Cross-linked mixed matrix membrane and symbiotic mixed matrix membrane based on in-situ method as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of gas separation and purification, and discloses a cross-linked mixed matrix membrane based on an in-situ method, a symbiotic mixed matrix membrane based on an in-situ method, and a preparation method and application of the cross-linked mixed matrix membrane and the symbiotic mixed matrix membrane. The cross-linked mixed matrix membrane and the symbiotic mixed matrix membrane are prepared based on an in-situ method, so that the phenomenon of filler agglomeration is effectively avoided. The gas separation performance of the cross-linked mixed matrix membrane and the symbiotic mixed matrix membrane is obviously improved, and by taking recovery of high-purity R32 and R125 from a mixed refrigerant R410A as an example, the two mixed matrix membranes have excellent separation performance in the aspects of permeability and separability and can be widely applied to the field of gas separation.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation and purification, and in particular to a cross-linked mixed matrix membrane and a symbiotic mixed matrix membrane based on an in-situ method, and a preparation method and application thereof. Background Art

[0002] Gas separation membrane technology has developed rapidly in the past two decades. Its main advantages include low cost, easy operation, small footprint, low energy consumption, etc. It is an extremely environmentally friendly technology and more competitive than traditional gas separation methods. Among the many polymers used in the field of gas separation, PIM-1 is one of the intrinsic microporous polymers (PIMs) with rigid and twisted structural units in the main chain that have been developed in recent years. This polymer itself has a microporous structure, so PIM-1 membranes usually have ultra-high permeability and selectivity close to the upper limit. However, due to the "trade-off" restriction relationship between the permeability and selectivity of polymer membranes, it is difficult for PIM-1 membranes to have both high permeability and high selectivity at the same time.

[0003] Adding metal organic frameworks (MOFs) to the polymer matrix to obtain a mixed matrix membrane is an effective way to overcome this limiting relationship. MOFs can not only effectively create more gas transport channels, but also have a pore size screening effect, which can enhance the separation performance of the membrane. However, if the MOFs content exceeds a certain level, agglomeration may occur, resulting in poor interfacial compatibility between the polymer matrix and the filler, causing interfacial defects in the mixed matrix membrane and significantly reducing the selectivity. Therefore, forming a matrix-filler interface with good compatibility is the key, and it is of great significance to develop a mixed matrix membrane with excellent interfacial compatibility between the polymer matrix and the filler. Summary of the invention

[0004] In view of this, the present invention provides a cross-linked mixed matrix membrane and a symbiotic mixed matrix membrane based on an in-situ method, and a preparation method and application thereof, in order to solve the problem that the interface compatibility between the polymer matrix and the filler of the current mixed matrix membrane is poor, resulting in interface defects in the mixed matrix membrane and significantly reducing the selectivity.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for preparing a cross-linked mixed matrix membrane based on an in-situ method, comprising the following steps:

[0007] (1) mixing an N,N-dimethylformamide solution of ZIF-8-NH2, 2,3,5,6-tetrafluoroterephthalonitrile, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-helicobiandane and a catalyst, and reacting the mixture to obtain a crosslinked precipitate;

[0008] (2) subjecting the cross-linked precipitate to a first washing, a first filtering, a first centrifugation and a first drying in sequence to obtain a cross-linked solid powder; mixing the cross-linked solid powder with chloroform to obtain a cross-linked membrane liquid; injecting the cross-linked membrane liquid into a mold to obtain a cross-linked membrane; subjecting the cross-linked membrane to a first solvent immersion and a second drying in sequence to obtain a cross-linked mixed matrix membrane.

[0009] Preferably, in the N,N-dimethylformamide solution of ZIF-8-NH2, the dosage ratio of ZIF-8-NH2 and N,N-dimethylformamide is 0.2-0.4 g: 15-25 mL; the catalyst includes potassium carbonate; the dosage ratio of ZIF-8-NH2, 2,3,5,6-tetrafluoroterephthalonitrile, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane and catalyst is 0.2-0.4 g: 2-4 mmol: 2-4 mmol: 5-7 mmol; the reaction temperature is 60-80°C, and the reaction time is 10-14 h.

[0010] Preferably, the reagents used for the first washing include water and N,N-dimethylformamide; the first drying and the second drying are vacuum drying, the vacuum degrees of the first drying and the second drying are independently 0.09-0.095 MPa, the temperatures of the first drying and the second drying are independently 90-110°C, and the times of the first drying and the second drying are independently 20-24 h; the amount ratio of ZIF-8-NH2 and chloroform used in the preparation process of the cross-linked mixed matrix membrane is 0.2-0.4 g: 15-25 mL; the solvent used for the first solvent soaking includes methanol.

[0011] The present invention also provides a cross-linked mixed matrix membrane prepared by the preparation method of the cross-linked mixed matrix membrane based on the in-situ method.

[0012] The invention also provides application of the cross-linked mixed matrix membrane in gas separation and purification.

[0013] The present invention also provides a method for preparing a symbiotic mixed matrix membrane based on an in-situ method, comprising the following steps:

[0014] (1) mixing a chloroform solution of PIM-1, a zinc nitrate solution, 2-methylimidazole, 2-aminobenzimidazole and a solvent to obtain a mixed solution; adding the mixed solution to methanol to obtain a symbiotic precipitate;

[0015] (2) The symbiotic precipitate is sequentially subjected to a second washing, a second filtration, a second centrifugation and a third drying to obtain a symbiotic solid powder; the symbiotic solid powder is mixed with chloroform to obtain a symbiotic membrane liquid; the symbiotic membrane liquid is injected into a mold to obtain a symbiotic membrane; the symbiotic membrane is sequentially subjected to a second solvent immersion and a fourth drying to obtain a symbiotic mixed matrix membrane.

[0016] Preferably, in the chloroform solution of PIM-1, the dosage ratio of PIM-1 to chloroform is 0.2-0.3 g:15-25 mL; the zinc nitrate solution is an aqueous solution of zinc nitrate, and the dosage ratio of zinc nitrate to water in the aqueous solution of zinc nitrate is 0.2-0.3 mmol:2-4 mL; the solvent includes water; the dosage ratio of PIM-1, zinc nitrate, 2-methylimidazole, 2-aminobenzimidazole and solvent is 0.2-0.3 g:0.2-0.3 mmol:2-4 mmol:10-12 mmol:5-7 mL; the dosage ratio of PIM-1 to methanol is 0.2-0.3 g:50-65 mL.

[0017] Preferably, the reagents used for the second washing include water and N,N-dimethylformamide; the third drying and the fourth drying are vacuum drying, the vacuum degrees of the third drying and the fourth drying are independently 0.09-0.095 MPa, the temperatures of the third drying and the fourth drying are independently 90-110°C, and the times of the third drying and the fourth drying are independently 20-24 h; in the preparation process of the symbiotic mixed matrix membrane, the amount ratio of PIM-1 in step (1) and chloroform in step (2) is 0.2-0.3 g: 15-25 mL; the solvent used for the first solvent soaking includes methanol.

[0018] The present invention also provides a symbiotic mixed matrix membrane prepared by the preparation method of the symbiotic mixed matrix membrane based on the in-situ method.

[0019] The present invention also provides application of the symbiotic mixed matrix membrane in gas separation and purification.

[0020] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0021] The cross-linked mixed matrix membrane of the present invention is mixed with amino-functionalized ZIF-8-NH2 into the synthetic solution of PIM-1 during the synthesis process of the intrinsic microporous polymer (PIM-1) for in-situ cross-linking. The amino groups on the surface of ZIF-8-NH2 can react with 2,3,5,6-tetrafluoroterephthalonitrile (DCTB), the synthetic monomer of PIM-1, so that ZIF-8-NH2 is grafted onto the surface of PIM-1, forming good filler-matrix interface compatibility. The symbiotic mixed matrix membrane of the present invention is mixed with PIM-1 into the synthetic solution of ZIF-8-NH2 for in-situ symbiosis during the synthesis process of ZIF-8-NH2. The nitrile group of PIM-1 can interact with the non-coordinated imidazole group on the surface of ZIF-8-NH2, effectively avoiding the phenomenon of filler agglomeration. The cross-linked mixed matrix membrane prepared based on the in-situ method and the PIM-1 in the symbiotic mixed matrix membrane have excellent binding properties with ZIF-8-NH2, and the gas separation performance is significantly improved. Taking the recovery of high-purity R32 and R125 from the mixed refrigerant R410A as an example, the two mixed matrix membranes have excellent separation performance in terms of permeability and separation, and can be widely used in the field of gas separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 The infrared spectra of ZIF-8-NH2 described in Example 1 and ZIF-8 described in Comparative Example 1;

[0024] Figure 2 The X-ray diffraction spectra of ZIF-8-NH2 described in Example 1 and ZIF-8 described in Comparative Example 1;

[0025] Figure 3 This is a scanning electron microscope image of the cross-section of the PIM-1@ZIF-8-NH2-crosslinked structure described in Example 1;

[0026] Figure 4 This is a cross-sectional scanning electron microscope image of the PIM-1@ZIF-8-NH2-symbiosis described in Example 2;

[0027] Figure 5 This is a cross-sectional scanning electron microscope image of PIM-1@ZIF-8-NH2 described in Comparative Example 1. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing a cross-linked mixed matrix membrane based on an in-situ method, comprising the following steps:

[0029] (1) mixing an N,N-dimethylformamide solution of ZIF-8-NH2, 2,3,5,6-tetrafluoroterephthalonitrile, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-helicobiandane and a catalyst, and reacting the mixture to obtain a crosslinked precipitate;

[0030] (2) subjecting the cross-linked precipitate to a first washing, a first filtering, a first centrifugation and a first drying in sequence to obtain a cross-linked solid powder; mixing the cross-linked solid powder with chloroform to obtain a cross-linked membrane liquid; injecting the cross-linked membrane liquid into a mold to obtain a cross-linked membrane; subjecting the cross-linked membrane to a first solvent immersion and a second drying in sequence to obtain a cross-linked mixed matrix membrane.

[0031] In the present invention, in the N,N-dimethylformamide solution of ZIF-8-NH2, the dosage ratio of ZIF-8-NH2 and N,N-dimethylformamide is preferably 0.2-0.4 g: 15-25 mL, more preferably 0.25-0.35 g: 18-24 mL, and more preferably 3 g: 20-22 mL; the catalyst comprises potassium carbonate; the dosage ratio of ZIF-8-NH2, 2,3,5,6-tetrafluoroterephthalonitrile, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane and the catalyst ... 0.4g: 2-4mmol: 2-4mmol: 5-7mmol, more preferably 0.25-0.35g: 2.5-3.5mmol: 2.5-3.5mmol: 5.5-6.5mmol, more preferably 0.3-0.32g: 2.8-3mmol: 2.8-3mmol: 6-6.2mmol; the reaction temperature is preferably 60-80°C, more preferably 65-75°C, more preferably 70-72°C; the reaction time is preferably 10-14h, more preferably 11-13h, more preferably 12-12.5h.

[0032] In the present invention, the reagents used for the first washing include water and N,N-dimethylformamide; the first washing includes the following steps: washing the cross-linked precipitate with water first and then with N,N-dimethylformamide; the number of washing with water and washing with N,N-dimethylformamide is preferably 1 to 3 times, more preferably 2 times; the speed of the first centrifugation is preferably 3000 to 5000 r / min, more preferably 3500 to 4000 r / min; the time of the first centrifugation is preferably 10 to 30 min, more preferably 15 to 25 min; the first drying and the second drying are vacuum drying, and the vacuum degree of the first drying and the second drying is independently preferably 0.09 to 0.095 MPa, It is further preferred to be 0.091-0.094MPa, and more preferably to be 0.092-0.093; the temperatures of the first drying and the second drying are independently preferably 90-110°C, and further preferably 95-105°C, and more preferably 100°C; the times of the first drying and the second drying are independently preferably 20-24h, and further preferably 21-23h, and more preferably 22h; in the preparation process of the cross-linked mixed matrix membrane, the amount ratio of ZIF-8-NH2 and chloroform is preferably 0.2-0.4g:15-25mL, and further preferably 0.25-0.35g:18-22mL, and more preferably 0.3g:19-20mL; the solvent used for the first solvent soaking includes methanol.

[0033] In the present invention, the preparation of ZIF-8-NH2 comprises the following steps: mixing 2-methylimidazole, 2-aminobenzimidazole and water and stirring to obtain a ligand solution; mixing the ligand solution and zinc nitrate solution and stirring for a first reaction, and then centrifuging, washing and drying for a third time to obtain ZIF-8-NH2;

[0034] The usage ratio of the 2-methylimidazole, 2-aminobenzimidazole and water is preferably 0.1-0.15 mol: 0.01-0.015 mol: 120-150 mL, more preferably 0.11-0.14 mol: 0.011-0.014 mol: 130-140 mL, and more preferably 0.12-0.13 mol: 0.012-0.013 mol: 135 mL;

[0035] The ratio of zinc nitrate to water in the zinc nitrate solution is preferably 0.002-0.0025 mol: 20-40 mL, more preferably 0.0021-0.0024 mol: 25-35 mL, and more preferably 0.0022-0.0023 mol: 30 mL;

[0036] The stirring time is preferably 0.5 to 1 h; the temperature of the first stirring reaction is preferably 20 to 30 ° C, more preferably 22 to 28 ° C, more preferably 25 to 27 ° C; the time of the first stirring reaction is preferably 1 to 4 h, more preferably 2 to 3 h; the stirring speed of the stirring and the first stirring reaction is independently preferably 200 to 400 r / min, more preferably 300 to 350 r / min;

[0037] The rotation speed of the third centrifugation is preferably 3000-5000 r / min, and more preferably 3500-4000 r / min; the time of the third centrifugation is preferably 10-30 min, and more preferably 15-25 min; the reagent used for the third washing includes methanol; the number of the third washing is preferably 1-4 times, and more preferably 2-3 times; the temperature of the first drying is preferably 120-140°C, and more preferably 130-135°C; the time of the first drying is preferably 12-24h, and more preferably 14-20h.

[0038] The present invention also provides a cross-linked mixed matrix membrane prepared by the preparation method of the cross-linked mixed matrix membrane based on the in-situ method.

[0039] The invention also provides application of the cross-linked mixed matrix membrane in gas separation and purification.

[0040] The present invention also provides a method for preparing a symbiotic mixed matrix membrane based on an in-situ method, comprising the following steps:

[0041] (1) mixing a chloroform solution of PIM-1, a zinc nitrate solution, 2-methylimidazole, 2-aminobenzimidazole and a solvent to obtain a mixed solution; adding the mixed solution to methanol to obtain a symbiotic precipitate;

[0042] (2) The symbiotic precipitate is sequentially subjected to a second washing, a second filtration, a second centrifugation and a third drying to obtain a symbiotic solid powder; the symbiotic solid powder is mixed with chloroform to obtain a symbiotic membrane liquid; the symbiotic membrane liquid is injected into a mold to obtain a symbiotic membrane; the symbiotic membrane is sequentially subjected to a second solvent immersion and a fourth drying to obtain a symbiotic mixed matrix membrane.

[0043] In the present invention, in the chloroform solution of PIM-1, the dosage ratio of PIM-1 to chloroform is preferably 0.2-0.3 g: 15-25 mL, more preferably 0.22-0.28 g: 19-22 mL, and more preferably 0.25-0.26 g: 20-21 mL; the zinc nitrate solution is an aqueous solution of zinc nitrate, and the dosage ratio of zinc nitrate to water in the aqueous solution of zinc nitrate is preferably 0.2-0.3 mmol: 2-4 mL, more preferably 0.22-0.28 mmol: 2.5-3.5 mL, and more preferably 0.25-0.26 mmol: 3 mL; the solvent includes water; the dosage ratio of PIM-1, zinc nitrate, 2-methylimidazole, 2-aminobenzimidazole and solvent is preferably 0 .2~0.3g:0.2~0.3mmol:2~4mmol:10~12mmol:5~7mL, further preferably 0.25~0.29g:0.25~0.28mmol:2.5~3.5mmol:10.5~11.5mmol:5.5~6.5mL, more preferably 0.26~0.28g:0.26~0.27mmol:2.8~3mmol:11~11.2mmol:5.8~6mL; the dosage ratio of the PIM-1 and methanol is preferably 0.2~0.3g:50~65mL, further preferably 0.22~0.28g:55~60mL, more preferably 0.25~0.26g:58~29mL.

[0044] In the present invention, the reagents used for the second washing include water and N,N-dimethylformamide; the second washing includes the following steps: washing the co-produced precipitate with water first and then with N,N-dimethylformamide; the number of washing with water and washing with N,N-dimethylformamide is preferably 1 to 3 times, more preferably 2 times; the speed of the second centrifugation is preferably 3000 to 5000 r / min, more preferably 3500 to 4000 r / min; the time of the second centrifugation is preferably 10 to 30 min, more preferably 15 to 25 min; the third drying and the fourth drying are vacuum drying, and the vacuum degree of the third drying and the fourth drying is independently preferably 0.09 to 0.095 MPa, more preferably 0. 091~0.094MPa, more preferably 0.092~0.093; the temperature of the third drying and the fourth drying is independently preferably 90~110℃, more preferably 95~105℃, more preferably 100℃; the time of the third drying and the fourth drying is independently preferably 20~24h, more preferably 21~23h, more preferably 22h; in the preparation process of the symbiotic mixed matrix membrane, the amount ratio of PIM-1 in step (1) and chloroform in step (2) is preferably 0.2~0.3g:15~25mL, more preferably 0.22~0.28g:18~22mL, more preferably 0.25~0.27g:19~20mL; the solvent used for the second solvent soaking includes methanol.

[0045] In the present invention, the preparation of PIM-1 comprises the following steps:

[0046] 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, tetrafluoroterephthalonitrile, potassium carbonate and N,N-dimethylformamide are mixed and dissolved and stirred for a second time to obtain a yellow solution; the yellow solution is subjected to a precipitation reaction, filtration, a fourth washing and a second drying in sequence to obtain PIM-1;

[0047] The usage ratio of the 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, tetrafluoroterephthalonitrile, potassium carbonate and N,N-dimethylformamide is preferably 9-12 mmol: 9-12 mmol: 30-50 mmol: 120-160 mL, and more preferably 10-11 mmol: 10-11 mmol: 40-45 mmol: 130-150 mL;

[0048] The dissolution is carried out under a protective atmosphere, the protective atmosphere includes nitrogen; the dissolution temperature is preferably 20-30°C, more preferably 22-28°C, more preferably 25-27°C; the second stirring reaction temperature is preferably 70-90°C, more preferably 80-85°C; the second stirring reaction time is preferably 72-78h, more preferably 74-76h;

[0049] The reagents used for the precipitation reaction include an aqueous solution of methanol, and the mass fraction of the aqueous solution of methanol is preferably 30-70%, and more preferably 47-50%; the reagents used for the fourth washing include water and N,N-dimethylformamide; the fourth washing includes the following steps: washing the filtered solid product with water first and then with N,N-dimethylformamide; the number of washings with water and washings with N,N-dimethylformamide is independently preferably 1 to 3 times, and more preferably 2 times; the temperature of the second drying is preferably 80-90°C, and more preferably 85-88°C; the time of the second drying is preferably 24-26h, and more preferably 25h.

[0050] The present invention also provides a symbiotic mixed matrix membrane prepared by the preparation method of the symbiotic mixed matrix membrane based on the in-situ method.

[0051] The present invention also provides application of the symbiotic mixed matrix membrane in gas separation and purification.

[0052] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] The preparation of ZIF-8-NH2 used in Example 1 includes the following steps: 9.85 g (0.12 mol) of 2-methylimidazole and 1.62 g (0.012 mol) of 2-aminobenzimidazole are dissolved in 90 mL and 50 mL of deionized water respectively, and after being completely dissolved, they are mixed together and stirred for 0.5 h at a stirring speed of 300 r / min to obtain a ligand solution; 0.744 g (0.0025 mol) of zinc nitrate hexahydrate is dissolved in 20 mL of deionized water to obtain Zn 2+ solution; the ligand solution and Zn 2+ After the solution was mixed and stirred at room temperature for 2 h (stirring speed was 300 r / min), the product was collected by centrifugation (centrifugal speed was 4000 r / min, centrifugal time was 15 min), and washed with methanol three times. Then, it was activated in a vacuum oven at 120°C overnight to obtain ZIF-8-NH2.

[0054] The preparation of PIM-1 used in Example 2 includes the following steps: 3.4 g (10 mmol) of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI), 2 g (10 mmol) of tetrafluoroterephthalonitrile (TFTPN) and 4.5 g (40 mmol) of potassium carbonate are dissolved in 150 mL of N,N-dimethylformamide (DMF), and the four are stirred and dissolved at room temperature and nitrogen atmosphere (stirring speed is 300 r / min), and then transferred to an oil bath pot preheated to 80° C. and stirred for 72 h at a stirring speed of 300 r / min to obtain a yellow solution. After cooling to room temperature, the solution is poured into an aqueous solution of methanol with a mass fraction of 47% to precipitate, and the obtained yellow solid is filtered, washed with deionized water and N,N-dimethylformamide (DMF) three times respectively, and then placed in a vacuum drying oven at 85° C. for 24 h to obtain PIM-1.

[0055] The preparation of ZIF-8 used in Comparative Example 1 includes the following steps: adding 3.3 g (0.04 mol) of 2-methylimidazole to 70 mL of methanol; adding 1.5 g (0.005 mol) of zinc nitrate hexahydrate to 70 mL of methanol; mixing the two solutions, stirring at room temperature for 24 hours, the stirring speed is 300 r / min, and then centrifuging, the centrifugal speed is 4000 r / min, the centrifugal time is 15 minutes, and the obtained solid is washed 3 times with methanol, and then dried in a vacuum drying oven at 80°C for 12 hours to obtain ZIF-8.

[0056] Example 1

[0057] (1) 0.3 g ZIF-8-NH2 was dissolved in 20 mL N,N-dimethylformamide (DMF), and the solution was then ultrasonically dispersed at a frequency of 50 kHz for 2 h;

[0058] (2) adding 0.6 g (3 mmol) of 2,3,5,6-tetrafluoroterephthalonitrile (DCTB), 1.021 g (3 mmol) of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI) and 1.244 g (6 mmol) of anhydrous K2CO3 to the solution obtained in step (1) to obtain a mixed solution; stirring the mixed solution at 70° C. for 12 h at a stirring speed of 300 r / min; after the stirring reaction is completed, centrifuging the obtained mixed solution at a centrifugal speed of 4000 r / min for 15 min to obtain a cross-linked precipitate;

[0059] (3) The cross-linked precipitate was washed twice with deionized water and then twice with N,N-dimethylformamide (DMF), and then filtered, centrifuged and vacuum dried in sequence to obtain a cross-linked solid powder; the centrifugal speed was 4000 r / min, the centrifugal time was 15 min, the vacuum degree of vacuum drying was 0.09 MPa, the vacuum drying temperature was 100° C., and the vacuum drying time was 24 h;

[0060] (4) dissolving the cross-linked solid powder in 20 mL of chloroform, stirring at room temperature for 6 h at a speed of 300 r / min, to obtain a cross-linked membrane solution;

[0061] (5) injecting the cross-linked membrane solution into a glass culture dish at room temperature, and obtaining a cross-linked membrane after the solvent evaporates completely;

[0062] (6) The cross-linked membrane was immersed in methanol and then vacuum dried to obtain a cross-linked mixed matrix membrane, denoted as PIM-1@ZIF-8-NH2-cross-linked; the immersion time was 24 h; the vacuum degree of vacuum drying was 0.09 MPa, the vacuum drying temperature was 100 °C, and the vacuum drying time was 24 h.

[0063] Example 2

[0064] (1) Dissolve 0.25 g of PIM-1 in 20 mL of chloroform and stir at room temperature for 6 h at a stirring speed of 300 r / min;

[0065] (2) Dissolve 0.186 g (0.25 mmol) of zinc nitrate hexahydrate in 3 mL of deionized water, then pour into the solution obtained in step (1) and mix for 30 min;

[0066] (3) Dissolve 0.405 g (3 mmol) of 2-aminobenzimidazole and 0.984 g (12 mmol) of 2-methylimidazole in 6 mL of deionized water, then pour into the solution obtained in step (2), and stir for 6 h at a stirring speed of 300 r / min to obtain a mixed solution; pour the mixed solution into 60 mL of methanol, and obtain a symbiotic precipitate by centrifugation; the centrifugation speed is 4000 r / min, and the centrifugation time is 15 min;

[0067] (4) The symbiotic precipitate was washed twice with deionized water and then twice with N,N-dimethylformamide (DMF), and then filtered, centrifuged and vacuum dried in sequence to obtain a symbiotic solid powder; the centrifugal speed was 4000 r / min, the centrifugal time was 15 min; the vacuum degree of vacuum drying was 0.09 MPa, the vacuum drying temperature was 100 ° C, and the vacuum drying time was 24 h;

[0068] (5) dissolving the symbiotic solid powder in 20 mL of chloroform, stirring at room temperature for 6 h at a speed of 300 r / min, to obtain a symbiotic membrane solution;

[0069] (6) injecting the symbiotic membrane solution into a glass culture dish at room temperature, and obtaining the symbiotic membrane after the solvent evaporates completely;

[0070] (7) The symbiotic membrane was immersed in methanol and then vacuum dried to obtain a symbiotic mixed matrix membrane, which was recorded as PIM-1@ZIF-8-NH2-symbiotic; the immersion time was 24 h; the vacuum degree of vacuum drying was 0.09 MPa, the vacuum drying temperature was 100 °C, and the vacuum drying time was 24 h.

[0071] Comparative Example 1

[0072] (1) Dissolve 0.25 g of PIM-1 in 20 mL of chloroform and stir at room temperature for 6 h at a stirring speed of 300 r / min;

[0073] (2) 0.05 g ZIF-8 was dissolved in 10 mL chloroform, and the solution was then ultrasonically dispersed at a frequency of 50 kHz for 2 h;

[0074] (3) mixing the two solutions obtained in step (1) and step (2), and stirring them fully at room temperature; the stirring rate is 300 r / min, and the stirring time is 4 h; and then ultrasonically oscillating at a frequency of 50 kHz for 2 h to obtain a membrane liquid;

[0075] (4) injecting the membrane solution into a glass culture dish at room temperature, and obtaining a mixed membrane after the solvent evaporates completely;

[0076] (5) The mixed membrane was immersed in methanol and then vacuum dried to obtain a mixed matrix membrane, denoted as PIM-1@ZIF-8-NH2; the immersion time was 24 h; the vacuum degree of vacuum drying was 0.09 MPa, the vacuum drying temperature was 100°C, and the vacuum drying time was 24 h.

[0077] Figure 1 The infrared spectra of ZIF-8-NH2 described in Example 1 and ZIF-8 described in Comparative Example 1 are shown in FIG. Figure 1 It can be seen that the ZIF-8-NH2 described in Example 1 has a peak at 3460 cm -1 、3378cm -1 and 916cm -1 The characteristic peak of ZIF-8 different from that of Comparative Example 1 appeared at 3460 cm -1 、3378cm -1 The new characteristic peaks at 916 cm are the symmetric and asymmetric stretching vibration peaks of -NH2. -1 The new characteristic peaks are the bending and swing vibration peaks of NH. The appearance of these three new characteristic peaks indicates that -NH2 is successfully embedded into the ZIF-8 structure.

[0078] Figure 2The X-ray diffraction spectra of ZIF-8-NH2 described in Example 1 and ZIF-8 described in Comparative Example 1 are shown in FIG. Figure 2 It can be seen that the ZIF-8-NH2 described in Example 1 has a high degree of crystallinity and the positions of several diffraction peaks are consistent with the diffraction peaks of ZIF-8, that is, the addition of 2-aminobenzimidazole has no particularly obvious effect on the crystal structure of ZIF-8-NH2.

[0079] Figure 3 This is a scanning electron microscope image of the cross-section of the PIM-1@ZIF-8-NH2-crosslinked structure described in Example 1; Figure 4 This is a cross-sectional scanning electron microscope image of the PIM-1@ZIF-8-NH2-symbiosis described in Example 2; Figure 5 This is a cross-sectional scanning electron microscope image of PIM-1@ZIF-8-NH2 described in Comparative Example 1. Figures 3 to 5 It can be seen that the dispersibility of ZIF-8-NH2 filler in the polymer matrix in the mixed matrix membranes prepared by the in-situ method described in Examples 1 and 2 is enhanced, and the in-situ method effectively avoids the phenomenon of filler agglomeration, while the mixed matrix membrane of Comparative Example 1 has filler agglomeration phenomenon.

[0080] Under the conditions of feed pressure of 0.11 MPa and temperature of 25 °C, permeation tests of PIM-1@ZIF-8-NH2-cross-linked, PIM-1@ZIF-8-NH2-symbiotic and PIM-1@ZIF-8-NH2 were carried out to recover high-purity R32 and R125 gases from the mixed refrigerant R410A. The results are shown in Table 1.

[0081] Table 1 Permeation test results of the membranes obtained in Examples 1 to 2 and Comparative Example 1

[0082]

[0083] As can be seen from Table 1, the gas separation performance of the mixed matrix membranes PIM-1@ZIF-8-NH2-crosslinked and PIM-1@ZIF-8-NH2-symbiotic based on the in-situ method in Examples 1 and 2 is enhanced. Compared with Comparative Example 1, the gas ideal selectivity of the PIM-1@ZIF-8-NH2-crosslinked described in Example 1 is improved, and the gas permeability of the PIM-1@ZIF-8-NH2-symbiotic described in Example 2 is improved.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a cross-linked mixed matrix membrane based on an in-situ method, characterized in that: The steps include: (1) mixing an N,N-dimethylformamide solution of ZIF-8-NH2, 2,3,5,6-tetrafluoroterephthalonitrile, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-helicobiandane and a catalyst, and reacting the mixture to obtain a crosslinked precipitate; (2) sequentially performing a first washing, a first filtering, a first centrifugation and a first drying on the cross-linked precipitate to obtain a cross-linked solid powder; Mixing the cross-linked solid powder and chloroform to obtain a cross-linked membrane solution; injecting a cross-linked film liquid into a mold to obtain a cross-linked film; The cross-linked membrane is sequentially subjected to a first solvent immersion and a second drying to obtain a cross-linked mixed matrix membrane.

2. The method for preparing a cross-linked mixed matrix membrane based on an in-situ method according to claim 1, characterized in that: In the N,N-dimethylformamide solution of ZIF-8-NH2, the dosage ratio of ZIF-8-NH2 and N,N-dimethylformamide is 0.2-0.4 g: 15-25 mL; the catalyst includes potassium carbonate; the dosage ratio of ZIF-8-NH2, 2,3,5,6-tetrafluoroterephthalonitrile, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane and catalyst is 0.2-0.4 g: 2-4 mmol: 2-4 mmol: 5-7 mmol; the reaction temperature is 60-80° C., and the reaction time is 10-14 h.

3. The method for preparing a cross-linked mixed matrix membrane based on an in-situ method according to claim 1 or 2, characterized in that: The reagents used for the first washing include water and N,N-dimethylformamide; the first drying and the second drying are vacuum drying, the vacuum degrees of the first drying and the second drying are independently 0.09-0.095MPa, the temperatures of the first drying and the second drying are independently 90-110°C, and the times of the first drying and the second drying are independently 20-24h; in the preparation process of the cross-linked mixed matrix membrane, the amount ratio of ZIF-8-NH2 and chloroform is 0.2-0.4g:15-25mL; the solvent used for the first solvent soaking includes methanol.

4. A cross-linked mixed matrix membrane prepared by the method for preparing a cross-linked mixed matrix membrane based on an in-situ method according to any one of claims 1 to 3.

5. Use of the cross-linked mixed matrix membrane according to claim 4 in gas separation and purification.

6. A method for preparing a symbiotic mixed matrix membrane based on an in-situ method, characterized in that: The steps include: (1) mixing a chloroform solution of PIM-1, a zinc nitrate solution, 2-methylimidazole, 2-aminobenzimidazole and a solvent to obtain a mixed solution; adding the mixed solution to methanol to obtain a symbiotic precipitate; (2) The symbiotic precipitate is sequentially subjected to a second washing, a second filtration, a second centrifugation and a third drying to obtain a symbiotic solid powder; the symbiotic solid powder is mixed with chloroform to obtain a symbiotic membrane liquid; the symbiotic membrane liquid is injected into a mold to obtain a symbiotic membrane; the symbiotic membrane is sequentially subjected to a second solvent immersion and a fourth drying to obtain a symbiotic mixed matrix membrane.

7. The method for preparing a symbiotic mixed matrix membrane based on an in-situ method according to claim 6, characterized in that: In the chloroform solution of PIM-1, the dosage ratio of PIM-1 to chloroform is 0.2-0.3 g: 15-25 mL; the zinc nitrate solution is an aqueous solution of zinc nitrate, and the dosage ratio of zinc nitrate to water in the aqueous solution of zinc nitrate is 0.2-0.3 mmol: 2-4 mL; the solvent includes water; the dosage ratio of PIM-1, zinc nitrate, 2-methylimidazole, 2-aminobenzimidazole and solvent is 0.2-0.3 g: 0.2-0.3 mmol: 2-4 mmol: 10-12 mmol: 5-7 mL; the dosage ratio of PIM-1 to methanol is 0.2-0.3 g: 50-65 mL.

8. The method for preparing a symbiotic mixed matrix membrane based on an in-situ method according to claim 6 or 7, characterized in that: The reagents used for the second washing include water and N,N-dimethylformamide; the third drying and the fourth drying are vacuum drying, the vacuum degrees of the third drying and the fourth drying are independently 0.09-0.095MPa, the temperatures of the third drying and the fourth drying are independently 90-110°C, and the times of the third drying and the fourth drying are independently 20-24h; in the preparation process of the symbiotic mixed matrix membrane, the amount ratio of PIM-1 in step (1) and chloroform in step (2) is 0.2-0.3g:15-25mL; the solvent used for the first solvent soaking includes methanol.

9. The symbiotic mixed matrix membrane prepared by the method for preparing a symbiotic mixed matrix membrane based on an in-situ method according to any one of claims 6 to 8.

10. Use of the symbiotic mixed matrix membrane according to claim 9 in gas separation and purification.

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