A perfluoroalcohol-modified aluminum-based MOF hybrid matrix membrane, its preparation method and application

Abstract

This invention discloses a perfluoroalcohol-modified aluminum-based MOF hybrid matrix membrane, its preparation method, and its applications. Perfluoroalcohol-modified aluminum-based MOF nanocrystals are obtained by adding perfluoroalcohol to a dispersion of aluminum-based MOF nanocrystals with polar surfaces. These nanocrystals are then uniformly blended with a polymer casting solution as a channel material, and a high-performance aluminum-based MOF hybrid matrix membrane is prepared by solution casting. The addition of perfluoroalcohol for modification maintains crystallinity and pore structure, significantly alters the surface properties of the nanocrystals, and improves the dispersibility of aluminum-based MOFs in the casting solution of the hybrid matrix membrane, solving common problems in hybrid matrix membranes such as poor interfacial compatibility and pore blockage. The aluminum-based MOF hybrid matrix membrane of this invention exhibits excellent molecular sieving ability and structural stability, enabling efficient separation of systems such as carbon dioxide / methane, ethylene / ethane, and alkane isomers.

Description

Technical Field

[0001] This invention specifically relates to an aluminum-based MOF hybrid matrix membrane modified with perfluoroalcohol, its preparation method, and its application. Background Technology

[0002] Aluminum-based MOFs have attracted much attention due to their diverse structures, high structural stability, low preparation cost, and simple scale-up synthesis, making them promising membrane materials for potential industrial applications. Blending aluminum-based MOFs with polymers to prepare hybrid matrix membranes has become a hot topic in the development of high-performance membranes. However, because aluminum-based MOF crystals typically possess high rigidity and surface energy, they often exhibit poor interfacial bonding when directly combined with polymer materials, resulting in poor interfacial compatibility, insufficient mechanical strength, and unsatisfactory separation performance.

[0003] To address this issue, coating MOFs with coatings or surfactants is a mainstream approach to enhance the interfacial compatibility between MOFs and polymers. However, the thickness and uniformity of the coating are often difficult to control, and the coating may peel off or degrade over time or during use, affecting the long-term stability and performance of the membrane. Introducing functionalized groups into the aluminum-based MOF framework through crystal engineering can also improve the interfacial compatibility of MOFs, but the selectivity and reactivity of different groups may be limited, leading to uneven surface modification, or in some cases, triggering side reactions that affect the overall performance of the membrane. Overall, obtaining aluminum-based MOF hybrid matrix membranes with high filler content and no interfacial defects using existing fabrication processes remains challenging. Summary of the Invention

[0004] In view of the shortcomings and deficiencies of the prior art, the purpose of this invention is to provide an aluminum-based MOF hybrid matrix membrane, in which the aluminum-based MOF and the matrix material have good compatibility, the membrane has excellent molecular sieving ability and structural stability, and can achieve efficient separation of systems such as carbon dioxide / methane, ethylene / ethane and alkane isomers.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An aluminum-based MOF hybrid matrix membrane, comprising a polymer and modified aluminum-based MOF nanocrystals, wherein the modified aluminum-based MOF nanocrystals are obtained by modifying aluminum-based MOF nanocrystals with perfluoroalcohols.

[0007] In some embodiments, the perfluoroalcohol is selected from one or more combinations of perfluorooctanol, perfluoroheptanol, perfluoropentanol, and perfluorooctylethanol.

[0008] In some embodiments, the mass of the modified aluminum-based MOF nanocrystals accounts for 5% to 40% of their total mass with that of the polymer.

[0009] In some embodiments, the aluminum-based MOF is selected from one or more combinations of CAU-23, CAU-10-NH2, KMF-1, MIL-53-NH2, and MOF-303.

[0010] In some embodiments, the water contact angle of the modified aluminum-based MOF nanocrystals is 90–140°.

[0011] In some embodiments, the modified aluminum-based MOF nanocrystals are prepared by a method comprising the following steps: dispersing the aluminum-based MOF nanocrystals in a solvent to obtain a dispersion; adding the perfluoroalcohol to the dispersion, mixing, centrifuging, and drying to obtain the modified aluminum-based MOF nanocrystals.

[0012] In some embodiments, the perfluoroalcohol has a mass fraction of 0.1% to 2.5% in the dispersion.

[0013] In some embodiments, the polymer is selected from polyimide and / or microporous polymer PIM-1, which is prepared by polymerization of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-helical bis-indane (TTSBI) and 2,3,5,6-tetrafluoroterephthalonitrile (TFTDN).

[0014] In some embodiments, the polyimide is prepared by polycondensation and dehydration of 4,4′-(hexafluoroisopropyl)phthalic anhydride (6FDA) and 2,4,6-trimethyl-1,3-phenylenediamine (DAM).

[0015] In existing technologies, conventional mixed matrix membranes often suffer from poor interfacial compatibility and pore blockage of MOF membrane crystals. The inventors of this application discovered that modifying aluminum-based MOF nanocrystals with perfluoroalcohols, due to the strong hydrophobicity of perfluoroalcohols, makes the modified aluminum-based MOF nanocrystals hydrophobic. This allows the aluminum-based MOF nanocrystals to significantly alter their surface properties while maintaining the crystallinity and pore structure of the aluminum-based MOF, resulting in sufficient hydrophobicity. Furthermore, because perfluoroalcohols can undergo esterification with the carboxyl groups on the surface of the aluminum-based MOF, the modified layer exhibits high uniformity and stability, significantly improving the dispersibility of aluminum-based MOFs in the casting solution of the mixed matrix membrane, thereby significantly improving the compatibility between the aluminum-based MOF nanocrystals and the polymer matrix. The resulting aluminum-based MOF mixed matrix membrane possesses excellent molecular sieving ability and structural stability, enabling efficient separation of systems such as carbon dioxide / methane, ethylene / ethane, and alkane isomers.

[0016] In some embodiments, the aluminum-based MOF hybrid matrix membrane is prepared by casting a casting solution comprising the polymer, modified aluminum-based MOF nanocrystals, and an organic solvent.

[0017] The present invention also provides a method for preparing the above-mentioned aluminum-based MOF hybrid matrix membrane, the method comprising the following steps: dispersing the aluminum-based MOF nanocrystals in a solvent to obtain a dispersion; adding the perfluoroalcohol to the dispersion, mixing, centrifuging, and drying to obtain the modified aluminum-based MOF nanocrystals; mixing the polymer, the modified aluminum-based MOF nanocrystals, and an organic solvent to obtain a casting solution; and casting the casting solution to obtain the aluminum-based MOF hybrid matrix membrane.

[0018] In some embodiments, the solvent is selected from one or more combinations of ethanol, methanol, and chloroform.

[0019] In some embodiments, the perfluoroalcohol has a mass fraction of 0.1% to 2.5% in the dispersion.

[0020] In some embodiments, the aluminum-based MOF nanocrystals have a mass fraction of 0.5% to 5% in the dispersion.

[0021] In some embodiments, the organic solvent is selected from one or more combinations of N,N-dimethylformamide, chloroform, and dichloromethane.

[0022] In some embodiments, the polymer mass fraction in the casting solution is 1.0% to 5.0%.

[0023] In some embodiments, the preparation method includes the following steps: dispersing the aluminum-based MOF nanocrystals in a solvent to obtain a dispersion; adding the perfluoroalcohol to the dispersion, stirring and mixing, centrifuging, washing, and vacuum drying to obtain the modified aluminum-based MOF nanocrystals; mixing the polymer, the modified aluminum-based MOF nanocrystals, and an organic solvent to obtain a casting solution; vacuum degassing the casting solution, transferring it to a mold, evaporating the solvent at room temperature, and vacuum drying to obtain the aluminum-based MOF mixed matrix film.

[0024] In some embodiments, the mixing time is 5 to 12 hours.

[0025] In some embodiments, when preparing the modified aluminum-based MOF nanocrystals, the vacuum drying temperature is 60–80°C and the vacuum drying time is 6–12 h.

[0026] In some embodiments, the solvent evaporation time is 12 to 48 hours.

[0027] In some embodiments, when preparing the aluminum-based MOF hybrid matrix membrane, the vacuum drying temperature is 60–80°C and the vacuum drying time is 12–24 h.

[0028] The present invention also provides the use of the above-mentioned aluminum-based MOF hybrid matrix membrane for gas or liquid separation.

[0029] Furthermore, the gas is selected from carbon dioxide / methane and ethylene / ethane; the liquid is a hexane isomer.

[0030] Furthermore, the hexane isomer can be a ternary mixture of n-hexane, 3-methylpentane, and 2,2-dimethylbutane.

[0031] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0032] This invention first modifies aluminum-based MOF nanocrystals with perfluoroalcohols. Due to the strong hydrophobicity of perfluoroalcohols, the modified aluminum-based MOF nanocrystals exhibit hydrophobicity, significantly altering their surface properties while maintaining the crystallinity and pore structure of the aluminum-based MOF, thus achieving sufficient hydrophobicity. Furthermore, the perfluoroalcohol's esterification reaction with the carboxyl groups on the aluminum-based MOF surface results in a highly uniform and stable modified layer, significantly improving the dispersibility of the aluminum-based MOF in the casting solution of the mixed matrix membrane, and consequently significantly improving the compatibility between the aluminum-based MOF nanocrystals and the polymer matrix. The resulting aluminum-based MOF mixed matrix membrane exhibits excellent molecular sieving ability and structural stability, enabling efficient separation of systems such as carbon dioxide / methane, ethylene / ethane, and alkane isomers. Attached Figure Description

[0033] Figure 1 Water contact angle of CAU-23 nanocrystals modified with different perfluorooctanoic acid dosages;

[0034] Figure 2 XRD patterns of CAU-23 nanocrystals modified with different amounts of perfluorooctanoic acid;

[0035] Figure 3 SEM images of the surface and cross-section of the aluminum-based MOF hybrid matrix film prepared in Example 1;

[0036] Figure 4 AFM image of the aluminum-based MOF hybrid matrix film prepared in Example 1;

[0037] Figure 5 EDS mapping image of the cross section of the aluminum-based MOF hybrid matrix film prepared in Example 2;

[0038] Figure 6 SEM images of the surface and cross-section of the aluminum-based MOF hybrid matrix film prepared for Comparative Example 1. Detailed Implementation

[0039] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention, but the present invention is not limited to the scope of the examples described.

[0040] Example 1

[0041] This embodiment provides an aluminum-based MOF hybrid matrix membrane, the specific preparation steps of which are as follows:

[0042] I. Perfluoroalcohol Modification

[0043] 0.5 g of CAU-23 nanocrystals were dispersed in 50 mL of ethanol solution to form a nanocrystal suspension. Then, a certain amount of perfluorooctanol was weighed and added to the CAU-23 nanocrystal ethanol dispersion. After stirring at room temperature for 24 h, the nanocrystals were washed three times by centrifugation with methanol, and finally dried at 60 °C in a vacuum drying oven for 12 h to obtain perfluorooctanol-modified CAU-23 nanocrystals.

[0044] Meanwhile, the surface hydrophobicity of CAU-23 nanocrystals can be easily altered by changing the mass percentage concentration of perfluorooctanol in the CAU-23 ethanol dispersion. Figure 1The static water contact angle data of CAU-23 nanocrystals modified with different perfluorooctanol additions (mass percentage in the dispersion) are presented. The results show that the water contact angle of CAU-23 nanocrystals increases monotonically with increasing perfluorooctanol addition. At a concentration of 1.0 wt%, the surface properties of CAU-23 change from hydrophilic to hydrophobic, demonstrating the strong interfacial energy modulation ability of perfluorools.

[0045] Figure 2 and Figure 3 The XRD and SEM images of the perfluorooctanoic acid (PFOA)-modified CAU-23 nanocrystals are shown, indicating that the modification step had no effect on the crystal structure integrity and morphology of the CAU-23 nanocrystals. Table 1 shows the specific surface area and pore volume data of the PFOA-modified CAU-23 nanocrystals obtained at 77 K based on the N2 adsorption-desorption isotherm. It can be seen that when the mass concentration of PFOA in the dispersion is below 2 wt.%, the specific surface area and pore volume of the modified CAU-23 only decrease slightly, while the average pore size remains basically unchanged. However, at 3 wt.%, the specific surface area and pore volume decrease significantly, indicating a greater impact on the porosity of CAU-23.

[0046] Table 1. Pore structure information of CAU-23 nanocrystals modified with different perfluorooctanoic acid concentrations.

[0047]

[0048] II. Preparation of PIM-1:

[0049] Dissolve 7.5 g of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindene (TTSBI) in 200 mL of methanol, and transfer the solution to a rotary evaporator flask. Install a rotary evaporator. Distill under reduced pressure at 220 rpm and 45 °C until 50 mL of solution remains. Add 100 mL of dichloromethane to the system and allow the precipitate to settle overnight. Collect the precipitate by vacuum drying at 60 °C and store it.

[0050] Dissolve 4.5 g of 2,3,5,6-tetrafluoroterephthalonitrile TFTDN in 75 mL of acetone, add deionized water dropwise until complete precipitation, dry under vacuum at 60 °C, and store.

[0051] Crude potassium carbonate was ground for 30 minutes, placed in a glass bottle, and vacuum dried at 130°C for 24 hours. After drying, it was stored to obtain fine potassium carbonate.

[0052] 3.4 g of purified TTSBI and 2.0 g of purified TFTDN were placed in a 250 mL three-necked flask, and 70 mL of N,N-dimethylacetamide was added. The mixture was stirred until the solution was clear. 4.15 g of fine potassium carbonate was added to the solution, and the apparatus was placed in a nitrogen atmosphere. The reaction was carried out at 65 °C with stirring for 72 h. The resulting bright yellow solution was poured into an 80 °C deionized hydrochloric acid solution (14 wt.%) and stirred at a constant temperature for 12 h to remove potassium carbonate. After filtration and drying, the dried sample was dissolved in 100 mL of chloroform and then transferred to methanol for precipitation by vacuum filtration. The precipitate was dried under vacuum for 24 h. Finally, the sample was washed with 100 mL of 4-dioxane, 100 mL of acetone, 100 mL of deionized water, and excess methanol to remove low molecular weight PIM-1 and unreacted raw materials. After washing, the sample was dried under vacuum at 60 °C for 24 h to obtain the PIM-1 sample for film formation. The synthesized PIM-1 has a molecular weight of 170,000 g / mol.

[0053] III. Membrane Preparation

[0054] A perfluorooctyl alcohol (PFOA)-modified CAU-23 / PIM-1 mixed matrix membrane was prepared using a solution casting method. 0.2 g of PFOA-modified CAU-23 nanocrystals (PFOA concentration 1 wt.%) were dispersed in 6 g of chloroform and sonicated for 20 min to obtain a CAU-23 nanocrystal dispersion. 0.3 g of the prepared PIM-1 sample was dissolved in 10 g of chloroform to obtain a PIM-1 casting solution, which was then mixed with the previously prepared CAU-23 nanocrystal dispersion to form a mixed matrix membrane casting solution with a nanocrystal content of 40% of the total mass of the nanocrystals and polymer. The solution was then degassed in an ultrasonic bath for 10 min. After degassed, the casting solution was transferred to a mold, which was placed on a horizontally aligned plate. The solvent, chloroform, was slowly evaporated at room temperature for 48 h, followed by vacuum drying at 60 °C for 24 h to form a film. Finally, the mixed matrix membrane was cut into small pieces with a diameter of approximately 3 cm using a die for performance testing. Pure PIM-1 films were prepared using the same method without the addition of CAU-23 nanocrystals.

[0055] Figures 3 to 5 The surface / cross-sectional SEM images, surface AFM images, and cross-sectional EDS mapping images of the obtained hybrid matrix membrane are shown. The results indicate that the hybrid matrix membrane is dense and free of interfacial defects, and the perfluorooctanoic acid-modified CAU-23 nanocrystals are uniformly dispersed in the PIM-1 matrix without aggregation. This membrane exhibits excellent separation performance for the hexane isomer ternary mixture system, with a separation factor of ~4.87 for (n-hexane + 3-methylpentane) / 2,2-dimethylbutane and a total permeate flux of ~1500 g·m⁻¹ for (n-hexane + 3-methylpentane). -2 ·h -1Furthermore, the separation performance showed no degradation after 100 hours of continuous operation. In comparison, the separation selectivity of the prepared hybrid matrix membrane was 3 times higher than that of pure phase PIM-1, and exceeded that of most previously reported membrane materials, demonstrating its potential for practical application.

[0056] Example 2

[0057] This embodiment provides an aluminum-based MOF hybrid matrix membrane, the specific preparation steps of which are as follows:

[0058] I. Perfluoroalcohol Modification

[0059] The preparation of 1 wt.% perfluorooctanoic acid-modified CAU-23 nanocrystals was the same as in Example 1.

[0060] II. Preparation of 6FDA-DAM:

[0061] A certain amount of diamine DAM was dissolved in N,N-dimethylacetamide to prepare a 20 wt.% solution, and then dianhydride FDA was added. The mixture was reacted at 5°C under nitrogen protection for 24 h to generate a polyamic acid solution. Then, acetic anhydride and triethanolamine in a molar ratio of 4:1 were added to the above solution, and the reaction was carried out at room temperature for 24 h to generate polyimide from polyamide. Finally, the solution was poured into sufficient methanol to precipitate the polymer, which was then dried under vacuum at 150°C for 12 h. The synthesized 6FDA-DAM had a molecular weight of 180,000 g / mol.

[0062] III. Membrane Preparation

[0063] The perfluorooctanoic acid modified CAU-23 / 6FDA-DAM mixed matrix membrane was also prepared using the solution casting method of Example 1.

[0064] 1 wt.% CAU-23 nanocrystals modified with perfluorooctyl alcohol were dispersed in chloroform and sonicated for 20 min to obtain a 10 mg / mL CAU-23 nanocrystal dispersion. 6FDA-DAM was first dried overnight under vacuum at 150 °C to remove residual moisture before use. 0.42 g of 6FDA-DAM was weighed and dissolved in 4.1 mL of chloroform, and stirred for 3 h. Subsequently, a certain amount of the aforementioned perfluorooctyl alcohol-modified CAU-23 nanocrystal dispersion was added to the 6FDA-DAM solution, and stirring was continued overnight to ensure uniform dispersion of the CAU-23 nanocrystals in the solution, resulting in a 6FDA-DAM mixed matrix membrane casting solution with nanocrystals comprising 40% of the total mass of the nanocrystals and polymer. The resulting suspension was poured into a flat glass dish, and the dish was placed in a desiccator pre-saturated with chloroform vapor. The desiccator was designed with a small outlet to reduce the solvent evaporation rate. After slow solvent evaporation for 3 days, a dense, defect-free mixed matrix membrane was obtained. The membrane was dried in a vacuum oven at 180°C for 24 hours to remove residual solvent, resulting in a dense, defect-free CAU-23 / 6FDA-DAM hybrid matrix membrane. Finally, the hybrid matrix membrane was cut into small pieces approximately 3 cm in diameter using a die for performance testing. Pure 6FDA-DAM membranes were prepared using the same method without the addition of CAU-23 nanocrystals.

[0065] The mixed matrix membrane was loaded into a membrane module for the separation of equimolar ethylene / ethane binary mixtures. The membrane achieved a selectivity of 3.7 for ethylene / ethane separation and an ethylene permeation flux of 135 Barrer. Compared to pure-phase 6FDA-DAM, both the ethylene / ethane separation selectivity and ethylene permeation flux were significantly improved, indicating that the prepared mixed matrix membrane has a defect-free interface and can leverage the advantages of CAU-23 nanocrystal channels, demonstrating promising application prospects.

[0066] Example 3

[0067] This embodiment provides an aluminum-based MOF hybrid matrix membrane, the preparation steps of which are basically the same as those in Example 1, except that: the CAU-23 nanocrystals are surface modified with 1 wt.% perfluorooctyl ethanol, and all other steps are the same as in Example 1.

[0068] The obtained membrane also exhibited excellent separation performance for the ternary mixture system of hexane isomers, with a separation factor of ~4.43 for (n-hexane + 3-methylpentane) / 2,2-dimethylbutane and a total permeate flux of ~1396 g·m⁻¹ for (n-hexane + 3-methylpentane). -2 ·h -1 Furthermore, the separation performance showed no decline after 100 hours of continuous operation.

[0069] Example 4

[0070] This embodiment provides an aluminum-based MOF hybrid matrix membrane, the preparation steps of which are basically the same as in Example 2, except that CAU-23 nanocrystals are replaced with CAU-10-NH2 nanocrystals. The resulting membrane exhibits excellent separation performance for equimolar carbon dioxide / methane binary mixtures, with a carbon dioxide / methane separation selectivity of 34 and an ethylene permeation flux of 650 Barrer.

[0071] Comparative Example 1

[0072] The process is essentially the same as in Example 1, except that the CAU-23 nanocrystals were not modified with perfluorooctanoic acid. The SEM image of the resulting film is shown below. Figure 6 As shown, the membrane exhibits obvious interfacial defects and particle aggregation, resulting in the prepared mixed matrix membrane having no hexane isomer separation capability. The separation factor for (n-hexane + 3-methylpentane) / 2,2-dimethylbutane is only 1.27, which is lower than the 1.56 of the pure PIM-1 membrane.

[0073] Comparative Example 2

[0074] The procedure was essentially the same as in Example 1, except that the concentration of perfluorooctanol in the dispersion was adjusted to 3 wt.%. As shown in Table 1, with the increase of the perfluorooctanol concentration to 3 wt.%, its effect on the porosity of CAU-23 was significant (Table 1), resulting in a significant decrease in the permeation flux of the prepared mixed matrix membrane, with a total permeation flux of only 756 g·m³ for (n-hexane + 3-methylpentane). -2 ·h -1 The separation factor for (n-hexane + 3-methylpentane) / 2,2-dimethylbutane is ~2.43.

[0075] Comparative Example 3

[0076] The process was essentially the same as in Example 2, except that the CAU-23 nanocrystals were not modified with perfluorooctanoic acid. The resulting membrane exhibited uneven particle dispersion and significant agglomeration, leading to the mixed matrix membrane lacking ethylene / ethane separation capability; the ethylene / ethane separation selectivity was only 1.32.

[0077] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An aluminum-based MOF hybrid matrix membrane, characterized in that: The aluminum-based MOF hybrid matrix membrane comprises a polymer and modified aluminum-based MOF nanocrystals. The modified aluminum-based MOF nanocrystals are obtained by modifying aluminum-based MOF nanocrystals with perfluoroalcohol. The aluminum-based MOF is selected from one or more combinations of CAU-23, CAU-10-NH2, KMF-1, MIL-53-NH2, and MOF-303. The modified aluminum-based MOF nanocrystals are prepared by a method comprising the following steps: dispersing the aluminum-based MOF nanocrystals in a solvent to obtain a dispersion; adding the perfluoroalcohol to the dispersion, mixing, centrifuging, and drying to obtain the modified aluminum-based MOF nanocrystals; the mass fraction of the perfluoroalcohol in the dispersion is 0.1% to 2.5%.

2. The aluminum-based MOF hybrid matrix membrane according to claim 1, characterized in that: The perfluoroalcohol is selected from one or more combinations of perfluorooctanol, perfluoroheptanol, perfluoropentanol, and perfluorooctylethanol.

3. The aluminum-based MOF hybrid matrix membrane according to claim 1, characterized in that: The mass percentage of the modified aluminum-based MOF nanocrystals to the total mass of the modified aluminum-based MOF nanocrystals and the polymer is 5% to 40%.

4. The aluminum-based MOF hybrid matrix membrane according to claim 1, characterized in that: The modified aluminum-based MOF nanocrystals have a water contact angle of 90~140°.

5. The aluminum-based MOF hybrid matrix membrane according to claim 1, characterized in that: The polymer is selected from polyimide and / or microporous polymer PIM-1, which is prepared by polymerization of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-helical bis-indane and 2,3,5,6-tetrafluoroterephthalonitrile.

6. The aluminum-based MOF hybrid matrix membrane according to claim 5, characterized in that: The polyimide was prepared by polycondensation and dehydration of 4,4′-(hexafluoroisopropyl)diphthalic anhydride and 2,4,6-trimethyl-1,3-phenylenediamine.

7. A method for preparing an aluminum-based MOF hybrid matrix membrane according to any one of claims 1-6, characterized in that: The preparation method includes the following steps: dispersing the aluminum-based MOF nanocrystals in a solvent to obtain a dispersion; adding the perfluorool to the dispersion, mixing, centrifuging, and drying to obtain the modified aluminum-based MOF nanocrystals; mixing the polymer, the modified aluminum-based MOF nanocrystals, and an organic solvent to obtain a casting solution; casting the casting solution to obtain the aluminum-based MOF mixed matrix film; the mass fraction of the perfluorool in the dispersion is 0.1%~2.5%.

8. The method for preparing an aluminum-based MOF hybrid matrix membrane according to claim 7, characterized in that: The solvent is selected from one or more combinations of ethanol, methanol, and chloroform.

9. The method for preparing the aluminum-based MOF hybrid matrix film according to claim 7, characterized in that: The mass fraction of the aluminum-based MOF nanocrystals in the dispersion is 0.5% to 5%.

10. The method for preparing the aluminum-based MOF hybrid matrix membrane according to claim 7, characterized in that: The organic solvent is selected from one or more combinations of N,N-dimethylformamide, chloroform and dichloromethane; and / or, the mass fraction of the polymer in the casting solution is 1.0% to 5.0%.

11. The method for preparing an aluminum-based MOF hybrid matrix membrane according to claim 7, characterized in that: The preparation method includes the following steps: dispersing the aluminum-based MOF nanocrystals in a solvent to obtain a dispersion; adding the perfluoroalcohol to the dispersion, stirring and mixing, centrifuging, washing, and vacuum drying to obtain the modified aluminum-based MOF nanocrystals; mixing the polymer, the modified aluminum-based MOF nanocrystals, and an organic solvent to obtain a casting solution; vacuum degassing the casting solution, transferring it to a mold, evaporating the solvent at room temperature, and vacuum drying to obtain the aluminum-based MOF mixed matrix film.

12. Use of the aluminum-based MOF hybrid matrix membrane according to any one of claims 1-6 for gas or liquid separation.

13. The use according to claim 12, characterized in that: The gas is selected from carbon dioxide / methane and ethylene / ethane; the liquid is a hexane isomer.

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