A polyimide mixed matrix membrane and a preparation method and application thereof

Abstract

The application discloses a polyimide mixed matrix membrane and a preparation method and application thereof. The polyimide mixed matrix membrane comprises polyimide and porous fillers. The porous fillers are selected from at least one of carbon nanotubes, carbon molecular sieves, hollow silica, hydrotalcite, metal organic frameworks, covalent organic frameworks and hydrogen-bond organic frameworks. The polyimide mixed matrix membrane is prepared by a liquid-liquid blending method, and the gas separation performance of the mixed matrix membrane is improved by a high-temperature annealing method in a specific temperature range. When the annealing temperature is slightly higher than the glass transition temperature, the annealing process can obviously increase the gas permeability and selectivity of the polyimide mixed matrix membrane. The method is simple and practical, and has a wide application prospect in gas separation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of gas membrane separation, and particularly relates to a polyimide mixed matrix membrane and a preparation method and application thereof. BACKGROUND

[0002] In the past few decades, membrane separation technology has become a mature technology for many energy-intensive separations. Compared with traditional technologies, membrane separation technology provides a more sustainable alternative due to its low energy consumption, small footprint, and easy modular design, and has very successful applications in natural gas purification, syngas treatment, and air separation, and is of great significance for carbon capture, utilization and storage (CCSU).

[0003] At present, pure polymer membranes still dominate in gas separation membranes, but there is a "Trade-off" limitation between the gas permeability and selectivity of pure polymer membranes, that is, the selectivity of the membrane with high permeability is low, and the permeability of the membrane with high selectivity is low. Mixed matrix membranes (MMMs) add fillers to the polymer base, combining the advantages of polymers and fillers, improving the gas separation performance, and providing an effective method to break the "Trade-off" limitation of pure polymers. However, the fillers in the mixed matrix membranes are prone to agglomeration, resulting in irregular voids in the membrane, causing non-selective gas permeation. And in glassy polymers, poor adhesion between fillers and glassy polymers often leads to non-selective interfacial defects. Therefore, it is crucial to select high-selectivity porous fillers and appropriate glassy polymer matrices during the preparation of mixed matrix membranes to obtain high-performance mixed matrix membranes (MMMs) with high dispersion, high loading, and no polymer-filler interfacial defects to meet various key separation challenges. SUMMARY

[0004] Based on the above technical problems, the purpose of the present application is to provide a polyimide mixed matrix membrane (MMMs) for gas separation and a preparation method and application thereof. The polyimide mixed matrix membrane is a membrane prepared by adding porous fillers to the pure polyimide membrane and heat treating it. After the introduction of the porous fillers and heat treatment, the prepared polyimide mixed matrix membrane has significantly improved gas separation performance.

[0005] Polyimide mixed matrix membrane is a kind of thin film by adding a certain amount of porous filler in polymer, thereby greatly improving the gas separation performance of pure polymer film on the basis of pure polymer film. Polyimide is a kind of polymer with imide repeating unit, which has wide temperature applicability, high chemical corrosion resistance and high strength. Aromatic polyimide material has good gas separation performance on the premise of combining the characteristics of polyimide itself, and introduces benzene ring structure to increase the rigidity of polymer chain segment. The dispersion of porous filler in polymer is improved by solvent exchange and ultrasonic dispersion of the filler, and the mechanical properties and separation performance of the mixed matrix membrane are improved by heat treatment of the mixed matrix membrane to reduce the interface defects of polymer-filler.

[0006] In one aspect of the present application, a polyimide mixed matrix membrane is provided, characterized in that,

[0007] The polyimide mixed matrix membrane comprises polyimide and porous filler.

[0008] The polyimide is selected from at least one of the structures of formula I-1, formula I-2 and formula I-3.

[0009]

[0010] wherein 0≤x≤1, 0≤y≤1, 0≤z≤1.

[0011] The R is selected from at least one of the structures of formula a-e.

[0012]

[0013] The porous filler is selected from at least one of carbon nanotube, carbon molecular sieve, hollow silica, hydrotalcite, metal organic framework, covalent organic framework and hydrogen-bonded organic framework.

[0014] Optionally, the polyimide is glassy polyimide, specifically glassy polyimide material at room temperature.

[0015] Optionally, the polyimide is selected from at least one of Kapton, Matrimid, P84, P84HT and fluorine-containing polyimide.

[0016] Optionally, in the polyimide mixed matrix membrane, the mass fraction of the porous filler is 1wt%-80wt%.

[0017] In another aspect of the present application, a preparation method of the above-mentioned polyimide mixed matrix membrane is provided, and the preparation method comprises:

[0018] (1) mixing polyimide and solvent A to form a polyimide solution;

[0019] (2) the porous filler stored in solvent B is subjected to solvent exchange with solvent A, and then mixed with solvent A and ultrasonically dispersed to obtain a blending liquid;

[0020] (3) the blending liquid is added to the polyimide solution to obtain a casting solution;

[0021] (4) the casting solution is placed on a glass plate to perform film drawing, and then is left to stand for a period of time I after film drawing, left to stand for a period of time II after demolding, and subjected to annealing treatment to obtain the polyimide mixed matrix film;

[0022] wherein the temperature T of the annealing treatment satisfies: T g -100 < T < T g +100, and T g is the glass transition temperature of the film material.

[0023] Optionally, the atmosphere of the annealing treatment is selected from one of vacuum, nitrogen, helium or carbon dioxide;

[0024] The heating rate of the annealing treatment is 0.1-20 ℃ / min;

[0025] During the annealing treatment, the time for staying at the temperature T of the annealing treatment is 0.1-72 h;

[0026] The cooling rate of the annealing treatment is 0.1-20 ℃ / min.

[0027] Optionally, the solvent A and the solvent B are independently selected from at least one of N-methylpyrrolidone, methanol, ethanol, water, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran and trichloromethane.

[0028] Optionally, in step (1), the mass concentration of the polyimide in the polyimide solution is 1-20 wt%.

[0029] Optionally, in step (2), the time for ultrasonic dispersion is 0.1-10 h.

[0030] Optionally, in the blending liquid, the mass concentration of the porous filler is 1-80 wt%.

[0031] Optionally, in step (3), the blending liquid is added to the stirred polyimide solution after ultrasonic dispersion for 0.1-24 h to obtain the casting solution;

[0032] The stirring time is 0.1-72 h, and the stirring speed is 10-1000 r / min.

[0033] Optionally, the temperature of the period of time I is 30-80 ℃, and the time for the period of time I is 0.5-36 h.

[0034] Optionally, the temperature of the standing I is independently selected from any value of 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or a range value between any two of the above.

[0035] Optionally, the time of the standing I is independently selected from any value of 13h, 15h, 24h or a range value between any two of the above.

[0036] Optionally, the standing II is carried out under vacuum condition.

[0037] The temperature of the standing II is 100-200℃.

[0038] The time of the standing II is 1-48h.

[0039] Optionally, the temperature of the standing II is independently selected from any value of 100℃, 120℃, 150℃, 180℃, 200℃ or a range value between any two of the above.

[0040] Optionally, the time of the standing II is independently selected from any value of 1h, 12h, 24h, 36h, 48h or a range value between any two of the above.

[0041] Optionally, the mass concentration of the polyimide in the casting solution is 1-20wt%.

[0042] The mass concentration of the porous filler in the polyimide is 1wt%-80wt%.

[0043] As a specific embodiment, the preparation method of the high-performance polyimide mixed matrix membrane comprises the following steps: ultrasonic dispersion, mixing, degassing, film scraping, film forming, film taking, vacuum treatment, and obtaining the mixed matrix membrane.

[0044] Specifically, the preparation method comprises the following steps:

[0045] (1) mixing the polyimide material and the solvent A in a certain proportion and stirring uniformly at room temperature to form a polyimide solution.

[0046] (2) carrying out solvent exchange on the filler stored in the solvent B and the solvent A, and then blending with a certain amount of the solvent A, and ultrasonic dispersion for 0.1-10h.

[0047] (3) slowly adding the blending solution of the filler and the solvent A into the polyimide solution, and stirring for at least 0.1h.

[0048] (4) using a film scraper to form a film on a glass plate with the casting solution obtained in step (3), and placing the film on a horizontal constant temperature heating plate at 30-80℃ for 0.5-36h, and then taking the film.

[0049] (5) The film obtained in step (4) is placed in a vacuum oven at 100-200 °C for at least 1 h and stored for use.

[0050] (6) The film obtained in step (5) is annealed by using a stepwise heating method, the annealing temperature is T, and the residence time is 0.1-72 h; T g -100 < T < T g +100; T g is the glass transition temperature of the film material.

[0051] Specifically, the mixture after the filler in solution B is replaced by solution A is ultrasonically treated for 0.1-24 h, and then added dropwise into the polymer solution in solvent A under stirring to obtain the casting film mixed solution.

[0052] In still another aspect of the present application, the polyimide mixed matrix film as described above is used in gas separation. The polyimide mixed matrix film after the annealing process has good gas separation performance and can be used in the field of gas separation.

[0053] The gas separation is at least one selected from H2 / CH4, H2 / N2, CO2 / CH4, CO2 / N2, O2 / N2, and He / CH4.

[0054] Optionally, the CH4 permeability coefficient of the polyimide mixed matrix film is 0.1-40 Barrer;

[0055] The N2 permeability coefficient of the polyimide mixed matrix film is 0.1-40 Barrer;

[0056] The O2 permeability coefficient of the polyimide mixed matrix film is 0.5-150 Barrer;

[0057] The CO2 permeability coefficient of the polyimide mixed matrix film is 2-700 Barrer;

[0058] The H2 permeability coefficient of the polyimide mixed matrix film is 7-760 Barrer;

[0059] The He permeability coefficient of the polyimide mixed matrix film is 7-730 Barrer.

[0060] Optionally, the H2 / CH4 selectivity of the polyimide mixed matrix film is 40-200;

[0061] The H2 / N2 selectivity of the polyimide mixed matrix film is 30-100;

[0062] The CO2 / CH4 selectivity of the polyimide mixed matrix film is 10-50;

[0063] The CO2 / N2 selectivity of the polyimide mixed matrix membrane is 10-50;

[0064] The O2 / N2 selectivity of the polyimide mixed matrix membrane is 2-10;

[0065] The He / CH4 selectivity of the polyimide mixed matrix membrane is 40-200.

[0066] In the present application, the range values of data all include the end point values, and only when 0 appears, the value of 0 is not taken.

[0067] The beneficial effects that can be produced by the present application include:

[0068] 1. The polyimide is used as the membrane material in the present application, and after heat treatment after film formation, the mechanical properties, gas permeability and selectivity are obviously improved

[0069] 2. The polyimide mixed matrix membrane material provided in the present application has a great improvement in permeability and selectivity compared with the pure polyimide membrane after high-temperature heat treatment (H2 / CH4, H2 / N2, CO2 / CH4, CO2 / N2, O2 / N2).

[0070] 3. The film forming and post-treatment method provided in the present application is simple and easy to operate, has a wide range of applications, and has a good practical application prospect.

[0071] 4. The polyimide mixed matrix membrane is prepared by liquid-liquid blending method, and the gas separation performance of the mixed matrix membrane is improved by high-temperature annealing method in a specific temperature range. When the annealing temperature is slightly higher than the glass transition temperature, the annealing process can obviously increase the toughness, gas permeability and selectivity of the polyimide mixed matrix membrane. This method is simple and practical, and has a relatively wide application prospect in gas separation. DETAILED DESCRIPTION

[0072] The present application will be described in detail below in combination with examples, but the present application is not limited to these examples.

[0073] Unless otherwise specified, the raw materials in the examples of the present application are purchased through commercial channels.

[0074] Comparative Example 1

[0075] The structure is

[0076]

[0077] Polyimide (P84HT) powder 6 g was dissolved in 44 g N-methyl pyrrolidone (NMP), after stirring at room temperature for 24 h, the solution was left to stand to remove bubbles, and then the film was made on a glass plate using a film doctor knife (the gap between the doctor knife and the glass plate was 300-500 μm), the film was taken off after being placed on a horizontal constant temperature heating plate at 50 °C for 15 h, and finally the film was stored in a vacuum oven at 150 °C for 2 d to obtain a P84HT polymer film.

[0078] Comparative Example 2

[0079] The P84HT polymer film prepared in Comparative Example 1 was subjected to annealing treatment, and the annealing procedure was as follows: under nitrogen atmosphere, the temperature was raised from room temperature to 400 °C at a rate of 2 °C / min, and then the temperature was lowered to room temperature after staying at 400 °C for one hour to obtain a heat-treated P84HT polymer film (P84HT-400).

[0080] Comparative Example 3

[0081] The P84HT polymer film prepared in Comparative Example 1 was subjected to annealing treatment, and the annealing procedure was as follows: under nitrogen atmosphere, the temperature was raised from room temperature to 450 °C at a rate of 2 °C / min, and then the temperature was lowered to room temperature after staying at 450 °C for one hour to obtain a heat-treated P84HT polymer film (P84HT-450).

[0082] Comparative Example 4

[0083] The structure was

[0084]

[0085] Polyimide (6FDA-DAM) powder 6 g was dissolved in 44 g N-methyl pyrrolidone (NMP), after stirring at room temperature for 24 h, the solution was left to stand to remove bubbles, and then the film was made on a glass plate using a film doctor knife (the gap between the doctor knife and the glass plate was 300-500 μm), the film was taken off after being placed on a horizontal constant temperature heating plate at 50 °C for 15 h, and finally the film was stored in a vacuum oven at 150 °C for 2 d to obtain a 6FDA-DAM polymer film.

[0086] Comparative Example 5

[0087] The 6FDA-DAM polymer film prepared in Comparative Example 4 was subjected to annealing treatment, and the annealing procedure was as follows: under nitrogen atmosphere, the temperature was raised from room temperature to 400 °C at a rate of 2 °C / min, and then the temperature was lowered to room temperature after staying at 400 °C for one hour to obtain a heat-treated 6FDA-DAM polymer film (6FDA-DAM-400).

[0088] The gas permeation properties of the P84HT polymer films in Comparative Examples 1, 2, and 3 and the 6FDA-DAM polymer films in Comparative Examples 4 and 5 and the gas mixture selectivity properties when the gas mixture was H2 / CH4, H2 / N2, CO2 / CH4, CO2 / N2, O2 / N2, and He / CH4 at 0.2 MPa and 35°C are shown in Tables 1 and 2.

[0089] Table 1 Gas permeation properties

[0090]

[0091] Table 2 Gas selectivity properties

[0092]

[0093] As can be seen from the separation properties of Comparative Examples 1-5, when the heat treatment temperature is greater than T g , the residual stress in the film is reduced, the chain segment motion space is increased, the free volume is increased, and the structural defects are eliminated, so that the gas permeability is multiplied, and the selectivity is also sharply increased. When the annealing temperature is higher than T g + 50, the residual stress in the film is reduced, the structural defects are eliminated, and part of the amide groups in the film are carbonized, exhibiting a small amount of molecular sieving characteristics, so that the gas permeability is increased, but the selectivity is slightly lower than that of Comparative Example 1.

[0094] Example 1

[0095] Polyimide (P84HT) powder 6 g was dissolved in 35.78 g of N-methyl pyrrolidone (NMP) and stirred at room temperature for 24 h. ZIF-8 stored in methanol after synthesis was used to replace methanol with NMP by solvent exchange to form a ZIF-8 colloidal solution (the mass concentration of ZIF-8 was 3.7 wt%). Then 8.53 g of the ZIF-8 colloidal solution was added dropwise to the stirring polyimide (P84HT) solution, and stirring was continued for 24 h. A film was prepared on a glass plate using a film doctor knife (the gap between the doctor knife and the glass plate was 300-500 μm), and the film was placed on a horizontal constant temperature heating plate at 50°C for 15 h, then removed, and finally stored in a vacuum oven at 150°C for 2 d to obtain a P84HT / ZIF-8 (5 wt%) mixed matrix film.

[0096] The prepared P84HT / ZIF-8 (5 wt%) mixed matrix film was annealed, and the annealing program was as follows: under a nitrogen atmosphere, the temperature was increased from room temperature to 400°C at a rate of 2°C / min, and after staying at 400°C for one hour, the temperature was decreased to room temperature to obtain a heat-treated P84HT / ZIF-8 (5 wt%)-400 mixed matrix film.

[0097] Example 2

[0098] The P84HT / ZIF-8(5wt%) mixed matrix membrane prepared in Example 1 was annealed, the annealing procedure was: from room temperature to 450℃ at a heating rate of 2℃ / min under nitrogen atmosphere, after staying at 450℃ for one hour, decreased to room temperature to obtain the heat-treated P84HT / ZIF-8(5wt%)-450 mixed matrix membrane.

[0099] Example 3

[0100] Polyimide (P84HT) powder 6g was dissolved in 26.65g N-methyl pyrrolidone (NMP) and stirred at room temperature for 24h, ZIF-8 stored in methanol after synthesis was used solvent exchange method to replace methanol with NMP to form colloidal ZIF-8 (the mass concentration of ZIF-8 was 3.7wt%), then 18.02g ZIF-8 colloidal solution was added dropwise into the stirring polyimide (P84HT) solution, and the stirring was continued for 24h, the film was prepared on a glass plate using a film doctor knife (the gap between the doctor knife and the glass plate was 300-500μm), the film was taken off after being placed on a horizontal constant temperature heating plate at 50℃ for 15h, and finally the film was stored in a vacuum oven at 150℃ for 2d to obtain the P84HT / ZIF-8(10wt%) mixed matrix membrane.

[0101] The P84HT / ZIF-8(10wt%) mixed matrix membrane prepared was annealed, the annealing procedure was: from room temperature to 400℃ at a heating rate of 2℃ / min under nitrogen atmosphere, after staying at 400℃ for one hour, decreased to room temperature to obtain the heat-treated P84HT / ZIF-8(10wt%)-400 mixed matrix membrane.

[0102] Example 4

[0103] The P84HT / ZIF-8(10wt%) mixed matrix membrane prepared in Example 3 was annealed, the annealing procedure was: from room temperature to 450℃ at a heating rate of 2℃ / min under nitrogen atmosphere, after staying at 450℃ for one hour, decreased to room temperature to obtain the heat-treated P84HT / ZIF-8(10wt%)-450 mixed matrix membrane.

[0104] Example 5

[0105] Polyimide (P84HT) powder 6 g was dissolved in 26.48 g N-methyl pyrrolidone (NMP) and stirred at room temperature for 24 h. ZIF-8 stored in methanol after synthesis was used to replace methanol with NMP by solvent exchange to form colloidal ZIF-8 (mass concentration of ZIF-8 was 6.4 wt%). Then 18.72 g ZIF-8 colloidal solution was added dropwise into the stirring polyimide (P84HT) solution. The stirring was continued for 24 h. The film was prepared on a glass plate using a doctor blade (gap between the doctor blade and the glass plate was 300-500 μιη). The film was taken off after being placed on a horizontal constant temperature heating plate at 50 °C for 15 h. Finally, the film was stored in a vacuum oven at 150 °C for 2 d to obtain a P84HT / ZIF-8 (16.6 wt%) mixed matrix membrane.

[0106] The prepared P84HT / ZIF-8 (16.6 wt%) mixed matrix membrane was annealed. The annealing procedure was as follows: from room temperature to 400 °C at a heating rate of 2 °C / min under nitrogen atmosphere, and then kept at 400 °C for one hour, and then decreased to room temperature to obtain a heat-treated P84HT / ZIF-8 (16.6 wt%) -400 mixed matrix membrane.

[0107] Example 6

[0108] Polyimide (P84HT) powder 6 g was dissolved in 26.48 g N-methyl pyrrolidone (NMP) and stirred at room temperature for 24 h. ZIF-8 stored in methanol after synthesis was used to replace methanol with NMP by solvent exchange to form colloidal ZIF-8 (mass concentration of ZIF-8 was 6.4 wt%). Then 18.72 g ZIF-8 colloidal solution was added dropwise into the stirring polyimide (P84HT) solution. The stirring was continued for 24 h. The film was prepared on a glass plate using a doctor blade (gap between the doctor blade and the glass plate was 300-500 μιη). The film was taken off after being placed on a horizontal constant temperature heating plate at 50 °C for 15 h. Finally, the film was stored in a vacuum oven at 150 °C for 2 d to obtain a P84HT / ZIF-8 (16.6 wt%) mixed matrix membrane.

[0109] The prepared P84HT / ZIF-8 (16.6 wt%) mixed matrix membrane was annealed. The annealing procedure was as follows: from room temperature to 400 °C at a heating rate of 2 °C / min under nitrogen atmosphere, and then kept at 400 °C for one hour, and then decreased to room temperature to obtain a heat-treated P84HT / ZIF-8 (16.6 wt%) -400 mixed matrix membrane.

[0110] The P84HT / ZIF-8 mixed matrix membranes and 6FDA / ZIF-8 mixed matrix membranes in Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Examples 1-6 under different heat treatment temperatures were tested for gas permeation performance, and the gas permeation performance under 0.2 MPa and 35℃, and the selectivity performance when the gas mixture was H2 / CH4, H2 / N2, CO2 / CH4, CO2 / N2, O2 / N2, He / CH4 were as shown in Tables 3 and 4.

[0111] Table 3 Gas permeation performance

[0112]

[0113] Table 4 Gas selectivity performance

[0114]

[0115] As can be seen from Tables 3-4, when the heat treatment temperature was 400℃, the addition of ZIF-8 greatly improved the permeability of the mixed matrix membrane in terms of permeability. And the higher the content of ZIF-8, the faster the gas permeability, which is due to the addition of porous nanofiller ZIF-8, the gas molecules realize double molecular channel permeation in the membrane, greatly improving the gas permeability. In terms of selectivity, the pore size selectivity of the porous nanofiller ZIF-8 makes the selectivity of the mixed matrix membrane increase.

[0116] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the preferred embodiments are disclosed as above, they are not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments, and all belong to the scope of the technical solution.

Claims

1. A method for preparing a polyimide hybrid matrix membrane, characterized by, The preparation method comprises: (1) mixing polyimide and solvent A to form a polyimide solution; (2) after solvent exchange of the porous filler stored in solvent B with solvent A, mixing the porous filler with solvent A and ultrasonic dispersion to obtain a blending liquid; (3) adding the blending liquid into the polyimide solution to obtain a casting solution; (4) placing the casting solution on a glass plate for film scraping, standing I, standing II after demolding, annealing treatment, and obtaining the polyimide mixed matrix film; wherein the annealing temperature T satisfies: T g -100 < T < +100 T g +100, T g is the glass transition temperature of the film material; The polyimide mixed matrix film comprises polyimide and a porous filler; The polyimide is a glassy polyimide; The polyimide is selected from at least one of the structures of formula I-1, formula I-2, and formula I-3; 0≤x≤1, 0≤y≤1, 0≤z≤1; The R is selected from at least one of the structures of formula a-e; The porous filler is selected from at least one of carbon nanotubes, carbon molecular sieves, hollow silica, hydrotalcite, metal organic frameworks, covalent organic frameworks, and hydrogen-bonded organic frameworks.

2. The preparation method of claim 1, wherein The polyimide is selected from at least one of Kapton, Matrimid, P84, P84HT, and fluorine-containing polyimide.

3. The preparation method according to claim 1, characterized in that, In the polyimide mixed matrix film, the mass fraction of the porous filler is 1wt%-80wt%.

4. The preparation method of claim 1, wherein The atmosphere of the annealing treatment is selected from one of vacuum, nitrogen, helium, and carbon dioxide; The heating rate of the annealing treatment is 0.1-20℃ / min; During the annealing treatment, the time of staying at the annealing treatment temperature T is 0.1-72 h; The cooling rate of the annealing treatment is 0.1-20℃ / min.

5. The preparation method of claim 1, wherein The solvent A and the solvent B are independently selected from at least one of N-methyl pyrrolidone, methanol, ethanol, water, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, and trichloromethane.

6. The preparation method of claim 1, wherein In step (1), the mass concentration of polyimide in the polyimide solution is 1-20wt%.

7. The preparation method of claim 1, wherein In step (2), the ultrasonic dispersion time is 0.1-10 h; In the blending liquid, the mass concentration of the porous filler is 1-80wt%.

8. The preparation method of claim 1, wherein In step (3), the blending liquid is added into the stirred polyimide solution after ultrasonic dispersion for 0.1-24 h to obtain the casting solution; The stirring time is 0.1-72 h, and the stirring speed is 10-1000 r / min.

9. The preparation method of claim 1, wherein In step (4), the standing I temperature is 30-80℃, and the standing I time is 0.5-36 h.

10. The preparation method of claim 1, wherein In step (4), the standing II is performed under vacuum condition; The temperature of the standing II is 100-200℃; The time of the standing II is 1-48h.

11. The preparation method according to claim 1, wherein, The mass concentration of the polyimide in the casting solution is 1-20wt%; The mass concentration of the porous filler in the polyimide is 1wt%-80wt%.

12. Use of a polyimide hybrid matrix membrane prepared according to the method of any one of claims 1 to 11 in gas separation. The gas separation is at least one selected from H2 / CH4, H2 / N2, CO2 / CH4, CO2 / N2, O2 / N2, He / CH4.

13. The use according to claim 12, wherein, The CH4 permeance coefficient of the polyimide mixed matrix membrane is 0.1-3 Barrer; The N2 permeance coefficient of the polyimide mixed matrix membrane is 0.1-3 Barrer; The O2 permeance coefficient of the polyimide mixed matrix membrane is 0.5-20 Barrer; The CO2 permeance coefficient of the polyimide mixed matrix membrane is 2-40 Barrer; The H2 permeance coefficient of the polyimide mixed matrix membrane is 7-160 Barrer; The He permeance coefficient of the polyimide mixed matrix membrane is 7-130 Barrer.

14. The use according to claim 12, wherein, The H2 / CH4 selectivity of the polyimide mixed matrix membrane is 40-200; The H2 / N2 selectivity of the polyimide mixed matrix membrane is 30-100; The CO2 / CH4 selectivity of the polyimide mixed matrix membrane is 10-50; The CO2 / N2 selectivity of the polyimide mixed matrix membrane is 10-50; The O2 / N2 selectivity of the polyimide mixed matrix membrane is 2-10; The He / CH4 selectivity of the polyimide mixed matrix membrane is 40-200.

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