Gas separation membrane based on metal organic cage as well as preparation method and application of gas separation membrane

Abstract

The invention relates to the technical field of gas separation membranes, in particular to a gas separation membrane based on a metal organic cage and a preparation method and application of the gas separation membrane based on the metal organic cage, a solution containing metal salt, an organic ligand and an organic solvent is prepared and reacts for 2-160 h at the temperature range of 50-200 DEG C, and a metal organic cage material is obtained; preparing a water-phase dispersion liquid containing a metal organic cage and an organic-phase reaction liquid containing polyacyl chloride or polyaldehyde; placing the organic phase reaction liquid on the surface of a support membrane to obtain a support membrane adsorbing an organic phase monomer; placing the water-phase dispersion liquid on the surface of a support membrane adsorbing an organic-phase monomer to obtain a nascent state separation membrane; the operation is repeated, the organic phase reaction liquid and the water phase dispersion liquid are poured on the surface of the nascent state separation membrane for multiple times, and the gas separation membrane based on the metal organic cage is obtained. The metal organic cage gas separation membrane prepared by the invention has high CO2 permeation rate, relatively high CO2 / N2 and CO2 / H2 separation factors and good long-term operation stability.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation membranes, and in particular to a gas separation membrane based on metal organic cages, and a preparation method and application thereof. Background Art

[0002] Human industrial activities release a large amount of greenhouse gases, which is the main cause of global warming. 2 The proportion is 77%, and the contribution to the greenhouse effect is 49%. 2 The efficient use of separation technology is of great significance to achieving carbon emission reduction.

[0003] Common CO 2 The main separation technologies include solvent absorption, pressure swing adsorption, cryogenic distillation and membrane separation. Gas membrane separation technology has the advantages of low energy consumption, simple process and green environmental protection, and is widely used in industrial flue gas CO 2 Capture has a wide range of application prospects. At present, membrane separation technology is widely used in air separation, organic vapor recovery, hydrogen recovery and natural gas (containing H 2 S, CO 2 However, it only occupies 10-20% of the global market share in the field of natural gas purification. 2 Capture and decarbonization of syngas are still in the laboratory development and industrial demonstration stage. 2 The insufficient separation performance of separation membranes seriously restricts their large-scale application in industry.

[0004] Metal-organic cages are discrete supramolecular coordination compounds with confined cavity structures that are self-assembled by coordination-driven self-assembly of metal ions or metal clusters with organic ligands. Metal-organic cages have internal cavities and inter-cage cavities of well-defined size and shape, large specific surface area and ordered microporous structure to promote the adsorption of guest molecules. Due to the weak inter-cage interaction force, metal-organic cages show good solubility in a variety of solvents. These characteristics make organic metal cages show great application potential in the field of gas adsorption and separation. However, the preparation of metal-organic cage gas separation membranes is mostly made of densely packed metal-organic cage crystals, or mixed with polymer matrix to prepare mixed matrix membranes. However, due to the weak intermolecular force of metal-organic cages, it is usually necessary to graft metal-organic cages to prepare pure organic metal cage membranes. The grafted molecules occupy the cavities inside and between cages, which limits the transmission of gas molecules. Preparing a mixed matrix membrane by mixing with a polymer matrix is ​​another method for preparing an organic metal cage membrane, but the agglomeration of the organic metal cage will affect the uniformity of the membrane, the agglomeration will hinder the effective transmission of gas molecules in the membrane, and the interface layer between the polymer and the metal organic cage is prone to defects, thereby reducing the selectivity of the membrane. In addition, the polymer matrix is ​​easy to penetrate into the pores of the metal organic cage, reducing the inherent pore size of the metal organic cage or even completely blocking it. Therefore, these methods cannot give full play to the pore advantages of the metal organic cage, greatly affecting the gas permeation rate and selectivity. In this regard, the present application proposes a method for preparing a high CO2-containing membrane by a simple interfacial polymerization method. 2 / N 2 Permeation-selective properties of metal-organic cage gas separation membranes. Summary of the invention

[0005] The purpose of the present invention is to provide a gas separation membrane based on metal organic cages and a preparation method and application thereof. The prepared metal organic cage gas separation membrane has high CO 2 Permeation rate, higher CO 2 / N 2 and CO 2 / H 2 Separation factor, and also has good long-term operation stability.

[0006] To achieve the above object, the present invention provides a method for preparing a gas separation membrane based on a metal organic cage, comprising the following steps: (1) preparing a solution containing a metal salt, an organic ligand, and an organic solvent, reacting the solution at a temperature ranging from 50 to 200 °C for 2 to 160 h, then washing the solution with an organic solvent, and drying the solution to obtain a metal organic cage material; the organic ligand is a small molecule having a polycarboxylic acid and an imidazole group ligand in the structural formula; (2) uniformly dispersing the metal organic cage material in water to obtain an aqueous dispersion containing the metal organic cage, and dissolving the polyacyl chloride or polyaldehyde monomer in an organic solvent II to obtain an organic reaction liquid containing the polyacyl chloride or polyaldehyde; (3) placing an organic phase reaction solution containing polyacyl chloride or polyaldehyde on the surface of a support membrane, allowing it to stand for 1 to 120 min, removing excess solution, and obtaining a support membrane for adsorbing organic phase monomers; then placing an aqueous phase dispersion containing metal organic cages on the surface of a support membrane for adsorbing organic phase monomers, allowing it to stand for 1 to 120 min, removing excess solution, and rinsing the membrane surface with deionized water to obtain a primary separation membrane; (4) Repeat the above operation to pour the organic phase reaction liquid and the aqueous phase dispersion liquid onto the surface of the primary separation membrane for multiple times to obtain a gas separation membrane based on metal organic cages.

[0007] Preferably, in step (1), the concentration of the metal salt is in the range of 0.01 to 3 mol·L -1 , the organic ligand concentration range is 0.01~3 mol·L -1 .

[0008] Preferably, in step (1), the metal salt includes one or more of copper acetate, copper nitrate, copper chloride, rhodium acetate, rhodium nitrate, cobalt acetate, cobalt nitrate, zirconium nitrate, zirconium acetate, zirconocene dichloride, indium nitrate, silver nitrate, ferrous nitrate, nickel nitrate, nickel acetate, rhenium nitrate, zinc nitrate, zinc acetate, chromium nitrate, chromium acetate, gallium nitrate, manganese nitrate, lead nitrate, titanium tetrachloride, and cadmium nitrate.

[0009] Preferably, in step (1), the organic ligand includes 1,4-benzenedicarboxylic acid, 2-amino-1,4-benzenedicarboxylic acid, 2-bromo-1,4-benzenedicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,5-dihydroxyterephthalic acid, 2,3-dihydroxyterephthalic acid, 2,5-bis(trifluoromethyl)terephthalic acid, 2,5-dihydroxyphthalic acid, 1,1'-biphenyl-4,4'-dicarboxylic acid, 2,3,5,6-tetrafluoroterephthalic acid, 4,5,9,10-tetrahydropyrene-2,7-dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, 2-chloroterephthalic acid, 2,5 -dichlorobenzoic acid, 2,5-dimethyl-1,4-phthalic acid, 4,4'-(1,2-ethynediyl)dibenzoic acid, 5,8-dicarboxy naphthalene-2-sulfonate sodium, 2,5-diaminoterephthalic acid, 4,6-dihydroxyisophthalic acid, tri-(4-imidazolylphenyl)amine, 1,2,3,4,5,6-hexa(1H-imidazol-1-yl)benzene, 4-(1H-imidazol-1-yl)benzoic acid methyl ester, tetrakis(4-imidazolephenyl)methane, 2,2'-biimidazole, tetrakis(1-imidazolephenyl)ethylene, bisimidazobutane, 2,6-di-(1-imidazole)pyridine, 4,5-dicyanoimidazole, 2-amino-4,5-dicyanoimidazole.

[0010] Preferably, in step (1), the organic solvent 1 comprises one or more of benzene, toluene, ethanol, acetone, acetonitrile, n-hexane, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, dichloromethane and chloroform.

[0011] Preferably, in step (2), the polyacyl chloride or polyaldehyde monomer includes 2,2',4,4'-biphenyltetracarboxylic acid chloride, 1,3,5-trimesoyl chloride, terephthaloyl chloride, phthaloyl chloride, isophthaloyl chloride, oxalyl chloride, malonyl chloride, methylmalonyl chloride, succinyl chloride, tetrafluorosuccinyl chloride, glutaryl chloride, hexafluoroglutaryl chloride, adipoyl chloride, octafluoroadipoyl chloride, pimeloyl chloride, suberyl chloride, azelayl chloride, Sebacoyl chloride, 4,4'-oxybis(benzoyl chloride), 1,4-phenylenediacryl chloride, azobenzene-4,4'-dicarbonyl chloride, diethylmalonyl chloride, o-phenylenedisulfonyl chloride, iso-phenylenedisulfonyl chloride, p-phenylenedisulfonyl chloride, 1,3,5-benzenetrisulfonyl chloride, 2,4-disulfonyl chloride-mesitylene, 4,4'-biphenylenedisulfonyl chloride, methylenedisulfonyl chloride, 2,6-naphthalenedisulfonyl chloride, 2,6-pyridinedicarbonyl chloride Acid chloride, dimethylmalonyl chloride, fumaryl chloride, 1,3,5-trialdehyde phloroglucinol, trimesic acid, terephthalaldehyde, biphenyl dicarboxaldehyde, 1,3,5-trialdehyde benzene, 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde, 1,3,5-tris(4-formylphenyl)benzene, 1,3,5-tris(4-formylphenyl)amine, 3,3'-bipyridine-dicarboxaldehyde, 2,5-dihydroxyterephthalaldehyde, One or more of 2-hydroxy-1,3,5-benzenetricarboxaldehyde, 2,5-dibromoterephthalaldehyde, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 2,4,6-trimethoxy-isophthalic acid trimesic acid, tetraaldehyde biphenyl, 2,4,6-tris(4-formylphenyl)-1,3,5-triazine, 1,3,5-tris(4-hydroxy-3'-aldehydephenyl)benzene, and 1,4-dialdehyde-2,5-divinylbenzene.

[0012] Preferably, in step (2), the second organic solvent comprises one or more of ethanol, acetone, mesitylene, acetonitrile, n-hexane, n-heptane, ethyl acetate, dimethyl sulfoxide and dichloromethane.

[0013] Preferably, in step (2), the mass concentration of the metal organic cage material in the aqueous dispersion is 0.1-5 g·L -1 The mass concentration of polyacyl chloride or polyaldehyde monomer in the organic phase reaction solution is 0.1~5 g·L -1 .

[0014] A gas separation membrane based on metal organic cages is prepared by the preparation method of the gas separation membrane based on metal organic cages.

[0015] Application of a gas separation membrane based on metal organic cages for CO separation in mixed gases 2 / N 2 and CO 2 / H 2 separation.

[0016] Mechanism of the present invention: The metal organic cage material of the present invention is formed by a solvothermal method to make metal ions react with polycarboxylic acid ligands or imidazole ligands to form a metal organic cage structure. The metal organic cage material has an adjustable pore structure and abundant reactive functional groups.

[0017] The metal-organic cage material undergoes a cross-linking reaction with polyacyl chlorides through the residual amine groups to form a long-range ordered, highly cross-linked and dense metal-organic cage gas separation membrane. The metal-organic cage has an ordered pore structure of a specific size, so that the prepared separation membrane has the same uniform and ordered pore structure as the metal-organic cage material. On the one hand, there are a large number of amino and carboxyl reactive groups inside the separation membrane pores, which can promote CO 2 On the other hand, the pore size of the designed metal organic cage membrane ranges from 0.35 to 0.65 nm, which is between a CO 2 The molecular dynamics diameter (0.33 nm) of a CO 2 Molecules and N 2 (0.36 nm) and the sum of the kinetic diameters of the molecules (0.69 nm). This pore size makes CO 2 Molecules can be transferred in the pores in the form of surface diffusion, which helps CO 2 The molecules pass through the pores quickly, and the pores adsorb CO 2 The pore size of the molecular back is further reduced, resulting in N 2 The molecules are blocked outside the pores, thereby reducing the passage of molecules such as nitrogen and improving the permeability selectivity of the prepared organic metal cage membrane. In addition, the ordered and regular pore structure of the metal organic cage material and its characteristics of being connected by coordination bonds give the metal organic cage gas separation membrane a higher CO 2 Transfer rate and high stability.

[0018] Beneficial effects of the present invention: (1) A gas separation membrane based on a metal organic cage in the present invention utilizes the ordered pore structure of the metal organic cage with a specific size to separate the CO 2 / N 2 , CO 2 / H 2 It can effectively separate molecules and has high gas molecule selectivity.

[0019] (2) A gas separation membrane based on a metal organic cage in the present invention has a long-range ordered regular pore structure, thereby having high CO 2 transmission rate, and has good long-term operation stability.

[0020] (3) The method for preparing a gas separation membrane based on a metal organic cage in the present invention has a simple preparation process, mild preparation conditions, a wide range of applications, and is easy to scale up and promote.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a preparation flow chart of the metal organic cage gas separation membrane of the present invention; Figure 2 is a surface scanning electron microscope image of the support film in Example 1 of the present invention; Figure 3 This is a surface scanning electron microscope image of a gas separation membrane based on a metal organic cage according to Example 1 of the present invention; Figure 4 This is a cross-sectional scanning electron microscope image of the gas separation membrane based on metal organic cages in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs. The above-mentioned features or features mentioned in the specific examples mentioned in the present invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0024] The method for detecting the gas permeability in the embodiment of the present invention is as follows: The selectivity and gas permeation rate of the metal organic cage gas separation membrane were tested using a laboratory-made membrane performance test device. The test system consists of gas cylinders, membrane cells, pipelines, pressure reducing valves, pressure and flow detectors, soap film flowmeters, gas chromatographs, pressure transmitters, and other components. The effective membrane area tested is 4.90 cm 2 , the test pressure is 1-5bar, and the test temperature is 25±0.5℃.

[0025] The calculation formula of gas permeation rate is as follows: R i =Q i / (ΔP i *A) in, R i For components i The penetration rate is in GPU [1 GPU = 10 -6 cm 3 (STP) cm-2 ·s -1 cmHg -1 = 3.35 × 10 -10 mol·m -2 ·s -1 ·Pa -1 ], 𝑄 𝑖 Indicates the permeate side components i The volume flow rate per unit time under standard conditions, in cm 3 (STP) s -1 , A Indicates the effective membrane area in cm 2 .

[0026] The selectivity of separation membranes for different gases is usually expressed by the separation factor α express, α It can be divided into ideal separation factor and real separation factor. For two gas phase components, the ideal separation factor α * It can be expressed as: 𝛼 * 𝑖 / 𝑗 =R * i / R * j in, R * i and R * j Respectively represent components i and j However, in the actual membrane separation process, the sample to be separated is a mixed gas containing multiple gases, so the actual test is mainly based on its real separation factor, which is defined as: 𝛼 𝑖 / 𝑗 =(y i / y j ) / (x i / x j ) in, 𝑦 𝑖 and 𝑦 𝑗 Respectively represent components i and j The mole fraction in the permeate gas, 𝑥𝑖 and 𝑥 𝑗 Respectively represent components i and j Mole fraction in the feed gas.

[0027] Test the separation performance of mixed gas: CO 2 / N 2 =15:85, CO 2 / H 2 =40:60. The volume flow rate of the gas was measured by a soap film flowmeter, and the mole fraction of the gas was measured using a gas chromatograph.

[0028] Example 1 See also Figures 1 to 4 As shown in the figure, the present invention provides a gas separation membrane based on metal organic cages, and the preparation method thereof comprises the following steps: (1) Prepare 0.1 mol·L -1 Indium nitrate and 0.15 mol·L -1 A solution of 2-amino-4,5-imidazole dicarbonitrile in N,N-dimethylformamide was reacted at 125 °C for 144 h, washed three times with N,N-dimethylformamide and then dried in vacuum at 80 °C for 24 h to obtain a metal organic cage material.

[0029] (2) Disperse the metal organic cage material evenly in water to prepare a 0.1 g·L -1 The aqueous dispersion of metal organic cages was prepared. -1 A n-hexane solution of 1,3,5-trimethylbenzenecarboxylic acid chloride was used as the organic phase reaction liquid.

[0030] (3) The organic phase reaction solution was placed on the surface of the polysulfone membrane, and allowed to stand at 25 °C for 5 min, after which the excess solution was removed to obtain a polysulfone membrane that adsorbed organic phase monomers. The aqueous phase dispersion containing the metal organic cage material was placed on the surface of the polysulfone membrane that adsorbed organic phase monomers, and allowed to stand at 25 °C for 20 min, after which the excess solution was removed and rinsed with deionized water to obtain a primary separation membrane.

[0031] (4) The organic phase reaction liquid and the aqueous phase dispersion are then placed on the surface of the primary separation membrane twice, respectively, and finally rinsed with deionized water to obtain a dense metal organic cage gas separation membrane.

[0032] The prepared metal organic cage gas separation membrane has good performance for CO separation at 1 bar. 2 、N 2 and H 2 The permeation rates of pure gas are 4300 GPU, 215 GPU and 935 GPU respectively; for mixed gas CO2 / N 2 and CO 2 / H 2 The separation factors reached 29 and 7 respectively, and the membrane could maintain stable separation performance during 24 h continuous operation.

[0033] Figure 3 is a surface scanning electron microscope image of a gas separation membrane based on a metal organic cage according to Example 1 of the present invention, Figure 4 is a cross-sectional scanning electron microscope image of a gas separation membrane based on a metal organic cage in Example 1 of the present invention, Figure 3 It can be seen from the figure that the surface of the metal organic cage membrane is smooth, dense and defect-free. Figure 4 It can be seen that the thickness of the selective separation layer of the metal-organic cage membrane is about 90 nm.

[0034] Example 2 The present invention provides a gas separation membrane based on metal organic cages, and the preparation method thereof comprises the following steps: (1) Prepare 0.15 mol·L -1 Zirconocene dichloride and 0.09 mol·L -1 A solution of 2-amino-1,4-phthalic acid in N,N-dimethylacetamide was reacted at 60°C for 10 h, washed three times with N,N-dimethylacetamide and dried at 40°C for 24 h to obtain a metal organic cage material.

[0035] (2) Disperse the metal organic cage material evenly in water to prepare a 0.1 g·L -1 The aqueous dispersion of metal organic cages was prepared. -1 A solution of terephthaloyl chloride in n-heptane was used as the organic phase reaction liquid.

[0036] (3) The organic phase reaction solution was placed on the surface of the polyethersulfone membrane, and allowed to stand at 25°C for 5 min, after which the excess solution was removed to obtain a polysulfone membrane that adsorbed organic phase monomers. The aqueous phase dispersion containing the metal organic cage material was placed on the surface of the polysulfone membrane that adsorbed organic phase monomers, and allowed to stand at 25°C for 20 min, after which the excess solution was removed and rinsed with deionized water to obtain a primary separation membrane.

[0037] (4) The organic phase reaction liquid and the aqueous phase dispersion are then placed on the surface of the primary separation membrane twice, respectively, and finally rinsed with deionized water to obtain a dense metal organic cage gas separation membrane.

[0038] The prepared metal organic cage gas separation membrane has good performance for CO 2 、N 2 and H 2The permeation rates of pure gas are 3200 GPU, 154 GPU and 617 GPU respectively; for the mixed gas CO 2 / N 2 and CO 2 / H 2 The separation factors reached 26 and 6 respectively, and the membrane could maintain stable separation performance during 24 h continuous operation.

[0039] Example 3 The present invention provides a gas separation membrane based on metal organic cages, and the preparation method thereof comprises the following steps: (1) Prepare 0.011 mol·L -1 Copper acetate and 0.01 mol·L -1 The methanol solution of 2-amino-1,4-phthalic acid was reacted at 80 °C for 72 h, washed three times with methanol and dried at 40 °C for 24 h to obtain the metal organic cage material.

[0040] (2) Disperse the metal organic cage material evenly in water to prepare a 0.1 g·L -1 The aqueous dispersion of metal organic cages was prepared. -1 A n-heptane solution of 2,5-dihydroxyterephthalaldehyde is used as the organic phase reaction liquid.

[0041] (3) The organic phase reaction solution was placed on the surface of the polyacrylonitrile membrane and allowed to stand at 25 °C for 5 min, after which the excess solution was removed to obtain a polyacrylonitrile membrane that adsorbed organic phase monomers. The aqueous phase dispersion containing the metal organic cage material was placed on the surface of the polyacrylonitrile membrane that adsorbed organic phase monomers and allowed to stand at 25 °C for 20 min, after which the excess solution was removed and rinsed with deionized water to obtain a primary separation membrane.

[0042] (4) The organic phase reaction liquid and the aqueous phase dispersion are then placed on the surface of the primary separation membrane twice, respectively, and finally rinsed with deionized water to obtain a dense metal organic cage gas separation membrane.

[0043] The prepared metal organic cage gas separation membrane has good performance for CO separation at 1 bar. 2 、N 2 and H 2 The permeation rates of pure gas were 3560 GPU, 251 GPU and 723 GPU respectively; for the mixed gas CO 2 / N 2 and CO 2 / H 2 The separation factors reached 24 and 6 respectively, and the membrane could maintain stable separation performance during 24h continuous operation.

[0044] Comparative Example 1 A gas separation membrane free of metal organic cage materials, the preparation method of which comprises the following steps: (1) Prepare 0.625 g·L -1 Prepare an aqueous solution of piperazine containing 0.66 g·L -1 A n-hexane solution of 1,3,5-benzenetricarboxylic acid chloride is used as the organic phase reaction liquid.

[0045] The organic phase reaction solution was placed on the surface of the polysulfone support membrane, and allowed to stand at 25°C for 10 min, after which the excess solution was removed to obtain a polysulfone membrane adsorbing organic phase monomers. The piperazine-containing aqueous phase solution was placed on the surface of the polysulfone membrane adsorbing organic phase monomers, and allowed to stand at 25°C for 10 min, after which the excess solution was removed, and the membrane surface was rinsed with deionized water to remove unreacted monomers, to obtain a gas separation membrane free of metal organic cage materials.

[0046] The prepared gas separation membrane without metal organic cage materials has good performance for CO separation at 1 bar. 2 、N 2 and H 2 The permeation rates of pure gas were 650 GPU, 54 GPU and 217 GPU respectively; for the mixed gas CO 2 / N 2 and CO 2 / H 2 The separation factors reached 14 and 4 respectively, and the membrane could maintain stable separation performance during 24 h continuous operation.

[0047] Therefore, the gas separation membrane based on metal organic cage provided by the present invention has higher CO 2 Permeation rate and better CO 2 / N 2 , CO 2 / H 2 Select Performance.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a gas separation membrane based on a metal organic cage, characterized in that: The following steps are involved: (1) preparing a solution containing a metal salt, an organic ligand, and an organic solvent, reacting the solution at a temperature ranging from 50 to 200 °C for 2 to 160 h, then washing the solution with an organic solvent, and drying the solution to obtain a metal organic cage material; the organic ligand is a small molecule containing a polycarboxylic acid or an imidazole group in the structural formula; (2) uniformly dispersing the metal organic cage material in water to obtain an aqueous dispersion containing the metal organic cage, and dissolving the polyacyl chloride or polyaldehyde monomer in an organic solvent II to obtain an organic reaction liquid containing the polyacyl chloride or polyaldehyde; (3) placing an organic phase reaction liquid containing polyacyl chloride or polyaldehyde on the surface of a support membrane, allowing it to stand for 1 to 120 min, removing excess solution, and obtaining a support membrane that adsorbs organic phase monomers; then placing an aqueous phase dispersion containing metal organic cages on the surface of a support membrane that adsorbs organic phase monomers, allowing it to stand for 1 to 120 min, removing excess solution, and rinsing the membrane surface with deionized water to obtain a primary separation membrane; (4) Repeat the above operation to pour the organic phase reaction liquid and the aqueous phase dispersion liquid onto the surface of the primary separation membrane for multiple times to obtain a gas separation membrane based on metal organic cages.

2. The method for preparing a gas separation membrane based on a metal organic cage according to claim 1, characterized in that: In step (1), the concentration of the metal salt is in the range of 0.01 to 3 mol·L -1 , the organic ligand concentration range is 0.01~3 mol·L -1 .

3. The method for preparing a gas separation membrane based on a metal organic cage according to claim 1, characterized in that: In step (1), the metal salt includes one or more of copper acetate, copper nitrate, copper chloride, rhodium acetate, rhodium nitrate, cobalt acetate, cobalt nitrate, zirconium nitrate, zirconium acetate, zirconocene dichloride, indium nitrate, silver nitrate, ferrous nitrate, nickel nitrate, nickel acetate, rhenium nitrate, zinc nitrate, zinc acetate, chromium nitrate, chromium acetate, gallium nitrate, manganese nitrate, lead nitrate, titanium tetrachloride, and cadmium nitrate.

4. The method for preparing a gas separation membrane based on a metal organic cage according to claim 1, characterized in that: In step (1), the organic ligand includes 1,4-benzenedicarboxylic acid, 2-amino-1,4-benzenedicarboxylic acid, 2-bromo-1,4-benzenedicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,5-dihydroxyterephthalic acid, 2,3-dihydroxyterephthalic acid, 2,5-bis(trifluoromethyl)terephthalic acid, 2,5-dihydroxyphthalic acid, 1,1'-biphenyl-4,4'-dicarboxylic acid, 2,3,5,6-tetrafluoroterephthalic acid, 4,5,9,10-tetrahydropyrene-2,7-dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, 2-chloroterephthalic acid, 2,5-di One or more of chloroparaben, 2,5-dimethyl-1,4-phthalic acid, 4,4'-(1,2-ethynediyl)dibenzoic acid, 5,8-dicarboxy naphthalene-2-sulfonate sodium, 2,5-diaminoterephthalic acid, 4,6-dihydroxyisophthalic acid, tri-(4-imidazolylphenyl)amine, 1,2,3,4,5,6-hexa(1H-imidazol-1-yl)benzene, 4-(1H-imidazol-1-yl)benzoic acid methyl ester, tetrakis(4-imidazolephenyl)methane, 2,2'-biimidazole, tetrakis(1-imidazolephenyl)ethylene, bisimidazobutane, 2,6-di-(1-imidazole)pyridine, 4,5-dicyanoimidazole, and 2-amino-4,5-dicyanoimidazole.

5. The method for preparing a gas separation membrane based on a metal organic cage according to claim 1, characterized in that: In step (1), the organic solvent 1 includes one or more of benzene, toluene, ethanol, N,N-dimethylformamide, N,N-dimethylacetamide, acetone, acetonitrile, n-hexane, ethyl acetate, dichloromethane and chloroform.

6. The method for preparing a gas separation membrane based on a metal organic cage according to claim 1, characterized in that: In step (2), the polyacyl chloride or polyaldehyde monomer includes 2,2',4,4'-biphenyltetracarboxylic acid chloride, 1,3,5-trimethylbenzenecarboxylic acid chloride, terephthaloyl chloride, phthaloyl chloride, isophthaloyl chloride, oxalyl chloride, malonyl chloride, methylmalonyl chloride, succinyl chloride, tetrafluorosuccinyl chloride, glutaryl chloride, hexafluoroglutaryl chloride, adipoyl chloride, octafluoroadipoyl chloride, pimeloyl chloride, suberyl chloride, azelayl chloride, sebacoyl chloride, Chlorine, 4,4'-oxybis(benzoyl chloride), 1,4-phenylenediacryl chloride, azobenzene-4,4'-dicarbonyl chloride, diethylmalonyl chloride, o-phenylenedisulfonyl chloride, iso-phenylenedisulfonyl chloride, p-phenylenedisulfonyl chloride, 1,3,5-benzenetrisulfonyl chloride, 2,4-disulfonyl chloride-mesitylene, 4,4'-biphenylenedisulfonyl chloride, methylenedisulfonyl chloride, 2,6-naphthalenedisulfonyl chloride, 2,6-pyridinedicarbonyl chloride , dimethylmalonyl chloride, fumaryl chloride, 1,3,5-trialdehyde phloroglucinol, trimesic acid, terephthalaldehyde, biphenyl dicarboxaldehyde, 1,3,5-trialdehyde benzene, 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde, 1,3,5-tris(4-formylphenyl)benzene, 1,3,5-tris(4-formylphenyl)amine, 3,3'-bipyridine-dicarboxaldehyde, 2,5-dihydroxyterephthalaldehyde, 2 -hydroxy-1,3,5-benzenetricarboxaldehyde, 2,5-dibromoterephthalaldehyde, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 2,4,6-trimethoxy-isophthalic acid, tetraaldehyde biphenyl, 2,4,6-tris(4-formylphenyl)-1,3,5-triazine, 1,3,5-tris(4-hydroxy-3'-formylphenyl)benzene, 1,4-dialdehyde-2,5-divinylbenzene or more.

7. The method for preparing a gas separation membrane based on a metal organic cage according to claim 1, characterized in that: In step (2), the organic solvent 2 includes one or more of ethanol, acetone, mesitylene, acetonitrile, n-hexane, n-heptane, ethyl acetate, dimethyl sulfoxide and dichloromethane.

8. The method for preparing a gas separation membrane based on a metal organic cage according to claim 1, characterized in that: In step (2), the mass concentration of the metal organic cage material in the aqueous dispersion is 0.1-5 g·L -1 The mass concentration of polyacyl chloride or polyaldehyde monomer in the organic phase reaction solution is 0.1~5 g·L -1 .

9. A gas separation membrane based on metal organic cages, characterized in that: The gas separation membrane is prepared by the method for preparing a metal organic cage-based gas separation membrane according to any one of claims 1 to 8.

10. An application of a gas separation membrane based on a metal organic cage, characterized in that: The metal organic cage based gas separation membrane as described in claim 9 is used for separation of CO2 / N2 and CO2 / H2 in mixed gas.

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