A method for preparing silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane

Abstract

The present invention provides a method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane. The present invention provides a method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane as follows: a template, a silicon source, and water are mixed in proportion, and the mixture is dried after being mixed evenly to obtain a mixture; a template, an aluminum source, an ammonium salt, a silver salt, ammonia water, and water are mixed evenly in order and proportion to obtain a mixed solution. The above mixture and the mixed solution are stirred evenly. Under steam-assisted conditions, the secondary mixture is subjected to aging and crystallization treatments in sequence to obtain a crystalline product. The silver-loaded SSZ-13 molecular sieve nanocrystal is uniformly dispersed in a polymer matrix solution as a filler, and a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane is obtained by ultrasonic stirring. The silver-loaded SSZ-13 molecular sieve nanocrystal prepared by the one-step method of the present invention is a single crystal structure, has high dispersibility and low agglomeration, can significantly increase the number of active centers, and avoids the problems of pore blockage and structural collapse that may be caused in the conventional synthesis treatment stage, which enables them to more fully exert the pore characteristics. They have shown significant advantages in terms of specific surface area, particle size, number of pore openings, and adsorption performance. The mixed matrix membrane prepared by using them as fillers can effectively reduce the defects and particle agglomeration of the inorganic / organic interface, thereby significantly improving the overall performance.

Description

Technical Field

[0001] The invention relates to the field of preparation of SSZ-13 molecular sieve membranes, and in particular to a method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane. Background Art

[0002] Traditional separation technologies generally include absorption, adsorption, low-temperature distillation, etc. However, these methods have shortcomings such as cumbersome operation, high cost, large volume, and high energy consumption. In contrast, membrane separation technology is regarded as an effective means to solve global problems such as environment and energy. Membrane separation technology has significant advantages such as high selectivity, easy modular design, simple operation, low energy consumption, and low cost. It is widely used in energy, electricity, petroleum, chemical and other industries, especially in the field of CO2 separation. Compared with traditional CO2 separation technology, membrane separation technology has unique advantages.

[0003] Mixed matrix membranes (MMMs) are a general term for membranes prepared by uniformly distributing filler particles in a polymer matrix. It combines the advantages of polymers in processability, mechanical properties and low cost, as well as the advantages of fillers in gas permeability and selectivity, and is expected to break through the trade-off effect between the permeability and selectivity of polymer membranes. At the same time, the preparation of mixed matrix membranes can utilize the existing mature processes for preparing polymer membranes, avoiding the difficulties faced in the preparation of crystalline material membranes, such as high difficulty, high cost, and difficulty in scale-up. Mixed matrix membranes have attracted the attention and research of many researchers in the field of membrane separation.

[0004] The addition of inorganic fillers, especially porous fillers, effectively increases the free volume fraction of the polymer, reduces the entanglement between polymer molecular segments, and reduces the mass transfer resistance of gas molecules in the membrane, thereby greatly improving the gas permeability of the mixed matrix membrane. However, due to the presence of the interfacial phase, the gas will choose the one with smaller diffusion resistance between the filler pores and the interfacial phase channel for penetration, so the state of the interfacial phase directly affects the working efficiency of the filler. When the interfacial phase is small, the gas will diffuse in the continuous filler pores, but due to the limited pore openings of the porous material, the gas transmission path may be extended. When the interfacial phase is relatively obvious, the interface defects may be connected to a pinhole-like structure due to the aggregation of the filler, giving the gas the opportunity to penetrate directly through the connected interface, resulting in the complete loss of selectivity of the mixed matrix membrane.

[0005] In order to improve the gas separation performance of mixed matrix membranes, the filler should provide a low-resistance pore structure with high gas permeability and sieving properties within the matrix, and can interact strongly with the polymer matrix to reduce the size of the interfacial phase.

[0006] However, inorganic / organic interface defects and agglomeration of inorganic particles will affect the gas diffusion path, resulting in reduced membrane separation performance. To meet this demand, we can use a novel preparation technology to prepare inorganic materials with high dispersibility and low agglomeration. This material has a larger external specific surface area, smaller particle size, and more pore openings, which can better play the pore characteristics, thereby improving membrane separation performance.

[0007] Molecular sieves have the above excellent characteristics. SSZ-13 is based on SiO4 and A104 tetrahedrons, which are connected by oxygen atoms and orderly arranged into a crystal structure with eight-membered ring channels and three-dimensional cross channels. SSZ-13 molecular sieve has uniform channels with a channel size of Specific surface area can reach 700m 2 / g, which is a small-pore molecular sieve. And SSZ-13 has a high CO2 adsorption capacity. These characteristics make SSZ-13 a promising candidate material for filling polymer matrices. However, the products obtained by current preparation technology are mostly porous materials with a particle size of more than 1μm, which limits the effective use of its pore characteristics, especially in the application of catalysis and adsorption. In order to improve the adsorption and catalytic performance, molecular sieves with the following characteristics are more ideal: (1) having a larger external specific surface area to increase the number of active centers; (2) reducing the particle size is conducive to the diffusion of reactants and products, thereby improving the catalyst efficiency and making ion exchange easier to occur; (3) having more pore openings to reduce the possibility of reactants blocking the pores, prolonging the catalyst operation cycle, and allowing ion exchange to be more fully carried out in the pores.

[0008] Although there is a technology for synthesizing SSZ-13 molecular sieve nanocrystals at present, its synthesis method has technical defects such as complex process, low synthesis efficiency, nano molecular sieve is not easy to separate and collect from mother liquor, requires a large amount of structure directing agent and mineralizer, high synthesis cost, and discharges a large amount of waste liquid to pollute the environment to varying degrees. And SSZ-13 is not easy to synthesize products with high crystallinity. In order to further improve its adsorption and catalytic performance, it is very easy to cause pore blockage and even structural collapse. This greatly limits the industrial production and application of SSZ-13 molecular sieve nanocrystals. Therefore, it is of great significance and value to develop a synthetic route of SSZ-13 molecular sieve nanocrystals with high crystallinity and metal load, and use it to synthesize mixed matrix membrane to solve the inorganic / organic interface defects and the agglomeration problem of inorganic particles. Summary of the invention

[0009] The present invention aims to solve several key problems in the prior art: first, the prior art has defects in the inorganic / organic interface and the phenomenon of inorganic particle agglomeration, which reduce the separation performance of the membrane by affecting the gas diffusion path. Secondly, SSZ-13 molecular sieve nanocrystals have deficiencies in crystallinity, complexity of the synthesis process, and synthesis efficiency, and are prone to pore blockage and even structural collapse when metal elements are introduced. In response to these problems, we propose a new preparation method for preparing silver-loaded SSZ-13 molecular sieve nanocrystals. By this method, SSZ-13 nanocrystals with high crystallinity and stable structure can be prepared. By introducing silver-ammine complexes during the synthesis process, silver-loaded SSZ-13 molecular sieve nanocrystals can be synthesized in one step, significantly increasing the number of active centers, and avoiding the problems of pore blockage and structural collapse that may be caused in the conventional synthesis treatment stage. In addition, the prepared nanocrystals are single crystal structures with high dispersibility and low agglomeration, which enables them to more effectively exert pore characteristics. And they show significant advantages in terms of specific surface area, particle size, number of pore openings, and adsorption performance. The mixed matrix membrane prepared using it as a filler can effectively reduce the problems of inorganic / organic interface defects and particle agglomeration, thereby improving the overall performance.

[0010] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane, comprising the following steps:

[0011] Step 1, fully mix the template: silicon source: water in a molar ratio of 1:0.5-5:30-50, mix evenly, and then dry at 40-60° C. to obtain a mixture;

[0012] Step 2, preparing a mixed solution by mixing the template: aluminum source: ammonium salt: silver salt: ammonia water: water in a molar ratio of 1: 0.02-0.3: 0.05-3.2: 0.02-4: 0-5.2: 30-50;

[0013] Step 3, adding the mixture in step 1 to the mixed solution in step 2 and stirring evenly, the experimental ratio after mixing is template: silicon source: aluminum source: ammonium salt: silver salt: ammonia water: water = 1: 0.2 ~ 3.8: 0.01 ~ 0.05: 0.03 ~ 2.3: 0.01 ~ 3.2: 0 ~ 4.5: 8 ~ 35.

[0014] Step 4, placing the mixture in step 3 into an open glass container, placing the glass container into a reaction kettle, and sequentially performing aging and crystallization treatments on the sample under steam-assisted conditions to obtain a crystalline product;

[0015] Step 5: The crystalline product is washed and dried in sequence, and then calcined in an air atmosphere to obtain Ag-loaded SSZ-13 molecular sieve nanocrystals, wherein the calcination process is performed in a stepwise manner.

[0016] Step 6: Disperse the silver-loaded SSZ-13 molecular sieve nanocrystals as fillers uniformly into the polymer matrix solution, and disperse by ultrasonic and magnetic stirring to obtain a casting solution containing fillers.

[0017] Step 7, subject the casting solution obtained in step 6 to ultrasonic degassing for 30 to 240 minutes, and let it stand for 5 to 15 minutes, then pour it onto a clean polytetrafluoroethylene plate, place it in a constant temperature oven at 40 to 80°C and dry it for 12 to 24 hours, then place it in a vacuum oven and continue to remove the solvent for 12 to 24 hours to obtain an SSZ-13 molecular sieve nanocrystal mixed matrix membrane loaded with Ag.

[0018] Further, the silicon source is one or more of white carbon black, porous silicon and silica sol;

[0019] Furthermore, the template agent in step 1 is N,N,N-trimethyl-adamantane ammonium hydroxide.

[0020] Furthermore, the aluminum source in step 2 is one or more of aluminum isopropoxide, aluminum oxide, aluminum hydroxide and aluminum chloride;

[0021] Furthermore, the ammonium salt in step 2 is one or more of ammonium chloride, ammonium nitrate, and ammonium bicarbonate.

[0022] Furthermore, the silver salt in step 2 is one or more of silver nitrate, silver chloride, silver iodide, silver fluoride, and silver bromide.

[0023] Furthermore, the drying process in step 1 should ensure that the final mass of the mixture does not exceed the initial total mass of the template and the silicon source. Specifically, the weight of the mixture after drying should be at least 90% of the initial total mass of the template and the silicon source, but not more than the total mass. Ensure that the weight loss of the template during the drying process is controlled within a reasonable range.

[0024] Furthermore, the order of adding the raw materials in step 2 is: first, add the aluminum source to the template, wait for it to be completely dissolved into a clear solution, and then add the ammonium salt in sequence. After the ammonium salt is completely dissolved, add the silver ammonia complex generated by the reaction of the silver salt and ammonia water, which helps the silver ions to be evenly synthesized into the framework structure of the nanocrystal, avoids the aggregation of metal particles, and prevents them from clogging the pores.

[0025] Furthermore, step 4, under steam-assisted conditions, sequentially aging and crystallizing the mixture specifically comprises the following steps: transferring the mixture into an open glass container, and then transferring the glass container into a hydrothermal reactor lining, adding deionized water into the reactor lining, wherein the volume of the deionized water accounts for 1 / 6 to 1 / 5 of the volume of the reactor lining, and preventing water outside the glass container from entering the glass container; aging the mixture at a temperature of 60 to 100° C. under steam-assisted conditions, and the aging time is 0 to 12 days; the crystallization treatment temperature is 20 to 120° C., and the crystallization time is 0 to 8 days.

[0026] Furthermore, the calcination in step 5 is carried out in an air atmosphere, and the calcination temperature is increased stepwise, first calcining at 120-150°C for 3-6 hours, then calcining at 220-260°C for 3-6 hours, and finally calcining at 500-580°C for 3-12 hours.

[0027] Furthermore, the preparation method of the polymer matrix solution in step 6 is to mix anhydrous ethanol and deionized water evenly, heat them to 60-120° C. under stirring in an oil bath, and then add the polymer matrix thereto and stir at 60-120° C. for 4-5 hours to completely dissolve it, thereby obtaining a polymer matrix solution;

[0028] The volume ratio of ethanol to water is 5-12:1-6;

[0029] The solid-liquid mass ratio of the polymer matrix solution is 1-10:90-150.

[0030] Furthermore, the polymer matrix in step 7 is one or more of polyamide copolyether (PEBA) and polyimide (PI).

[0031] Furthermore, the mass fraction of the silver-loaded SSZ-13 molecular sieve nanocrystals in the casting solution in step 6 is 1 to 40 wt%.

[0032] The invention discloses a method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane. By this method, SSZ-13 nanocrystals with high crystallinity and stable structure can be prepared. By introducing silver-ammine complexes in the synthesis process, the silver-loaded SSZ-13 molecular sieve nanocrystals can be synthesized in one step, the number of active centers is significantly increased, and the problems of pore blockage and structural collapse that may be caused in the conventional synthesis treatment stage are avoided. In addition, the prepared nanocrystals are single crystal structures, have high dispersibility and low agglomeration, which enables them to more effectively exert pore characteristics. And they all show significant advantages in terms of specific surface area, particle size, number of pore openings and adsorption performance. The mixed matrix membrane prepared by using it as a filler can effectively reduce the problems of inorganic / organic interface defects and particle agglomeration, thereby improving overall performance.

[0033] The silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane prepared by the present invention can be applied to multiple fields such as petroleum, chemical industry, environmental protection, etc., and has broad market prospects. For example, the silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane prepared by the present invention is applied to the separation and purification of CO2, wherein the CO2 permeation evaluation of the silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane can greatly improve the selectivity of CO2 / N2. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the XRD pattern of the silver-loaded SSZ-13 molecular sieve nanocrystals prepared in Example 1 of the present invention.

[0035] Figure 2 This is a SEM image of the silver-loaded SSZ-13 molecular sieve nanocrystals prepared in Example 1 of the present invention.

[0036] Figure 3 This is the SEM image of SSZ-13 prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] The present invention provides a method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane, comprising the following steps:

[0039] Step 1) the template: silicon source: water are fully mixed in a molar ratio of 1:0.5 to 5:30 to 50, and after being mixed evenly, dried at 40-60° C. to obtain a mixture, wherein the drying process should ensure that the final mass of the mixture does not exceed the initial total mass of the template and the silicon source, and is greater than 90% of the initial total mass of the template and the silicon source;

[0040] Step 2) The template: aluminum source: ammonium salt: silver salt: ammonia water: water are prepared in a molar ratio of 1: 0.02-0.3: 0.05-3.2: 0.02-4: 0-5.2: 30-50 to obtain a mixed solution. The order of adding the above raw materials is as follows: first, the aluminum source is added to the template, and after it is completely dissolved into a clear solution, the ammonium salt is added in sequence. After the ammonium salt is completely dissolved, the silver-ammine complex generated by the reaction of the silver salt and ammonia water is added;

[0041] Step 3) adding the mixture in step 1 to the mixed solution in step 2 and stirring evenly, the experimental ratio after mixing is template agent: silicon source: aluminum source: ammonium salt: silver salt: ammonia water: water = 1: 0.2-3.8: 0.01-0.05: 0.03-2.3: 0.01-3.2: 0-4.5: 8-35;

[0042] Step 4) transferring the mixture in step 3 into an open glass container, and then transferring the glass container into a hydrothermal reactor liner, adding deionized water into the reactor liner, wherein the volume of the deionized water accounts for 1 / 6 to 1 / 5 of the volume of the reactor liner, and preventing water outside the glass container from entering the glass container; aging the mixture at a temperature of 60 to 100° C. under steam-assisted conditions, wherein the aging time is 0 to 12 days; the crystallization temperature is 20 to 120° C., and the crystallization time is 0 to 8 days;

[0043] Step 5) washing and drying the crystal product in sequence, and calcining in air atmosphere to obtain silver-loaded SSZ-13 molecular sieve nanocrystals, wherein the calcination process is stepwise heating, first calcining at 120-150° C. for 3-6 hours, then calcining at 220-260° C. for 3-6 hours, and finally calcining at 500-580° C. for 3-12 hours;

[0044] Step 6) anhydrous ethanol and deionized water are mixed uniformly, heated to 60-120° C. under stirring in an oil bath, and then a polymer matrix is ​​added thereto, maintained at 60-120° C. and stirred for 4-5 hours to completely dissolve the polymer matrix solution, wherein the volume ratio of ethanol to water is 5-12:1-6, and the solid-liquid mass ratio of the polymer matrix solution is 1-10:90-150, and silver-loaded SSZ-13 molecular sieve nanocrystals are uniformly dispersed in the polymer matrix solution as a filler, and dispersed by ultrasonic and magnetic stirring to obtain a casting solution containing the filler, wherein the mass fraction of silver-loaded SSZ-13 molecular sieve nanocrystals in the casting solution is 1-40wt%;

[0045] Step 7) The casting solution obtained in step 6 is subjected to ultrasonic degassing for 30 to 240 minutes and allowed to stand for 5 to 15 minutes, then poured onto a clean polytetrafluoroethylene plate, placed in a constant temperature oven at 40 to 80° C. and dried for 12 to 24 hours, and then placed in a vacuum oven to continue to remove the solvent for 12 to 24 hours to obtain a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane.

[0046] Further, the silicon source is one or more of white carbon black, porous silicon and silica sol;

[0047] Furthermore, the template agent in step 1 is N,N,N-trimethyl-adamantane ammonium hydroxide.

[0048] Furthermore, the aluminum source in step 2 is one or more of aluminum isopropoxide, aluminum oxide, aluminum hydroxide and aluminum chloride;

[0049] Furthermore, the ammonium salt in step 2 is one or more of ammonium chloride, ammonium nitrate, and ammonium bicarbonate.

[0050] Furthermore, the silver salt in step 2 is one or more of silver nitrate, silver chloride, silver iodide, silver fluoride, and silver bromide.

[0051] Furthermore, the polymer matrix in step 7 is one or more of polyamide copolyether (PEBA) and polyimide (PI).

[0052] The invention discloses a method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal, wherein the synthesis step is simple, the synthesis efficiency is high, and the SSZ-13 nanocrystal with high crystallinity and stable structure can be prepared. The silver-loaded SSZ-13 molecular sieve nanocrystal can be synthesized in one step by introducing a silver-ammine complex during the synthesis process, thereby significantly increasing the number of active centers and avoiding the problems of pore blockage and structural collapse that may be caused in the conventional synthesis treatment stage. In addition, the prepared nanocrystal is a single crystal structure with high dispersibility and low agglomeration, which enables them to more effectively exert pore characteristics. The nanocrystal also exhibits significant advantages in terms of specific surface area, particle size, number of pore openings, and adsorption performance. The mixed matrix membrane prepared by using the nanocrystal as a filler can effectively reduce the problems of inorganic / organic interface defects and particle agglomeration, thereby improving overall performance.

[0053] Example 1

[0054] Step 1, 4 g of 25% by mass N,N,N-trimethyl-adamantane ammonium hydroxide and 1.0 g of white carbon black are fully mixed to form a liquid gel after uniform mixing, and dried in a 40° C. forced air drying oven for 10 hours to obtain a mixture;

[0055] Step 2, dissolving 0.12 g of aluminum isopropoxide in 5.4 g of 25% N,N,N-trimethyl-adamantane ammonium hydroxide, adding 0.05 g of ammonium nitrate, and then adding 0.1 g of silver nitrate after dissolution, stirring evenly to obtain a mixed solution;

[0056] Step 3: Add the mixture in step 1 to the mixed solution in step 2 and stir evenly.

[0057] Step 4, placing the mixture in step 3 into an open glass container, placing the glass container into a 100 mL hydrothermal reactor, adding 5 mL of deionized water into the reactor and outside the glass container, aging the sample at 90° C. for 3 days and crystallizing at 160° C. for 3 days under steam-assisted conditions to obtain a crystalline product;

[0058] Step 5: The crystalline product is washed and dried in sequence, and then calcined in an air atmosphere to obtain silver-loaded SSZ-13 molecular sieve nanocrystals, wherein the calcination process is stepwise heated, calcined at 120°C for 3 hours, then calcined at 240°C for 3 hours, and then calcined at 550°C for 12 hours to obtain silver-loaded SSZ-13 molecular sieve nanocrystals.

[0059] Step 6: Weigh 18 mL of ethanol and 9 mL of distilled water, mix them, heat them to 80° C. under stirring, and then add 1.05 g of Pebax-1657 to it and keep stirring at 80° C. for 5 hours to completely dissolve it to obtain a polymer matrix solution. 0.05 g of silver-loaded SSZ-13 molecular sieve nanocrystals as fillers are uniformly dispersed into 6.53 g of the polymer matrix solution, and the speed is stirred at 1000 rpm / min for 30 minutes for dispersion, and ultrasonic stirring and dispersion are performed for 30 minutes to obtain a casting solution containing fillers.

[0060] Step 7: ultrasonically degas the casting solution obtained in step 6 for 30 minutes, and let it stand for 15 minutes, then pour it onto a clean polytetrafluoroethylene plate, put it in a constant temperature oven at 80°C and dry it for 24 hours, then put it in a vacuum oven and continue to remove the solvent for 24 hours to obtain a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane.

[0061] like Figure 1 The silver-loaded SSZ-13 molecular sieve nanocrystals are well crystallized, without an amorphous phase, and the peak positions are consistent with the standard CHA topology spectrum. Figure 1 There are no impurity peaks other than SSZ-13, no other zeolite impurities and silver peaks, which proves that silver ions directly participate in the synthesis of the internal framework of the molecular sieve, and the silver-ammine complex synthesis system has good dispersion and no agglomeration occurs. Figure 2 As shown, the particle size of the silver-loaded SSZ-13 molecular sieve nanocrystals is uniform, about 200 nm, and has good dispersion, proving that the nanocrystals have been successfully synthesized.

[0062] The separation performance of the mixed matrix membrane was tested to be PCO2=128.98 Barrer and CO2 / N2 selectivity 78.73.

[0063] Example 2

[0064] Step 1, 5g of 25% by mass N,N,N-trimethyl-adamantane ammonium hydroxide and 0.8g of white carbon black are fully mixed to form a liquid gel after uniform mixing, and dried in a 50° C. air drying oven for 8 hours to obtain a mixture;

[0065] Step 2: Dissolve 0.08 g of aluminum isopropoxide in 6 g of 25% N,N,N-trimethyl-adamantane ammonium hydroxide, add 0.05 g of ammonium chloride, and after dissolving, add 0.1 g of silver chloride and a silver-ammine complex prepared by 3 mL of ammonia water, and mix well;

[0066] Step 3: Add the mixture in step 1 to the mixed solution in step 2 and stir evenly.

[0067] Step 4, placing the mixture in step 3 into an open glass container, placing the glass container into a 100 mL hydrothermal reactor, adding 5 mL of deionized water into the reactor and outside the glass container, aging the sample at 90° C. for 3 days and crystallizing at 160° C. for 3 days under steam-assisted conditions to obtain a crystalline product;

[0068] Step 5: The crystalline product is washed and dried in sequence, and then calcined in an air atmosphere to obtain silver-loaded SSZ-13 molecular sieve nanocrystals, wherein the calcination process is stepwise heated, calcined at 120°C for 3 hours, then calcined at 240°C for 3 hours, and then calcined at 550°C for 12 hours to obtain silver-loaded SSZ-13 molecular sieve nanocrystals.

[0069] Step 6: Weigh 18 mL of ethanol and 9 mL of distilled water, mix them, heat them to 80°C under stirring, then add 2.1 g of Pebax-1657 and keep stirring at 80°C for 5 hours to completely dissolve them to obtain a polymer matrix solution. Disperse 0.1 g of molecular sieve nanocrystals as fillers evenly into 6.83 g of the polymer matrix solution at 1000 rpm / min, stir for 30 min, and stir and disperse under ultrasound for 30 min to obtain a casting solution containing fillers.

[0070] Step 7: ultrasonically degas the casting solution obtained in step 6 for 30 minutes, and let it stand for 15 minutes, then pour it onto a clean polytetrafluoroethylene plate, put it in a constant temperature oven at 80°C and dry it for 24 hours, then put it in a vacuum oven and continue to remove the solvent for 24 hours to obtain a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane.

[0071] The separation performance of the mixed matrix membrane was tested to be PCO2=180.98 Barrer and CO2 / N2 selectivity 89.65.

[0072] Example 3

[0073] Step 1, 10g of 25% by mass N,N,N-trimethyl-adamantane ammonium hydroxide and 1.2g of 4-white carbon black are fully mixed, and placed in a vacuum oven at 40°C for 8 hours to obtain a mixture;

[0074] Step 2, dissolve 0.05g aluminum oxide in 7.2g N,N,N-trimethyl-adamantane ammonium hydroxide with a mass fraction of 25%, add 0.10g ammonium nitrate, and then add 0.24g silver chloride and 3mL ammonia water to prepare a silver ammonia complex after dissolution, and mix well;

[0075] Step 3: Add the mixture in step 1 to the mixed solution in step 2 and stir evenly.

[0076] Step 4, placing the mixture in step 3 into an open glass container, placing the glass container into a 100 mL hydrothermal reactor, adding 5 mL of deionized water into the reactor and outside the glass container, aging the sample at 90° C. for 3 days and crystallizing at 160° C. for 2 days under steam-assisted conditions to obtain a crystalline product;

[0077] Step 5: The crystalline product is washed and dried in sequence, and then calcined in an air atmosphere to obtain silver-loaded SSZ-13 molecular sieve nanocrystals, wherein the calcination process is stepwise heated, calcined at 120°C for 3 hours, then calcined at 240°C for 3 hours, and then calcined at 550°C for 12 hours to obtain silver-loaded SSZ-13 molecular sieve nanocrystals.

[0078] Step 6: Weigh 18 mL of ethanol and 9 mL of distilled water, mix them, heat them to 80°C under stirring, then add 2.08 g of Pebax-1657 and keep stirring at 80°C for 5 hours to completely dissolve them to obtain a polymer matrix solution. Disperse 0.05 g of molecular sieve nanocrystals as fillers evenly into 6.83 g of the polymer matrix solution at 1000 rpm / min, stir for 30 min, and stir and disperse under ultrasound for 30 min to obtain a casting solution containing fillers.

[0079] Step 7: ultrasonically degas the casting solution obtained in step 6 for 30 minutes, and let it stand for 15 minutes, then pour it onto a clean polytetrafluoroethylene plate, put it in a constant temperature oven at 80°C and dry it for 24 hours, then put it in a vacuum oven and continue to remove the solvent for 24 hours to obtain a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane.

[0080] The separation performance of the mixed matrix membrane was tested to be PCO2=160.98 Barrer and CO2 / N2 selectivity 82.95.

[0081] Example 4

[0082] Step 1, 12g of 25% N,N,N-trimethyl-adamantane ammonium hydroxide and 3.75g of 40% silica sol are fully mixed, and the mixture is still in liquid state after being mixed evenly, and placed in a vacuum oven at 40°C for 8 hours to obtain a mixture;

[0083] Step 2: Dissolve 0.05 g of aluminum oxide in 6 g of 25% N,N,N-trimethyl-adamantane ammonium hydroxide, add 0.10 g of ammonium nitrate, and after it is dissolved, add 0.4 g of silver nitrate and mix well.

[0084] Step 3: Add the mixture in step 1 to the mixed solution in step 2 and stir evenly.

[0085] Step 4, placing the mixture in step 3 into an open glass container, placing the glass container into a 100 mL hydrothermal reactor, adding 5 mL of deionized water into the reactor and outside the glass container, aging the sample at 70° C. for 4 days and crystallizing at 160° C. for 5 days under steam-assisted conditions to obtain a crystalline product;

[0086] Step 5: The crystalline product is washed and dried in sequence, and then calcined in an air atmosphere to obtain silver-loaded SSZ-13 molecular sieve nanocrystals, wherein the calcination process is stepwise heated, calcined at 120°C for 3 hours, then calcined at 240°C for 3 hours, and then calcined at 550°C for 12 hours to obtain silver-loaded SSZ-13 molecular sieve nanocrystals.

[0087] Step 6: Weigh 18 mL of ethanol and 9 mL of distilled water, mix them, heat them to 80°C under stirring, then add 0.2 g of Pebax-1657 and keep stirring at 80°C for 5 hours to completely dissolve them to obtain a polymer matrix solution. Disperse 0.15 g of molecular sieve nanocrystals as fillers evenly into 6.68 g of the polymer matrix solution at 1000 rpm / min, stir for 30 min, and stir and disperse under ultrasound for 30 min to obtain a casting solution containing fillers.

[0088] Step 7: ultrasonically degas the casting solution obtained in step 6 for 30 minutes, and let it stand for 15 minutes, then pour it onto a clean polytetrafluoroethylene plate, put it in a constant temperature oven at 80°C and dry it for 24 hours, then put it in a vacuum oven and continue to remove the solvent for 24 hours to obtain a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane.

[0089] The separation performance of the mixed matrix membrane was tested to be PCO2=145.98 Barrer and CO2 / N2 selectivity 80.95.

[0090] Comparative Example 1

[0091] Step 1: Evenly stir 5.486 g of N,N,N-trimethyl-adamantane ammonium hydroxide, 0.01 g of sodium aluminate, and 0.06 g of ammonium chloride, then add 0.8 g of white carbon black, and stir evenly to obtain a mixture.

[0092] Step 2: transfer the above mixture into the lining of a hydrothermal reactor, add 5 ml of deionized water into the lining; age the mixture at 25° C. for 3 days; heat the hydrothermal reactor to 160° C., crystallize the mixture for 24 hours, and obtain a crystalline product.

[0093] Step 3: The crystalline product is centrifugally washed three times, dried at 50° C. for 8 hours, and calcined at 550° C. for 4 hours in a muffle furnace to obtain SSZ-13 molecular sieve.

[0094] Step 4: Weigh 18 mL of ethanol and 9 mL of distilled water, mix them, heat them to 80°C under stirring, then add 2.12 g of Pebax-1657 (polyamide copolymer) and keep stirring at 80°C for 8 hours to completely dissolve it to prepare a polymer matrix solution. Disperse 0.05 g of SSZ-13 molecular sieve as filler into 6.5 g of polymer matrix solution at 1000 rpm / min, stir for 60 min, and stir and disperse under ultrasonic for 30 min to obtain a casting solution containing filler.

[0095] Step 5: ultrasonically degas the casting solution obtained in step 4 for 60 minutes, let it stand for 10 minutes, then pour it onto a clean polytetrafluoroethylene plate, put it in an 80°C constant temperature oven to dry for 24 hours, and then put it in a vacuum oven to evacuate and continue to remove the solvent for 24 hours to obtain an SSZ-13 molecular sieve mixed matrix membrane.

[0096] The separation performance of the mixed matrix membrane was tested to be PCO2=90.98 Barrer and CO2 / N2 selectivity 55.73.

[0097] Figure 3 As shown, the SSZ-13 molecular sieve prepared by conventional methods (obtained after treatment in step 3) is a micron-sized crystal, which is large and irregular in size. The mixed matrix membrane prepared by the crystal is easy to agglomerate, and the prepared membrane material is uneven, resulting in many defects.

Claims

1. A method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane, characterized in that: The following steps are involved: Step 1, fully mix the template: silicon source: water in a molar ratio of 1:0.5-5:30-50, mix evenly, and then dry at 40-60° C. to obtain a mixture; Step 2, preparing a mixed solution by mixing template agent: aluminum source: ammonium salt: silver salt: ammonia water: water in a molar ratio of 1: 0.02-0.3: 0.05-3.2: 0.02-4: 0-5.2: 30-50; Step 3, adding the mixture in step 1 to the mixed solution in step 2 and stirring evenly, the experimental ratio after mixing is template agent: silicon source: aluminum source: ammonium salt: silver salt: ammonia water: water = 1: 0.2~3.8: 0.01~0.05: 0.03~2.3: 0.01~3.2: 0~4.5: 8~35; Step 4, placing the mixture in step 3 into an open glass container, placing the glass container into a reactor, and sequentially performing aging and crystallization treatments on the sample under steam-assisted conditions to obtain a crystalline product; Step 5, washing and drying the crystal product in sequence, and calcining in an air atmosphere to obtain silver-loaded SSZ-13 molecular sieve nanocrystals, wherein the calcination process is stepwise heated; Step 6, uniformly dispersing the silver-loaded SSZ-13 molecular sieve nanocrystals as fillers into the polymer matrix solution, and dispersing by ultrasonic and magnetic stirring to obtain a casting solution containing fillers; Step 7, subject the casting solution obtained in step 6 to ultrasonic degassing for 30 to 240 minutes, and let it stand for 5 to 15 minutes, then pour it onto a clean polytetrafluoroethylene plate, place it in a constant temperature oven at 40 to 80°C and dry it for 12 to 24 hours, then place it in a vacuum oven and continue to remove the solvent for 12 to 24 hours to obtain a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane.

2. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1, characterized in that: The silicon source in step 1 is one or more of white carbon black, porous silicon and silica sol; And / or, the template agent in step 1 is N,N,N-trimethyl-adamantane ammonium hydroxide; And / or, the aluminum source in step 2 is one or more of aluminum isopropoxide, aluminum oxide, aluminum hydroxide and aluminum chloride; And / or, the ammonium salt in step 2 is one or more of ammonium chloride, ammonium nitrate, and ammonium bicarbonate; And / or, the silver salt in step 2 is one or more of silver nitrate, silver chloride, silver iodide, silver fluoride, and silver bromide.

3. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1, characterized in that: The drying process in step 1 should ensure that the final mass of the mixture does not exceed the initial total mass of the template and the silicon source.

4. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1, characterized in that: The mass of the mixture after drying in step 1 should be at least 90% of the initial total mass of the template and the silicon source, but should not exceed the total mass, so as to ensure that the mass loss of the template during the drying process of the mixture is controlled within a reasonable range.

5. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1 or 2, characterized in that: The order of adding the raw materials in step 2 is: first add the aluminum source to the template, wait for it to completely dissolve into a clear solution, then add the ammonium salt in sequence, after the ammonium salt is completely dissolved, add the silver ammonia complex generated by the reaction of the silver salt and ammonia water, which helps to evenly synthesize the silver ions into the skeleton structure of the nanocrystal, avoid the aggregation of metal particles, and prevent them from clogging the pores.

6. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1, characterized in that: Step 4: Under steam-assisted conditions, the mixture is subjected to aging and crystallization treatments in sequence, which specifically includes the following steps: the mixture is transferred into an open glass container, and the glass container is then transferred into a hydrothermal reactor liner, deionized water is added into the reactor liner, and the volume of the deionized water accounts for 1 / 6 to 1 / 5 of the volume of the reactor liner, and water outside the glass container is prevented from entering the glass container; the mixture is subjected to aging treatment at a temperature of 60 to 100° C. and under steam-assisted conditions, the aging time is 0 to 12 days; the crystallization treatment temperature is 20 to 120° C., and the crystallization time is 0 to 8 days.

7. A method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1, characterized in that: The calcination in step 5 is carried out in an air atmosphere, and the calcination temperature is increased stepwise, first calcining at 120-150°C for 3-6 hours, then calcining at 220-260°C for 3-6 hours, and finally calcining at 500-580°C for 3-12 hours.

8. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1, characterized in that: The preparation method of the polymer matrix solution in step 6 is to mix anhydrous ethanol and deionized water evenly, and heat them to 60-120° C. under stirring in an oil bath. Then, a polymer matrix is ​​added thereto and stirred at 60 to 120° C. for 4 to 5 hours to completely dissolve the polymer matrix solution; The volume ratio of ethanol to water is 5-12:1-6; The solid-liquid mass ratio of the polymer matrix solution is 1-10:90-150.

9. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1 or 8, characterized in that: In step 6, the polymer matrix is ​​one or more of polyamide copolyether PEBA and polyimide PI.

10. The method for preparing a silver-loaded SSZ-13 molecular sieve nanocrystal mixed matrix membrane according to claim 1, characterized in that: The mass fraction of the silver-loaded SSZ-13 molecular sieve nanocrystals in the casting solution in step 6 is 1 to 40 wt%.

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