A carbon dioxide separation membrane and a method for preparing the same

Abstract

The present application relates to a composition for forming a carbon dioxide separation membrane, a carbon dioxide separation membrane and a preparation method thereof, the composition comprising a polymer and an organic salt, the organic salt being prepared by reacting an organic acid with an organic base; the organic acid comprising a basic group and an acidic group, the basic group comprising an amino group and / or an imino group, the acidic group comprising one or more of a carboxylic acid group, a phosphoric acid group, a sulfuric acid group, a sulfonic acid group; the organic base comprising one or more of guanidine and its derivatives, piperazine and its derivatives. The composition for forming a carbon dioxide separation membrane according to an embodiment of the present application can be used to prepare a carbon dioxide gas separation membrane, and can enable the gas separation membrane to have a higher carbon dioxide permeation rate.

Description

TECHNICAL FIELD

[0001] The present application relates to membrane separation, and in particular to a separation membrane for separating carbon dioxide. BACKGROUND

[0002] In order to address the serious environmental problem of global warming, greenhouse gas emissions from power plants and energy-intensive industries (such as cement, steel and steel mills) should be reduced. Due to the important role of fossil energy in industrial development, simply relying on the development of clean energy is not enough to achieve zero carbon dioxide emissions within a given time. Carbon dioxide capture, utilization and storage technology (CCUS) is currently the "bottom" technology for realizing low-carbon utilization of fossil energy. Carbon dioxide capture technology can be divided into three process procedures: post-combustion capture, pre-combustion capture and oxygen-enriched combustion capture, among which post-combustion carbon dioxide capture is considered a feasible solution for existing plants.

[0003] Absorption refers to the process of selectively absorbing gases in a mixed component by the absorbent according to its own properties, and is the most widely used method for separating carbon dioxide. However, absorption also has many disadvantages, such as relatively complex absorption process, unstable absorption efficiency, and secondary pollution in the absorption liquid regeneration process. In contrast, membrane separation for capturing carbon dioxide has no phase change and no secondary pollution. Gas membrane separation has become one of the most promising carbon dioxide capture technologies due to its low cost, simple device, low operating cost, high efficiency and greenness.

[0004] The core of gas membrane separation technology is gas separation membrane, and the core of the membrane is the selection of membrane materials, which has a significant impact on the entire separation process. The selection of gas separation membrane materials should take into account both permeation performance and selectivity. Facilitated transport membranes are a type of membrane that contains functional groups or structural units that can reversibly react with target components to enhance the transport of target components in the membrane. It can overcome the limitation of ordinary high polymer membranes that permeation performance and selectivity are mutually exclusive, and thus achieve high permeability and high selectivity of separation membranes at the same time. Therefore, facilitated transport membranes are considered to be a type of separation membrane with great development potential. However, gas membrane separation technology has not been widely used, mainly due to the insufficient performance of membrane materials and the instability of large-area prepared membrane materials. Therefore, it is of great significance to develop high-performance carbon dioxide capture membrane materials and prepare membranes with stable performance for achieving the dual carbon goal. SUMMARY

[0005] To overcome at least one of the above-mentioned drawbacks of the prior art, in a first aspect, one embodiment of the present application provides a composition for forming a carbon dioxide separation membrane, comprising a polymer and an organic salt; the organic salt is prepared by reacting an organic acid with an organic base; the organic acid comprises one or more basic groups and one or more acidic groups, the basic group(s) comprising an amino group and / or an imino group, and the acidic group(s) comprising one or more of a carboxylic acid group, a phosphoric acid group, a sulfuric acid group, and a sulfonic acid group; and the organic base comprises one or more of guanidine and derivatives thereof, and piperazine and derivatives thereof.

[0006] In a second aspect, one embodiment of the present application provides a carbon dioxide separation membrane, comprising a polymer layer, the raw material for preparing the polymer layer comprising the above-mentioned composition.

[0007] In a third aspect, one embodiment of the present application provides a method for preparing the above-mentioned carbon dioxide separation membrane, comprising the following steps:

[0008] providing a mixed solution, the mixed solution comprising the composition and a solvent; and

[0009] coating the mixed solution on the support layer, and drying to obtain the carbon dioxide separation membrane.

[0010] The composition for forming a carbon dioxide separation membrane according to one embodiment of the present application can be used to prepare a carbon dioxide gas separation membrane, and can enable the gas separation membrane to have a higher carbon dioxide permeation rate. DETAILED DESCRIPTION

[0011] The typical embodiments embodying the features and advantages of the present application will be described in detail hereinafter with reference to the accompanying drawings. It should be understood that the present application can be varied in a wide variety of ways, all of which are not necessarily described and making reference to the accompanying drawings, in which like numerals refer to like elements throughout the drawings. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0012] In one embodiment, the present application provides a composition for forming a carbon dioxide separation membrane, comprising a polymer and an organic salt; the organic salt is prepared by reacting an organic acid with an organic base; the organic acid comprises one or more basic groups and one or more acidic groups, the basic group(s) comprising an amino group (-NH2) and / or an imino group (-NH-), and the acidic group(s) comprising one or more of a carboxylic acid group (-COOH), a phosphoric acid group (-PO(OH)2), a sulfuric acid group (-OSO2OH), and a sulfonic acid group (-SO2OH); and the organic base comprises one or more of guanidine and derivatives thereof, and piperazine and derivatives thereof.

[0013] The composition of one embodiment of the present application can be used to prepare a facilitated transport membrane for carbon dioxide separation, wherein the polymer is a matrix and the organic salt is used as a carbon dioxide carrier; during operation, carbon dioxide in the gas to be treated can act on the organic salt, the organic salt can load carbon dioxide and move in the membrane and release carbon dioxide, thereby transferring carbon dioxide from the gas inlet side of the membrane to the permeate side, so as to realize the separation of carbon dioxide from other components in the gas.

[0014] The organic salt of one embodiment of the present application is stable in nature, not easy to volatilize, and has a high carbon dioxide loading capacity, and when used as a carbon dioxide carrier in a carbon dioxide separation membrane, the prepared separation membrane has high carbon dioxide selectivity and permeability.

[0015] In one embodiment, the carboxyl group-containing organic acid includes amino acids, oligopeptides, tranexamic acid and derivatives thereof; further, the amino acid is an organic compound containing a basic amino group and an acidic carboxyl group, including natural amino acids and unnatural amino acids, the natural amino acids include glycine, alanine, valine, leucine, isoleucine, methionine (methionine), proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, selenocysteine, pyrrolysine, etc., and the unnatural amino acid is mainly a derivative of the natural amino acid.

[0016] In one embodiment, the oligopeptide is prepared by dehydration condensation of 2-3 amino acids, and includes one or more of lysyl-proline, prolyl-isoleucine, prolyl-tryptophan, alanyl-glutamine, lysyl-phenylalanyl-lysine, lysyl-prolyl-valine, lysyl-lysyl-lysine.

[0017] In one embodiment, the carboxyl group-containing organic acid has the following general formula, wherein R1 represents hydrogen, a hydrocarbon group containing 1-7 carbon atoms or a substituted hydrocarbon group, the substituent in the substituted hydrocarbon group can be an amino group, a carboxyl group, a phosphoric acid group, a hydroxyl group, an acetyl group; R2 represents an alkylene group containing 1-7 carbon atoms or a substituted alkylene group, the substituent in the substituted alkylene group can be an amino group, a carboxyl group, a phosphoric acid group, a hydroxyl group, an acetyl group. Alternatively, R1 and R2 can be connected by a chemical bond and form a cyclic structure containing 2-7 carbon atoms together with the N atom.

[0018]

[0019] In one embodiment, the number of carbon atoms contained in R1 or R2 can be 1, 2, 3, 4, 5, 6 or 7.

[0020] In one embodiment, R1can be an alkyl or substituted alkyl group containing 1 to 7 carbon atoms, such as methyl, ethyl; R2can be an alkylene or substituted alkylene group containing 1 to 7 carbon atoms, such as methylene, ethylene.

[0021] In one embodiment, the organic acid containing a phosphonic acid group comprises 1 to 10 carbon atoms, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; further, the organic acid containing a phosphonic acid group includes aminomethylphosphonic acid, 2-aminoethylphosphonic acid, 3-aminopropylphosphonic acid, 4-aminobutane phosphonic acid.

[0022] In one embodiment, the organic acid containing a sulfonic acid group or a sulfonic acid group comprises 1 to 10 carbon atoms, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; further, the organic acid containing a sulfonic acid group or a sulfonic acid group includes sulfamic acid, naphthylamine sulfonic acid, aminomethyl sulfonic acid, 2-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 3-aminopropanesulfonic acid, 4-aminotoluene-3-sulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid, 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 5-amino-2-naphthalenesulfonic acid, hydroxylamine-O-sulfonic acid.

[0023] In one embodiment, guanidine and its derivatives include one or more of guanidine hydrochloride, guanidine sulfate, guanidine phosphate, guanidine carbonate, guanidine propionate, sulfaguanidine, guanidinoacetic acid, dimethylguanidine, N-phenylethylguanidine, phenylguanidine, guanidobutylamine sulfate, guanidine sulfamic acid, acetylguanidine, biguanide hydrochloride, methylguanidine hydrochloride, ethylguanidine hydrochloride, 1-(tert-butoxycarbonyl)guanidine.

[0024] In one embodiment, piperazine and its derivatives include one or more of piperazine, piperazinone, 2-methylpiperazine, N-ethylpiperazine, 1-formaldehyde piperazine, N-aminoethylpiperazine, 2,3-diaminopiperazine, 1-(2-pyridyl)piperazine, 1-(4-pyridyl)piperazine, homopiperazine, piperazine-2-carboxylic acid, piperazine-1-sulfonamide.

[0025] In one embodiment, the organic acid is selected from one or more of lysine, lysyl-proline, lysyl-lysyl-lysine, tranexamic acid, naphthylamine sulfonic acid, proline, aminomethylphosphonic acid, 2,4-diaminobenzenesulfonic acid; the organic base is selected from one or more of sulfaguanidine, piperazine, N-aminoethylpiperazine, 2,3-diaminopiperazine, 1-(2-pyrimidinyl)piperazine, 1-(2-pyridyl)piperazine, dimethylguanidine.

[0026] The kind of the polymer is not particularly limited, and it can be a polymer suitable for film formation. In order to further improve the performance of the separation membrane, the polymer is preferably one having a carbon dioxide loading capacity, and for example, the polymer can be one or more of polyvinyl alcohol, polyvinyl amine, polyallyl amine, polyacrylamide, polyethylene imine, cellulose, chitosan, and polyamide-amine.

[0027] In one embodiment, the number average molecular weight of the polymer can be 1 to 6 million, further 30 to 1 million, for example, 50,000, 100,000, 200,000, 250,000, 350,000, 400,000, 450,000, 500,000, 600,000, 700,000, 800,000, 900,000, 2 million, 3 million, 4 million, or 5 million.

[0028] In one embodiment, the ratio of the amount of the organic salt to the amount of the polymer is (0.01 to 0.6) mol:(1 to 20) g, for example, 0.1 mol:(1 to 2) g, 0.2 mol:(1 to 2) g, 0.3 mol:(1 to 2) g, 0.4 mol:(1 to 2) g, 0.5 mol:(1 to 2) g, (0.01 to 0.6) mol:3 g, (0.01 to 0.6) mol:5 g, (0.01 to 0.6) mol:8 g, (0.01 to 0.6) mol:10 g, (0.01 to 0.6) mol:12 g, (0.01 to 0.6) mol:15 g, or (0.01 to 0.6) mol:18 g.

[0029] One embodiment of the present application provides a carbon dioxide separation membrane including a polymer layer having a structure allowing a gas to pass therethrough, the polymer layer being prepared from a raw material including the above-mentioned composition.

[0030] In one embodiment, the carbon dioxide separation membrane includes a support layer on which the polymer layer is disposed, the support layer being used to provide the carbon dioxide separation membrane with good mechanical strength, the support layer having a porous structure to allow a gas to pass therethrough. Further, the material of the support layer includes one or more of ceramic, metal oxide, polyolefin-based resin, polysulfone-based resin, polyvinylidene fluoride, and polydimethylsiloxane.

[0031] One embodiment of the present application provides a method of preparing the above-mentioned carbon dioxide separation membrane, including the following steps:

[0032] S1: providing a mixed solution (or coating solution) including the above-mentioned organic salt, polymer, and solvent; and

[0033] S2: coating the mixed solution on a support layer, and drying to prepare the carbon dioxide separation membrane.

[0034] In one embodiment, the solvent of step S1 includes water.

[0035] In one embodiment, the preparation of the carbon dioxide carrier organic salt comprises:

[0036] configuring an aqueous organic acid solution;

[0037] configuring an aqueous organic base solution; and

[0038] mixing the aqueous organic acid solution and the aqueous organic base solution to perform a neutralization reaction to obtain the organic salt.

[0039] In one embodiment, the reaction temperature of the aqueous organic acid solution and the aqueous organic base solution can be 20-60°C, such as 22°C, 25°C, 28°C, 30°C, 32°C, 35°C, 40°C, 45°C, 50°C, 55°C; the reaction time can be 0.5-4h, such as 1h, 1.5h, 2h, 2.5h, 3h, 3.5h.

[0040] In one embodiment, in the preparation of the organic salt, the molar ratio of the organic acid to the organic base used can be 1:(0.9-1.1), further 1:1. For example, an equal volume of the aqueous organic acid solution and the aqueous organic base solution with equal molar concentration can be used for the reaction.

[0041] In one embodiment, the carbon dioxide carrier and the high molecular polymer can be dissolved in water (such as deionized water) to configure a mixed solution. Further, in the mixed solution, the mass percentage concentration of the polymer can be 0.1-2.0%, such as 0.2%, 0.25%, 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%; the concentration of the organic salt can be 0.01-0.6mol / L, such as 0.02mol / L, 0.05mol / L, 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L, 0.5mol / L.

[0042] In one embodiment, in step S2, the coating thickness of the mixed solution on the support layer can be 50-500μm, such as 60μm, 80μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm; the coating speed can be 2-10cm / s, such as 3cm / s, 4cm / s, 5cm / s, 6cm / s, 7cm / s, 8cm / s, 9cm / s.

[0043] In one embodiment, the drying process of step S2 can be performed for 5-48 hours, such as 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, 22 hours, 24 hours, 25 hours, 28 hours, 30 hours, 32 hours, 35 hours, 36 hours, 40 hours, 45 hours. The drying process can be performed under constant temperature and humidity, such as in a constant temperature and humidity box. The temperature of the drying process can be 30-80°C, such as 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C. The relative humidity of the drying process can be 20-60%, such as 30%, 35%, 40%, 45%, 50%, 55%.

[0044] The carbon dioxide carrier organic salt of one embodiment of the present application has the advantages of high loading capacity and stable properties compared to existing carbon dioxide carriers, and when used to prepare a gas separation membrane, a facilitated transport membrane with high permeation rate and high selectivity can be prepared.

[0045] The carbon dioxide separation membrane of one embodiment of the present application can be used to treat a gas containing carbon dioxide, in particular a gas containing carbon dioxide and nitrogen.

[0046] The carbon dioxide separation membrane of one embodiment of the present application has a carbon dioxide permeation rate of 800-4000 GPU, further 1000-4000 GPU, such as 1100 GPU, 1200 GPU, 1300 GPU, 1400 GPU, 1500 GPU, 1600 GPU, 1700 GPU, 1800 GPU, 2000 GPU, 2200 GPU, 2500 GPU, 2600 GPU, 2800 GPU, 3000 GPU, 3200 GPU, 3500 GPU, 3800 GPU, for a carbon dioxide / nitrogen mixed gas, and a separation factor of 15-120, further 40-120, such as 20, 30, 35, 42, 45, 46, 48, 50, 52, 55, 58, 60, 70, 80, 90, 100, 110, for carbon dioxide / nitrogen. The above parameters are measured at a pressure of 0.1-2.0 bar and room temperature.

[0047] The carbon dioxide separation membrane of one embodiment of the present application is further described below in combination with specific examples. Unless otherwise specified, the raw materials used are commercially available. In a few cases, the prepared organic acid or organic base solution can be a suspension, and the organic salt solution obtained after mixing the organic acid and organic base is a clear solution.

[0048] Example 1

[0049] (1) Lysine was used as the organic acid to prepare a 0.4 mol / L lysine aqueous solution;

[0050] (2) Take sulfaguanidine as an organic base, dissolve in boiling water, and prepare a 0.4 mol / L sulfaguanidine aqueous solution;

[0051] (3) Take equal volumes of the above lysine aqueous solution and sulfaguanidine aqueous solution, mix and heat to 60°C, stir for 2 h, and prepare a carbon dioxide carrier aqueous solution;

[0052] (4) Prepare a polymer solution containing 0.1% (mass percentage, the same below) polyvinyl alcohol, 0.1% polyvinylamine, and 0.05% polyacrylamide;

[0053] (5) Take 1 mL of the above carbon dioxide carrier aqueous solution and 9 mL of the above polymer solution to mix thoroughly to obtain a coating solution;

[0054] (6) Use a composite film of polyether sulfone and polydimethylsiloxane as a porous support layer, and use a doctor blade to coat the film on the surface at a thickness of 100 μm and a speed of 5 cm / s; then transfer the obtained structure to a constant temperature and humidity chamber with a temperature of 40°C and a relative humidity of 30% for drying for 24 h, and prepare a carbon dioxide carrier-containing gas separation membrane.

[0055] Example 2

[0056] This example uses the same raw materials and process as in Example 1 to prepare a gas separation membrane, with the only difference being that the organic acid is lysyl-proline and the organic base is piperazine.

[0057] Example 3

[0058] This example uses the same raw materials and process as in Example 2 to prepare a gas separation membrane, with the only difference being that the organic acid is lysyl-lysyl-lysine.

[0059] Example 4

[0060] This example uses the same raw materials and process as in Example 1 to prepare a gas separation membrane, with the only difference being that the organic acid is tranexamic acid, the organic base is N-aminoethylpiperazine, and the concentrations of the organic acid aqueous solution and the organic base aqueous solution are both 1 mol / L.

[0061] Example 5

[0062] This example uses the same raw materials and process as in Example 1 to prepare a gas separation membrane, with the only difference being that the organic acid is naphthylamine sulfonic acid, the organic base is 2,3-diaminopiperazine, and the concentrations of the organic acid aqueous solution and the organic base aqueous solution are both 1 mol / L.

[0063] Example 6

[0064] The gas separation membrane is prepared by using the same raw materials and process as in Embodiment 1, except that proline is used as the organic acid and 1-(2-pyridyl)piperazine is used as the organic base.

[0065] Embodiment 7

[0066] The gas separation membrane is prepared by using the same raw materials and process as in Embodiment 1, except that aminomethyl phosphonic acid is used as the organic acid and 1-(2-pyrimidyl)piperazine is used as the organic base.

[0067] Embodiment 8

[0068] The gas separation membrane is prepared by using the same raw materials and process as in Embodiment 1, except that 2,4-diaminobenzenesulfonic acid is used as the organic acid and dimethyl guanidine is used as the organic base, and the concentrations of the aqueous organic acid solution and the aqueous organic base solution are both 1 mol / L.

[0069] Embodiment 9

[0070] The gas separation membrane is prepared by using the same raw materials and process as in Embodiment 2, except that 6 mL of the aqueous carbon dioxide carrier solution and 4 mL of the polymer solution are mixed in step (5).

[0071] Embodiment 10

[0072] The gas separation membrane is prepared by using the same raw materials and process as in Embodiment 2, except that the thickness of the blade coating in step (6) is 200 μm and the speed is 4 cm / s.

[0073] Embodiment 11

[0074] The gas separation membrane is prepared by using the same raw materials and process as in Embodiment 1, except that 0.1 mL of the aqueous carbon dioxide carrier solution and 9.9 mL of the polymer solution are mixed in step (5).

[0075] Embodiment 12

[0076] The gas separation membrane is prepared by using the same raw materials and process as in Embodiment 2, except that 4 mL of the aqueous carbon dioxide carrier solution and 6 mL of the polymer solution are mixed in step (5), and the thickness of the blade coating in step (6) is 200 μm and the speed is 4 cm / s.

[0077] Embodiment 13

[0078] (1) Lysine is used as the organic acid to prepare a 1 mol / L aqueous lysine solution;

[0079] (2) 2,3-diaminopiperazine is used as the organic base to prepare a 1 mol / L aqueous 2,3-diaminopiperazine solution;

[0080] (3) Take equal volume of the above lysine aqueous solution and 2,3-diaminopiperazine aqueous solution, mix and heat to 40℃, stir for 4h, to prepare carbon dioxide carrier aqueous solution;

[0081] (4) Prepare a polymer solution comprising 0.1% (mass percentage, the same below) polyvinyl alcohol, 1% polyvinylamine, 0.01% polyacrylamide, 0.1% polyethyleneimine;

[0082] (5) Take 1 mL of the above carbon dioxide carrier aqueous solution and 9 mL of the above polymer solution to mix thoroughly to obtain a coating solution;

[0083] (6) Use a polyvinylidene fluoride membrane as a porous support layer, and coat the membrane on the surface with a doctor blade thickness of 200μm at a speed of 10cm / s; then transfer the obtained structure to a constant temperature and humidity chamber with a temperature of 40℃ and a relative humidity of 30% for drying for 24h, to prepare a gas separation membrane containing a carbon dioxide carrier.

[0084] Comparative Example 1

[0085] This comparative example uses substantially the same raw materials and process as Example 1 to prepare a gas separation membrane, the only difference being that steps (1) (2) (3) (5) are not used, i.e. no organic salt is added as a carrier in the prepared gas separation membrane.

[0086] Comparative Example 2

[0087] This comparative example uses substantially the same raw materials and process as Example 6 to prepare a gas separation membrane, the only difference being that the base is inorganic sodium hydroxide.

[0088] Under the conditions of 25℃ and 2bar of feed gas pressure, using CO2 / N2(15 / 85vol) mixed gas as the test gas, the permeation rates of the above-mentioned examples and comparative examples of the gas separation membrane for carbon dioxide and nitrogen gas humidified to a relative humidity of 90% were tested, and the CO2 / N2 separation factor (i.e. the ratio of CO2 permeation rate to N2 permeation rate) was calculated, and the specific results are shown in Table 1.

[0089] Specific testing process is as follows: cut the gas separation membrane to the appropriate size and fix it in the membrane cell; connect the feed gas (CO2 / N2 mixed gas) to the membrane cell, control the output pressure of the feed gas with a pressure reducing valve, and make the mixed gas saturated or other humidity conditions by passing through the humidification tank and the dehumidification tank before contacting the membrane to be tested in the membrane cell; part of the gas in the feed gas permeates through the membrane, and is then sent to the gas chromatograph by the sweeping gas (He) to analyze the gas composition on the permeation side of the membrane.

[0090] Table 1

[0091]

[0092]

[0093] According to Example 1, Comparative Example 1 and Table 1, the CO2permeation rate and separation factor of the gas separation membrane of Example 1 are much higher than those of Comparative Example 1, indicating that the use of the organic salt carrier can greatly improve the carbon dioxide permeation rate and selectivity of the gas separation membrane.

[0094] According to Examples 1 to 3, Examples 6 to 7, Comparative Example 2 and Table 1, under the same conditions, the CO2permeation rate and separation factor of the gas separation membranes of Examples 1 to 3 and 6 to 7 using the organic salt carrier are much higher than those of the gas separation membrane of Comparative Example 2 using the inorganic salt carrier, indicating that the performance of the organic salt carrier of the embodiments of the present application is better than that of the inorganic salt carrier.

[0095] According to Examples 1 and 11, compared with Example 11, the gas separation membrane of Example 1 contains more carbon dioxide carrier organic salt, and from Table 1, the CO2permeation rate and separation factor of the gas separation membrane of Example 1 are greater than those of the gas separation membrane of Example 11. This result indicates that appropriately increasing the content of the carbon dioxide carrier in the gas separation membrane can improve the CO2permeation rate and separation factor. In addition, according to Examples 2 and 9 and Table 1, compared with Example 2, the content of the carbon dioxide carrier in the gas separation membrane of Example 9 is greatly increased, which can improve the CO2permeation rate, but the separation factor decreases. This shows that too high content of the organic salt carrier can reduce the selectivity of the membrane. In summary, the ratio of the amount of the organic salt to the amount of the polymer is preferably (0.02-0.12) mol:(1-2.25) g.

[0096] According to Examples 1 and 2 and Table 1, compared with Example 1, the CO2permeation rate of the gas separation membrane of Example 2 is higher, indicating that the organic salt prepared by lysyl-proline and piperazine reaction has a higher carbon dioxide loading capacity than the organic salt prepared by lysine and sulfaguanidine reaction.

[0097] According to Examples 2 and 3 and Table 1, compared with Example 3, the gas separation membrane of Example 2 has a higher CO2permeation rate and a similar separation factor, indicating that the performance of the carrier of the organic salt prepared by lysyl-proline and piperazine reaction is better than that of the organic salt prepared by lysyl-lysyl-lysine and piperazine reaction.

[0098] According to Examples 1, 3-8 and Table 1, the gas separation membrane of Example 1 has higher CO2 permeation rate and separation factor than Examples 3-8, indicating that the organic salt carrier prepared by lysine and sulfaguanidine reaction has better performance than the organic salts prepared by lysyl-lysyl-lysine and piperazine reaction.

[0099] According to Examples 2, 4, 5, 6, 7, 8 and Table 1, the gas separation membrane of Example 2 has higher CO2 permeation rate than Examples 4, 5, 6, 7, 8, indicating that the organic salt prepared by lysyl-proline and piperazine reaction has higher carbon dioxide loading capacity than other organic salts such as tranexamic acid and N-aminoethylpiperazine.

[0100] According to Examples 3, 6, 7 and Table 1, the gas separation membrane of Example 6 has higher CO2 permeation rate and separation factor than Examples 3, 7, indicating that the organic salt carrier prepared by proline and 1-(2-pyridyl)piperazine reaction has better performance than the organic salts prepared by lysyl-lysyl-lysine and piperazine reaction and the organic salt prepared by aminomethylphosphonic acid and 1-(2-pyrimidyl)piperazine reaction.

[0101] According to Examples 4, 5, 6, 8 and Table 1, the concentration of the organic salt of Example 6 is less than that of the organic salts of Examples 4, 5, 8, but the gas separation membrane of Example 6 has higher CO2 permeation rate and separation factor than Examples 4, 5, 8, indicating that the organic salt carrier of Example 6 has better performance than the organic salt carriers of Examples 4, 5, 8. Further, the gas separation membranes of Examples 4, 5 have higher CO2 permeation rate and separation factor than Example 8, indicating that the organic salt carriers of Examples 4, 5 have better performance than the organic salt carrier of Example 8.

[0102] In combination with the above results, to improve the comprehensive performance of the separation membrane, the carbon dioxide carrier is preferably the organic salt prepared by lysine and sulfaguanidine reaction (Example 1), the organic salt prepared by lysyl-proline and piperazine reaction (Example 2), the organic salt prepared by proline and 1-(2-pyridyl)piperazine reaction (Example 6), the organic salt prepared by tranexamic acid and N-aminoethylpiperazine reaction (Example 4), and the organic salt prepared by naphthylamine sulfonic acid and 2,3-diaminopiperazine reaction (Example 5); further preferably the organic salt prepared by lysine and sulfaguanidine reaction (Example 1), the organic salt prepared by lysyl-proline and piperazine reaction (Example 2), and the organic salt prepared by proline and 1-(2-pyridyl)piperazine reaction (Example 6); and more preferably the organic salt prepared by lysine and sulfaguanidine reaction (Example 1) and the organic salt prepared by lysyl-proline and piperazine reaction (Example 2).

[0103] According to the above results, the organic acid for preparing the organic salt is preferably lysine, lysyl-proline, proline, tranexamic acid, naphthylamine sulfonic acid; further preferably lysine, lysyl-proline, proline; more further preferably lysine, lysyl-proline. The organic base for preparing the organic salt is preferably sulfaguanidine, piperazine, 1-(2-pyridyl)piperazine, N-aminoethylpiperazine, 2,3-diaminopiperazine, further preferably sulfaguanidine, piperazine, 1-(2-pyridyl)piperazine; more further preferably sulfaguanidine, piperazine.

[0104] Compared with Example 2, Example 10 can improve the permeation selectivity of the membrane by optimizing the doctor blade thickness and the doctor blade speed. Thus, the coating thickness of the mixed solution on the support layer is preferably 180-220 μm, further preferably 190-210 μm, more further preferably 200 μm; the coating speed is preferably 4-5 cm / s.

[0105] Example 12 can further improve the permeation selectivity of the membrane by optimizing the carrier content, the doctor blade thickness and the doctor blade speed. Example 13 changes the support layer type and the membrane preparation conditions, and suitable separation membranes can also be prepared for different support layers.

[0106] Unless specifically defined, the terms used in the present application are understood to have the meanings commonly used by those skilled in the art.

[0107] The embodiments described in the present application are only for illustrative purposes, and are not intended to limit the protection scope of the present application. Those skilled in the art can make various other replacements, changes and improvements within the scope of the present application, and thus the present application is not limited to the above embodiments, but is only limited by the claims.

Claims

1. A composition for forming a carbon dioxide separation membrane, comprising a polymer and an organic salt; wherein the ratio of the organic salt to the polymer is (0.01–0.6) mol:(1–20) g; wherein the organic salt is prepared by reacting an organic acid with an organic base; wherein the organic acid comprises a basic group and an acidic group, the basic group comprising amino and / or imino groups, and the acidic group comprising one or more of carboxylic acid groups, phosphate groups, sulfate groups, and sulfonic acid groups; wherein the organic base comprises one or more of guanidine and its derivatives, and piperazine and its derivatives. The organic acid containing a carboxylic acid group is selected from one or more of amino acids, oligopeptides, and tranexamic acid; The amino acids include one or more of the following: alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, selenocysteine, and pyrrolidone. The guanidine and its derivatives include one or more of guanidine hydrochloride, guanidine sulfate, guanidine phosphate, guanidine carbonate, guanidine propionate, sulfanilamide guanidine, guanidinoacetic acid, dimethyl biguanide, N-phenylethyl biguanide, phenyl biguanide, guanidinobutylamine sulfate, guanidine aminosulfonate, acetyl guanidine, diguanidine hydrochloride, methyl guanidine hydrochloride, ethyl guanidine hydrochloride, and 1-(tert-butyloxycarbonyl)guanidine; The piperazine and its derivatives include one or more of piperazine, piperazine ketone, 2-methylpiperazine, N-ethylpiperazine, 1-formaldehyde piperazine, N-aminoethylpiperazine, 2,3-diaminopiperazine, 1-(2-pyridyl)piperazine, 1-(4-pyridyl)piperazine, homopiperazine, piperazine-2-carboxylic acid, and piperazine-1-sulfonamide; The oligopeptide is prepared by dehydration condensation of 2 to 3 amino acids, including one or more of lysyl-proline, prolyl-isoleucine, prolyl-tryptophan, alanyl-glutamine, lysyl-phenylalanyl-lysine, lysyl-prolyl-valine, and lysyl-lysyl-lysine. The organic acid containing a phosphate group is selected from one or more of aminomethylphosphonic acid, 2-aminoethylphosphonic acid, 3-aminopropylphosphonic acid, and 4-aminobutanephosphonic acid; the organic acid containing a sulfate group or a sulfonic acid group is selected from one or more of aminosulfonic acid, naphthylamine sulfonic acid, aminomethanesulfonic acid, 2-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 3-aminopropanesulfonic acid, 4-aminotoluene-3-sulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid, 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 5-amino-2-naphthalenesulfonic acid, and hydroxylamine-O-sulfonic acid.

2. The composition according to claim 1, wherein, The organic acid is selected from one or more of lysine, lysyl-proline, lysyl-lysyl-lysine, tranexamic acid, naphthylamine sulfonic acid, proline, aminomethylphosphonic acid, and 2,4-diaminobenzenesulfonic acid; the organic base is selected from one or more of sulfaguanidine, piperazine, N-aminoethylpiperazine, 2,3-diaminopiperazine, 1-(2-pyridyl)piperazine, 1-(2-pyrimidinyl)piperazine, and dimethylbiguanide; and / or, The polymer includes one or more of polyvinyl alcohol, polyvinylamine, polyallylamine, polyacrylamide, polyethyleneimine, cellulose, chitosan, and polyamide-amine; and / or, The number-average molecular weight of the polymer is 1 to 6 million.

3. The composition according to claim 1, wherein, The organic salt is selected from one or more of the following organic salts: organic salt obtained by reacting lysine with sulfanilamide, organic salt obtained by reacting lysyl-proline with piperazine, organic salt obtained by reacting proline with 1-(2-pyridyl)piperazine, organic salt obtained by reacting tranexamic acid with N-aminoethylpiperazine, and organic salt obtained by reacting naphthylamine sulfonic acid with 2,3-diaminopiperazine.

4. A carbon dioxide separation membrane comprising a polymer layer, wherein the polymer layer is prepared from the composition of any one of claims 1 to 3.

5. The carbon dioxide separation membrane according to claim 4, comprising a support layer, wherein the polymer layer is disposed on the support layer; the material of the support layer includes one or more of ceramics, metal oxides, polyolefins, polysulfones, polyvinylidene fluoride, and polydimethylsiloxane.

6. The method for preparing the carbon dioxide separation membrane according to claim 5, comprising the following steps: Provide a mixture comprising the composition and a solvent; and The mixture is coated onto the support layer and dried to obtain the carbon dioxide separation membrane.

7. The method according to claim 6, wherein, In the mixture, the polymer has a mass percentage concentration of 0.1–2.0%, and the organic salt has a concentration of 0.01–0.6 mol / L; and / or, The coating thickness of the mixture is 50–500 μm; the coating speed is 2–10 cm / s.

8. The method according to claim 6, wherein, The coating thickness of the mixture is 180–220 μm; the coating speed is 4–5 cm / s.

9. The method according to claim 6, wherein, The drying process is carried out at a temperature of 30–80°C and a relative humidity of 20–60%.

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