1.0~50.0:

1.

9. The preparation method according to claim 1, characterized in that, In step S3), the aging process includes: mixing the crystallized product with a directing agent and performing the aging process.

10. The preparation method according to claim 9, characterized in that, The directing agent includes polyvinyl alcohol and / or polyvinylpyrrolidone.

11. The preparation method according to claim 9, characterized in that, The mass ratio of the crystallized product to the directing agent is 1:0.01~0.

1.

12. The preparation method according to claim 1, characterized in that, The 13X molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3 cm³. 3 / g~0.5 cm 3 / g, specific surface area 700 m² 2 / g~950 m 2 / g.

13. A 13X molecular sieve prepared using the method for preparing 13X molecular sieve according to any one of claims 1 to 12, characterized in that, The 13X molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3 cm³. 3 / g~0.5 cm 3 / g, specific surface area 700 m² 2 / g~950 m 2 / g.

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