Gas separation membrane based on covalent organic framework 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 covalent organic framework and a preparation method and application thereof, and the preparation method comprises the following steps: preparing a mixed solution containing a polyamine monomer, a polyaldehyde monomer and an organic solvent, and reacting to obtain a COF material; the preparation method comprises the following steps: preparing an amine micromolecule aqueous solution, adding a COF material, and mixing until adsorption equilibrium to obtain NH2-COF; preparing a water-phase reaction solution containing NH2-COF and an organic-phase reaction solution containing multi-acyl chloride; the water-phase reaction liquid is in contact with the surface of the support membrane, and is in contact with the organic-phase reaction liquid after excess liquid is removed, and a nascent state COF membrane is obtained through reaction; and carrying out heat treatment on the nascent state COF membrane at 30-90 DEG C for 1-30 minutes to obtain the COF gas separation membrane. The gas separation membrane prepared by the invention can realize efficient separation of carbon dioxide / nitrogen and carbon dioxide / methane, and solves the problem of low selectivity of a COF membrane in separation of carbon dioxide / nitrogen and carbon dioxide / methane in the prior art.

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 a covalent organic framework, and a preparation method and application thereof. Background Art

[0002] CO2 is the most important greenhouse gas, and its main source is industrial coal-fired flue gas. Carbon capture technology is the abbreviation of carbon dioxide capture, utilization and storage technology. It can separate, enrich and utilize the CO2 produced by fossil fuel combustion, thereby reducing the impact of the greenhouse gas effect. In addition, the industrial application of CO2 separation also includes hydrogen purification (CO2 / H2 separation) and natural gas purification (CO2 / CH4 separation).

[0003] At present, the main CO2 capture technologies include absorption, adsorption, and membrane separation. Membrane separation CO2 capture uses the pressure difference on both sides of the membrane as a driving force to achieve gas separation based on the different permeation rates of each component in the membrane. Compared with traditional CO2 capture technology, gas separation membrane technology is an environmentally friendly separation technology with the advantages of low energy consumption, low cost, high efficiency, no phase change of permeated substances, high operating continuity, and high equipment integration, becoming the representative of the second generation of carbon capture technology.

[0004] Polymer membrane materials have the advantages of easy processing, good film-forming properties, and high toughness, and have become common gas separation membrane materials for industrial applications. However, there is often a trade-off between the gas permeability and selectivity of polymer membrane materials. Therefore, the development of high-performance gas separation membrane materials is of great significance for achieving efficient separation of carbon dioxide / nitrogen and carbon dioxide / methane, and promoting the industrialization of carbon dioxide emission reduction and methane purification.

[0005] Covalent organic framework (COFs) materials are crystalline porous materials with two-dimensional or three-dimensional structures formed by covalent bonds of light elements (C, N, O, B, H, etc.) and reversible polymerization reactions controlled by thermodynamics. Compared with traditional amorphous polymer membranes, COFs membranes have orderly and regular pores, which are expected to break the trade-off between permeability and selectivity and achieve ultrafast gas molecule transmission and screening. However, the pore size (>1 nm) of COFs materials in existing technologies is much larger than the kinetic diameter of common gas molecules (H2, N2, CO2, CH4, etc.), making it difficult to achieve selective separation of gas molecules. Summary of the invention

[0006] The purpose of the present invention is to provide a gas separation membrane based on a covalent organic framework, and a preparation method and application thereof. The prepared gas separation membrane can achieve efficient separation of carbon dioxide / nitrogen and carbon dioxide / methane, and solve the problem of low selectivity of COF membranes in the separation of carbon dioxide / nitrogen and carbon dioxide / methane in the prior art.

[0007] To achieve the above object, the present invention provides a method for preparing a gas separation membrane based on a covalent organic framework, comprising the following steps: (1) preparing a mixed solution containing a polyamine monomer, a polyaldehyde monomer, and an organic solvent, reacting the mixture at 50-200 °C for 12-72 h, and then washing and drying the mixture to obtain a COF material; (2) preparing an aqueous solution of amine small molecules, adding COF material, mixing until adsorption equilibrium, centrifuging and drying to obtain the aminated COF material NH2-COF; (3) uniformly dispersing NH2-COF in water to obtain an aqueous phase reaction liquid containing NH2-COF; dissolving polyacyl chloride monomers in an organic solvent to obtain an organic phase reaction liquid containing polyacyl chloride; (4) After the aqueous phase reaction liquid contacts the support membrane surface for 1 to 30 minutes, the excess liquid is removed and then contacted with the organic phase reaction liquid for 5 to 60 minutes to obtain the primary COF membrane; (5) The nascent COF membrane is heat treated at 30-90 °C for 1-30 min to obtain a COF gas separation membrane.

[0008] Preferably, the concentration of the polyamine monomer in the mixed solution of step (1) is in the range of 0.1 to 5 mol·L -1 The concentration of polyaldehyde monomers ranges from 0.1 to 5 mol·L -1 .

[0009] Preferably, in step (1), the polyamine monomer includes one or more of p-phenylenediamine, piperazine, 2,5-dimethyl-p-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 2-sulfonic acid-1,4-phenylenediamine, m-phenylenediamine and o-phenylenediamine.

[0010] Preferably, in step (1), the polyaldehyde monomer includes one or more of 2,4,6-triformylphloroglucinol, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 4,4'-biphenyldicarboxaldehyde, 2,2'-bipyridine-5,5'-dicarboxaldehyde, 2,5-dihydroxyterephthalaldehyde, 1,4-dialdehyde-2,5-divinylbenzene, 2,3,5,6-tetrafluorobenzaldehyde, glyoxal, glutaraldehyde, adipaldehyde, 1,3-succinaldehyde, terephthalaldehyde, 2,5-dichloroterephthalaldehyde and 3,3',5,5'-tetraaldehyde-4,4'-dihydroxybiphenyl.

[0011] Preferably, the organic solvents in step (1) and step (3) include one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, benzene, toluene, mesitylene, ethanol, acetone, acetonitrile, n-hexane, ethyl acetate, dichloromethane and chloroform.

[0012] Preferably, in step (2), the amine small molecule includes one or more of ethylenediamine, propylenediamine, polyethyleneimine, monoethanolamine, diethanolamine, polyoxyethylenediamine, triethanolamine, m-phenylenediamine, adipic acid diamine, piperazine, o-phenylenediamine, polyethylene polyamine, p-phenylenediamine, and polyvinylamine; The concentration of amine small molecules in the aqueous solution is 0.1~5 mol·L -1 The adsorption equilibrium time is 0.5~24 h.

[0013] Preferably, in step (3), the polyacyl chloride monomer includes one or more of phthalate disulfonyl chloride, isophthalate disulfonyl chloride, 4,4'-biphenyl disulfonyl chloride, 2,6-pyridine dicarbonyl chloride, terephthalate disulfonyl chloride, fumaroyl chloride, 1,3,5-trimesoyl chloride, terephthaloyl chloride, octafluoroadipoyl chloride, phthaloyl chloride, azelayl chloride, isophthaloyl chloride, oxalyl chloride, hexafluoroglutaryl chloride, malonyl chloride, methylmalonyl chloride, succinoyl chloride, tetrafluorosuccinoyl chloride, glutaryl chloride, adipoyl chloride, pimeloyl chloride, suberyl chloride, and sebacoyl chloride.

[0014] Preferably, in step (3), the mass concentration of NH2-COF in the aqueous reaction solution is 0.1-5 g·L -1 The mass concentration of polyacyl chloride in the organic phase reaction solution is 0.1~5 g·L -1 .

[0015] A gas separation membrane based on a covalent organic framework is prepared by the preparation method of the gas separation membrane based on a covalent organic framework.

[0016] An application of a gas separation membrane based on a covalent organic framework for the separation of carbon dioxide / nitrogen and carbon dioxide / methane systems.

[0017] Mechanism of the present invention: The present invention uses an aminated COF material as a water phase reaction monomer and a polyacyl chloride as an organic phase reaction monomer to prepare a gas separation membrane based on a covalent organic framework through an interfacial reaction. The COF material has an ordered pore structure of a specific size, which provides a fast and selective channel for gas transmission, and the aminated COF material obtained by adsorbing small amine molecules contains a large number of amino groups in the pores, which can reduce the COF pore size on the one hand and increase the adsorption amount of CO2 in the COF pores on the other hand. Therefore, the aminated COF membrane constructed by the above method is suitable for the selective and rapid transmission of CO2 molecules, thereby realizing the efficient separation of carbon dioxide / nitrogen and carbon dioxide / methane.

[0018] Beneficial effects of the present invention: (1) A gas separation membrane based on a covalent organic framework of the present invention has excellent structural stability and good long-term operation stability; (2) A gas separation membrane based on a covalent organic framework of the present invention has a high carbon dioxide permeation rate and a moderate carbon dioxide / nitrogen selectivity, and can be applied to capture carbon dioxide from flue gas; (3) A gas separation membrane based on a covalent organic framework of the present invention has a high carbon dioxide permeation rate and a moderate carbon dioxide / methane selectivity, and can be applied to methane purification in natural gas, shale gas, coalbed methane and other systems; (4) The present invention provides a method for preparing a gas separation membrane based on a covalent organic framework. The method is simple, the preparation conditions are mild, and it is easy to realize industrial production.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a surface scanning electron microscope image of the polysulfone-based membrane in Example 1 of the present invention; Figure 2 This is a surface scanning electron microscope image of the COF gas separation membrane in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] 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.

[0022] There is no particular limitation on the sources of all raw materials in the present invention and the following examples, and any raw materials available on the market may be used.

[0023] The method for detecting the gas permeation rate in the embodiment of the present invention is as follows: The membrane permeation selectivity performance test system was used to test the membrane permeation rate of CO2, N2 and CH4. The test system included a membrane pool, pipeline, regulating valve, pressure gauge, soap film flowmeter and gas chromatograph. The effective membrane area tested was 4.91 cm 2 , the test pressure is 1~6 bar, and the test temperature is 20±1 ℃.

[0024] The calculation formula of gas permeation rate is as follows: R i =Q i / (A·△P i ), Where R i is the penetration rate of component i, in GPU (1 GPU = 10 -6 cm 3 (STP) cm -2 ·s -1 cmHg -1 ), Q i is the volume flow rate of component i at standard temperature and pressure (STP), in cm 3 (STP) / s; ΔP i is the partial pressure difference of component i on both sides of the membrane, in cmHg; A is the effective membrane area, in cm 2 .

[0025] The selectivity of separation membranes is often evaluated by separation selectivity, i.e., separation factor (α). Commonly used separation factors include ideal separation factor and true separation factor.

[0026] When using pure gas for testing, the ideal separation factor of components i and j is α * i / j The definition is: In the formula, R i and R j are the permeation rates of components i and j, respectively.

[0027] For a gas mixture containing two components i and j, the true separation factor is α' i / j The definition is: In the formula, y i 、y j are the mole fractions of components i and j in the permeate gas, respectively;x i 、x j are the mole fractions of components i and j in the feed gas, respectively.

[0028] Example 1 The present invention provides a gas separation membrane based on a covalent organic framework, and a preparation method thereof comprises the following steps: (1) Prepare 0.2 mol·L -1 Piperazine and 0.1 mol·L -1 The toluene solution of terephthalaldehyde was reacted at 100 °C for 72 h, washed three times with toluene and ethanol, and dried at 80 °C for 24 h to obtain the COF material.

[0029] (2) Prepare the solution at a concentration of 1 mol·L -1 The COF material powder was mixed with the monoethanolamine aqueous solution, stirred for 8 h, and then centrifuged and dried to obtain the NH2-COF material.

[0030] (3) Prepare a solution containing 0.5 g·L -1 The aqueous reaction solution of NH2-COF material was prepared to contain 0.5 g·L -1 A n-hexane solution of 1,3,5-trimethylbenzenecarboxylic acid chloride was used as the organic phase reaction liquid.

[0031] (4) The aqueous reaction liquid was allowed to contact with the surface of the polysulfone-based membrane for 10 min. After removing the excess solution on the surface, the aqueous reaction liquid was allowed to contact with the organic reaction liquid. After reacting for 10 min, the excess reaction liquid was removed and the residual organic phase monomer on the surface was washed with n-hexane to obtain a primary COF membrane.

[0032] (5) The prepared nascent COF membrane was heat treated at 80 °C for 10 min to obtain a COF gas separation membrane.

[0033] After testing, the COF gas separation membrane has a CO2 permeability rate of 1000 GPU, a CO2 / N2 separation factor of 28, and a CO2 / CH4 separation factor of 17.

[0034] Figure 1 is a surface scanning electron microscope image of the polysulfone base membrane in Example 1 of the present invention, Figure 1 It can be seen that the surface of the polysulfone-based membrane is smooth; Figure 2 is a surface scanning electron microscope image of the COF gas separation membrane in Example 1 of the present invention, Figure 2 It can be seen that the surface of the COF gas separation membrane shows accumulated NH2-COF nanoparticles.

[0035] Example 2 The present invention provides a gas separation membrane based on a covalent organic framework, and a preparation method thereof comprises the following steps: (1) Prepare 0.3 mol·L -1 2,5-Dimethyl-p-phenylenediamine and 0.1 mol·L -1 The toluene solution of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde was reacted at 100 °C for 72 h, washed three times with toluene and ethanol, and dried at 80 °C for 24 h to obtain the COF material.

[0036] (2) Prepare the solution at a concentration of 1 mol·L -1 The COF material powder is mixed with the polyethylene polyamine aqueous solution, stirred for 8 h, centrifuged and dried to obtain NH2-COF material.

[0037] (3) Prepare a solution containing 0.3 g·L -1 The aqueous phase reaction solution of NH2-COF material was prepared to contain 1.5 g·L -1 A solution of terephthaloyl chloride in n-heptane was used as the organic phase reaction liquid.

[0038] (4) The aqueous reaction liquid was allowed to contact with the surface of the polyacrylonitrile-based membrane for 5 min. After removing the excess solution on the surface, the aqueous reaction liquid was allowed to contact with the organic reaction liquid. After reacting for 5 min, the excess reaction liquid was removed and the residual organic phase monomer on the surface was washed with n-heptane to obtain a nascent COF membrane.

[0039] (5) The prepared nascent COF membrane was heat treated at 80 °C for 5 min to obtain a COF gas separation membrane.

[0040] After testing, the COF gas separation membrane has a CO2 permeability of 800 GPU, a CO2 / N2 separation factor of 35, and a CO2 / CH4 separation factor of 23.

[0041] Example 3 The present invention provides a gas separation membrane based on a covalent organic framework, and a preparation method thereof comprises the following steps: (1) Prepare 0.2 mol·L -1 1,3,5-triaminobenzene and 0.1 mol·L -1 The toluene solution of terephthalaldehyde was reacted at 100 °C for 72 h, washed three times with toluene and ethanol, and dried at 80 °C for 24 h to obtain the COF material.

[0042] (2) Prepare the solution at a concentration of 1 mol·L -1 The COF material powder was mixed with the polyethyleneimine aqueous solution, stirred for 20 h, and then centrifuged and dried to obtain the NH2-COF material.

[0043] (3) Prepare a solution containing 0.5 g·L -1 The aqueous reaction solution of NH2-COF material was prepared to contain 1.0 g·L -1 A n-heptane solution of isophthaloyl chloride was used as the organic phase reaction liquid.

[0044] (4) The aqueous reaction liquid was allowed to contact with the surface of the polyethersulfone-based membrane for 5 minutes. After removing the excess solution on the surface, the aqueous reaction liquid was allowed to contact with the organic reaction liquid. After reacting for 5 minutes, the excess reaction liquid was removed and the residual organic phase monomer on the surface was washed with n-heptane to obtain a primary COF membrane.

[0045] (5) The prepared nascent COF membrane was heat treated at 80 °C for 5 min to obtain a COF gas separation membrane.

[0046] After testing, the COF gas separation membrane has a CO2 permeability rate of 1100 GPU, a CO2 / N2 separation factor of 40, and a CO2 / CH4 separation factor of 26.

[0047] Example 4 The present invention provides a gas separation membrane based on a covalent organic framework, and a preparation method thereof comprises the following steps: (1) Prepare 0.2 mol·L -1 p-phenylenediamine and 0.1 mol·L -1 The toluene solution of terephthalaldehyde was reacted at 100 °C for 72 h, washed three times with toluene and ethanol, and dried at 80 °C for 24 h to obtain the COF material.

[0048] (2) Prepare the solution at a concentration of 1 mol·L -1 The COF powder was mixed with the adipic acid diamine aqueous solution, stirred for 10 h, centrifuged and dried to obtain NH2-COF material.

[0049] (3) Prepare a solution containing 0.5 g·L -1 The aqueous reaction solution of NH2-COF material was prepared to contain 1.0 g·L -1 Suberoyl chloride in n-heptane was used as the organic phase reaction liquid.

[0050] (4) The aqueous reaction liquid was allowed to contact with the surface of the polyethersulfone-based membrane for 5 minutes. After removing the excess solution on the surface, the aqueous reaction liquid was allowed to contact with the organic reaction liquid. After reacting for 5 minutes, the excess reaction liquid was removed and the residual organic phase monomer on the surface was washed with n-heptane to obtain a primary COF membrane.

[0051] (5) The prepared nascent COF membrane was heat treated at 80 °C for 5 min to obtain a COF gas separation membrane.

[0052] After testing, the COF gas separation membrane has a CO2 permeability rate of 1200 GPU, a CO2 / N2 separation factor of 32, and a CO2 / CH4 separation factor of 25.

[0053] Example 5 The present invention provides a gas separation membrane based on a covalent organic framework, and a preparation method thereof comprises the following steps: (1) Prepare 0.2 mol·L -1 p-phenylenediamine and 0.1 mol·L -1 The toluene solution of terephthalaldehyde was reacted at 100 °C for 72 h, washed three times with toluene and ethanol, and dried at 80 °C for 24 h to obtain the COF material.

[0054] (2) Prepare a solution containing 0.5 g·L -1 The aqueous reaction solution of pure COF material was prepared to contain 1.0 g·L -1 Suberoyl chloride in n-heptane was used as the organic phase reaction liquid.

[0055] (3) The aqueous reaction liquid was allowed to contact with the surface of the polyethersulfone-based membrane for 5 min. After removing the excess solution on the surface, the aqueous reaction liquid was allowed to contact with the organic reaction liquid. After reacting for 5 min, the excess reaction liquid was removed and the residual organic phase monomer on the surface was washed with n-heptane to obtain a primary COF membrane.

[0056] (4) The prepared nascent COF membrane was heat treated at 80 °C for 5 min to obtain an unaminated COF gas separation membrane.

[0057] After testing, the CO2 permeation rate of the unaminated COF gas separation membrane obtained reached 400 GPU, the CO2 / N2 separation factor was 18, and the CO2 / CH4 separation factor was 8.

[0058] In summary, the covalent organic framework membrane prepared by the present invention has a high carbon dioxide permeation rate, good structural stability and long-term operation stability, and can achieve efficient separation of carbon dioxide / nitrogen and carbon dioxide / methane.

[0059] 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 covalent organic framework, characterized in that: The following steps are involved: (1) preparing a mixed solution containing a polyamine monomer, a polyaldehyde monomer, and an organic solvent, reacting the mixture at 50-200°C for 12-72 hours, and then washing and drying the mixture to obtain a COF material; (2) preparing an aqueous solution of amine small molecules, adding COF material, mixing until adsorption equilibrium, centrifuging and drying to obtain the aminated COF material NH2-COF; (3) uniformly dispersing NH2-COF in water to obtain an aqueous phase reaction liquid containing NH2-COF; dissolving polyacyl chloride monomers in an organic solvent to obtain an organic phase reaction liquid containing polyacyl chloride; (4) The aqueous phase reaction liquid is in contact with the support membrane surface for 1 to 30 minutes, and after removing the excess liquid, it is in contact with the organic phase reaction liquid for 5 to 60 minutes to obtain the primary COF membrane; (5) The nascent COF membrane is heat treated at 30-90 °C for 1-30 min to obtain a COF gas separation membrane.

2. The method for preparing a gas separation membrane based on a covalent organic framework according to claim 1, characterized in that: The concentration of the polyamine monomer in the mixed solution of step (1) is in the range of 0.1 to 5 mol·L -1 The concentration of polyaldehyde monomers ranges from 0.1 to 5 mol·L -1 .

3. The method for preparing a gas separation membrane based on a covalent organic framework according to claim 1, characterized in that: In step (1), the polyamine monomer includes one or more of p-phenylenediamine, piperazine, 2,5-dimethyl-p-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 2-sulfonic acid-1,4-phenylenediamine, m-phenylenediamine and o-phenylenediamine.

4. The method for preparing a gas separation membrane based on a covalent organic framework according to claim 1, characterized in that: In step (1), the polyaldehyde monomer includes one or more of 2,4,6-triformylphloroglucinol, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 4,4'-biphenyldicarboxaldehyde, 2,2'-bipyridine-5,5'-dicarboxaldehyde, 2,5-dihydroxyterephthalaldehyde, 1,4-dialdehyde-2,5-divinylbenzene, 2,3,5,6-tetrafluorobenzaldehyde, glyoxal, glutaraldehyde, adipaldehyde, 1,3-succinaldehyde, terephthalaldehyde, 2,5-dichloroterephthalaldehyde and 3,3',5,5'-tetraaldehyde-4,4'-dihydroxybiphenyl.

5. The method for preparing a gas separation membrane based on a covalent organic framework according to claim 1, characterized in that: The organic solvents in step (1) and step (3) include one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, benzene, toluene, mesitylene, ethanol, acetone, acetonitrile, n-hexane, ethyl acetate, dichloromethane and chloroform.

6. The method for preparing a gas separation membrane based on a covalent organic framework according to claim 1, characterized in that: In step (2), the amine small molecule includes one or more of ethylenediamine, propylenediamine, polyethyleneimine, monoethanolamine, diethanolamine, polyoxyethylenediamine, triethanolamine, m-phenylenediamine, adipic acid diamine, piperazine, o-phenylenediamine, polyethylene polyamine, p-phenylenediamine, and polyethyleneamine; The concentration of amine small molecules in the aqueous solution is 0.1~5 mol·L -1 The adsorption equilibrium time is 0.5~24 h.

7. The method for preparing a gas separation membrane based on a covalent organic framework according to claim 1, characterized in that: In step (3), the polyacyl chloride monomer includes one or more of phthaloyl chloride, isophthaloyl chloride, 4,4'-biphenyl disulfonyl chloride, 2,6-pyridine dicarbonyl chloride, terephthaloyl chloride, fumaroyl chloride, 1,3,5-trimethylol chloride, terephthaloyl chloride, octafluoroadipoyl chloride, phthaloyl chloride, azelayl chloride, isophthaloyl chloride, oxalyl chloride, hexafluoroglutaryl chloride, malonyl chloride, methylmalonyl chloride, succinoyl chloride, tetrafluorosuccinoyl chloride, glutaryl chloride, adipoyl chloride, pimeloyl chloride, suberyl chloride, and sebacoyl chloride.

8. The method for preparing a gas separation membrane based on a covalent organic framework according to claim 1, characterized in that: In step (3), the mass concentration of NH2-COF in the aqueous reaction solution is 0.1~5g·L -1 The mass concentration of polyacyl chloride in the organic phase reaction solution is 0.1~5 g·L -1 .

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

10. An application of a gas separation membrane based on a covalent organic framework, characterized in that: The covalent organic framework-based gas separation membrane as described in claim 9 is used for the separation of carbon dioxide / nitrogen and carbon dioxide / methane systems.

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