A gas separation membrane, its preparation method and use

Abstract

The application belongs to the technical field of flue gas treatment, and particularly relates to a gas separation membrane and a preparation method and application thereof. The gas separation membrane provided by the application comprises polyvinylamine and silver nanowires. The silver nanowires in the gas separation membrane are embedded into polyvinylamine segments, can effectively disturb the ordered rearrangement of the polyvinylamine segments, weaken the hydrogen bond action between NH2-NH2 in the polyvinylamine segments, thereby inhibiting the formation of crystalline regions, optimizing the performance of the polyvinylamine membrane, and finally achieving the purpose of simultaneously improving the CO2 permeation performance and the selectivity performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of flue gas treatment, and particularly relates to a gas separation membrane and a preparation method and application thereof. BACKGROUND

[0002] Membrane separation is a low-energy, modular, and non-secondary pollution carbon dioxide separation technology, which has broad development prospects in the field of carbon dioxide capture.

[0003] The key to membrane separation carbon dioxide technology is membrane material. Developing a membrane material with high carbon dioxide permeability and separation coefficient is the current research hotspot. By introducing active groups into the polymer membrane, the transmembrane transport of target substances can be promoted, thereby breaking through the limitations of traditional organic membranes and realizing high permeability and high selectivity. In addition, the separation components are strengthened in the membrane by reversible chemical reaction with the carrier, thereby realizing efficient separation.

[0004] Among the many facilitated transport membrane materials, polyvinylamine (PVAm) membrane has the leading position in permeation and separation performance, and has the possibility of being the first to realize large-scale industrial application. The group that can transport carbon dioxide in the PVAm membrane is the primary amine group (-NH2), and the carbon dioxide separation performance mainly depends on the content of the primary amine group and the efficiency of carbon dioxide transport. Increasing the content of the primary amine group in the PVAm membrane is beneficial to increasing the permeation rate and separation coefficient of carbon dioxide, but too high content of the primary amine group will lead to regular arrangement of the polymer chain and formation of a crystalline region, thereby reducing the separation efficiency. Therefore, how to avoid the problems caused by too high content of the primary amine group is an urgent problem to be solved at the present stage. SUMMARY

[0005] The present application is based on the findings and recognitions of the inventors on the following facts and problems:

[0006] Professor Wang Zhi's research group of Tianjin University cross-linked modified PVAm with ethylenediamine (EDA) to prepare PVAm-EDA / PSf composite membranes with more compact structure and more carriers; the research group of Norwegian University of Science and Technology developed a variety of flat composite membranes and hollow fiber composite membranes for separating CO2 / N2 mixed gas. However, although this composite membrane performs excellently in CO2 / N2 separation, both of the two polymer materials used in this membrane contain polar functional groups, and the interaction of the polar functional groups may lead to the formation of a crystalline region, thereby affecting the performance of the membrane. Moreover, due to the interaction of these polar groups, the efficiency of the functional groups will also be reduced.

[0007] A research group of Liu Chengcen from Taiyuan University of Technology introduced halloysite nanotubes (HNTs) into polyvinylamine (PVAm) to prepare a PVAm-HNTs / PSf mixed matrix membrane. The CO2 permeation rate of the mixed matrix membrane can reach 178 GPU, and the CO2 / N2 selectivity is 83. However, due to the complex preparation process and high cost of halloysite nanotubes, it cannot realize industrial mass production.

[0008] The present application aims to at least solve one of the technical problems in the related art. To this end, the embodiments of the present application propose a gas separation membrane, in which silver nanowires are embedded in PVAm segments, which can effectively disrupt the ordered rearrangement of PVAm segments, weaken the hydrogen bonding between NH2-NH2 in PVAm segments, thereby inhibiting the formation of crystalline regions, optimizing the performance of PVAm membranes, and ultimately achieving the purpose of simultaneously improving the CO2 permeation performance and selectivity performance.

[0009] The gas separation membrane according to an embodiment of the present application comprises polyvinylamine and silver nanowires.

[0010] The gas separation membrane according to an embodiment of the present application has the following advantages and technical effects: 1. In the embodiments of the present application, polyvinylamine is used as the film-forming material for the gas separation membrane. The primary amino group on the polyvinylamine can attract carbon dioxide on the flue gas side and transfer it to the other side of the membrane, thereby realizing the separation of carbon dioxide in the flue gas; 2. In the embodiments of the present application, the silver nanowires loaded in PVAm can provide adsorption sites and play a physical adsorption role, thereby improving the separation efficiency of carbon dioxide; 3. In the embodiments of the present application, the silver nanowires are embedded in the polyvinylamine segments, which can effectively disrupt the ordered rearrangement of PVAm segments, weaken the hydrogen bonding between NH2-NH2 in PVAm segments, thereby inhibiting the formation of crystalline regions, optimizing the performance of PVAm membranes, and ultimately achieving the purpose of simultaneously improving the CO2 permeation performance and selectivity performance.

[0011] In some embodiments, the content of the silver nanowires in the gas separation membrane is 10-70wt%.

[0012] In some embodiments, the length of the silver nanowires is 5-25pm, and the diameter is 20-200nm.

[0013] In some embodiments, the viscosity average molecular weight of the polyvinylamine is 10000-50000kDa.

[0014] In some embodiments, the thickness of the gas separation membrane is 300-800nm.

[0015] The application further provides a preparation method of the gas separation membrane.

[0016] In some embodiments, the concentration of the silver nanowire solution is 1-10 wt%;

[0017] In some embodiments, the concentration of the polyvinylamine solution is 0.1-5 wt%;

[0018] In some embodiments, the content of the silver nanowire in the gas separation membrane is 10-70 wt%.

[0019] In some embodiments, the preparation method of the polyvinylamine solution comprises: dissolving N-vinyl formamide and 2,2-azobis(2-methylpropylimine) dihydrochloride in deionized water, performing free radical polymerization under nitrogen protection after heating, to obtain a polyvinyl formamide solution; then adding hydrochloric acid solution to the polyvinyl formamide solution, performing hydrolysis after heating, adding ice alcohol after the reaction, drying the product to obtain polyvinylamine hydrochloride solid; dissolving the polyvinylamine hydrochloride solid in deionized water, and then adding anion exchange resin for anion exchange, and vacuum filtration to obtain a polyvinylamine solution;

[0020] Preferably, the ratio of the amount of N-vinyl formamide to 2,2-azobis(2-methylpropylimine) dihydrochloride is (10-40 g):(0.02-0.1 g);

[0021] In some embodiments, the temperature of the free radical polymerization is 50-70°C, and the time of the free radical polymerization is 4-10 h;

[0022] In some embodiments, the temperature of the hydrolysis is 60-80°C, and the time of the hydrolysis is 2-5 h;

[0023] In some embodiments, the concentration of the hydrochloric acid solution is 30-38 wt%, and the content of hydrochloric acid in the mixed solution of the polyvinyl formamide solution and the hydrochloric acid solution is 10-20 wt%.

[0024] In some embodiments, the preparation method of the silver nanowire solution comprises: adding polyvinylpyrrolidone to ethylene glycol, performing reaction after heating, cooling, adding silver nitrate solution and ferric chloride solution, cooling after the formation of silver nanowires, and performing centrifugal treatment with acetone to obtain a precipitate, and preparing a silver nanowire solution with ethanol as a solvent;

[0025] Preferably, the ratio of the amount of polyvinylpyrrolidone to ethylene glycol is 4-20 g / L;

[0026] and / or, the concentration of the silver nitrate solution is 0.01-0.1 mol / L, the concentration of the ferric chloride solution is 0.1-1 mol / L, and the volume ratio of the ethylene glycol, the silver nitrate solution and the ferric chloride solution is (1-10):(1-5):1;

[0027] and / or, the temperature of the reaction is 140-180℃, and the time of the reaction is 0.5-2h.

[0028] The application further provides an application of the gas separation membrane or the gas separation membrane prepared by the preparation method in separating carbon dioxide in flue gas. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a SEM image of silver nanowires prepared in Example 1;

[0030] Figure 2 is a SEM image of the gas separation membrane prepared in Example 5. DETAILED DESCRIPTION

[0031] Embodiments of the application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0032] A gas separation membrane according to an embodiment of the application comprises polyvinylamine (PVAm) and silver nanowires (AgNWs).

[0033] The gas separation membrane according to an embodiment of the application uses polyvinylamine as a film-forming material. The primary amino group on the polyvinylamine can attract carbon dioxide on the flue gas side and transfer it to the other side of the membrane, thereby realizing separation of carbon dioxide in the flue gas. The silver nanowires loaded in the polyvinylamine can provide adsorption sites and play a physical adsorption role, thereby improving the separation efficiency of carbon dioxide. The silver nanowires are embedded in the polyvinylamine segments, which can effectively disrupt the ordered rearrangement of the polyvinylamine segments, weaken the hydrogen bonding between NH2-NH2 in the polyvinylamine segments, thereby inhibiting the formation of crystalline regions, optimizing the performance of the polyvinylamine membrane, and ultimately achieving the purpose of simultaneously improving the CO2 permeation performance and selectivity.

[0034] In some embodiments, preferably, the content in the gas separation membrane is 10-70 wt%.

[0035] In the embodiment of the present application, the content of silver nanowires is preferably selected, which is beneficial to the uniform dispersion of silver nanowires in polyvinylamine and prevents the occurrence of agglomeration, so that the prepared gas separation membrane has a higher gas permeation rate and separation factor; if the content of silver nanowires is too low, the disturbing effect on the ordered rearrangement of polyvinylamine segments is reduced, which further leads to a too low gas permeation rate of the polyvinylamine membrane; if the content of silver nanowires is too high, the interfacial compatibility of silver nanowires and polyvinylamine is poor, the dispersion effect of silver nanowires in polyvinylamine is reduced, which leads to a too low separation factor of the polyvinylamine membrane.

[0036] In some embodiments, preferably, the length of the silver nanowires is 5-25 μm, and the diameter is 20-200 nm. It can be understood that the length of the silver nanowires is the average length, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm or 25 μm; and the diameter is the average diameter, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm or 200 nm.

[0037] In the embodiment of the present application, the size of the silver nanowires is preferably selected, and the silver nanowires with appropriate length and diameter can be better dispersed in polyvinylamine and have a better disturbing effect on the ordered rearrangement of polyvinylamine segments; if the length is too long or the diameter is too large, the dispersibility of the silver nanowires in the polyvinylamine solution will be poor, and defects are prone to occur after film formation; if the length is too short or the diameter is too small, the disturbing effect on the ordered rearrangement of polyvinylamine segments is poor, which reduces the separation efficiency of the gas separation membrane.

[0038] In some embodiments, preferably, the viscosity average molecular weight of the polyvinylamine is 10,000-50,000 kDa.

[0039] In the embodiment of the present application, the molecular weight of the polyvinylamine is preferably selected; if the molecular weight of the polyvinylamine is too large, the flowability is reduced due to the long polymer chain, the pore in the prepared gas separation membrane is small, which leads to a reduced gas permeation rate of the separation membrane; if the molecular weight of the polyvinylamine is too small, the polymer chain is short, the pore in the prepared gas separation membrane is large, which leads to a too low separation factor of the separation membrane.

[0040] In some embodiments, preferably, the thickness of the gas separation membrane is 300-800 nm.

[0041] In the embodiment of the present application, the thickness of the gas separation membrane is preferably selected; if the thickness is too large, the resistance of gas transmission is relatively large, which easily leads to too low gas permeation rate, and if the thickness is too small, the permeation rate is increased, but which leads to too low separation factor.

[0042] The embodiment of the present application further provides a preparation method of the gas separation membrane, comprising: mixing a silver nanowire solution and a polyvinylamine solution to obtain a mixed solution, coating the mixed solution on an ultrafiltration membrane to prepare a PVAm-AgNWs wet membrane, and performing drying treatment to obtain the gas separation membrane.

[0043] In some embodiments, preferably, the concentration of the silver nanowire solution is 1-10 wt%;

[0044] and / or, the concentration of the polyvinylamine solution is 0.1-5 wt%;

[0045] and / or, the content of the silver nanowire in the gas separation membrane is 10-70 wt%.

[0046] Further preferably, the silver nanowire solution and the polyvinylamine solution are mixed and then subjected to ultrasonic treatment, and the ultrasonic treatment time is 2-4 h.

[0047] In some embodiments, preferably, the preparation method of the polyvinylamine solution comprises: dissolving N-vinyl formamide (NVF) and 2,2-azobis(2-methylpropylimino) dihydrochloride (AIBA) in deionized water, performing free radical polymerization reaction after warming under nitrogen protection to obtain a polyvinyl formamide (PNVF) solution; then adding hydrochloric acid solution to the polyvinyl formamide solution, performing hydrolysis reaction after warming, adding ice alcohol after the reaction, and drying the product to obtain polyvinylamine hydrochloride solid; dissolving the polyvinylamine hydrochloride solid in deionized water, and then adding anion exchange resin to perform anion exchange, and vacuum filtration to obtain a polyvinylamine solution;

[0048] Further preferably, the use amount ratio of the N-vinyl formamide and the 2,2-azobis(2-methylpropylimino) dihydrochloride is (10-40 g):(0.02-0.1 g);

[0049] and / or, the temperature of the free radical polymerization reaction is 50-70℃, and the free radical polymerization reaction time is 4-10 h;

[0050] and / or, the temperature of the hydrolysis reaction is 60-80℃, and the hydrolysis reaction time is 2-5 h;

[0051] and / or, the concentration of the hydrochloric acid solution is 30-38 wt%, and the content of hydrochloric acid in the mixed solution of the polyvinyl formamide solution and the hydrochloric acid solution is 10-20 wt%.

[0052] Further preferably, the ice ethanol is used in an amount of 100-5000 mL; and the anion exchange resin is a strong basic anion exchange resin of type 717.

[0053] In some embodiments, preferably, the concentration of the polyvinyl formamide (PNVF) solution is 8-12 wt%. Further preferably, the concentration of the polyvinyl formamide (PNVF) solution is 10 wt%. In order to avoid the adverse effects of the instability of the concentration of the polyvinyl formamide (PNVF) solution on the reaction, the polyvinyl formamide (PNVF) solution is often dried first, and then deionized water is used to prepare a solution with a concentration of 8-12 wt%.

[0054] In some embodiments, preferably, the preparation method of the silver nanowire (AgNWs) solution comprises: adding polyvinylpyrrolidone (PVP) into ethylene glycol (EG), and then performing a reaction after warming and cooling, and then adding silver nitrate (AgNO3) solution and ferric chloride (FeCl3) solution, cooling the silver nanowires after they are formed, and performing centrifugal treatment on the silver nanowires with acetone to obtain a precipitate, and then preparing a silver nanowire solution with ethanol as a solvent.

[0055] Further preferably, the use amount ratio of the polyvinylpyrrolidone and the ethylene glycol is 4-20 g / L.

[0056] Further preferably, the concentration of the silver nitrate solution is 0.01-0.1 mol / L, the concentration of the ferric chloride solution is 0.1-1 mol / L, and the volume ratio of the ethylene glycol, the silver nitrate solution and the ferric chloride solution is (1-10):(1-5):1.

[0057] Further preferably, the temperature of the reaction is 140-180℃, and the reaction time is 0.5-2 h.

[0058] Further preferably, the EG is preheated in an oil bath at 110-130℃ for 0.5-2 h to remove the water therein; and / or the cooling comprises reducing the temperature to 30℃.

[0059] In the embodiments of the present application, the preparation process is more controllable and low in cost, and the prepared silver nanowires are uniform in size and can be uniformly doped in the polyvinylamine, thereby reducing the generation of defects in the film forming process.

[0060] In some embodiments, preferably, the centrifugal treatment time is 6-12 h. Further preferably, the preparation method of the silver nanowire (AgNWs) solution further comprises washing the precipitate with ethanol and performing centrifugal treatment on the precipitate at a speed of 1000-5000 rpm for 3 times, each time for 6 min.

[0061] In some embodiments, preferably, the ultrafiltration membrane comprises a PSf ultrafiltration membrane, the surface of the PSf ultrafiltration membrane is cleaned with deionized water before the blade coating, and the PSf ultrafiltration membrane is fixed on a flat glass panel after being dried.

[0062] The application also provides the use of the gas separation membrane or the gas separation membrane prepared by the preparation method in the separation of carbon dioxide in flue gas.

[0063] The application will be described in detail below with reference to specific embodiments and drawings.

[0064] Embodiment 1

[0065] (1) Preparation of polyvinylamine solution: 10 g of deionized water was added to a three-necked flask, 40 g of N-vinyl formamide (NVF) was added under stirring, and then 0.057 g of 2,2-azobis(2-methylpropylimide) dihydrochloride (AIBA) was added to completely dissolve it; then the reaction system was vacuumed and filled with nitrogen, and the gas in the reaction system was replaced for 3 times. Under the protection of nitrogen, the temperature was raised to 50°C, and the free radical polymerization reaction was carried out for 8 hours to obtain a polyvinyl formamide (PNVF) solution with a concentration of 10 wt%. Then a certain amount of concentrated hydrochloric acid solution with a concentration of 36 wt% was added to the polyvinyl formamide (PNVF) solution, so that the content of hydrochloric acid in the mixed solution of polyvinyl formamide solution and hydrochloric acid solution was 10 wt%, and the temperature was raised to 70°C for hydrolysis reaction for 3 h. When the temperature of the reaction system dropped to room temperature (25°C), 400 mL of ice ethanol was added to obtain a white solid polyvinylamine hydrochloride precipitate, and the product was vacuum dried at room temperature (25°C) for 24 h to obtain a polyvinylamine hydrochloride solid product. The polyvinylamine hydrochloride solid product was dissolved in deionized water to prepare a 1.0 wt% solution, and then an excess of 717 type strong basic anion exchange resin was added to the solution for anion exchange, and finally vacuum filtration was performed to obtain a PVAm solution with a concentration of 1.0 wt%.

[0066] (2) Preparation of silver nanowire (AgNWs) solution: 25 mL of ethylene glycol (EG) was placed in a three-necked flask and preheated in an oil bath at 110 °C for 0.5 h to remove moisture. 0.25 g of polyvinylpyrrolidone (PVP) was added to the EG, and the mixture was heated to 150 °C and reacted for 0.5 h, followed by cooling to 30 °C. Then, 10 mL of 0.1 mol / L AgNO3 solution and 3 mL of 1 mol / L FeCl3 solution were added. After AgNWs gradually formed, the mixture was cooled to 30 °C and centrifuged with acetone for 6 h until the precipitate and supernatant showed clear separation. The precipitate was removed, washed with ethanol, and centrifuged three times at 3000 rpm for 6 min each time to obtain AgNWs. A silver nanowire solution with a content of 5 wt% was prepared using ethanol as the solvent.

[0067] (3) Preparation of PVAm-AgNWs separation membrane: 1 mL of silver nanowire solution was added to 20 mL of PVAm solution, stirred evenly, and sonicated for 2 h to obtain PVAm-AgNWs mixture. The front and back sides of the polysulfone PSf ultrafiltration membrane were washed with deionized water. After the surface was dried, the membrane was fixed on a flat glass panel. The distance between the doctor blade and the PSf membrane surface was adjusted to control the wet coating thickness to 200 μm. The PVAm-AgNWs solution was uniformly coated on the PSf ultrafiltration membrane to obtain the PVAm-AgNWs wet membrane. The membrane was placed in a constant temperature and humidity chamber and dried for 48 h (temperature 30℃, relative humidity 40%) to obtain the PVAm-AgNWs gas separation membrane.

[0068] In the gas separation membrane prepared in this embodiment, the viscosity-average molecular weight of polyvinylamine is 49000 kDa, the content of silver nanowires is 12 wt%, the average length of silver nanowires is 16 μm, the average diameter of silver nanowires is 50 nm, and the thickness of the gas separation membrane is 500 nm.

[0069] The silver nanowires prepared in this embodiment were characterized by SEM, and the results are shown in the attached figure. Figure 1 As shown, from Figure 1 As can be seen, the prepared silver nanowires have very good size uniformity.

[0070] Example 2

[0071] The preparation method of this embodiment is the same as that of Example 1, except that in step (3), the amount of silver nanowire solution used is 2 mL.

[0072] In this embodiment, the content of silver nanowires in the gas separation membrane is 22 wt%.

[0073] Example 3

[0074] The preparation method of this embodiment is the same as that of Example 1, except that in step (3), the amount of silver nanowire solution used is 5 mL.

[0075] In this embodiment, the gas separation membrane contains 40 wt% silver nanowires.

[0076] Example 4

[0077] The preparation method of this embodiment is the same as that of Example 1, except that in step (3), the amount of silver nanowire solution used is 7 mL.

[0078] In this embodiment, the gas separation membrane contains 49 wt% silver nanowires.

[0079] Example 5

[0080] The preparation method of this embodiment is the same as that of Example 1, except that in step (3), the amount of silver nanowire solution used is 10 mL.

[0081] In this embodiment, the gas separation membrane contains 58 wt% silver nanowires.

[0082] The gas separation membrane prepared in this embodiment was characterized by SEM, and the results are shown in the attached figure. Figure 2 As shown, from Figure 2 It can be seen that the silver nanowires and the polyethyleneamine matrix have very good compatibility, and the gas separation membrane prepared has no obvious defects.

[0083] Example 6

[0084] The preparation method of this embodiment is the same as that of Example 1, except that in step (3), the amount of silver nanowire solution used is 15 mL.

[0085] In this embodiment, the content of silver nanowires in the gas separation membrane is 68 wt%.

[0086] Comparative Example 1

[0087] The preparation method of the comparative example is the same as that of Example 1, except that step (2) is omitted and step (3) is to directly apply the PVAm solution obtained in step (1) onto the PSf ultrafiltration membrane, control the thickness of the wet coating to be 200 μm, and then place it in a constant temperature and humidity chamber to dry for 48 h.

[0088] Performance testing

[0089] The performance of the PVAm-CDs separation membrane was tested by using a separation membrane performance evaluation device (MGPT-I type separation membrane performance evaluation device, Dalian Karebon Technology Co., Ltd.). The feed gas was first humidified to saturation humidity in a humidification tank and then was tested in a membrane cell. The feed gas was a CO2 / N2 mixture, the sweeping gas was helium, the pressure was 0.1 MPa, and the permeation side pressure was normal pressure. The permeation side gas entered a gas chromatograph, the obtained peak area was analyzed to obtain the separation coefficient, and the gas permeation rate was measured by an electronic diaphragm flowmeter. The test results are shown in Table 1.

[0090] Table 1

[0091]

[0092] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0093] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and the changes, modifications, replacements and variations of the above embodiments made by those skilled in the art are within the protection scope of the present application.

Claims

1. A gas separation membrane characterized in that, The gas separation membrane comprises polyvinylamine and silver nanowires. The length of the silver nanowires is 5-25 μm, and the diameter is 20-200 nm. The preparation method of the gas separation membrane comprises the following steps: mixing a silver nanowire solution and a polyvinylamine solution to obtain a mixed solution, coating the mixed solution on an ultrafiltration membrane to obtain a polyvinylamine-silver nanowire wet membrane, and drying the wet membrane to obtain the gas separation membrane.

2. The gas separation membrane of claim 1, wherein, The content of the silver nanowires in the gas separation membrane is 10-70 wt%.

3. The gas separation membrane according to claim 1 or 2, characterized in that, The viscosity-average molecular weight of the polyvinylamine is 10,000-50,000 kDa.

4. The gas separation membrane of claim 1, wherein, The thickness of the gas separation membrane is 300-800 nm.

5. The method for producing a gas separation membrane according to any one of claims 1 to 4, characterized by, The gas separation membrane comprises: The preparation method of the gas separation membrane comprises the following steps: mixing a silver nanowire solution and a polyvinylamine solution to obtain a mixed solution, coating the mixed solution on an ultrafiltration membrane to obtain a polyvinylamine-silver nanowire wet membrane, and drying the wet membrane to obtain the gas separation membrane.

6. The method for producing a gas separation membrane according to claim 5, wherein The concentration of the silver nanowire solution is 1-10 wt%; And / or, the concentration of the polyvinylamine solution is 0.1-5 wt%; And / or, the content of the silver nanowires in the gas separation membrane is 10-70 wt%.

7. The method for producing a gas separation membrane according to claim 5 or 6, characterized by, The preparation method of the polyvinylamine solution comprises the following steps: dissolving N-vinylformamide and 2,2-azobis(2-methylpropylimine) dihydrochloride in deionized water, performing a free radical polymerization reaction after temperature rising under nitrogen protection to obtain a polyvinylformamide solution, adding a hydrochloric acid solution to the polyvinylformamide solution after temperature rising to perform a hydrolysis reaction, adding ice alcohol after the reaction, drying the product to obtain polyvinylamine hydrochloride solid, dissolving the polyvinylamine hydrochloride solid in deionized water, adding an anion exchange resin to perform anion exchange, and vacuum filtering to obtain the polyvinylamine solution. The ratio of the use amount of the N-vinylformamide to the 2,2-azobis(2-methylpropylimine) dihydrochloride is (10-40 g):(0.02-0.1 g). And / or, the temperature of the free radical polymerization reaction is 50-70 ℃, and the time of the free radical polymerization reaction is 4-10 h. And / or, the temperature of the hydrolysis reaction is 60-80 ℃, and the time of the hydrolysis reaction is 2-5 h. And / or, the concentration of the hydrochloric acid solution is 30-38 wt%, and the content of the hydrochloric acid in the mixed solution of the polyvinylformamide solution and the hydrochloric acid solution is 10-20 wt%.

8. The method for producing a gas separation membrane according to claim 5 or 6, characterized by, The preparation method of the silver nanowire solution comprises the following steps: adding polyvinylpyrrolidone to ethylene glycol, performing a reaction after temperature rising, cooling, adding a silver nitrate solution and a ferric chloride solution, cooling the silver nanowires after formation, performing centrifugal treatment with acetone to obtain a precipitate, and preparing a silver nanowire solution with ethanol as a solvent. The ratio of the use amount of the polyvinylpyrrolidone to the ethylene glycol is 4-20 g / L. And / or, the concentration of the silver nitrate solution is 0.01-0.1 mol / L, the concentration of the ferric chloride solution is 0.1-1 mol / L, and the volume ratio of the ethylene glycol, the silver nitrate solution and the ferric chloride solution is (1-10):(1-5):

1. And / or, the temperature of the reaction is 140-180 ℃, and the time of the reaction is 0.5-2 h.

9. Use of a gas separation membrane according to any one of claims 1 to 4 or a gas separation membrane produced according to the production process of any one of claims 5 to 8 for separating carbon dioxide from flue gas.

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