A mixed matrix membrane and methods of making and using the same

Abstract

The application relates to the technical field of film materials, in particular to a mixed matrix membrane and a preparation method and application thereof. Toluene is added into a viscous polyamine acid solution, the temperature is increased to 200-250 DEG C, and stirring reaction is carried out for 5-8 hours, then the precipitate is obtained through centrifugation, the precipitate is washed with methanol for 3-5 times, and the product COOH-PI is obtained through drying; zinc nitrate hexahydrate and 2-methyl imidazole are dissolved in methanol, stirring reaction is carried out at room temperature for 3-8 hours, then the product is taken out and centrifuged, the product is washed with anhydrous methanol for 3-5 times, and ZIF-8 is obtained through drying; NH2-ZIF-8 is synthesized by using the same method; COOH-PI is added into DMF and stirred to obtain a PI solution, ZIF-8 and NH2-ZIF-8 are respectively added into DMF, and MOF suspension is obtained through ultrasonic treatment for 2-5 hours, then the MOF suspension is added into the PI solution, stirring is carried out at room temperature for 24-36 hours, the casting solution obtained is poured into a flat and clean glass plate, heating is carried out at 60-65 DEG C for 24-48 hours, then the formed membrane is dried to obtain the mixed matrix membrane. The preparation condition of the mixed matrix membrane is mild, the stability of the membrane is obviously improved, and the mixed matrix membrane has high selective permeability to helium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of membrane materials, in particular to a mixed matrix membrane and a preparation method and application thereof. BACKGROUND

[0002] Helium (He) is a rare and high-value gas, which has the characteristics of lighter than air, liquid temperature close to thermodynamic zero, inertness, etc. It has strong diffusivity, good thermal conductivity, low density, low solubility, low latent heat of evaporation and other properties, and has wide application in the fields of electronics, optical fiber manufacturing, weather balloons / airships, aerospace and cryogenics. A small amount of helium is contained in air, natural gas and some mineral springs containing radioactive elements, but for industrial production, most of the helium in the world comes from natural gas. As a potential application technology in the preparation process of helium, gas separation membrane shows more and more feasibility in the preparation of helium from natural gas. Studies have shown that compared with pure polymer membranes, mixed matrix membranes (MMMs) prepared by using polymer as matrix and adding appropriate porous or non-porous inorganic fillers can exhibit better gas selectivity and permeability.

[0003] In recent years, various inorganic fillers such as inorganic oxides, carbon materials, zeolites, and newly developed microporous molecular sieve materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have been widely used in the preparation of MMMs, which combine the excellent separation performance of inorganic fillers and the good film-forming performance of high polymer materials, and are considered as a potential membrane material for gas separation. Although the MMMs have significantly improved gas separation performance compared with traditional polymer membranes, the membrane stability problems including plasticization and aging still exist and are even more serious. The essence of these problems is the flexibility of polymer chains, especially caused by the weak interaction between the polymer matrix and the fillers contained in the interface. Therefore, it is undoubtedly beneficial to limit the movement of flexible chain segments by enhancing the interfacial interaction between the polymer matrix and the fillers.

[0004] Introducing chemical reactions to construct covalent bonds on the polymer matrix-filler interface is a common strategy and method to improve the rigidity of polymer chains and the stability of membranes. Among them, thermal crosslinking is a widely used chemical reaction. However, the current thermal crosslinking reaction usually requires a relatively high reaction temperature (as high as 350-450℃) to complete, which leads to the brittleness of the membrane during operation and easy breakage. In addition, some thermally unstable fillers such as MOFs may decompose during thermal treatment, and it is impossible to maintain their microporous structure at such a high temperature. Therefore, it is very important and necessary to develop an efficient and less destructive method to crosslink the polymer matrix-filler interface to improve the stability of the membrane and retain the performance of the membrane. SUMMARY

[0005] Therefore, the present application aims to provide a mixed matrix membrane and a preparation method and application thereof, and solve the problem of poor stability of the existing mixed matrix membrane due to the high-temperature cross-linking reaction.

[0006] The present application solves the above technical problems by the following technical means:

[0007] The first aspect of the present application is to provide a mixed matrix membrane, comprising the following raw materials in parts by weight: COOH-PI 1.75-3.5 parts, ZIF-8 0.02-0.1 parts, NH2-ZIF-8 0.02-0.1 parts.

[0008] In combination with the first aspect, in some embodiments, the mass ratio of ZIF-8 and NH2-ZIF-8 is 1:1.

[0009] The second aspect of the present application is to provide a preparation method of a mixed matrix membrane, comprising the following steps:

[0010] Synthesis of COOH-PI: under a nitrogen atmosphere, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 3,5-diaminobenzoic acid and 4,4-(hexafluoroisopropyl) diphenyl dicarboxylic anhydride are dissolved in anhydrous NMP, stirred at room temperature for 1-5 h to form a viscous polyamine acid solution, toluene is added, and the temperature is raised to 200-250 DEG C and stirred for 5-8 h, during which water is removed by azeotropic distillation, then centrifuged to obtain a precipitate, washed with methanol for 3-5 times, dried to obtain the product COOH-PI;

[0011] Synthesis of ZIF-8: zinc nitrate hexahydrate and 2-methylimidazole are dissolved in methanol, stirred at room temperature for 3-8 h, then centrifuged, the obtained precipitate is washed with anhydrous methanol for 3-5 times, and dried to obtain ZIF-8;

[0012] Synthesis of NH2-ZIF-8: zinc nitrate hexahydrate, 2-methylimidazole and 2-aminobenzimidazole are dissolved in methanol, stirred at room temperature for 3-8 h, then centrifuged, the obtained precipitate is washed with anhydrous methanol for 3-5 times, and dried to obtain NH2-ZIF-8;

[0013] Preparation of MMMs: COOH-PI is added to DMF and stirred to dissolve for 24-36 h to obtain a PI solution, ZIF-8 and NH2-ZIF-8 are respectively added to DMF, and ultrasonic treatment is performed for 2-5 h to obtain a MOF suspension, then the MOF suspension is added to the PI solution, and stirred at room temperature for 24-36 h, the obtained casting solution is poured into a flat and clean glass plate, heated at 60-65 DEG C for 24-48 h, then the formed membrane is dried to obtain a mixed matrix membrane.

[0014] In combination with the second aspect, in some embodiments, in the synthesis step of the COOH-PI, the 2,3,5,6-tetramethyl-1,4-benzenediamine is 2.62-3.75 parts by weight, the 3,5-diaminobenzoic acid is 0.61-1.93 parts by weight, and the 4,4-(hexafluoroisopropyl) diphenyl dicarboxylic anhydride is 8.88-10.53 parts by weight.

[0015] In combination with the second aspect, in some embodiments, in the synthesis step of the COOH-PI, the precipitate after washing with methanol is dried at a temperature of 120-150℃ under vacuum for 24-48h.

[0016] In combination with the second aspect, in some embodiments, in the synthesis step of the ZIF-8, the zinc nitrate hexahydrate is 2.97-3.64 parts by weight, and the 2-methylimidazole is 6.56-7.91 parts by weight.

[0017] In combination with the second aspect, in some embodiments, in the synthesis step of the NH2-ZIF-8, the zinc nitrate hexahydrate is 2.97-3.64 parts by weight, the 2-methylimidazole is 6.24-7.32 parts by weight, and the 2-aminobenzimidazole is 0.53-1.02 parts by weight.

[0018] In combination with the second aspect, in some embodiments, in the preparation step of the MMM, the COOH-PI is 1.75-3.5 parts by weight, the ZIF-8 is 0.02-0.1 parts by weight, and the NH2-ZIF-8 is 0.02-0.1 parts by weight. 2- The ZIF-8 is 0.02-0.1 parts by weight.

[0019] In combination with the second aspect, in some embodiments, in the preparation step of the MMM, the drying temperature for drying the formed film is 150℃, and the drying time is 24-48h.

[0020] The third aspect of the present application provides the use of the above-mentioned mixed matrix membrane in the separation and purification of helium.

[0021] The application adopts amine group functionalized ZIF-8 (NH2-ZIF-8) nanoparticles with different particle sizes as fillers, and selects carboxylic acid functionalized PI (COOH-PI) as a polymer matrix. The dehydration reaction of amine groups and carboxylic acid groups at 150 DEG C in vacuum induces the formation of amide bonds. Under this relatively mild reaction condition, the stability of the membrane is obviously improved, and the permeability and selectivity of the membrane are also improved. The mixed matrix membrane of the application has high selective permeability to helium. In the gas detection results, the helium permeation coefficient of the mixed matrix membrane of the application can reach 121.4 bar, the selectivity coefficient of He / CH4 is 57.6, and the selectivity coefficient of He / N2 is 49.9. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 XRD spectra of ZIF-8-NH2, ZIF-8Simulated and ZIF-8-COOH in Example 1. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the application will be clearly and completely described in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0024] In the following examples, the specific conditions not noted are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The raw materials, equipment or instruments not noted by the manufacturer are all conventional products that can be obtained by market purchase.

[0025] The application aims to build strong interactions on MOF / polymer MMM, and aims to improve the stability of the membrane without sacrificing the separation performance. The application adopts amine group functionalized ZIF-8 (NH2-ZIF-8) nanoparticles with different particle sizes as fillers, and selects carboxylic acid functionalized PI (COOH-PI) as a polymer matrix. The dehydration reaction of amine groups and carboxylic acid groups at 150 DEG C in vacuum induces the formation of amide bonds. Under this relatively mild reaction condition, the stability of the membrane is obviously improved, and the permeability and selectivity of the membrane are also improved.

[0026] Example 1

[0027] The preparation method of the mixed matrix membrane of the embodiment is as follows:

[0028] (1) Synthesis of COOH-PI: 2.69 g of 2,3,5,6-tetramethyl-l,4-phenylenediamine, 0.93 g of 3,5-diaminobenzoic acid (DABA), and 9.53 g of 4,4-(hexafluoroisopropyl)diphthalic anhydride (6FDA) were dissolved in 100 mL of anhydrous NMP under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 3 h to form a viscous polyamine acid solution. Then, 80 mL of toluene was added to the flask, and the reaction mixture was stirred at 200 °C for 5 h. During this period, water was removed from the reaction mixture by azeotropic distillation. Subsequently, the solution was centrifuged to obtain the product, which was collected by precipitation with methanol, washed with methanol three times, and dried at 120 °C under vacuum for 24 h.

[0029] (2) Synthesis of ZIF-8 and NH2-ZIF-8: 3.04 g of zinc nitrate hexahydrate and 6.91 g of 2-methylimidazole were dissolved in 200 mL of methanol. After stirring at room temperature for 5 h, the reaction mixture was removed and centrifuged. The resulting product was washed with anhydrous methanol three times and finally dried at 100 °C under vacuum for 24 h to obtain ZIF-8.

[0030] 3.04 g of zinc nitrate hexahydrate, 6.32 g of 2-methylimidazole, and 0.83 g of 2- aminobenzimidazole were dissolved in 200 mL of methanol. After stirring at room temperature for 5 h, the reaction mixture was removed and centrifuged. The resulting product was washed with anhydrous methanol three times and finally dried at 100 °C under vacuum for 24 h to obtain NH2-ZIF-8, the XRD pattern of which is shown in Figure 1

[0031] (3) Preparation of MMMs: Polyimide / MOF MMMs were prepared by a solution casting method. 2.5 g of polyimide was dissolved in 50 mL of DMF by stirring for 24 h. Meanwhile, 0.05 g of ZIF-8 and 0.05 g of NH2-ZIF-8 were added to 30 mL of DMF, respectively, and ultrasonicated for 2 h to obtain suspensions. Subsequently, the MOF suspensions were added to the PI solution, which was stirred at room temperature for 24 h to obtain a casting solution. The casting solution was poured onto a flat and clean glass plate and heated at 60 °C for 24 h to achieve slow solvent evaporation. Then, the dried membrane was transferred to a vacuum oven at 150 °C and left for 24 h to remove residual solvents and form interfacial amide bonds, thereby obtaining a mixed matrix membrane.

[0032] Figure 1 XRD patterns of ZIF-8-NH2, ZIF-8 Simulated, and ZIF-8-COOH in this example.

[0033] Example 2

[0034] The preparation method of the mixed matrix membrane of this example is as follows: ​

[0035] (1) Synthesis of COOH-PI: 3.28 g of 2,3,5,6-tetramethyl-l,4-phenylenediamine, 1.17 g of 3,5-diaminobenzoic acid (DABA), and 9.91 g of 4,4-(hexafluoroisopropyl)diphthalic anhydride (6FDA) were dissolved in 150 mL of anhydrous NMP under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 5 h to form a viscous polyamine acid solution. Then, 100 mL of toluene was added to the flask, and the reaction mixture was stirred at 250 °C for 8 h. During this period, water was removed from the reaction mixture by azeotropic distillation. Subsequently, the solution was centrifuged to obtain the product, which was collected by precipitation with methanol, washed with methanol 5 times, and dried at 150 °C under vacuum for 48 h.

[0036] (2) Synthesis of ZIF-8 and NH2-ZIF-8: 3.24 g of zinc nitrate hexahydrate and 7.21 g of 2-methylimidazole were dissolved in 300 mL of methanol. After stirring at room temperature for 7 h, the reaction was removed and centrifuged. The resulting product was washed with anhydrous methanol 5 times, and finally dried at 120 °C under vacuum for 48 h to obtain ZIF-8.

[0037] 3.24 g of zinc nitrate hexahydrate, 7.02 g of 2-methylimidazole, and 0.93 g of 2- aminobenzimidazole were dissolved in 300 mL of methanol. After stirring at room temperature for 7 h, the reaction was removed and centrifuged. The resulting product was washed with anhydrous methanol 5 times, and finally dried at 120 °C under vacuum for 48 h to obtain NH2-ZIF-8.

[0038] (3) Preparation of MMMs:

[0039] The polyimide / MOF MMMs were prepared by a solution casting method. 2.87 g of polyimide was dissolved in 70 mL of DMF by stirring for 36 h. Meanwhile, 0.1 g of ZIF-8 and 0.1 g of NH2-ZIF-8 were added to 50 mL of DMF, respectively, and ultrasonicated for 5 h to obtain suspensions. Subsequently, the MOF suspensions were added to the PI solution, which was stirred at room temperature for 36 h to obtain a casting solution. The casting solution was poured into a flat and clean glass plate and heated at 65 °C for 48 h to achieve slow solvent evaporation. Then, the dried membrane was transferred to a vacuum oven at 150 °C and placed for 48 h to remove the residual solvent and form interfacial amide bonds, thereby obtaining the mixed matrix membrane.

[0040] Example 3

[0041] The preparation method of the mixed matrix membrane of this example is as follows:

[0042] (1) Synthesis of COOH-PI: 2.62 g of 2,3,5,6-tetramethyl-l,4-phenylenediamine, 0.61 g of 3,5-diaminobenzoic acid (DABA), and 8.88 g of 4,4-(hexafluoroisopropyl)diphthalic anhydride (6FDA) were dissolved in 75 mL of anhydrous NMP under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 1 h to form a viscous polyamine acid solution. Then, 75 mL of toluene was added to the flask, and the reaction mixture was stirred at 200 °C for 6 h. During this period, water was removed from the reaction mixture by azeotropic distillation. The solution was then centrifuged to obtain the product, which was collected by precipitation with methanol, washed with methanol four times, and dried at 130 °C under vacuum for 35 h.

[0043] (2) Synthesis of ZIF-8 and NH2-ZIF-8: 2.97 g of zinc nitrate hexahydrate and 6.56 g of 2-methylimidazole were dissolved in 300 mL of methanol. After stirring at room temperature for 3 h, the reaction mixture was removed and centrifuged. The resulting product was washed with anhydrous methanol four times and finally dried at 110 °C under vacuum for 35 h to obtain ZIF-8.

[0044] 3.24 g of zinc nitrate hexahydrate, 6.24 g of 2-methylimidazole, and 0.53 g of 2- aminobenzimidazole were dissolved in 300 mL of methanol. After stirring at room temperature for 3 h, the reaction mixture was removed and centrifuged. The resulting product was washed with anhydrous methanol four times and finally dried at 110 °C under vacuum for 35 h to obtain NH2-ZIF-8.

[0045] (3) Preparation of MMMs:

[0046] The polyimide / MOF MMMs were prepared by a solution casting method. 1.75 g of polyimide was dissolved in 70 mL of DMF by stirring for 30 h. Meanwhile, 0.02 g of ZIF-8 and 0.02 g of NH2-ZIF-8 were added to 40 mL of DMF, respectively, and ultrasonicated for 3 h to obtain suspensions. Then, the MOF suspensions were added to the PI solution, which was stirred at room temperature for 30 h to obtain a casting solution. The casting solution was poured onto a flat and clean glass plate and heated at 65 °C for 48 h to achieve slow solvent evaporation. Then, the dried membrane was transferred to a vacuum oven at 150 °C and left for 48 h to remove the residual solvent and form interfacial amide bonds, thereby obtaining a mixed matrix membrane.

[0047] Example 4

[0048] The preparation method of the mixed matrix membrane of this example is as follows:

[0049] (1) Synthesis of COOH-PI: 3.75 g of 2,3,5,6-tetramethyl-1,4-phenylenediamine, 1.93 g of 3,5-diaminobenzoic acid (DABA) and 10.53 g of 4,4-(hexafluoroisopropyl)diphthalic anhydride (6FDA) were dissolved in 100 mL of anhydrous NMP under nitrogen atmosphere. The reaction mixture was stirred at room temperature for 3 h to form a viscous polyamine acid solution. Then, 85 mL of toluene was added to the flask, and the reaction mixture was stirred at 220 °C for 6 h. During this period, water was removed from the reaction mixture by azeotropic distillation. Subsequently, the solution was centrifuged to obtain the product, which was collected by precipitation with methanol, washed with methanol 4 times, and dried at 130 °C under vacuum for 35 h.

[0050] (2) Synthesis of ZIF-8 and NH2-ZIF-8: 3.64 g of zinc nitrate hexahydrate and 7.91 g of 2-methylimidazole were dissolved in 300 mL of methanol. After stirring at room temperature for 8 h, the reaction mixture was removed and centrifuged. The resulting product was washed with anhydrous methanol 4 times, and finally dried at 110 °C under vacuum for 35 h to obtain ZIF-8.

[0051] 3.64 g of zinc nitrate hexahydrate, 7.32 g of 2-methylimidazole and 1.02 g of 2- aminobenzimidazole were dissolved in 300 mL of methanol. After stirring at room temperature for 8 h, the reaction mixture was removed and centrifuged. The resulting product was washed with anhydrous methanol 4 times, and finally dried at 110 °C under vacuum for 35 h to obtain NH2-ZIF-8.

[0052] (3) Preparation of MMMs:

[0053] The polyimide / MOF MMMs were prepared by a solution casting method. 3.5 g of polyimide was dissolved in 75 mL of DMF by stirring for 30 h. Meanwhile, 0.05 g of ZIF-8 and 0.05 g of NH2-ZIF-8 were added to 40 mL of DMF, respectively, and ultrasonicated for 3 h to obtain suspensions. Then, the MOF suspensions were added to the PI solution, which was stirred at room temperature for 30 h to obtain a casting solution. The casting solution was poured into a flat and clean glass plate and heated at 65 °C for 48 h to achieve slow solvent evaporation. Then, the dried membrane was transferred to a vacuum oven at 150 °C and placed for 48 h to remove the residual solvent and form the interfacial amide bond, thereby obtaining the mixed matrix membrane.

[0054] Gas separation performance test of the mixed matrix membranes prepared in Examples 1-4: The gas permeation performance and separation performance of the mixed matrix membranes prepared in Examples 1-4 were evaluated at room temperature by using the constant volume pressure swing method, and the test gas pair was He, CH4 and N2. The test results are shown in Table 1.

[0055] Table 1

[0056] Examples Helium permeation coefficient (bar) Selectivity of He / CH4 Selectivity to He / N2 Example 1 121.4 57.6 49.9 Example 2 118.7 55.3 47.9 Example 3 115.1 56.7 48.3 Example 4 117.3 53.2 47.8

[0057] The data in Table 1 show that the mixed matrix membrane of the application has high selectivity for helium, and has high selectivity coefficient for helium in both He / CH4 and He / N2 systems, so the mixed matrix membrane of the application can be used for separation and purification of helium.

[0058] The above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the present application, and all modifications and equivalent replacements should be covered in the scope of the claims of the present application. The technical, shape and structure parts not described in detail in the present application are all known technologies.

Claims

1. A mixed matrix membrane characterized in that, The raw materials include the following weight parts: COOH-PI 1.75-3.5 parts, ZIF-8 0.02-0.1 parts, NH2-ZIF-8 0.02-0.1 parts; The mass ratio of the ZIF-8 and NH2-ZIF-8 is 1:1; The preparation method of the mixed matrix membrane comprises the following steps: The synthesis of COOH-PI, under a nitrogen atmosphere, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 3,5-diaminobenzoic acid and 4,4-(hexafluoroisopropyl) diphenyl dicarboxylic anhydride are dissolved in anhydrous NMP, stirring at room temperature for 1-5 h to form a viscous polyamine acid solution, toluene is added, and the reaction is stirred at 200-250 DEG C for 5-8 h, during which water is removed by azeotropic distillation, and then the precipitate is obtained by centrifugation, washed with methanol for 3-5 times, dried to obtain the product COOH-PI; The synthesis of ZIF-8, zinc nitrate hexahydrate and 2-methylimidazole are dissolved in methanol, stirring at room temperature for 3-8 h, then centrifuged, the obtained precipitate is washed with anhydrous methanol for 3-5 times, dried to obtain ZIF-8; The synthesis of NH2-ZIF-8, zinc nitrate hexahydrate, 2-methylimidazole and 2-aminobenzimidazole are dissolved in methanol, stirring at room temperature for 3-8 h, then centrifuged, the obtained precipitate is washed with anhydrous methanol for 3-5 times, dried to obtain NH2-ZIF-8; The preparation of MMMs, COOH-PI is added into DMF and stirred to dissolve for 24-36 h to obtain a PI solution, ZIF-8 and NH2-ZIF-8 are respectively added into DMF, ultrasonic for 2-5 h to obtain a MOF suspension, then the MOF suspension is added into the PI solution, stirring at room temperature for 24-36 h to obtain a casting solution, the casting solution is poured into a flat and clean glass plate, heated at 60-65 DEG C for 24-48 h, and then the formed membrane is dried to obtain a mixed matrix membrane.

2. The hybrid matrix membrane of claim 1, wherein, In the synthesis step of the COOH-PI, the weight parts of the 2,3,5,6-tetramethyl-1,4-phenylenediamine is 2.62-3.75 parts, the weight parts of the 3,5-diaminobenzoic acid is 0.61-1.93 parts, and the weight parts of the 4,4-(hexafluoroisopropyl) diphenyl dicarboxylic anhydride is 8.88-10.53 parts.

3. The hybrid matrix membrane of claim 2, wherein, In the synthesis step of the COOH-PI, the precipitate after washing with methanol is dried at a temperature of 120-150 DEG C under vacuum for 24-48 h.

4. The hybrid matrix membrane of claim 3, wherein, In the synthesis step of the ZIF-8, the weight parts of the zinc nitrate hexahydrate is 2.97-3.64 parts, and the weight parts of the 2-methylimidazole is 6.56-7.91 parts.

5. The hybrid matrix membrane of claim 4, wherein, In the synthesis step of the NH2-ZIF-8, the weight parts of the zinc nitrate hexahydrate is 2.97-3.64 parts, the weight parts of the 2-methylimidazole is 6.24-7.32 parts, and the weight parts of the 2-aminobenzimidazole is 0.53-1.02 parts.

6. The hybrid matrix membrane of claim 5, wherein, In the preparation step of the MMMs, the weight fraction of COOH-PI is 1.75-3.5 parts, the weight fraction of ZIF-8 is 0.02-0.1 parts, the weight fraction of NH 2- The weight fraction of ZIF-8 is 0.02-0.1 parts.

7. The hybrid matrix membrane of claim 6, wherein, In the preparation step of the MMMs, the drying temperature of the formed membrane is 150 DEG C, and the drying time is 24-48 h.

8. The use of the mixed matrix membrane according to any one of claims 1-7 in helium gas separation and purification.

Images