SSZ-13 molecular sieve as well as preparation method and application thereof

Abstract

The invention provides an SSZ-13 molecular sieve as well as a preparation method and application thereof, the preparation method comprises the following steps: mixing activated silica-alumina minerals, SSZ-13 seed crystals, a silicon source, a template agent and a second alkali source to obtain dry glue, and then carrying out crystallization treatment on the dry glue in the presence of water vapor to obtain the SSZ-13 molecular sieve. According to the preparation method, a solvent is not adopted, a small amount of deionized water is used for providing a steam phase, the utilization rate of the raw materials can be increased, the high solid yield is obtained, the loss of a solid phase is reduced, no alkaline wastewater is generated, and the synthesis cost of the SSZ-13 molecular sieve is remarkably reduced. When the SSZ-13 molecular sieve prepared by the method is used for CO2 / CH4 adsorption separation, the SSZ-13 molecular sieve has relatively high separation selectivity.

Description

Technical Field

[0001] The present application relates to chemical synthesis technology and its application field, and in particular to an SSZ-13 molecular sieve and its preparation method and application. Background Art

[0002] SSZ-13 molecular sieve has a chabazite (CHA) topological structure, which is composed of silicon-oxygen and aluminum-oxygen tetrahedra connected end to end through oxygen atoms, orderly arranged into a crystal structure with eight-membered ring channels and three-dimensional cross channels. It is a small-pore molecular sieve with a pore size of 0.38nm×0.38nm and a specific surface area of ​​up to 700m 2 / g, has good hydrothermal stability, acidity adjustability, ion exchangeability, high activity and high selectivity, and has broad application prospects.

[0003] In the prior art, the hydrothermal synthesis method is usually used to prepare SSZ-13 molecular sieves. However, on the one hand, the product yield of the traditional hydrothermal synthesis method is low, usually 20-40wt% of the mass of the added solid raw materials; on the other hand, the method requires a large amount of solvent (water or alcohol) as a hydrothermal medium, and subsequent product washing and other processes will also consume a large amount of water, thereby generating a large amount of organic wastewater, which requires additional energy to treat these organic wastewaters; on the other hand, the hydrothermal method usually needs to be carried out under high temperature and high pressure conditions, and the high pressure conditions undoubtedly increase the quality requirements for the materials of the process equipment and increase the equipment investment. It can be seen that the traditional hydrothermal method not only has low atomic utilization, but also high cost.

[0004] In order to solve some problems existing in the prior art, those skilled in the art have provided some corresponding solutions. Using N, N, N-trimethyladamantane ammonium hydroxide (TMADaOH) as a structure directing agent, with a tetravalent silicon source, a trivalent aluminum source, hydroxide ions, and an inorganic cation source as raw materials, a secondary gel powder is prepared, and the secondary gel powder is subjected to steam-assisted crystallization to obtain a crystallized product, which is then calcined to obtain an SSZ-13 type zeolite molecular sieve. Although this method abandons a large amount of dependence on water and reduces the emission of pollutants, the amount of the structure directing agent (i.e., template agent) used is large, and its molar ratio is as high as 24%, and the product after crystallization also needs to be calcined at high temperature, which shows that the cost and energy consumption of the method are high. Another method does not add any solvent, and obtains the final product SSZ-13 molecular sieve by solid phase grinding, crystallization reaction, and high-temperature roasting between the raw materials. Although this method minimizes the use of solvent water and obtains a higher product yield, the amount of template used in this method (measured in TMAda+ / SiO2 molar ratio) is greater than 0.3, which shows that the synthesis cost is still high.

[0005] In summary, it is of immeasurable importance to develop a high-yield, low-cost, and environmentally friendly preparation method for obtaining high-crystallinity SSZ-13 molecular sieve. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides a method for preparing high-crystallinity SSZ-13 molecular sieves. This method can synthesize SSZ-13 molecular sieves under solvent-free, water vapor-assisted crystallization conditions, and has the advantages of high product crystallinity, high yield, simple synthesis process, low production cost, and environmental friendliness.

[0007] In a first aspect, the present application provides a method for preparing SSZ-13 molecular sieve, comprising the following steps:

[0008] Mixing activated silica-alumina mineral, SSZ-13 seed crystals, a silicon source, a template agent, and a second alkali source to obtain a dry glue;

[0009] The dry gel is crystallized in the presence of water vapor to obtain the SSZ-13 molecular sieve.

[0010] In a possible embodiment, the preparation process of the activated silica-alumina mineral includes: activating the silica-alumina mineral with a first alkali source to obtain the activated silica-alumina mineral;

[0011] Preferably, the mass ratio of the first alkali source to the silica-alumina mineral is (1.2-1.4):1;

[0012] Preferably, the first alkali source comprises sodium hydroxide and / or potassium hydroxide;

[0013] Preferably, in the first alkali source, the molar ratio of sodium hydroxide to the first alkali source is (0.66-1):1.

[0014] In one possible embodiment, the template includes N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH);

[0015] Preferably, the molar ratio of the N,N,N-trimethyl-1-adamantyl ammonium hydroxide to the silicon source is (0.035-0.1):1.

[0016] In one possible implementation, the mass ratio of the SSZ-13 seed crystal to the silicon source is (5.0-10.0):100.

[0017] In one possible embodiment, the second alkali source includes sodium hydroxide and / or potassium hydroxide;

[0018] Preferably, in the second alkali source, the molar ratio of sodium hydroxide to the second alkali source is (0.5-1):1.

[0019] In one possible embodiment, the process of mixing the activated silica-alumina mineral, SSZ-13 seed crystals, silicon source, template, and second alkali source comprises:

[0020] Mechanically mixing the activated silica-alumina mineral with SSZ-13 seed crystals to obtain a first mixture;

[0021] Mechanically mixing the first mixture, the silicon source, and the template to obtain a second mixture;

[0022] Mechanically mixing the second mixture with the second alkali source to obtain the dry glue;

[0023] Preferably, in the dry glue, the molar ratio of the alkali source, the silicon source, the aluminum source and the template agent is (3.5-12.0): (20-120): 1: (1-6).

[0024] In one possible embodiment, the mechanical mixing includes grinding and / or ball milling;

[0025] and / or, the particle size of the activated silica-alumina mineral is less than 200 mesh;

[0026] And / or, the particle size of the second mixture is less than 200 mesh.

[0027] In one possible embodiment, the crystallization treatment is performed using a reactor comprising a reaction section and a kettle bottom section; the process of subjecting the dry gel to crystallization in the presence of water vapor comprises: placing the dry gel in the reaction section, adding water to the kettle bottom section, and causing the water to generate water vapor, which enters the reaction section, so that the dry gel in the reaction section undergoes the crystallization treatment in the presence of the water vapor to obtain the SSZ-13 molecular sieve;

[0028] Preferably, the mass ratio of water to dry glue is (3.0-10.0):1;

[0029] Preferably, the crystallization temperature during the crystallization treatment is 155-185° C., and the crystallization time is 24-48 hours.

[0030] In a second aspect, the present application further provides an SSZ-13 molecular sieve, wherein the SSZ-13 molecular sieve is prepared by the above-mentioned preparation method;

[0031] Preferably, the relative crystallinity of the SSZ-13 molecular sieve is greater than or equal to 60%;

[0032] Preferably, the SSZ-13 molecular sieve comprises micropores and mesopores;

[0033] Preferably, the micropore volume of the SSZ-13 molecular sieve is less than or equal to 0.076 cm 3 / g; and / or, the mesopore volume of the SSZ-13 molecular sieve is less than or equal to 0.189 cm 3 / g;

[0034] Preferably, the specific surface area of ​​the SSZ-13 molecular sieve is less than or equal to 605m 2 / g.

[0035] In a third aspect, the present application also provides a method for separating CO2 and CH4, comprising the following steps: using a separation agent to separate CO2 and CH4 in a mixed gas containing CO2 and CH4, the separation agent comprising the SSZ-13 molecular sieve prepared by the SSZ-13 molecular sieve preparation method described above or the SSZ-13 molecular sieve described above.

[0036] Beneficial Effects: The present invention mixes activated silica-alumina mineral, SSZ-13 seed crystals, a silicon source, a template, and a second alkali source in the absence of solvent to obtain a dry gel, which is then crystallized in the presence of water vapor to obtain the SSZ-13 molecular sieve. The preparation method, in the absence of solvent, produces a high-yield, high-crystallinity SSZ-13 molecular sieve through water vapor-assisted crystallization. Furthermore, the preparation cost is low, no secondary pollution is generated, and the environmentally friendly SSZ-13 molecular sieve can be used for the adsorption separation of CO2 and CH4 in a CO2 / CH4 gas mixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0038] Figure 1 Schematic diagram of the process for preparing SSZ-13 molecular sieves according to Examples 1-10 of the present application;

[0039] Figure 2 Schematic diagram of the crystallization of the dry gel described in Examples 1-10 of the present application in the presence of water vapor in a reaction kettle;

[0040] Figure 3 XRD spectra of the SSZ-13 seed crystals used in Examples 1-10 and Comparative Examples 1-3 of the present invention;

[0041] Figure 4 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 1 of the present application;

[0042] Figure 5 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 2 of the present application;

[0043] Figure 6 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 3 of the present application;

[0044] Figure 7 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 4 of the present application;

[0045] Figure 8 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 5 of the present application;

[0046] Figure 9 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 6 of the present application;

[0047] Figure 10 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 7 of the present application;

[0048] Figure 11 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 8 of the present application;

[0049] Figure 12 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 9 of the present application;

[0050] Figure 13 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Example 10 of the present application;

[0051] Figure 14 This is the XRD spectrum of the sample obtained in Comparative Example 1 of this application;

[0052] Figure 15 This is the XRD spectrum of the sample obtained in Comparative Example 2 of this application;

[0053] Figure 16 This is the XRD spectrum of the SSZ-13 molecular sieve obtained in Comparative Example 3 of this application;

[0054] Figure 17a This is a 10,000-fold magnified SEM image of the SSZ-13 molecular sieve obtained in Example 1 of the present application;

[0055] Figure 17b This is a 20,000-fold magnified SEM image of the SSZ-13 molecular sieve obtained in Example 1 of the present application;

[0056] Figure 18a This is a 10,000-fold magnified SEM image of the SSZ-13 molecular sieve obtained in Example 2 of the present application;

[0057] Figure 18b This is a 20,000-fold magnified SEM image of the SSZ-13 molecular sieve obtained in Example 2 of the present application;

[0058] Figure 19a This is a 10,000-fold magnified SEM image of the SSZ-13 molecular sieve obtained in Example 3 of the present application;

[0059] Figure 19b This is a 20,000-fold magnified SEM image of the SSZ-13 molecular sieve obtained in Example 3 of the present application;

[0060] Figure 20a This is a N2 adsorption-desorption isotherm curve of the SSZ-13 molecular sieve obtained in Example 1 of the present invention;

[0061] Figure 20b This is a N2 adsorption-desorption isotherm curve of the SSZ-13 molecular sieve obtained in Example 2 of the present invention;

[0062] Figure 21 This is the test result of using the SSZ-13 molecular sieve obtained in Example 1 of the present invention for CO2 / CH4 gas separation.

[0063] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0064] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0065] The first aspect of the present invention provides a method for preparing SSZ-13 molecular sieve, comprising the following steps:

[0066] Mixing activated silica-alumina mineral, SSZ-13 seed crystals, a silicon source, a template agent, and a second alkali source to obtain a dry glue;

[0067] The dry gel is crystallized in the presence of water vapor to obtain the SSZ-13 molecular sieve.

[0068] In the present invention, an activated silica-alumina mineral replaces all aluminum-based chemical reagents and some silicon-based chemical reagents required in the dry glue preparation process, and no solvent is used when the activated silica-alumina mineral, SSZ-13 seed crystals, silicon source, template, and second alkali source are mixed. During mixing, the second alkali source generates hydroxyl groups on the crystal surfaces of the SSZ-13 seed crystals, enabling the SSZ-13 seed crystals to form bonds with the highly active silica-alumina species in the activated silica-alumina mineral, thereby enabling the activated silica-alumina mineral and SSZ-13 seed crystals to synergistically induce SSZ-13 nucleation. In addition, the second alkali source also has the function of inducing the activated silica-alumina mineral to transform into secondary structural units of the SSZ-13 molecular sieve and nucleation precursors. During the crystallization process, the solvent water does not directly contact the dry glue, but enters the dry glue gap in the form of water vapor, further dissolving the silicon aluminum source in the dry glue, and then under the synergistic effect of the SSZ-13 seed crystals and the template agent, promotes the crystallization of the amorphous dry glue into crystals. Therefore, the present invention can synthesize SSZ-13 molecular sieves with higher solid yields under the conditions of solvent-free, water vapor-assisted crystallization, significantly reducing the synthesis cost of SSZ-13 molecular sieves. The preparation method also does not have secondary pollution and is very environmentally friendly. The higher crystallinity of the prepared SSZ-13 molecular sieve can be used for the separation of CO2 and CH4 in a mixed gas containing CO2 / CH4.

[0069] In some specific embodiments, the preparation process of the activated silica-alumina mineral includes: activating the silica-alumina mineral with a first alkali source to obtain the activated silica-alumina mineral.

[0070] In some specific embodiments, the silica-aluminum mineral includes at least one of kaolin, metakaolin, rectorite, attapulgite, bentonite, and montmorillonite.

[0071] In some specific embodiments, the SiO2 content in the silica-aluminum mineral is 40-70wt%, specifically, the SiO2 content of kaolin is 50.5wt%, the SiO2 content of metakaolin is 50.5wt%, the SiO2 content of rectorite is 43.3wt%, the SiO2 content of attapulgite is 52.2wt%, the SiO2 content of attapulgite is 52.2wt%, the SiO2 content of bentonite is 68.2wt%, and the SiO content of montmorillonite is 58.6wt%.

[0072] In some specific embodiments, the Al2O3 content of the silica-alumina mineral is 11-45 wt%. Specifically, the Al2O3 content of kaolin is 44.6 wt%; the Al2O3 content of kaolin is 44.6 wt%; the Al2O3 content of rectorite is 37.1 wt%; the Al2O3 content of attapulgite is 13.7 wt%; the Al2O3 content of bentonite is 10.7 wt%; and the Al2O3 content of montmorillonite is 14.3 wt%.

[0073] Since kaolin, rectorite and bentonite are cheap and readily available, have a stable silicon-aluminum ratio and a low impurity content, in specific implementation, it is preferred that the silicon-aluminum mineral is at least one of kaolin, rectorite and bentonite.

[0074] The present invention activates the silica-alumina mineral to disrupt its crystal structure, producing a large number of oligomeric silica-alumina species. These oligomeric silica-alumina species can be more efficiently converted into secondary structural units and nucleation precursors during the crystallization process, thereby being effectively utilized in the molecular sieve crystallization and topological structure assembly process.

[0075] The present invention is not limited to the above activation treatment method, and can be achieved by alkali fusion activation method, sub-molten salt activation method and pseudo-solid phase activation method. For economic considerations (energy consumption, material consumption, etc.), sub-molten salt activation method and pseudo-solid phase activation method are preferred.

[0076] In specific implementation, when the alkali fusion activation method is selected, the process of using the first alkali source to activate the silica-alumina mineral includes: mixing the first alkali source with the silica-alumina mineral and placing it in a high-temperature muffle furnace for roasting for 5-8 hours, setting the temperature to be 10°C higher than the melting point of the alkali, and obtaining an alkali fusion activation product after roasting; when the sub-molten salt activation method is selected, it includes: preparing the first alkali source and water into an alkali solution in a mass ratio of 1: (5-10), and then adding the silica-alumina mineral, stirring continuously for 10-15 minutes to form a suspension, placing the suspension at 200-300°C for activation treatment for 2-5 hours to obtain a sub-molten salt activation product, placing the sub-molten salt activation product in a grinder to obtain a crushed sub-molten salt activation product, and sieving it to below 200 mesh to obtain an activated silica-alumina mineral.

[0077] When the pseudo-solid-phase activation method is selected, the process of activating the silica-alumina mineral using the first alkali source includes: mixing the silica-alumina mineral and the first alkali source, placing the mixture in a grinder and treating it for 2 minutes under the conditions of an output power of 800W and a rotation speed of 26000r / min to obtain an alkaline earth mixture, adding water equivalent to 8-17wt% of the total mass of the solid to the alkaline earth mixture, stirring and mixing evenly, placing it in an extruder for mixing, and then extruding to obtain a wet strip with a diameter of 1.5-2.0mm, placing the wet strip at 150°C for 3-6h to obtain a pseudo-solid-phase activated product.

[0078] In some specific embodiments, the content of active silicon in the activated silica-alumina mineral is not less than 90 wt% of the silicon content in the silica-alumina mineral. Preferably, the content of active silicon in the activated silica-alumina mineral accounts for 91.0-93.8 wt% of the silicon content in the silica-alumina mineral, for example, 91.0 wt%, 91.6 wt%, 92.0 wt%, 92.5 wt%, 92.7 wt%, 93.2 wt%, 93.8 wt%, etc. The ratios listed here do not serve as a limit, and other ratios that meet the ratio range are applicable.

[0079] In some specific embodiments, the content of active aluminum in the activated silica-alumina mineral is not less than 90 wt% of the aluminum content in the silica-alumina mineral. Preferably, the content of active aluminum in the activated silica-alumina mineral accounts for 90.1-93.5 wt% of the aluminum content in the silica-alumina mineral, for example, 90.1 wt%, 90.3 wt%, 90.5 wt%, 90.7 wt%, 90.9 wt%, 91.6 wt%, 91.8 wt%, 92.5 wt%, 93.8 wt%, etc. The ratios listed here are not limiting, and other ratios that meet the ratio range are applicable.

[0080] The above-mentioned active silicon specifically refers to a silicon species in an activated silica-alumina mineral that can be extracted from an acid or alkaline solution and can provide a silicon source for the synthesis of molecular sieves. The above-mentioned active aluminum refers to an aluminum species in an activated silica-alumina mineral that can be extracted from an acid or alkaline solution and can provide an aluminum source for the synthesis of molecular sieves. The contents of active silicon and active aluminum in the silica-alumina mineral can both be measured using an inductively coupled plasma spectrometer (ICP). Specifically, the ICP test is performed by dissolving the activated silica-alumina mineral in a 0.1 mol / L dilute hydrochloric acid solution.

[0081] When the active silicon and active aluminum contents are lower than the above ranges, it indicates that the silica-alumina mineral has not been fully activated. The inactivated silica-alumina mineral is then transferred in situ to the final crystallized SSZ-13 molecular sieve, resulting in the resulting product being a non-pure SSZ-13 molecular sieve. Therefore, the present invention controls the active silicon and active aluminum contents in the activated silica-alumina mineral to be greater than 90 wt% of the silicon and aluminum contents in the silica-alumina mineral.

[0082] Furthermore, the mass ratio of the first alkali source to the silica-alumina mineral is (1.2-1.4):1.

[0083] In the above-mentioned activation treatment process, when the mass ratio of the first alkali source used to the silica-alumina mineral is controlled to be (1.2-1.4): 1, such as 1.2:1, 1.3:1, 1.4:1, etc., it is beneficial to activate the silica-alumina mineral. After the silica-alumina mineral is activated using the first alkali source, highly active oligomeric silica-alumina species can be obtained. Of course, the ratios listed here do not play a limiting role, and other ratios that meet the ratio range are applicable. When the amount of the first alkali source is too much, it will lead to an increase in the viscosity of the activation system, a decrease in fluidity, a decrease in mass transfer and activation effects, and also cause the activation system to be too corrosive; when the content of the first alkali source is too little, it will cause the silica-alumina mineral to fail to be fully activated, and the resulting activated silica-alumina mineral contains low levels of active silicon and active aluminum, which is not conducive to the formation of SSZ-13 molecular sieve.

[0084] Furthermore, the first alkali source includes sodium hydroxide and / or potassium hydroxide.

[0085] Furthermore, in the first alkali source, the molar ratio of sodium hydroxide to the first alkali source is (0.66-1):1.

[0086] The first alkali source may include an inorganic base, specifically sodium hydroxide and / or potassium hydroxide. When the molar ratio of sodium hydroxide to the first alkali source in the first alkali source is controlled to be (0.66-1): 1, such as 0.66: 1, 0.75: 1, 0.85: 1, 0.95: 1, 1: 1, etc., the silica-aluminum mineral can be completely activated, and the ratio of different alkali metal cations in the activated silica-aluminum mineral is located in an interval that is conducive to guiding the nucleation and growth of the SSZ-13 molecular sieve, and a higher crystallinity SSZ-13 molecular sieve can be obtained. The ratios cited here do not play a limiting role, and other ratios that meet the ratio range are applicable.

[0087] It should be noted that, in the specific implementation process, the mass of the required first alkali source is calculated according to the mass ratio of the required first alkali source to the silica-alumina mineral, and the mass of the first alkali source is converted into a molar amount of sodium hydroxide of equal mass. When the first alkali source includes both sodium hydroxide and potassium hydroxide, the molar amount of sodium hydroxide actually contained in the first alkali source is subtracted from the molar amount of sodium hydroxide of equal mass converted according to the mass of the first alkali source. The remaining molar amount is the molar amount of potassium hydroxide included in the first alkali source, and the mass of potassium hydroxide to be added is calculated based on this molar amount.

[0088] In some specific embodiments, the templating agent includes N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH).

[0089] Since SSZ-13 molecular sieve belongs to CHA type molecular sieve, its skeleton is composed of double six-membered rings (D6R), forming an ellipsoidal cage and an eight-membered ring window. This structure requires the template molecule to accurately match the size and shape of the cage. The adamantyl group contained in N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH) is a rigid, three-dimensional hydrophobic group, whose size is highly consistent with the cavity of the CHA cage, which can effectively fill and stabilize the cage structure. The quaternary ammonium cation ((CH3)3N in TMAdaOH) + -adamantane) can interact electrostatically with negatively charged regions in the aluminosilicate framework (such as AlO4 - ) combined, significantly reducing the energy barrier during the synthesis process, promoting the directional growth of the CHA skeleton. Therefore, the template agent in the present invention is preferably TMAdaOH.

[0090] In some specific embodiments, the molar ratio of the N,N,N-trimethyl-1-adamantyl ammonium hydroxide to the silicon source is (0.035-0.1):1, preferably (0.05-0.1):1, specifically, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, etc. It should be noted that the above-mentioned ratios are not limiting, and other ratios that meet the above ratio range are applicable.

[0091] In the present invention, the template agent TMAdaOH plays the core role of "structure directing agent" and "pore forming agent" in the synthesis of SSZ-13 molecular sieve, stabilizing the skeleton in the early stage of crystal growth, balancing the skeleton charge, and ultimately forming an SSZ-13 molecular sieve with a specific eight-membered ring pore structure. The more it is used, the more perfect the structure of the prepared SSZ-13 molecular sieve. The inventors found that when the molar ratio of TMAdaOH to the silicon source exceeds a certain value, the structure of the obtained SSZ-13 molecular sieve does not change significantly. Taking into account the preparation cost, the present invention limits the molar ratio of the template agent TMAdaOH used to the silicon source to (0.035-0.1):1, preferably (0.05-0.1):1.

[0092] In the above-mentioned process of preparing the dry glue, the mass ratio of the SSZ-13 seed crystals to the silicon source is (5.0-10.0):100, for example, 5.0:100, 6.0:100, 7.0:100, 8.0:100, 9.0:100, 10.0:100, etc. It should be noted that the above-mentioned ratios are not limiting, and other ratios that meet the above-mentioned ratio range are applicable.

[0093] Because SSZ-13 seed crystals act as crystal nuclei, providing a readily ordered surface for the silica-alumina species, the dry gel can grow directly on the seed crystal surface, significantly reducing the activation energy required for nucleation and thereby increasing the dry gel's crystallization rate. Excessive amounts of SSZ-13 seed crystals in the dry gel can affect the crystallinity of the SSZ-13 molecular sieve. This also reduces reliance on templates, regulates crystal morphology, and lowers synthesis costs. However, excessive amounts of SSZ-13 seed crystals do not significantly improve the crystallinity of the SSZ-13 molecular sieve, but instead increase preparation costs.

[0094] In some specific embodiments, the second alkali source may also include an inorganic base, specifically sodium hydroxide and / or potassium hydroxide. Preferably, in the second alkali source, the molar ratio of sodium hydroxide to the second alkali source is (0.5-1):1, for example, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, etc. It should be noted that the above-mentioned ratios are not limiting, and other ratios that meet the above ratio range are applicable.

[0095] The hydroxide ions in the sodium hydroxide in the second alkaline source promote the hydrolysis and depolymerization of the silicon and aluminum sources, forming reactive silicate or aluminate monomers. This facilitates the dissolution of the silicon and aluminum sources in water vapor, thereby yielding a highly crystallin SSZ-13 molecular sieve. Insufficient sodium hydroxide content results in an uneven dry gel and the formation of amorphous impurities. Excessive sodium hydroxide content can corrode the nucleated crystals during crystallization, destabilizing the CHA framework.

[0096] In some specific embodiments, the first alkaline source and the second alkaline source may be the same or different.

[0097] In the above-mentioned first alkali source and second alkali source, the molar ratio of sodium hydroxide to the alkali source is calculated based on Na2O and MOH (total molar number of alkali); the molar ratio of SSZ-13 seed crystals to silicon source is calculated based on SiO2; the molar ratio of alkali source, silicon source, aluminum source and template is calculated based on M2O, SiO2, Al2O3 and TMADaOH.

[0098] In some specific embodiments, the silicon source includes at least one of white carbon black, silica sol, silica gel and diatomaceous earth. Considering the crystallinity of SSZ-13 molecular sieve, the silicon source preferably includes white carbon black and / or silica gel.

[0099] In some specific embodiments, the process of mixing the activated silica-alumina mineral, SSZ-13 seed crystals, a silicon source, a template, and a second alkali source comprises:

[0100] Mechanically mixing the activated silica-alumina mineral with SSZ-13 seed crystals to obtain a first mixture;

[0101] Mechanically mixing the first mixture, the silicon source, and the template to obtain a second mixture;

[0102] The second mixture is mechanically mixed with the second alkali source to obtain the dry glue.

[0103] In the process of preparing the dry glue, the inventors found that adding the template agent for mechanical treatment before adding the second alkali source for mechanical treatment resulted in a higher mixing uniformity of the obtained mixed system compared to mixing the template agent and the second alkali source together for mechanical treatment. This is because the template agent contains water. If the second alkali source is added without mechanical treatment, a high concentration of alkaline solution will form locally, and the silicon-aluminum source will dissolve rapidly, resulting in a sharp increase in local viscosity. At this time, mechanical treatment will make it difficult to mix the raw materials evenly, thereby affecting the crystallinity of the SSZ-13 molecular sieve.

[0104] In some specific embodiments, in the dry gel, the molar ratio of the alkali source, the silicon source, the aluminum source and the template is (3.5-12.0): (20-120): 1: (1-6).

[0105] In the present invention, the molar ratio of the alkali source, silicon source, aluminum source and template agent in the dry glue will also affect the quality of the SSZ-13 molecular sieve synthesis result. When the alkali source is used in excessive amounts, the pH of the dry glue will deviate from the SSZ-13 molecular sieve synthesis range, reducing the silicon source utilization rate and product yield, etc., which is not conducive to the synthesis of SSZ-13 molecular sieve and is not conducive to the operation of the equipment; and when the alkali source content is too little, the SSZ-13 molecular sieve cannot be synthesized. If the amount of template agent is reduced, a pure phase SSZ-13 molecular sieve cannot be obtained. Increasing the amount of template agent not only does not significantly enhance the synthesis effect of SSZ-13 molecular sieve, but also increases the preparation cost. By controlling the molar ratio of the alkali source, silicon source, aluminum source and template agent in the dry glue, the synthesis cost can be reduced, and a SSZ-13 molecular sieve with a higher degree of crystallinity can be obtained, thereby achieving efficient separation of CO2 and CH4 gases.

[0106] The present invention calculates the amount of other raw materials required for synthesizing the dry glue according to the amount of the aluminum source in the activated silica-alumina mineral, and the missing silicon source and alkali source are calculated and added according to the corresponding molar ratio in the dry glue.

[0107] When activated aluminosilicates and SSZ-13 seed crystals are present simultaneously in the SSZ-13 molecular sieve synthesis system, they act as independent nucleation-inducing units, resulting in a competitive nucleation effect. The SSZ-13 seed crystals act as crystal nuclei, shortening the precursor's nucleation induction period and increasing the crystallization rate. Furthermore, they act as guides, providing an attachment surface for the aluminosilicates in the dry gel and promoting their orderly growth along crystal planes. The activated aluminosilicate, serving as the aluminum source for SSZ-13 molecular sieve synthesis, also exhibits a similar nucleation-inducing effect as the seed crystals. Without proper treatment of the activated silica-alumina mineral and SSZ-13 seed crystals, the resulting dry gel will not lead to the formation of SSZ-13 molecular sieves. Therefore, the present invention uniformly combines the activated silica-alumina mineral and SSZ-13 seed crystals through mechanical treatment: the mixed alkali source, during mechanical treatment, can form hydroxyl groups on the SSZ-13 seed crystal molecules, which can form bonds with highly active silica-alumina species, forming some Si-O-Si and Si-O-Al bonds. This allows the activated silica-alumina mineral and SSZ-13 seed crystals to synergistically induce SSZ-13 nucleation, avoiding competitive nucleation between the two. Therefore, in some specific embodiments, the mechanical mixing includes grinding and / or ball milling.

[0108] In some specific embodiments, the particle size of the activated silica-alumina mineral is less than 200 mesh. This is because the activated silica-alumina mineral of this size can form a better mutual bonding interaction with the SSZ-13 molecular sieve, thereby facilitating the preparation of the SSZ-13 molecular sieve. The present invention is not limited to the method for treating the activated silica-alumina mineral to a particle size of less than 200 mesh. For example, it can be achieved by crushing, grinding, and screening.

[0109] In some specific embodiments, the particle size of the second mixture is less than 200 mesh. When the particle size of the second mixture is controlled to be less than 200 mesh, it is beneficial to reduce the concentration gradient inside and outside the second mixture particles, accelerate the nucleation rate, and thus promote the formation of SSZ-13 molecular sieve nucleation precursors. At the same time, the particle size of the second mixture affects the particle size of the prepared molecular sieve. When the particle size of the second mixture is less than 200 mesh, the prepared SSZ-13 molecular sieve has a small and uniform particle size.

[0110] In some specific embodiments, the dry gel is crystallized using a reactor comprising a reaction section and a bottom section. The process of crystallizing the dry gel in the presence of water vapor comprises: placing the dry gel in the reaction section, adding water to the bottom section, and causing the water to generate water vapor, which enters the reaction section, so that the dry gel in the reaction section undergoes the crystallization process in the presence of the water vapor to obtain the SSZ-13 molecular sieve.

[0111] When steam-assisted crystallization of the dry gel is performed using water vapor, the water vapor at the bottom of the reactor acts as the steam source during the crystallization process. As the airflow rises, it comes into contact with the dry gel, enters the gel voids, and adsorbs and condenses, dissolving the silicon and aluminum sources in the gel and enhancing the free diffusion of ions. This promotes the migration of active species within the gel and their participation in crystal nucleation and growth, thereby accelerating the conversion of the gel into molecular sieve crystals. To increase the purity of the resulting molecular sieve, deionized water is preferably used during the crystallization process.

[0112] In some specific embodiments, the mass ratio of water to dry glue during the crystallization process is (3.0-10.0):1.

[0113] During the crystallization treatment, the inventors found that the more water is added, the faster the crystallization rate of the dry glue. When the amount of water added exceeds a certain value, the crystallization rate of the dry glue will tend to be stable. Therefore, in the present invention, the mass ratio of water to dry glue is preferably (3.0-10.0):1, for example, 3.0:1, 4.0:1, 5.0:1, 6.0:1, 7.0:1, 8.0:1, 9.0:1, 10.0:1, etc. The ratios listed here are not limiting, and other ratios that meet the ratio range are applicable.

[0114] During the crystallization, the crystallization temperature is 155-185° C., and the crystallization time is 24-48 hours.

[0115] In the present invention, the crystallization temperature of steam crystallization affects the crystallization rate and crystallinity of the molecular sieve. According to the inventors' research, the crystallization temperature of the crystallization treatment in the present invention is preferably 155°C-185°C. When the crystallization temperature is 155°C, the crystallization rate of the dry gel is low, and the time required for complete crystallization of the dry gel is longer. When the crystallization temperature is 185°C, the silicon and aluminum sources in the dry gel will dissolve faster, but the system has limited substances with structure-directing effects, and there is a possibility that some silicon and aluminum sources will assemble to form impurities, affecting the purity of the product. Taking into account the crystallization rate, crystallinity, and purity of the product, the preferred crystallization temperature is 165°C.

[0116] As the SiO2 / Al2O3 ratio increases, the proportion of aluminum source decreases, the rate of nucleation decreases, and the time required for nucleation increases: Molecular sieves with high SiO2 / Al2O3 generally have higher framework stability, and their crystal structure takes longer to form. Therefore, in the present invention, when the crystallization time required for the dry gel is increased, the crystallization time can be extended from 24 hours to 48 hours.

[0117] During the crystallization process, the water is present in the form of steam and does not directly dissolve in the dry glue. Consequently, the amount of water involved in dissolving the dry glue is relatively small, limiting losses caused by the dissolution of the silicon and aluminum sources in water and improving raw material utilization. After crystallization is complete, water condenses at the bottom of the reactor, resulting in a moist solid powder. This product can be dried to obtain a solid phase without centrifugation, further reducing solid phase loss and improving solid yield. Furthermore, no alkaline wastewater is generated, reducing synthesis costs.

[0118] The relative crystallinity of the SSZ-13 molecular sieve prepared by the present invention is greater than or equal to 60%. Preferably, the relative crystallinity of the obtained SSZ-13 molecular sieve is in the range of 60-100.47%. For example, it can be 60.02%, 61.43%, 62.08%, 71.00%, 81.15%, 83.82%, 90.24%, 99.58%, 100.00% and 100.47%. This is because after optimizing the use of the template, the concentration of the cations in the mixed alkali solution, the silicon-aluminum ratio in the dry gel, and the crystallization temperature, the obtained dry gel crystals can tend to form a CHA topological structure, and the relative crystallinity of the finally obtained SSZ-13 molecular sieve is relatively high.

[0119] It should be noted that the relative crystallinity mentioned in the present invention is expressed as the percentage of the intensity of the molecular sieve sample to be tested in a selected region of the XRD spectrum divided by the intensity of the reference sample in the same region. In the present invention, the reference sample is the SSZ-13 molecular sieve obtained in Example 1.

[0120] In some specific embodiments, the SSZ-13 molecular sieve comprises micropores and mesopores.

[0121] In some specific embodiments, the micropore volume of the SSZ-13 molecular sieve is less than or equal to 0.076 cm 3 / g, preferably, the micropore volume of the SSZ-13 molecular sieve is 0.071-0.076cm 3 / g.

[0122] In some specific embodiments, the mesopore volume of the SSZ-13 molecular sieve is less than or equal to 0.189 cm 3 / g, preferably, the mesopore volume of the SSZ-13 molecular sieve is 0.184-0.189cm 3 / g.

[0123] The SSZ-13 molecular sieve produced by the preparation method provided herein contains secondary pores, namely mesopores. The presence of the mesopores shortens the path for gases to enter the micropores, reducing the diffusion time of gases in the molecular sieve. Furthermore, the mesopores act as a buffer, preventing heavy particles and impurities from clogging the micropore entrances. This results in higher CO2 and CH4 separation efficiency.

[0124] In some specific embodiments, the specific surface area of ​​the SSZ-13 molecular sieve is less than or equal to 605m 2 / g, preferably, the specific surface area of ​​the SSZ-13 molecular sieve is 478-605cm 3 / g.

[0125] The SSZ-13 molecular sieve prepared by the preparation method provided by the present invention has a higher specific surface area, can provide more adsorption sites, and improve the adsorption capacity of CO2.

[0126] The present invention also provides the aforementioned SSZ-13 molecular sieve for use in separating CO2 and CH4 from a mixed gas containing these gases, exhibiting excellent separation selectivity: CH4 has an extremely short penetration time through the SSZ-13 molecular sieve, while CO2 has a penetration time of up to 1600 seconds. This demonstrates that the SSZ-13 molecular sieve synthesized by the present invention can achieve highly efficient separation of CO2 and CH4 gases.

[0127] The present invention is described in more detail below through specific examples.

[0128] The flow charts of Examples 1-10 of the present invention are as follows Figure 1 shown.

[0129] Example 1

[0130] 1) Preparation of activated silica-alumina minerals

[0131] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and after continuous stirring for 10 minutes, the activation kettle is placed in an oven at 250°C for activation for 3 hours to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0132] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1;

[0133] The contents of active silicon and active aluminum in activated kaolin are 91.6wt% and 90.7wt% of the silicon source and aluminum source in kaolin respectively;

[0134] 2) Preparation of dry glue

[0135] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt% TMADaOH solution were added to the first mixture, ground for 10 minutes, and sieved to less than 200 mesh to obtain a second mixture, and 0.404 g of 99 wt% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0136] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystal to silicon source is 10:100;

[0137] 3) Preparation of SSZ-13 molecular sieve

[0138] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0139] The mass ratio of deionized water to dry glue is 5:1.

[0140] Example 2

[0141] 1) Preparation of activated silica-alumina minerals

[0142] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0143] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 91 wt% and 92 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0144] 2) Preparation of dry glue

[0145] 0.224 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.545 g of silica gel (300-400 mesh) and 1.127 g of a 25 wt% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.376 g of 99 wt% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0146] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.215:0.018:1:0.017:0.05:1.409; the mass ratio of SSZ-13 seed crystals to silicon source is 10:100;

[0147] 3) Preparation of SSZ-13 molecular sieve

[0148] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 48 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0149] The mass ratio of deionized water to dry glue is 5:1.

[0150] Example 3

[0151] 1) Preparation of activated natural silica-alumina minerals

[0152] Sodium hydroxide is used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 1.2g of sodium hydroxide and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in a 250°C oven for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0153] The molar ratio of sodium hydroxide to the first alkali source is 1:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 93.8 wt% and 90.1 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0154] 2) Preparation of dry glue

[0155] 0.683 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.434 g of silica gel (300-400 mesh) and 1.127 g of a 25 wt% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.054 g of 99 wt% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0156] The molar ratio of Na2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.2:1:0.05:0.05:1.409; the mass ratio of SSZ-13 seed crystals to silicon source is 10:100;

[0157] 3) Preparation of SSZ-13 molecular sieve

[0158] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0159] The mass ratio of deionized water to dry glue is 5:1.

[0160] Example 4

[0161] 1) Preparation of activated silica-alumina minerals

[0162] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0163] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 92.5 wt% and 90.9 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0164] 2) Preparation of dry glue

[0165] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt.% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.404 g of 99 wt.% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0166] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystal to silicon source is 10:100;

[0167] 3) Preparation of SSZ-13 molecular sieve

[0168] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 12 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0169] The mass ratio of deionized water to dry glue is 5:1.

[0170] Example 5

[0171] 1) Preparation of activated silica-alumina minerals

[0172] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0173] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 92.0 wt% and 91.8 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0174] 2) Preparation of dry glue

[0175] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.404 g of 99 wt% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0176] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystal to silicon source is 10:100;

[0177] 3) Preparation of SSZ-13 molecular sieve

[0178] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 155°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0179] The mass ratio of deionized water to dry glue is 5:1.

[0180] Example 6

[0181] 1) Preparation of activated natural silica-alumina minerals

[0182] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0183] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 92.7 wt% and 93.5 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0184] 2) Preparation of dry glue

[0185] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt.% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.404 g of 99 wt.% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0186] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystal to silicon source is 10:100;

[0187] 3) Preparation of SSZ-13 molecular sieve

[0188] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 185°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0189] The mass ratio of deionized water to dry glue is 5:1.

[0190] Example 7

[0191] 1) Preparation of activated silica-alumina minerals

[0192] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0193] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 93.2 wt% and 92.5 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0194] 2) Preparation of dry glue

[0195] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.404 g of 99 wt% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0196] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystals to silicon source is 5:100;

[0197] 3) Preparation of SSZ-13 molecular sieve

[0198] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0199] The mass ratio of deionized water to dry glue is 5:1.

[0200] Example 8

[0201] 1) Preparation of activated silica-alumina minerals

[0202] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0203] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 91.6 wt% and 90.3 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0204] 2) Preparation of dry glue

[0205] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt.% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.404 g of 99 wt.% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0206] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystal to silicon source is 10:100;

[0207] 3) Preparation of SSZ-13 molecular sieve

[0208] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0209] The mass ratio of deionized water to dry glue is 3:1.

[0210] Example 9

[0211] 1) Preparation of activated silica-alumina minerals

[0212] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0213] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 92.7 wt% and 90.5 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0214] 2) Preparation of dry glue

[0215] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.404 g of 99 wt% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0216] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystal to silicon source is 10:100;

[0217] 3) Preparation of SSZ-13 molecular sieve

[0218] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0219] The mass ratio of deionized water to dry glue is 10:1.

[0220] Example 10

[0221] 1) Preparation of activated natural silica-alumina minerals

[0222] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0223] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1; the contents of active silicon and active aluminum in the activated kaolin are 92.5 wt% and 91.6 wt% of the silicon source and aluminum source in the kaolin, respectively;

[0224] 2) Preparation of dry glue

[0225] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and pulverized in a pulverizer (output power 800 W, speed 26000 r / min) for 20 seconds to obtain a first mixture, which was sieved to less than 200 mesh; 1.505 g of silica gel (300-400 mesh) and 1.127 g of 25 wt.% TMADaOH solution were added to the first mixture to obtain a second mixture; the second mixture was ball milled in a ball mill at 100 rpm for 20 minutes and sieved to obtain a dry gel;

[0226] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.067:0.032:1:0.029:0.05:1.409; the mass ratio of SSZ-13 seed crystals to silicon source is 10:100;

[0227] 3) Preparation of SSZ-13 molecular sieve

[0228] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the dried glue was placed at a crystallization temperature of 165°C after sealing. The dried glue was crystallized in the presence of water vapor for 24 hours. After the crystallization was completed, the dried glue was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0229] The mass ratio of deionized water to dry glue is 5:1.

[0230] Comparative Example 1

[0231] 1) Preparation of activated silica-alumina minerals

[0232] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0233] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1;

[0234] 2) Preparation of dry glue

[0235] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) was added to the first mixture and ground for 10 minutes to obtain a second mixture; 0.404 g of 99 wt.% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0236] The molar ratio of Na2O, K2O, SiO2, and Al2O3 in the dry gel is 0.247:0.027:1:0.025; the mass ratio of SSZ-13 seed crystals to silicon source is 10:100;

[0237] 3) Preparation of SSZ-13 molecular sieve

[0238] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the mixture was sealed and placed at 165°C for crystallization for 24 hours. After the crystallization was completed, the mixture was cooled to 20-30°C, and the sample was transferred to 80°C for drying for 3 hours to obtain molecular sieve mixed crystals.

[0239] The mass ratio of deionized water to dry glue is 5:1.

[0240] Comparative Example 2

[0241] 1) Preparation of activated silica-alumina minerals

[0242] Sodium hydroxide and potassium hydroxide are used as the first alkali source, and kaolin is activated by a sub-molten salt activation method. The specific steps are as follows: 8.0g of sodium hydroxide, 5.6g of potassium hydroxide, and 60g of deionized water are mixed and added to a polytetrafluoroethylene activation kettle, 10g of kaolin is added under stirring, and the activation kettle is placed in an oven at 250°C for activation for 3h to obtain activated kaolin; the activated kaolin is crushed and sieved to less than 200 mesh;

[0243] The molar ratio of sodium hydroxide to the first alkali source is 0.66:1; the mass ratio of the first alkali source to kaolin is 1.2:1;

[0244] 2) Preparation of dry glue

[0245] 0.367 g of activated kaolin and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.517 g of silica gel (300-400 mesh) and 1.127 g of 25 wt.% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.404 g of 99 wt.% sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0246] The molar ratio of Na2O, K2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.247:0.027:1:0.025:0.05:1.409; the mass ratio of SSZ-13 seed crystals to silicon source is 10:100;

[0247] 3) Preparation of SSZ-13 molecular sieve

[0248] The dry glue was placed in a polytetrafluoroethylene liner, sealed and placed at a crystallization temperature of 165°C to allow the dry glue to crystallize for 24 hours in the absence of water vapor. After the crystallization was completed, it was cooled to 20-30°C and the sample was transferred to 80°C for drying for 3 hours to obtain a solid product.

[0249] Comparative Example 3

[0250] 1) Preparation of dry glue

[0251] 0.546 g of 98 wt.% NaAlO2 and 0.16 g of SSZ-13 seed crystals were mixed and ground in a mortar for 5 minutes to obtain a first mixture; 1.6 g of silica gel (300-400 mesh) and 1.127 g of 25 wt.% TMADaOH solution were added to the first mixture and ground for 10 minutes to obtain a second mixture, and 0.060 g of sodium hydroxide was added and ground for 5 minutes to obtain a dry gel;

[0252] The molar ratio of Na2O, SiO2, Al2O3, TMAdaOH and H2O in the dry gel is 0.2:1:0.05:0.05:1.409; the mass ratio of SSZ-13 seed crystals to silicon source is 10:100;

[0253] 2) Preparation of SSZ-13 molecular sieve

[0254] The dry glue was placed on a bracket lined with polytetrafluoroethylene, deionized water was added to the bottom of the polytetrafluoroethylene liner, and the mixture was sealed and placed at 165°C for crystallization for 24 hours. After the crystallization was completed, the mixture was cooled to 20-30°C and the sample was transferred to 80°C for drying for 3 hours to obtain SSZ-13 molecular sieve;

[0255] The mass ratio of deionized water to dry glue is 5:1.

[0256] Test Example 1

[0257] The crystallization of the molecular sieves prepared in Examples 1-10 and Comparative Examples 1-3 of the present invention was characterized by XRD spectra. Figure 3-16. The crystallinity of the SSZ-13 molecular sieve prepared in Example 1 is set to 100%, and the ratio of the sum of the peak areas when 2θ is 9.5°, 13°, 16°, 18°, 21°, 23°, 25°, 26.5° and 31° in the XRD spectra of the SSZ-13 molecular sieves prepared in Examples 1-10 of the present invention and Comparative Example 3 to the sum of the peak areas of the SSZ-13 seed crystals is calculated to obtain the relative crystallinity of the SSZ-13 molecular sieves prepared in Examples 1-10 of the present invention and Comparative Example 3. The results are shown in Table 1.

[0258] Table 1 Relative crystallinity of SSZ-13 molecular sieves prepared in Examples 1-10 and Comparative Example 3

[0259] sample Relative crystallinity sample Relative crystallinity Example 1 100.00％ Example 7 60.02％ Example 2 100.47％ Example 8 71.00％ Example 3 99.58％ Example 9 83.82％ Example 4 62.08％ Example 10 81.15％ Example 5 61.43％ Comparative Example 3 58.02％ Example 6 90.24％

[0260] according to Figure 4-16 It can be seen that the SSZ-13 molecular sieves prepared in Examples 1-10 and Comparative Example 3 are pure phases without the presence of impurity crystals. The product of Comparative Example 1 is a mixed crystal of mordenite and PHI molecular sieve, and the product of Comparative Example 2 is an amorphous phase, failing to synthesize SSZ-13 molecular sieve. As shown in Table 1, the relative crystallinity of the SSZ-13 molecular sieves prepared in Examples 1-10 of the present invention is not less than 60.02%, which is significantly higher than that of Comparative Example 3.

[0261] Compared with Comparative Examples 1-3, Examples 1-10 all obtained pure phase SSZ-13 molecular sieves, which shows that whether SSZ-13 seed crystals are added and whether water vapor is used to assist crystallization of the dry gel determines the crystal phase structure of the product, while whether activated silica-alumina minerals are used affects the crystallinity of the obtained SSZ-13 molecular sieve. Adding a small amount of SSZ-13 seed crystals and using water vapor to assist crystallization of the dry gel can obtain pure phase SSZ-13 molecular sieves. Using activated silica-alumina minerals as one of the raw materials can obtain pure phase SSZ-13 molecular sieves with high crystallinity.

[0262] Compared to Examples 4-6, the SSZ-13 molecular sieve obtained in Example 1 exhibited higher crystallinity, indicating that the crystallization rate of the dry gel was lower at lower crystallization temperatures. Higher crystallization temperatures, however, accelerated the dissolution of the silica and alumina sources in the dry gel. Furthermore, the limited availability of structure-directing substances in the dry gel led to the assembly of some silica and alumina sources, resulting in an impurity phase, which affected the crystallinity of the SSZ-13 molecular sieve. Controlling the crystallization time of the dry gel in the presence of water vapor to 24-48 hours and the temperature to 165°C was beneficial for obtaining SSZ-13 molecular sieves with higher crystallinity.

[0263] Compared with Example 7, the SSZ-13 molecular sieve obtained in Example 1 has a higher crystallinity. This shows that when preparing the dry gel, the crystallinity of the SSZ-13 obtained when the mass ratio of the SSZ-13 seed crystal to the silicon source is 10:100 is higher than the crystallinity of the SSZ-13 molecular sieve obtained when the mass ratio of the SSZ-13 seed crystal to the silicon source is 5:100. That is, within the range of the mass ratio of the SSZ-13 seed crystal to the silicon source of (5-10):100, the more SSZ-13 seed crystals are added, the higher the crystallinity of the obtained SSZ-13 molecular sieve.

[0264] Compared with Examples 8-9, the SSZ-13 molecular sieve obtained in Example 1 has a higher degree of crystallinity, which indicates that when the dry glue is crystallized in the presence of water vapor, the mass ratio of water vapor to dry glue is controlled to (3.0-10.0):1, a SSZ-13 molecular sieve with higher crystallinity can be obtained.

[0265] Compared with Example 10, the SSZ-13 molecular sieve obtained in Example 1 has a higher crystallinity, which indicates that when preparing the dry glue, grinding can make the mixing degree between the activated silica-alumina mineral and SSZ-13 better, and the prepared SSZ-13 molecular sieve has a higher crystallinity.

[0266] Test Example 2

[0267] The solid yields of Examples 1-10 and Comparative Example 3 were obtained by calculating the ratio of the mass of the SSZ-13 molecular sieves obtained in Examples 1-10 and Comparative Example 3 after drying to the dry basis mass of the raw materials input when preparing the dry gel in Examples 1-10 and Comparative Example 3. The results are shown in Table 2.

[0268] Table 2 Solid yield of SSZ-13 molecular sieve prepared in Examples 1-10 and Comparative Example 3

[0269] sample Solid yield sample Solid yield Example 1 78.70％ Example 7 89.74％ Example 2 79.72％ Example 8 82.89％ Example 3 77.85％ Example 9 73.40％ Example 4 82.59％ Example 10 90.20％ Example 5 81.24％ Comparative Example 3 64.58％ Example 6 81.34％

[0270] According to the data in Table 2, the preparation method provided by the present invention can obtain a solid yield of SSZ-13 molecular sieve of not less than 73%.

[0271] It should be noted that in the present invention, the solid yield of SSZ-13 molecular sieve is related to the solubility of the raw materials during steam-assisted crystallization of the dry gel: in a specific embodiment, when the solubility of the components in the dry gel in steam is high, each component will have a certain mass loss as the steam condenses, resulting in a lower solid yield.

[0272] Test Example 3

[0273] The micromorphology of SSZ-13 molecular sieve was characterized by SEM images.

[0274] Figure 17a 、 Figure 17b 、 Figure 18a 、 Figure 18b 、 Figure 19a 、 Figure 19b The following are SEM photos of the SSZ-13 molecular sieves prepared in Examples 1-3 at a magnification of 10,000 times and 20,000 times, respectively; SEM photos of the SSZ-13 molecular sieves prepared in Example 2 at a magnification of 10,000 times and 20,000 times, respectively; and SEM photos of the SSZ-13 molecular sieves prepared in Example 3 at a magnification of 10,000 times and 20,000 times. The products prepared in Examples 1-3 of the present invention are all nanoscale SSZ-13 molecular sieves with a cubic morphology. The average particle size of the SSZ-13 molecular sieve obtained in Example 1 is 717 nm, the average particle size of the SSZ-13 molecular sieve obtained in Example 2 is 596 nm, and the average particle size of the SSZ-13 molecular sieve obtained in Example 3 is 460 nm.

[0275] Test Example 4

[0276] The nitrogen adsorption and desorption isotherms were measured by a high-performance fully automatic gas adsorption instrument, thereby obtaining the specific surface area, micropore volume and mesopore volume of the SSZ-13 molecular sieves prepared in Examples 1 and 2 of the present invention.

[0277] Figure 20a 、 Figure 20b The nitrogen adsorption and desorption isotherms of the SSZ-13 molecular sieves prepared in Example 1 and Example 2 of the present invention are shown in Figure 1. According to calculations, the specific surface area of ​​the SSZ-13 molecular sieve obtained in Example 1 of the present invention reaches 478 m 2 / g, and the micropore volume is 0.071cm 3 / g, and the mesopore volume is 0.189 cm 3 / g; the specific surface area obtained in Example 2 reaches 605m 2 / g, micropore volume is 0.076cm 3 / g, and the mesopore volume is 0.184 cm 3 / g. It can be seen that the SSZ-13 molecular sieve obtained by the preparation method provided by the present invention has a relatively excellent pore structure, which is beneficial to the separation of CO2 / CH4.

[0278] Test Example 5

[0279] The separation effect of SSZ-13 molecular sieve synthesized in Example 1 on CO2 / CH4 gas is characterized by the breakthrough curve. Figure 21Specifically, 1.0 g of the SSZ-13 molecular sieve synthesized in Example 1 was loaded into a penetration column with an inner diameter of 4.0 mm and a sample length of 93 mm. The column was then degassed at 300°C for 3 hours using He as the purge gas at a flow rate of 5 mL / s. After degassing, the temperature was lowered to 25°C. Once the temperature stabilized, a CO2 / CH4 mixture (50% / 50% by volume) was introduced at a flow rate of 5 mL / s. The gas concentration at the penetration column outlet was recorded by mass spectrometry.

[0280] according to Figure 21 It can be seen that when the SSZ-13 molecular sieve prepared in Example 1 of the present invention is used for CO2 / CH4 gas separation, the CH4 breakthrough time is extremely short and the CO2 breakthrough time is as long as 1600s, which shows that the synthesized SSZ-13 molecular sieve can achieve efficient separation of CO2 and CH4 gases.

[0281] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. A method for preparing SSZ-13 molecular sieve, characterized in that: The following steps are involved: Mixing activated silica-alumina mineral, SSZ-13 seed crystals, a silicon source, a template agent, and a second alkali source to obtain a dry glue; The dry gel is crystallized in the presence of water vapor to obtain the SSZ-13 molecular sieve.

2. The method for preparing SSZ-13 molecular sieve according to claim 1, wherein The preparation process of the activated silica-alumina mineral comprises: using a first alkali source to activate the silica-alumina mineral to obtain the activated silica-alumina mineral; Preferably, the mass ratio of the first alkali source to the silica-alumina mineral is (1.2-1.4):1; Preferably, the first alkali source comprises sodium hydroxide and / or potassium hydroxide; Preferably, in the first alkali source, the molar ratio of sodium hydroxide to the first alkali source is (0.66-1):

1.

3. The method for preparing the SSZ-13 molecular sieve according to claim 1 or 2, wherein: The template includes N,N,N-trimethyl-1-adamantyl ammonium hydroxide; Preferably, the molar ratio of the N,N,N-trimethyl-1-adamantyl ammonium hydroxide to the silicon source is (0.035-0.1):

1.

4. The method for preparing the SSZ-13 molecular sieve according to any one of claims 1 to 3, wherein: The mass ratio of the SSZ-13 seed crystal to the silicon source is (5.0-10.0):

100.

5. The method for preparing the SSZ-13 molecular sieve according to any one of claims 1 to 4, wherein: The second alkaline source includes sodium hydroxide and / or potassium hydroxide; Preferably, in the second alkali source, the molar ratio of sodium hydroxide to the second alkali source is (0.5-1):

1.

6. The method for preparing the SSZ-13 molecular sieve according to any one of claims 1 to 5, characterized in that: The process of mixing the activated silica-alumina mineral, SSZ-13 seed crystals, a silicon source, a template and a second alkali source comprises: Mechanically mixing the activated silica-alumina mineral with SSZ-13 seed crystals to obtain a first mixture; Mechanically mixing the first mixture, the silicon source, and the template to obtain a second mixture; Mechanically mixing the second mixture with the second alkali source to obtain the dry glue; Preferably, in the dry glue, the molar ratio of the alkali source, the silicon source, the aluminum source and the template is (3.5-12.0): (20-120): 1: (1-6).

7. The method for preparing SSZ-13 molecular sieve according to any one of claims 1 to 6, characterized in that: The mechanical mixing includes grinding and / or ball milling; and / or, the particle size of the activated silica-alumina mineral is less than 200 mesh; And / or, the particle size of the second mixture is less than 200 mesh.

8. The method for preparing SSZ-13 molecular sieve according to any one of claims 1 to 7, characterized in that: The crystallization treatment is performed using a reactor comprising a reaction section and a kettle bottom section; the process of subjecting the dry gel to crystallization in the presence of water vapor comprises: placing the dry gel in the reaction section, adding water to the kettle bottom section, and causing the water to generate water vapor, and the water vapor enters the reaction section, so that the dry gel in the reaction section undergoes the crystallization treatment in the presence of the water vapor, thereby obtaining the SSZ-13 molecular sieve; Preferably, the mass ratio of water to dry glue is (3.0-10.0):1; Preferably, the crystallization temperature during the crystallization treatment is 155-185° C., and the crystallization time is 24-48 hours.

9. An SSZ-13 molecular sieve, characterized in that Prepared by the preparation method of SSZ-13 molecular sieve according to any one of claims 1 to 8; Preferably, the relative crystallinity of the SSZ-13 molecular sieve is greater than or equal to 60%; Preferably, the SSZ-13 molecular sieve comprises micropores and mesopores; Preferably, the pore size of the SSZ-13 molecular sieve is less than or equal to 0.076 cm 3 / g; and / or, the mesopore diameter of the SSZ-13 molecular sieve is less than or equal to 0.189 cm 3 / g; Preferably, the specific surface area of ​​the SSZ-13 molecular sieve is less than or equal to 605m 2 / g.

10. A method for separating CO2 and CH4, characterized in that: The following steps are involved: A separation agent is used to separate CO2 and CH4 from a mixed gas containing CO2 and CH4, wherein the separation agent comprises the SSZ-13 molecular sieve prepared by the SSZ-13 molecular sieve preparation method according to any one of claims 1 to 8 or the SSZ-13 molecular sieve according to claim 9.

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