A hydrogen-bonded cross-linked covalent organic framework composite membrane, its preparation method and application

Abstract

This invention provides a method for preparing a hydrogen-bonded crosslinked covalent organic framework (COF) composite membrane and its application in gas separation, belonging to the field of gas separation membranes. The composite membrane is composed of COF and a polyhydroxy polymer: first, COF nanosheets are prepared; then, they are mixed with hydroxy polymers, such as carboxymethyl cellulose, polyethylene glycol, and polyvinyl alcohol, to obtain an assembly dispersion. Using a vacuum-assisted self-assembly method, this dispersion is filtered onto the surface of a polymeric ultrafiltration membrane, and after drying, the hydrogen-bonded crosslinked covalent organic framework composite membrane is obtained. The raw materials for the membrane material are readily available, and the method is simple. Due to the chemical similarity between the hydroxy polymer and the COF nanosheets, the assembly interface is more uniform, thereby macroscopically improving the mechanical strength of the composite material. Because the hydroxy polymer weaves the COF nanosheets, the pore size of the COF is reduced due to the shielding effect. The composite membrane, used for H2 / CO2 separation, exhibits high selectivity and operational stability, and has good application prospects in the field of hydrogen separation.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, and specifically relates to a hydrogen-bonded cross-linked covalent organic framework composite membrane. The membrane is composed of covalent organic framework (COF) nanosheets and hydroxyl polymers (such as carboxymethyl cellulose, polyethylene glycol and polyvinyl alcohol), and is used for the efficient separation of H2 / CO2. Background Technology

[0002] Hydrogen is an ideal energy carrier, and using it to replace coal or natural gas as an energy source holds promise for mitigating global climate change and localized air pollution. Hydrogen purification frequently occurs during hydrogen production processes such as water-gas shift reactions, steam reforming, and hydrogen recovery from purge gas and dehydrogenation reactions. Hydrogen must be separated from carbon dioxide, carbon monoxide, hydrocarbons, and other impurities. Hydrogen purification can be achieved through techniques such as pressure swing adsorption (PSA), cryogenic distillation, and membrane separation. Compared to energy-intensive methods like PSA and cryogenic distillation, membrane separation offers advantages such as high separation efficiency, low energy consumption, and continuous operation, making it a promising method for hydrogen purification.

[0003] Covalent organic frameworks (COFs) are a new class of crystalline nanoporous polymers, crystalline framework materials composed of organic monomers linked by covalent bonds. COFs possess highly tunable, ordered nanochannels, chemical diversity, and excellent stability, showing great promise for precise molecular separation. However, traditional pure COF membranes face difficulties in film formation and have relatively large pore sizes, which can lead to an unsatisfactory balance between selectivity and permeability in gas separation applications. Therefore, it is necessary to improve traditional COF membranes to enhance their film-forming properties and address the issue of large pore sizes, enabling their application in the efficient separation of H2 / CO2. Summary of the Invention

[0004] To address the limitations of existing technologies and simultaneously improve membrane permeability and selectivity, this study designs and prepares a hydrogen-linked covalent organic framework (COFrame) composite membrane using covalent organic framework nanosheets and hydroxyl polymers as assembly units. The aim is to leverage the shielding effect of the hydrogen-linked COFrame nanosheets and hydroxyl polymers to promote the sieving and separation of gas molecules within the membrane. Furthermore, the well-developed and uniform interface between the COFrame nanosheets and the hydroxyl polymer enhances the mechanical stability and stretchable flexibility of the composite membrane. To date, no literature has reported on the application of hydrogen-linked COFrame composite membranes for H2 / CO2 separation. The preparation method of this invention is simple and controllable, and the prepared composite membrane can be used for H2 / CO2 separation, exhibiting high separation performance and operational stability.

[0005] The present invention is achieved through the following technical solution: a hydrogen-bonded cross-linked covalent organic framework composite membrane, its preparation method and application. The preparation method is simple and controllable. The composite membrane is composed of covalent organic framework nanosheets and hydroxyl polymers, and is prepared by a two-step method of ultrasonic dispersion uniform assembly and vacuum-assisted self-assembly. The thickness of the membrane is 15 nm-500 nm.

[0006] The hydrogen-bonded cross-linked covalent organic framework composite membrane of the present invention comprises, wherein the COF nanosheets are one or more of TpPa-SO3H, TpBd-(SO3H)2, TpPa-COOH, TpEB, and TpTGCl, preferably TpPa-SO3H nanosheets, and the COF nanosheets are prepared by a single-phase method; the hydroxyl polymer chain is any one of carboxymethyl cellulose, polyethylene glycol, and polyvinyl alcohol, and its molecular weight is any one of 5K, 10K, and 20K; the hydroxyl polymer induces the COF nanosheets to form assemblies through hydrogen bonding interactions.

[0007] Step 1) Preparation of TpPa-SO3H covalent organic framework dispersion: Dissolve 1,3,5-tricarboxaldehyde-resorcinol monomer in dimethyl sulfoxide to prepare a 4.24 mg / mL solution. -1 The aldehyde monomer solution was ultrasonically dispersed, and the 2,5-diaminobenzenesulfonic acid monomer was dissolved in dimethyl sulfoxide to prepare a 5.64 mg / mL solution. -1 The amine monomer solution was ultrasonically dispersed. The aldehyde monomer and amine monomer solutions were mixed, with a volume ratio of 1:1, and reacted at 25°C for 1 day. After the reaction was completed, the mixture was dialyzed for 3 days to obtain a covalent organic framework nanosheet dispersion.

[0008] Step 2) Pre-assembly of hydrogen-bonded covalent organic frameworks: The covalent organic framework dispersion obtained in step 1) is prepared to a concentration of 0.005 mg / mL. -1 -0.1 mg mL -1 A dispersion of covalent organic framework nanosheets was prepared with a concentration of 0.1 mg / mL. -1 -2 mg mL -1 Hydroxypolymer aqueous solution: Mix the two solutions in a ratio of 1:1 to 8:1 and stir for 1 hour to obtain the assembled dispersion.

[0009] Step 3) Preparation of hydrogen-bonded covalent organic framework composite membrane: The assembly dispersion obtained in step 2 is diluted to a volume concentration of 5%-20%. The aqueous solution of the composite material is filtered onto the surface of a polyacrylonitrile porous membrane by vacuum-assisted self-assembly to prepare a hydrogen-bonded covalent organic framework membrane. The membrane is dried at 30°C for 24 hours to obtain a covalent organic framework composite membrane with a thickness of 15 nm-500 nm.

[0010] When the hydrogen-bonded covalent organic framework composite membrane prepared in this invention was used for H2 / CO2 separation, the H2 permeation rate was 850-1267 GPU and the H2 / CO2 selectivity was 30-38 under the conditions of operating temperature of 25°C and pressure of 1 bar.

[0011] Compared with the prior art, the advantages of the present invention are as follows:

[0012] Based on the hydrogen-bonded interactions between hydroxyl polymers and COF nanosheets, the preparation process of hydrogen-crosslinked covalent organic framework composite membranes is simple, highly controllable, uses readily available raw materials, and is a universal method. Utilizing the chemical similarity between the polymer and COF nanosheets, the prepared composite membranes exhibit superior macroscopic mechanical properties, including strength, ductility, and flexibility. This successfully solves the problems of difficult film formation and large pore size associated with traditional pure COF membranes. The hydrogen-crosslinked covalent organic framework possesses a finer pore structure and excellent separation performance, demonstrating high selectivity and permeability in H2 / CO2 separation applications. Furthermore, this preparation method is simple, feasible, and has potential industrial application value. Attached Figure Description

[0013] Figure 1 These are scanning electron microscope images of the assembly prepared in Example 1;

[0014] Figure 2 This is a cross-sectional electron microscope image of membrane 1 prepared in Example 2 of the present invention;

[0015] Figure 3 This is a surface electron microscope image of film 1 prepared in Example 2 of the present invention;

[0016] Figure 4 This is a cross-sectional electron microscope image of membrane 2 prepared in Example 4 of the present invention;

[0017] Figure 5 This is an electron microscope image of the surface of film 2 obtained in Example 4 of the present invention;

[0018] Figure 6 This is a cross-sectional electron microscope image of the membrane 3 prepared in Example 6 of the present invention;

[0019] Figure 7 This is an electron microscope image of the surface of the film 3 prepared in Example 6 of the present invention;

[0020] Figure 8 This is a transmission electron microscope image of the covalent organic framework dispersion prepared in Comparative Example 1 of this invention;

[0021] Figure 9 This is a cross-sectional electron microscope image of the membrane 4 prepared in Comparative Example 1 of the present invention.

[0022] Figure 10 This is an electron microscope image of the surface of the film 4 prepared in Comparative Example 1 of the present invention;

[0023] Figure 11 This is a comparison chart of the H2 permeation rate and H2 / CO2 selectivity of membranes 1-6 and control membranes;

[0024] Figure 12 This is a schematic diagram illustrating the preparation and gas sieving of a hydrogen-bonded covalent organic framework composite membrane. Detailed Implementation

[0025] This invention provides a method for preparing a hydrogen-bonded cross-linked covalent organic framework composite membrane for H2 / CO2 separation. The invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The hydrogen-bonded crosslinked covalent organic framework composite membrane of the present invention comprises a COF nanosheet that is any one of TpPa-SO3H, TpBd-(SO3H)2, TpPa-COOH, TpEB, and TpTGCl, and is prepared by Schiff base reaction; the hydroxyl polymer is any one of carboxymethyl cellulose, polyethylene glycol, and polyvinyl alcohol, and has a molecular weight of 5K, 10K, or 20K; the hydroxyl polymer chains induce the COF nanosheets to form an assembled dispersion through hydrogen bonding interactions.

[0027] Example 1: Preparation of a hydrogen-bonded cross-linked covalent organic framework composite membrane, the steps are as follows:

[0028] Step 1) Preparation of covalent organic framework dispersion: Weigh 21.2 mg of 1,3,5-tricarboxymethyl phloroglucinol and dissolve it in 5 mL of dimethyl sulfoxide solution to prepare a 4.24 mg / mL solution. -1 Aldehyde monomer solution: Weigh 28.2 mg of 2,5-diaminobenzenesulfonic acid and dissolve it in 5 mL of dimethyl sulfoxide solution to prepare a 5.64 mg / mL solution. -1 The amine monomer solution was mixed with two solutions and ultrasonically dispersed. The mixture was reacted for 24 hours to obtain a yellow-brown solution. The solution was then dialyzed with deionized water using a 30,000 Da dialysis bag for 3 days to obtain a covalent organic framework dispersion.

[0029] Step 2) Preparation of the assembly dispersion: Dilute 0.5 mL of the covalent organic framework dispersion obtained in Step 1 to 100 mL to prepare a solution with a concentration of 0.005 mg / mL. -1 A dispersion of covalent organic framework nanosheets; 80 mg of carboxymethyl cellulose (CMC, M w =20 K) was dissolved in 80 mL of deionized water to prepare a concentration of 0.1 mg / mL. -1 Hydroxypolymer aqueous solution: The two solutions above were thoroughly mixed and stirred at room temperature for 1 hour to obtain the assembled dispersion. The scanning electron microscope image of the assembly is shown below. Figure 1 As shown.

[0030] Step 3) Preparation of hydrogen-bonded covalent organic framework composite membrane: Dilute 2 mL of the assembly dispersion obtained in Step 2 to 20 mL; deposit the assembly dispersion onto the surface of porous polyacrylonitrile by vacuum-assisted self-assembly, and formulate the resulting hydrogen-bonded covalent organic framework / hydroxyl polymer composite membrane to a concentration of 0.005 mg / mL. -1 An aqueous solution of the assembly dispersion was filtered onto the surface of a polyacrylonitrile porous membrane using a vacuum-assisted self-assembly method to form a covalent organic framework membrane with hydrogen bonding. The membrane was dried at 30°C for 24 hours to obtain a covalent organic framework composite membrane with a thickness of 15 nm, denoted as membrane 1.

[0031] The hydrogen-bonded covalent organic framework composite membrane (membrane 1) prepared in this invention was used for H2 / CO2 separation. Under the conditions of operating temperature of 25°C and pressure of 1 bar, the H2 permeation rate was 2145 GPU and the H2 / CO2 selectivity was 9.8.

[0032] Example 2: Preparation of hydrogen-bonded crosslinked covalent organic framework composite membrane: The preparation process was basically the same as in Example 1, except that: the 0.5 mL covalent organic framework dispersion from step 2 was diluted to 5 mL to prepare a concentration of 0.1 mg / mL. -1 A dispersion of covalent organic framework nanosheets was prepared by dissolving 80 mg of carboxymethyl cellulose (CMC, Mw = 20 K) in 40 mL of deionized water to obtain a concentration of 2 mg / mL. -1 Hydroxypolymer aqueous solution: Mix the two solutions thoroughly and stir at room temperature for 1 hour to obtain the assembled dispersion.

[0033] Step 3) Preparation of hydrogen-bonded covalent organic framework composite membrane: Dilute 2 mL of the assembly dispersion obtained in Step 2 to 20 mL; deposit the assembly dispersion onto the surface of porous polyacrylonitrile by vacuum-assisted self-assembly, and formulate the resulting hydrogen-bonded covalent organic framework / hydroxyl polymer composite membrane to a concentration of 0.005 mg / mL. -1 An aqueous solution of the assembly dispersion was filtered onto the surface of a polyacrylonitrile porous membrane using a vacuum-assisted self-assembly method to form a hydrogen-bonded covalent organic framework membrane. After drying at 30°C for 24 hours, a covalent organic framework composite membrane with a thickness of 500 nm was obtained. This membrane is denoted as membrane 2. Figure 2 This is a cross-sectional electron microscope image of membrane 2. Figure 3 This is an electron microscope image of the surface of membrane 2.

[0034] The hydrogen-bonded covalent organic framework composite membrane (membrane 2) prepared in this invention was used for H2 / CO2 separation. Under the conditions of operating temperature of 25°C and pressure of 1 bar, the H2 permeation rate was 910 GPU and the H2 / CO2 selectivity was 37.2.

[0035] Example 3 Preparation of hydrogen-bonded cross-linked covalent organic framework composite membrane: The preparation process is basically the same as in Example 1, except that: carboxymethyl cellulose (CMC, M) in step 2 is used... w =20 K) was changed to polyethylene glycol (PEG, M w =5 K). Dilute 0.5 mL of the covalent organic framework dispersion from step 2 to 5 mL to prepare a concentration of 0.1 mg / mL. -1 A dispersion of covalent organic framework nanosheets was prepared by dissolving 80 mg of polyethylene glycol (PEG, Mw=5 K) in 80 mL of deionized water to obtain a concentration of 0.1 mg / mL. -1 Hydroxypolymer aqueous solution: Mix the two solutions thoroughly and stir at room temperature for 1 hour to obtain the assembled dispersion.

[0036] Step 3) Preparation of hydrogen-bonded covalent organic framework composite membrane: Dilute 2 mL of the assembly dispersion obtained in Step 2 to 20 mL; deposit the assembly dispersion onto the surface of porous polyacrylonitrile by vacuum-assisted self-assembly, and formulate the resulting hydrogen-bonded covalent organic framework / hydroxyl polymer composite membrane to a concentration of 0.005 mg / mL. -1 An aqueous solution of the assembly dispersion was filtered onto the surface of a polyacrylonitrile porous membrane using a vacuum-assisted self-assembly method to form a covalent organic framework membrane with hydrogen bonding. The membrane was dried at 30°C for 24 hours to obtain a covalent organic framework composite membrane with a thickness of 15 nm, denoted as membrane 3.

[0037] The hydrogen-bonded covalent organic framework composite membrane (membrane 3) prepared in this invention was used for H2 / CO2 separation. Under the conditions of operating temperature of 25°C and pressure of 1 bar, the H2 permeation rate was 1850 GPU and the H2 / CO2 selectivity was 11.

[0038] Example 4: Preparation of hydrogen-bonded crosslinked covalent organic framework composite membrane: The preparation process was basically the same as in Example 1, except that: the 0.5 mL covalent organic framework dispersion from step 2 was diluted to 5 mL to prepare a concentration of 0.1 mg / mL. -1 A dispersion of covalent organic framework nanosheets; 80 mg of polyethylene glycol (PEG, Mw=5 K) was dissolved in 40 mL of deionized water to prepare a concentration of 2 mg / mL. -1 Hydroxypolymer aqueous solution: Mix the two solutions thoroughly and stir at room temperature for 1 hour to obtain the assembled dispersion.

[0039] Step 3) Preparation of hydrogen-bonded covalent organic framework composite membrane: Dilute 2 mL of the assembly dispersion obtained in Step 2 to 20 mL; deposit the assembly dispersion onto the surface of porous polyacrylonitrile by vacuum-assisted self-assembly, and formulate the resulting hydrogen-bonded covalent organic framework / hydroxyl polymer composite membrane to a concentration of 0.005 mg / mL. -1 An aqueous solution of the assembly dispersion was filtered onto the surface of a polyacrylonitrile porous membrane using a vacuum-assisted self-assembly method to form a hydrogen-bonded covalent organic framework membrane. After drying at 30°C for 24 hours, a covalent organic framework composite membrane with a thickness of 500 nm was obtained. This membrane is designated as membrane 4. Figure 4 This is a cross-sectional electron microscope image of membrane 4. Figure 5 This is an electron microscope image of the surface of film 4.

[0040] The hydrogen-bonded covalent organic framework composite membrane (membrane 4) prepared in this invention was used for H2 / CO2 separation. Under the conditions of operating temperature of 25°C and pressure of 1 bar, the H2 permeation rate was 850 GPU and the H2 / CO2 selectivity was 30.

[0041] Example 5 Preparation of hydrogen-bonded cross-linked covalent organic framework composite membrane: The preparation process is basically the same as in Example 1, except that: carboxymethyl cellulose (CMC, M) in step 2 is used... w =20 K) was replaced with polyvinyl alcohol (PVA, M) w =20 K). The preparation process is basically the same as in Example 1, except that: the 0.5 mL covalent organic framework dispersion from step 2 was diluted to 5 mL to prepare a concentration of 0.1 mg / mL. -1 A dispersion of covalent organic framework nanosheets was prepared by dissolving 80 mg of polyvinyl alcohol (PVA, Mw=20 K) in 80 mL of deionized water to obtain a concentration of 0.1 mg / mL. -1 Hydroxypolymer aqueous solution: Mix the two solutions thoroughly and stir at room temperature for 1 hour to obtain the assembled dispersion.

[0042] Step 3) Preparation of hydrogen-bonded covalent organic framework composite membrane: Dilute 2 mL of the assembly dispersion obtained in Step 2 to 20 mL; deposit the assembly dispersion onto the surface of porous polyacrylonitrile using vacuum-assisted self-assembly; prepare a 0.005 mg mL⁻¹ aqueous solution of the resulting hydrogen-bonded covalent organic framework / hydroxyl polymer composite material. Filter the aqueous solution of the assembly dispersion onto the surface of the porous polyacrylonitrile membrane using vacuum-assisted self-assembly to form a hydrogen-bonded covalent organic framework membrane. Dry at 30 °C for 24 hours to obtain a covalent organic framework composite membrane with a thickness of 15 nm. This membrane is denoted as membrane 5.

[0043] The hydrogen-bonded covalent organic framework composite membrane (membrane 5) prepared in this invention was used for H2 / CO2 separation. Under the conditions of operating temperature of 25°C and pressure of 1 bar, the H2 permeation rate was 2289 GPU and the H2 / CO2 selectivity was 10.

[0044] Example 6: Preparation of hydrogen-bonded crosslinked covalent organic framework composite membrane: The preparation process was basically the same as in Example 1, except that: the 0.5 mL covalent organic framework dispersion from step 2 was diluted to 5 mL to prepare a concentration of 0.1 mg / mL. -1 A dispersion of covalent organic framework nanosheets; 80 mg of polyvinyl alcohol (PVA, Mw=20 K) was dissolved in 40 mL of deionized water to prepare a concentration of 2 mg / mL. -1 Hydroxypolymer aqueous solution: Mix the two solutions thoroughly and stir at room temperature for 1 hour to obtain the assembled dispersion.

[0045] Step 3) Preparation of hydrogen-bonded covalent organic framework composite membrane: Dilute 2 mL of the assembly dispersion obtained in Step 2 to 20 mL; deposit the assembly dispersion onto the surface of porous polyacrylonitrile by vacuum-assisted self-assembly, and formulate the resulting hydrogen-bonded covalent organic framework / hydroxyl polymer composite membrane to a concentration of 0.005 mg / mL. -1 An aqueous solution of the assembly dispersion was filtered onto the surface of a polyacrylonitrile porous membrane using a vacuum-assisted self-assembly method to form a hydrogen-bonded covalent organic framework membrane. After drying at 30°C for 24 hours, a covalent organic framework composite membrane with a thickness of 500 nm was obtained. This membrane is denoted as membrane 6. Figure 6 This is a cross-sectional electron microscope image of membrane 6. Figure 7 This is an electron microscope image of the surface of film 6.

[0046] The hydrogen-bonded covalent organic framework composite membrane (membrane 6) prepared in this invention was used for H2 / CO2 separation. Under the conditions of operating temperature of 25°C and pressure of 1 bar, the H2 permeation rate was 1267 GPU and the H2 / CO2 selectivity was 38.

[0047] Comparative Example 1: Preparation of covalent organic framework membranes, including the preparation of TpPa-SO3H COF nanosheet dispersion and the preparation of COF membranes, as follows:

[0048] Step 1: The preparation process of the covalent organic framework nanosheet dispersion is the same as in Example 1. The transmission electron microscopy (TEM) results of the nanosheets are shown below. Figure 8 As shown.

[0049] Step 2: Preparation of the covalent organic framework membrane: 2 mL of the covalent organic framework dispersion obtained in Step 1 was diluted to 10 mL; the covalent organic framework dispersion was filtered onto the surface of a polyacrylonitrile porous membrane using a vacuum-assisted self-assembly method, and dried at 30°C for 24 hours to obtain a covalent organic framework membrane with a thickness of 500 nm. This COF membrane was designated as the control membrane. Figure 9 This is a cross-sectional electron microscope image of the contrast membrane. Figure 10 This is a surface electron microscope image of the contrast film.

[0050] When the control membrane was used for H2 / CO2 separation, the H2 permeation rate was 1818 GPU and the H2 / CO2 selectivity was 3.2 under the conditions of operating temperature of 25℃ and pressure of 1 bar.

[0051] Comparative examples and comparative cases demonstrate that the composite membrane prepared by inducing COF nanosheets through hydrogen-bonded crosslinking interactions significantly improves separation performance. The hydrogen-bonded interaction between the hydroxyl polymer and the COF nanosheets plays a crucial role, with the spatial arrangement and conformation of the hydroxyl polymer chains providing hydrogen bond sites. Compared to the original COF nanosheets, the polymer-crosslinked nanosheets exhibit superior mechanical strength and flexibility. This process partially repairs internal stacking defects, resulting in no obvious pinholes or stacking depressions on the membrane surface and cross-section. Furthermore, the polymer's shielding effect on the COF nanosheets reduces the pore size to some extent, and the multiple hydroxyl sites within the pores form an affinity confinement layer with CO2, further reducing the effective pore size, allowing H2 molecules to pass through rapidly. Figure 11 This is a comparison chart of the H2 permeation rate and H2 / CO2 selectivity of membranes 1-3 and the control membrane. The prepared hydrogen-bonded cross-linked covalent organic framework composite membrane achieves a breakthrough in separation performance and has great application prospects in the field of hydrogen separation.

[0052] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.

Claims

1. A method for preparing a hydrogen-bonded crosslinked covalent organic framework (COF) composite membrane, characterized in that, First, COF nanosheets with a high aspect ratio are prepared, and then they are mixed with a hydroxyl polymer in a certain proportion to form a uniform assembly dispersion in an appropriate solvent. The mixture is then deposited on a porous support membrane by vacuum-assisted self-assembly. After heat treatment at a certain temperature, a hydrogen-bonded covalent organic framework composite membrane is formed. The COF nanosheets are obtained by Schiff base reaction of TpPa-SO3H nanosheets, and the hydroxyl polymer is one or more of carboxymethyl cellulose, polyethylene glycol, and polyvinyl alcohol.

2. The method for preparing the hydrogen-bonded crosslinked covalent organic framework composite membrane according to claim 1, characterized in that, COF nanosheets and hydroxyl polymers are mixed in a certain proportion, wherein the concentration of the COF nanosheet colloidal dispersion is in the range of 0.005 mg·mL. -1 -0.1 mg·mL -1 Let this be solution A; the polymer is dissolved in deionized water to prepare a concentration range of 0.1 mg / mL. -1 -2 mg·mL -1 Let A be denoted as solution B; mix and stir solutions A and B in a ratio of 1:1 to 8:1 to prepare a dispersion of hydrogen-bonded covalent organic framework assembly.

3. The method for preparing the hydrogen-bonded crosslinked covalent organic framework composite membrane according to claim 2, characterized in that, The hydrogen-bonded covalent organic framework assembly dispersion is diluted with a certain volume of deionized water, and the dispersion is deposited on the surface of a porous support membrane by vacuum-assisted self-assembly. The porous support membrane is any one of polyacrylonitrile, polyethersulfone, polypropylene, polysulfone, and polytetrafluoroethylene.

4. A hydrogen-bonded crosslinked covalent organic framework (COF) composite membrane, characterized in that, It is prepared according to any one of claims 1-3.

5. The application of the hydrogen-bonded cross-linked covalent organic framework composite membrane as described in claim 4 in H2 / CO2 separation, characterized in that: Under conditions of 25°C and 1 bar pressure, the prepared composite membrane was tested to have an H2 permeation rate of 850-2289 GPUs and an H2 / CO2 selectivity of 9.8-38.

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