Gas separation membrane as well as preparation method and application thereof
By subjecting polysulfone polymer membranes to oxygen-enriched microwave plasma treatment and chitosan modification, and then combining them with MOF layers to form a multilayer gas separation membrane, the problem of insufficient selectivity in propylene/propane separation in existing technologies is solved, achieving higher separation efficiency and selectivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 北京潜锋科技有限公司
- Filing Date
- 2026-03-02
- Publication Date
- 2026-05-05
AI Technical Summary
Existing gas separation membrane materials cannot meet industrial requirements for the separation of mixed gases such as propylene/propane, and there is a mutual constraint between permeability and selectivity.
A multilayer gas separation membrane was formed by physically modifying a polysulfone polymer membrane using oxygen-enriched microwave plasma technology, combining it with chemical modification of chitosan with a specific degree of deacetylation, and then compositing it with a metal-organic framework (MOF) layer.
It significantly improves the separation selectivity of gas separation membranes for mixed gases such as propylene/propane, enhances molecular sieving ability and affinity difference separation effect, and has broad industrial application prospects.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of gas separation membrane technology, and in particular to a gas separation membrane, its preparation method, and its application. Background Technology
[0002] Gas separation is a crucial technological step in modern industrial production and daily life. Many industries, such as chemical, energy, and environmental protection, heavily rely on efficient gas separation technologies to separate, purify, and recycle different gas components. Taking the chemical industry as an example, in the production of propylene and propane, they often exist as a mixed gas. As an important chemical raw material, the purity of propylene has a decisive impact on the quality of subsequent products and production efficiency.
[0003] In recent years, gas separation membrane technology, as an emerging gas separation method, has received widespread attention and in-depth research due to its significant advantages such as low energy consumption, simple operation, compact equipment, and environmental friendliness. The core of gas separation membranes lies in their membrane materials, whose performance directly determines the separation efficiency and selectivity. Currently, common gas separation membrane materials mainly include polymer membranes, inorganic membranes, and composite membranes. However, the gas separation performance of existing gas separation membrane materials still needs improvement; their gas permeability and selectivity are mutually restrictive, making it difficult to meet the high selectivity requirements of industrial applications such as the separation of mixed gases like propylene / propane. Summary of the Invention
[0004] To address the above problems, this invention provides a gas separation membrane, its preparation method, and its application.
[0005] In a first aspect, the present invention provides a gas separation membrane, comprising a modified polysulfone polymer membrane and a MOF layer located on at least a portion of the surface of the modified polysulfone polymer membrane; The modified polysulfone polymer membrane is obtained by sequentially subjecting the polysulfone polymer membrane to oxygen-enriched microwave plasma physical modification treatment and chitosan chemical modification treatment, wherein the degree of deacetylation of the chitosan is 70%~85%.
[0006] Furthermore, the polysulfone polymer membrane includes at least one of polysulfone ultrafiltration membrane and polyethersulfone ultrafiltration membrane.
[0007] Furthermore, the material of the MOF layer includes at least one of ZIF-8, ZIF-67, and ZIF-90.
[0008] Furthermore, the degree of deacetylation of the chitosan is 80%.
[0009] In a second aspect, the present invention provides a method for preparing the gas separation membrane described in the first aspect, comprising the following steps: The first polysulfone polymer membrane was obtained by treating the polysulfone polymer membrane with oxygen-enriched microwave plasma. Chitosan solution was spin-coated onto the first polysulfone polymer film and then heat-treated to obtain a modified polysulfone polymer film. The modified polysulfone polymer membrane was immersed in the MOF synthesis solution and then dried to obtain the gas separation membrane.
[0010] Furthermore, the working conditions parameters of the oxygen-enriched microwave plasma treatment include: the working medium is a mixed gas composed of oxygen and argon in a volume ratio of (8~12):1, the microwave power is 300W~400W, and the treatment time is 60s~90s.
[0011] Further, the step of spin-coating the chitosan solution onto the first polysulfone polymer film and then heat-treating it to obtain the modified polysulfone polymer film includes the following processes: Chitosan was dissolved in an aqueous acetic acid solution to obtain a chitosan solution with a mass fraction of 2% to 3%. The chitosan solution was spin-coated onto the first polysulfone polymer film at a spin-coating speed of 800 rpm to 1200 rpm and a spin-coating time of 50 s to 70 s. Then, the heat treatment was carried out at a temperature of 80 ℃ to 90 ℃ for 1 h to 2 h to obtain the modified polysulfone polymer film.
[0012] Further, the step of immersing the modified polysulfone polymer membrane in a MOF synthesis solution and then drying it to obtain the gas separation membrane includes the following processes: The MOF synthesis solution was prepared according to the chemical composition of the MOF material. The modified polysulfone polymer membrane was placed in the MOF synthesis solution and immersed for 10 min to 60 min at 25℃ to 45℃ and 0.8 bar to 1.2 bar. The membrane was then removed and dried to obtain the gas separation membrane.
[0013] Thirdly, the present invention provides the application of a gas separation membrane as described in any one of the first aspects or a gas separation membrane prepared by the method described in any one of the second aspects in the separation of mixed gases.
[0014] Furthermore, the mixed gas includes a mixture of propylene and propane.
[0015] The technical solutions provided in the embodiments of the present invention have at least the following advantages compared with the prior art: This invention provides a gas separation membrane, its preparation method, and its application. The invention primarily utilizes oxygen-enriched microwave plasma technology and chitosan with a specific degree of deacetylation for a combined physical-chemical modification of a polysulfone polymer membrane. This modified membrane is then composited with a metal-organic framework (MOF) layer to form a multilayer gas separation membrane. This significantly improves the separation selectivity of the gas separation membrane for mixed gases such as propylene / propane, and has broad application prospects. Specifically: This invention first uses oxygen-enriched microwave plasma to treat a polysulfone polymer membrane, forming more active sites and providing an anchor for the chemical modification of chitosan. Then, chitosan with a suitable degree of deacetylation is introduced, maintaining mechanical strength while avoiding excessive crystallization that leads to decreased permeability. Sufficient amino active sites enhance interfacial bonding. Simultaneously, the amino groups can coordinate with metal ions in the MOF synthesis solution, guiding the subsequent directional growth of the MOF. Finally, the MOF is deposited on the surface of the modified polysulfone polymer membrane through in-situ synthesis, forming a multi-layered gradient gas separation membrane with a "polysulfone substrate - chitosan intermediate layer - MOF functional layer" structure. This enhances molecular sieving ability and affinity-based separation effects, thereby improving the selective separation of mixed gases such as propylene / propane, and has broad industrial application prospects. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0017] In a first aspect, the present invention provides a gas separation membrane, comprising a modified polysulfone polymer membrane and a MOF layer located on at least a portion of the surface of the modified polysulfone polymer membrane; The modified polysulfone polymer membrane is obtained by sequentially subjecting the polysulfone polymer membrane to oxygen-enriched microwave plasma physical modification treatment and chitosan chemical modification treatment, wherein the degree of deacetylation of the chitosan is 70%~85%.
[0018] The gas separation membrane provided by this invention uses oxygen-enriched microwave plasma technology and chitosan with a specific degree of deacetylation to perform physical-chemical combined modification of polysulfone polymer membranes, and then combines them with metal-organic framework (MOF) layers to form a multilayer gas separation membrane. This significantly improves the separation selectivity of the gas separation membrane for mixed gases such as propylene / propane, and has broad application prospects.
[0019] In the embodiments of this application, the polysulfone polymer membrane is a separation membrane made of a polymer compound whose main chain contains repeating sulfone groups and arylene groups. Commercially available polysulfone (PSF) or polyethersulfone (PES) products such as microfiltration (pore size 0.1-10μm) and ultrafiltration (pore size 1-100nm) can be directly selected.
[0020] In the embodiments of this application, the degree of deacetylation (DD) of chitosan is an indicator that measures the degree of deacetylation in chitosan molecules. It is usually expressed as a percentage (%) and commercially available products such as C915936 (70% deacetylation), C915934 (80% deacetylation), and S24914-100g (85% deacetylation) can be directly selected.
[0021] In the embodiments of this application, MOF (Metal-Organic Framework) is a type of porous crystalline material formed by the self-assembly of metal ions (or metal clusters) and organic ligands through coordination bonds. Its constituent units generally include metal nodes (usually composed of transition metal ions (such as zinc, copper, iron, zirconium, etc.) or metal clusters (such as Zr6-O8), which serve as "connection points" of the framework) and organic ligands (containing oxygen, nitrogen, and other polydentate ligands, such as carboxylic acids and nitrogen-containing heterocycles). The organic ligands are connected to the metal nodes through coordination bonds to form one-dimensional, two-dimensional, or three-dimensional structures.
[0022] In one embodiment of the present invention, the polysulfone-based polymer membrane includes at least one of a polysulfone ultrafiltration membrane and a polyethersulfone ultrafiltration membrane. The polysulfone-based ultrafiltration polymer membrane of the present invention preferably has a pore size of 40nm-70nm, for example, 40nm, 50nm, 60nm, 70nm, etc.
[0023] In one embodiment of the present invention, the material of the MOF layer includes at least one of ZIF-8, ZIF-67 and ZIF-90.
[0024] In the embodiments of this application, ZIF-8, ZIF-67 and ZIF-90 are all typical metal-organic framework materials, and can be made in-house or purchased directly from commercially available products according to the preparation processes disclosed in the prior art.
[0025] In one embodiment of the present invention, the degree of deacetylation of the chitosan is 80%.
[0026] In a second aspect, the present invention provides a method for preparing the gas separation membrane described in the first aspect, comprising the following steps: The first polysulfone polymer membrane was obtained by treating the polysulfone polymer membrane with oxygen-enriched microwave plasma. Chitosan solution was spin-coated onto the first polysulfone polymer film and then heat-treated to obtain a modified polysulfone polymer film. The modified polysulfone polymer membrane was immersed in the MOF synthesis solution and then dried to obtain the gas separation membrane.
[0027] This invention first uses oxygen-enriched microwave plasma to treat a polysulfone polymer membrane, forming more active sites and providing an anchor for the chemical modification of chitosan. Then, chitosan with a suitable degree of deacetylation is introduced, maintaining mechanical strength while avoiding excessive crystallization that leads to decreased permeability. Sufficient amino active sites enhance interfacial bonding. Simultaneously, the amino groups can coordinate with metal ions in the MOF synthesis solution, guiding the subsequent directional growth of the MOF. Finally, the MOF is deposited on the surface of the modified polysulfone polymer membrane through in-situ synthesis, forming a multi-layered gradient gas separation membrane with a "polysulfone substrate - chitosan intermediate layer - MOF functional layer" structure. This enhances molecular sieving ability and affinity-based separation effects, thereby improving the selective separation of mixed gases such as propylene / propane, and has broad industrial application prospects.
[0028] In one embodiment of the present invention, the working conditions for the oxygen-enriched microwave plasma treatment include: the working medium is a mixed gas composed of oxygen and argon in a volume ratio of (8~12):1; the microwave power is 300W~400W; and the treatment time is 60s~90s. Preferably, the working conditions for the oxygen-enriched microwave plasma treatment include: the working medium is a mixed gas composed of oxygen and argon in a volume ratio of 10:1; the microwave power is 355W; and the treatment time is 70s.
[0029] In one embodiment of the present invention, the step of spin-coating a chitosan solution onto the first polysulfone polymer film and then subjecting it to heat treatment to obtain a modified polysulfone polymer film includes the following process: Chitosan is dissolved in an aqueous acetic acid solution (for example, an aqueous acetic acid solution composed of acetic acid and water in a mass ratio of 2:95) to obtain a chitosan solution with a mass fraction of 2% to 3%. The chitosan solution was spin-coated onto the first polysulfone polymer film at a spin-coating speed of 800 rpm to 1200 rpm and a spin-coating time of 50 s to 70 s. Then, the heat treatment was carried out at a temperature of 80 ℃ to 90 ℃ for 1 h to 2 h to obtain the modified polysulfone polymer film.
[0030] In the embodiments of this application, the spin coating speed can be 800 rpm, 900 rpm, 1100 rpm, 1200 rpm, etc.; the spin coating time can be 50 s, 55 s, 60 s, 70 s, etc. The amount of chitosan added can be further controlled by controlling the spin coating speed, spin coating time, and the concentration of the chitosan solution.
[0031] In the embodiments of this application, the heat treatment temperature can be 85°C, 88°C, etc., and the heat treatment time can be 1.5h, 2h, etc.
[0032] In one embodiment of the present invention, the step of immersing the modified polysulfone polymer membrane in a MOF synthesis solution and then drying it to obtain the gas separation membrane includes the following process: The MOF synthesis solution was prepared according to the chemical composition of the MOF material. The modified polysulfone polymer membrane is placed in the MOF synthesis solution and immersed for 10 to 60 minutes (e.g., 15, 20, 35, or 40 minutes) at 25°C to 45°C (e.g., 30°C, 35, or 40°C) and 0.8 bar to 1.2 bar (e.g., 1 bar). The membrane is then removed and dried to obtain the gas separation membrane. Thus, MOF is deposited on the surface of the modified polysulfone polymer membrane through in-situ synthesis, ultimately forming a multilayer gradient structure gas separation membrane consisting of a polysulfone substrate, a chitosan intermediate layer, and a MOF functional layer.
[0033] Thirdly, the present invention provides the application of a gas separation membrane as described in any one of the first aspects or a gas separation membrane prepared by the method described in any one of the second aspects in the separation of mixed gases.
[0034] In one embodiment of the present invention, the mixed gas includes a mixed gas composed of propylene and propane.
[0035] It should be noted that, unless otherwise specified, the raw materials involved in the gas separation membrane provided by this invention can be self-made according to the preparation process disclosed in the prior art or commercially available products can be directly used; at the same time, unless otherwise specified, the preparation process operation steps and parameters involved can be carried out according to the preparation process disclosed in the prior art or using existing equipment, and this invention document will not elaborate further.
[0036] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.
[0037] Example 1 This example provides a gas separation membrane, including a modified polysulfone polymer membrane and an MOF layer located on at least a portion of the surface of the modified polysulfone polymer membrane; the modified polysulfone polymer membrane is obtained by sequentially subjecting the polysulfone polymer membrane to oxygen-enriched microwave plasma physical modification treatment and chitosan chemical modification treatment, wherein the degree of deacetylation of the chitosan is 80%, and the polysulfone polymer membrane is a commercially available polyethersulfone ultrafiltration membrane.
[0038] The preparation method of the above-mentioned gas separation membrane includes the following steps: A polysulfone polymer membrane was subjected to oxygen-enriched microwave plasma treatment. The working medium for the oxygen-enriched microwave plasma treatment was a mixed gas composed of oxygen and argon in a volume ratio of 10:1. The microwave power was 355W, and the treatment time was 70s, resulting in a first polysulfone polymer membrane. Chitosan was dissolved in an aqueous acetic acid solution (an aqueous acetic acid solution composed of acetic acid and water in a mass ratio of 2:95) to obtain a chitosan solution with a mass fraction of 2.5%. The chitosan solution was spin-coated onto the first polysulfone polymer membrane at a spin-coating speed of 1000rpm and a spin-coating time of 60s. Subsequently, the membrane was heat-treated at 85°C for 1.5h to obtain the modified polysulfone polymer membrane.
[0039] Based on the chemical composition of MOF materials, the formulated amounts of organic ligands, metal salts, and solvents are mixed and stirred until completely dissolved to obtain a MOF synthesis solution. The organic ligand is 2-methylimidazole with a concentration of 0.4 M; the metal salt is cobalt acetate with a concentration of 0.01 M; and the solvent is water and methanol in a volume ratio of 1:2.
[0040] The modified polysulfone polymer membrane was placed in the MOF synthesis solution and immersed for 30 minutes at 40°C and 1.0 bar. The membrane was then removed and dried to obtain the gas separation membrane.
[0041] Example 2 This example provides a gas separation membrane, including a modified polysulfone polymer membrane and an MOF layer located on at least a portion of the surface of the modified polysulfone polymer membrane; the modified polysulfone polymer membrane is obtained by sequentially subjecting the polysulfone polymer membrane to oxygen-enriched microwave plasma physical modification treatment and chitosan chemical modification treatment, wherein the degree of deacetylation of the chitosan is 70%, and the polysulfone polymer membrane is a commercially available polyethersulfone ultrafiltration membrane.
[0042] The preparation method of the above-mentioned gas separation membrane includes the following steps: A polysulfone polymer membrane was subjected to oxygen-enriched microwave plasma treatment. The working medium for the oxygen-enriched microwave plasma treatment was a mixed gas composed of oxygen and argon in a volume ratio of 8:1. The microwave power was 300W, and the treatment time was 90s, to obtain a first polysulfone polymer membrane. Chitosan was dissolved in an aqueous acetic acid solution (an aqueous acetic acid solution composed of acetic acid and water in a mass ratio of 2:95) to obtain a chitosan solution with a mass fraction of 2%. The chitosan solution was spin-coated onto the first polysulfone polymer membrane at a spin-coating speed of 800rpm and a spin-coating time of 70s, and then heat-treated at 85°C for 1.5h to obtain the modified polysulfone polymer membrane.
[0043] Based on the chemical composition of MOF materials, the formulated amounts of organic ligands, metal salts, and solvents are mixed and stirred until completely dissolved to obtain a MOF synthesis solution. The organic ligand is 2-methylimidazole with a concentration of 0.4 M; the metal salt is cobalt acetate with a concentration of 0.01 M; and the solvent is water and methanol in a volume ratio of 1:2.
[0044] The modified polysulfone polymer membrane was placed in the MOF synthesis solution and immersed for 35 minutes at 35°C and 1.0 bar. The membrane was then removed and dried to obtain the gas separation membrane.
[0045] Example 3 This example provides a gas separation membrane, including a modified polysulfone polymer membrane and an MOF layer located on at least a portion of the surface of the modified polysulfone polymer membrane; the modified polysulfone polymer membrane is obtained by sequentially subjecting the polysulfone polymer membrane to oxygen-enriched microwave plasma physical modification treatment and chitosan chemical modification treatment, wherein the degree of deacetylation of the chitosan is 85%, and the polysulfone polymer membrane is a commercially available polyethersulfone ultrafiltration membrane.
[0046] The preparation method of the above-mentioned gas separation membrane includes the following steps: A polysulfone polymer membrane was subjected to oxygen-enriched microwave plasma treatment. The working medium for the oxygen-enriched microwave plasma treatment was a mixed gas composed of oxygen and argon in a volume ratio of 12:1. The microwave power was 400W, and the treatment time was 60s, to obtain a first polysulfone polymer membrane. Chitosan was dissolved in an aqueous acetic acid solution (an aqueous acetic acid solution composed of acetic acid and water in a mass ratio of 2:95) to obtain a chitosan solution with a mass fraction of 3%. The chitosan solution was spin-coated onto the first polysulfone polymer membrane at a spin-coating speed of 1200rpm and a spin-coating time of 50s, and then heat-treated at 85°C for 1.5h to obtain the modified polysulfone polymer membrane.
[0047] Based on the chemical composition of MOF materials, the formulated amounts of organic ligands, metal salts, and solvents are mixed and stirred until completely dissolved to obtain a MOF synthesis solution. The organic ligand is 2-methylimidazole with a concentration of 0.4 M; the metal salt is cobalt acetate with a concentration of 0.01 M; and the solvent is water and methanol in a volume ratio of 1:2.
[0048] The modified polysulfone polymer membrane was placed in the MOF synthesis solution and immersed for 28 minutes at 42°C and 1.0 bar. The membrane was then removed and dried to obtain the gas separation membrane.
[0049] Comparative Example 1 This example provides a gas separation membrane and its preparation method, which differs from Example 1 only in that: (1) The modified polysulfone polymer membrane was adjusted to the commercially available polyethersulfone ultrafiltration membrane in Example 1 (i.e., without oxygen-enriched microwave plasma physical modification treatment and chitosan chemical modification treatment).
[0050] Comparative Example 2 This example provides a gas separation membrane and its preparation method, which differs from Example 1 only in that: (1) The modified polysulfone polymer membrane was adjusted to the first polysulfone polymer membrane in Example 1 (i.e., without chitosan chemical modification treatment).
[0051] Comparative Example 3 This example provides a gas separation membrane and its preparation method, which differs from Example 1 only in that: (1) The modified polysulfone polymer membrane was adjusted to: spin-coating the chitosan solution in Example 1 onto the commercially available polyethersulfone ultrafiltration membrane in Example 1 at a spin-coating speed of 1000 rpm and a spin-coating time of 60 s, and then heat-treated at 85°C for 1.5 h to obtain the modified polysulfone polymer membrane (i.e., without oxygen-enriched microwave plasma treatment).
[0052] Test case This test example examines the gas separation performance of the gas separation membranes provided in the embodiments and comparative examples according to the test methods disclosed in the prior art. The test method is as follows: The prepared gas separation membrane is placed in a custom-designed membrane chamber, and both sides of the membrane are sealed with silicone gaskets. The feed gas volumetric flow rate is 50 ml / min. 1. Air is introduced into the outlet, and the permeate side of the membrane is purged with Ar gas at a rate of 50 ml / min to quickly remove the gas that has permeated through the membrane, ensuring that the transmembrane partial pressure difference of the gases to be separated is one atmosphere. The purge gas outlet is connected to a gas chromatograph to test the concentration of the separated components on the permeate side. Before introducing the gas chromatograph, a soap bubble flow meter is used to measure the total outlet flow rate on the outlet side, and the gas content is analyzed using gas chromatography to calculate the permeability of propylene or propane and the propylene / propane selectivity.
[0053] The test results are shown in Table 1.
[0054] Table 1 As shown in Table 1, compared with Comparative Examples 1-3, the gas separation membrane provided in this embodiment of the invention has superior gas separation performance, with its propylene / propane selectivity maintained above 90%. This indicates that the present invention, through physical-chemical combined modification of polysulfone polymer membranes using oxygen-enriched microwave plasma technology and chitosan with a specific degree of deacetylation, and then composites it with a metal-organic framework (MOF) layer, can significantly improve the separation selectivity of gas separation membranes for mixed gases such as propylene / propane, and has broad prospects for industrial applications.
[0055] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.
[0056] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.
Claims
1. A gas separation membrane, characterized in that, It includes a modified polysulfone polymer film and a MOF layer located on at least a portion of the surface of the modified polysulfone polymer film; The modified polysulfone polymer membrane is obtained by sequentially subjecting the polysulfone polymer membrane to oxygen-enriched microwave plasma physical modification treatment and chitosan chemical modification treatment, wherein the degree of deacetylation of the chitosan is 70%~85%.
2. The gas separation membrane according to claim 1, characterized in that, The polysulfone polymer membrane includes at least one of polysulfone ultrafiltration membrane and polyethersulfone ultrafiltration membrane.
3. The gas separation membrane according to claim 1, characterized in that, The material of the MOF layer includes at least one of ZIF-8, ZIF-67, and ZIF-90.
4. The gas separation membrane according to claim 1, characterized in that, The degree of deacetylation of the chitosan is 80%.
5. A method for preparing a gas separation membrane according to any one of claims 1 to 4, characterized in that, Includes the following steps: The first polysulfone polymer membrane was obtained by treating the polysulfone polymer membrane with oxygen-enriched microwave plasma. Chitosan solution was spin-coated onto the first polysulfone polymer film and then heat-treated to obtain a modified polysulfone polymer film. The modified polysulfone polymer membrane was immersed in the MOF synthesis solution and then dried to obtain the gas separation membrane.
6. The method for preparing the gas separation membrane according to claim 5, characterized in that, The working conditions parameters for the oxygen-enriched microwave plasma treatment include: the working medium is a mixed gas composed of oxygen and argon with a volume ratio of (8~12):1; the microwave power is 300W~400W; and the treatment time is 60s~90s.
7. The method for preparing the gas separation membrane according to claim 5, characterized in that, The steps of spin-coating a chitosan solution onto the first polysulfone polymer film and then heat-treating it to obtain a modified polysulfone polymer film include the following processes: Chitosan was dissolved in an aqueous acetic acid solution to obtain a chitosan solution with a mass fraction of 2% to 3%. The chitosan solution was spin-coated onto the first polysulfone polymer film at a spin-coating speed of 800 rpm to 1200 rpm and a spin-coating time of 50 s to 70 s. Then, the heat treatment was carried out at a temperature of 80 ℃ to 90 ℃ for 1 h to 2 h to obtain the modified polysulfone polymer film.
8. The method for preparing the gas separation membrane according to claim 5, characterized in that, The steps of immersing the modified polysulfone polymer membrane in a MOF synthesis solution and then drying it to obtain the gas separation membrane include the following processes: The MOF synthesis solution was prepared according to the chemical composition of the MOF material. The modified polysulfone polymer membrane was placed in the MOF synthesis solution and immersed for 10 min to 60 min at 25℃ to 45℃ and 0.8 bar to 1.2 bar. The membrane was then removed and dried to obtain the gas separation membrane.
9. The application of a gas separation membrane according to any one of claims 1 to 4 or a gas separation membrane prepared by the method of any one of claims 5 to 8 in the separation of mixed gases.
10. The application according to claim 9, characterized in that, The mixed gas includes a mixture of propylene and propane.