Method for producing a composite membrane and composite membrane and use of the composite membrane as a carbon dioxide separation membrane

Abstract

The application relates to the technical field of gas separation membrane materials, and discloses a preparation method of a composite membrane, the composite membrane and application of the composite membrane in the field of carbon dioxide separation. The method comprises the following steps: S1, soaking a base film in an acyl chloride solution; S2, soaking the product obtained in step S1 in a solution containing a diamine monomer and an acid absorbent to perform an interfacial polymerization reaction, wherein the diamine monomer contains an ether oxygen chain segment, and the number of ether oxygen bonds is greater than or equal to 2; and S3, drying the product obtained in step S2. The method is characterized in that the base film is soaked in the acyl chloride solution to uniformly spread the acyl chloride on the surface of the base film, and then the base film is soaked in the solution rich in the ether oxygen chain segment diamine monomer, so that the acyl chloride and the ether oxygen chain segment rich diamine monomer utilize the interfacial polymerization reaction to obtain the ether oxygen chain segment rich polyamide composite membrane which is excellent in permeation performance and separation performance.

Description

Technical Field

[0001] This invention relates to the field of gas separation membrane material technology, specifically to a method for preparing a composite membrane, the composite membrane itself, and its application as a carbon dioxide separation membrane. Background Technology

[0002] With the development of economic globalization, environmental and energy issues have become urgent problems to be solved in economic development. The combustion of traditional fossil fuels such as coal and oil has brought about serious environmental pollution problems. The large-scale emission of CO2 has caused the global greenhouse effect, leading to rising global temperatures, damage to ecosystems, and seriously threatening the survival of life on Earth. Therefore, CO2 emission reduction has become a major global issue. Currently, common CO2 separation technologies include cryogenic separation, adsorption, absorption, and membrane separation. Membrane separation has advantages such as low fixed investment, simple operation, low energy consumption, and small footprint, and has a promising future in the field of CO2 separation. Currently, polymer membranes used for gas separation have advantages such as good mechanical stability, ease of scale-up, and low cost and availability, and have attracted widespread attention from researchers.

[0003] However, the poor permeation or separation performance of polymer membranes currently used for gas separation limits their practical application prospects. Therefore, there is an urgent need to research and develop separation membranes with better performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of poor permeation or separation performance of polymer membranes used for gas separation in the prior art, and to provide a method for preparing a composite membrane, the composite membrane, and its application as a carbon dioxide separation membrane. The method involves immersing a base membrane in an acyl chloride solution to uniformly spread the acyl chloride on the surface of the base membrane, and then immersing it in a solution of diamine monomers rich in ether oxygen segments, so that the acyl chloride and the diamine monomers rich in ether oxygen segments can undergo an interfacial polymerization reaction to obtain a polyamide composite membrane rich in ether oxygen segments with excellent permeation and separation performance.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a composite membrane, the method comprising the following steps:

[0006] S1. Immerse the base film in an acyl chloride solution;

[0007] S2. The product obtained in step S1 is immersed in a solution containing a diamine monomer and an acid absorbent to carry out an interfacial polymerization reaction, wherein the diamine monomer contains an ether oxygen segment and the number of ether oxygen bonds is ≥2.

[0008] S3. Dry the product obtained in step S2.

[0009] Preferably, in step S1, the base film includes a polymer support layer and an intermediate layer covering the surface of the polymer support layer, wherein the intermediate layer is a polydimethylsiloxane layer and / or a derivative layer thereof.

[0010] Preferably, the polymer support layer is made of at least one of polysulfone, polyacrylonitrile, and polyethersulfone.

[0011] Preferably, in step S1, the acyl chloride in the acyl chloride solution has two carbonyl chloride functional groups and / or three carbonyl chloride functional groups.

[0012] Preferably, the acyl chloride in the acyl chloride solution is selected from at least one of terephthaloyl chloride, isophthaloyl chloride, trimesoyl chloride, glutaryl chloride, and adipyl chloride.

[0013] Preferably, in step S1, the concentration of acyl chloride in the acyl chloride solution is 0.4~5 g / L, more preferably 2-2.5 g / L.

[0014] Preferably, the solvent of the acyl chloride solution is selected from at least one of n-pentane, n-hexane, n-heptane, and cyclohexane.

[0015] Preferably, in step S1, the soaking time is 10 seconds to 2 minutes.

[0016] Preferably, in the solution containing diamine monomer and acid absorbent described in step S2, the concentration of the diamine monomer is 0.2~10 g / L, more preferably 2~5 g / L.

[0017] Preferably, the diamine monomer is 2,2'-(ethylenedioxy)bis(ethylamine) and / or O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol.

[0018] More preferably, the molecular weight of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 400-1000, preferably 600.

[0019] Preferably, in the solution containing diamine monomer and acid absorbent described in step S2, the concentration of the acid absorbent is 0.2~1.6 g / L.

[0020] Preferably, the acid absorbent is selected from at least one of sodium hydroxide, sodium bicarbonate, and sodium carbonate.

[0021] Preferably, in step S2, the reaction time of the interfacial polymerization reaction is 10s to 2min, more preferably 10s to 1min.

[0022] Preferably, in step S3, the drying temperature is 40~80℃, more preferably 45~60℃; and the time is 5~20min.

[0023] A second aspect of the present invention provides a composite membrane prepared by the method described above.

[0024] A third aspect of the present invention provides a composite membrane prepared by the method described above and its application as a carbon dioxide separation membrane.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] (1) The method of the present invention involves soaking the base membrane in an acyl chloride solution to spread the acyl chloride evenly on the surface of the base membrane, and then soaking the obtained product in a solution of diamine monomers rich in ether oxygen segments, so that the acyl chloride and diamine monomers rich in ether oxygen segments can undergo interfacial polymerization reaction. The resulting polyamide composite membranes rich in ether oxygen segments have good permeation and separation performance.

[0027] (2) The experimental conditions of the present invention are easy to control, and the obtained ether-rich oxygen-chain segment polyamide membrane has excellent film-forming properties. The composite membrane prepared has excellent permeability selectivity and high repeatability. This preparation process can be used for scale-up production to prepare CO2 separation composite membranes in batches.

[0028] (3) The composite membranes prepared by this invention were tested with a mixed gas (CO2 / N2 15 / 85). The results showed that the composite membranes prepared by this invention all had good CO2 permeation rates and separation factors. In a preferred embodiment, by controlling the molecular weight of the diamine monomer and the concentrations of the diamine monomer and acyl chloride, the composite membranes prepared by interfacial polymerization had better permeation and separation performance. When O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (ED-600) with a molecular weight of 600 and a concentration of 2.5 g / L was used as the inorganic phase monomer, the composite membrane obtained by interfacial polymerization with trimesoyl pyromellitic chloride at a concentration of 2.1 g / L had the best performance. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the composite membrane prepared according to the present invention, wherein the polyamide rich in ether oxygen segments serves as the separation layer, and the intermediate layer of silicone rubber is coated on the surface of the ultrafiltration membrane as the support layer.

[0030] Figure 2 The image shown is a scanning electron microscope image of the surface structure of the composite membrane prepared in Example 2, demonstrating that after the silicone rubber intermediate layer is coated onto the ultrafiltration membrane, a polyamide separation layer rich in ether oxygen segments can be polymerized at its surface interface. Detailed Implementation

[0031] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] The method for preparing the composite membrane provided by the present invention includes the following steps:

[0034] S1. Immerse the base film in an acyl chloride solution;

[0035] S2. The product obtained in step S1 is immersed in a solution containing a diamine monomer and an acid absorbent to carry out an interfacial polymerization reaction, wherein the diamine monomer contains an ether oxygen segment and the number of ether oxygen bonds is ≥2.

[0036] S3. Dry the product obtained in step S2.

[0037] In the method described in this invention, the inventors discovered that by immersing the base membrane in an acyl chloride solution in a specific order to allow the acyl chloride to spread evenly on the surface of the base membrane, and then immersing the resulting product in a solution containing a specific diamine monomer, the acyl chloride and the diamine monomer undergo an interfacial polymerization reaction, thereby obtaining a composite membrane with good permeability and separation performance. Due to the polymerization reaction, a polyamide separation layer is formed on the surface of the composite membrane on the base membrane.

[0038] In this invention, the base membrane can be a polymer membrane commonly used in the art. In a preferred embodiment, the base membrane in step S1 is a base membrane with an intermediate layer, that is, the base membrane includes a polymer support layer and an intermediate layer coated on the surface of the polymer support layer, wherein the intermediate layer is a polydimethylsiloxane layer and / or its derivative layer; in this invention, coating the surface of the polymer support layer with a polydimethylsiloxane layer and / or its derivative layer is to prevent the formed polyamide separation layer from seeping into the pores of the polymer support layer, causing a sharp drop in performance. In some embodiments, the polymer support layer can be made of at least one selected from polysulfone, polyacrylonitrile, and polyethersulfone. Preferably, the polymer support layer is an ultrafiltration membrane made of polysulfone, polyacrylonitrile, or polyethersulfone.

[0039] In this invention, the acyl chloride is a reactive monomer that undergoes interfacial polymerization with a diamine monomer. In some embodiments, the acyl chloride in the acyl chloride solution is an acyl chloride having two carbonyl chloride functional groups and / or three carbonyl chloride functional groups. In some more specific embodiments, the acyl chloride in the acyl chloride solution includes, but is not limited to, at least one of terephthaloyl chloride, isophthaloyl chloride, trimesoyl chloride, glutaryl chloride, and adipyl chloride. In a more preferred embodiment, the acyl chloride in the acyl chloride solution is isophthaloyl chloride and / or trimesoyl chloride.

[0040] In some embodiments, the concentration of acyl chloride in the acyl chloride solution in step S1 can be 0.4~5 g / L, for example 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, or 5 g / L. In the method described in this invention, if the concentration of acyl chloride in the acyl chloride solution is too high, the interfacial polymerization of the acyl chloride and diamine monomer will result in excessively high polymer crosslinking degree and membrane thickness, thereby reducing the CO2 permeation performance of the prepared composite membrane. If the concentration of acyl chloride in the acyl chloride solution is too low, the polymer crosslinking degree will decrease, the membrane thickness will decrease, leading to reduced CO2 selectivity, and may even cause unstable interfacial polymerization and failure to form a membrane. To ensure that the prepared composite membrane has both excellent permeation and separation performance, and further improve the performance of the composite membrane, in a preferred embodiment, the concentration of acyl chloride in the acyl chloride solution is 2-2.5 g / L.

[0041] In this invention, the acyl chloride solution can be an organic solution. The solvent for the acyl chloride solution can be a conventional choice in the art; in some embodiments, the solvent for the acyl chloride solution can be selected from at least one of n-pentane, n-hexane, n-heptane, and cyclohexane.

[0042] In some embodiments, the soaking time in step S1 can be 10 seconds to 2 minutes, for example, 10 seconds, 30 seconds, 1 minute, 1.5 minutes, or 2 minutes. In this invention, the soaking time in step S1 is only required to ensure that the acyl chloride can be evenly spread on the surface of the base film.

[0043] In this invention, the method further includes: after immersing the base film in the acyl chloride solution, removing the base film and allowing it to stand to allow the solution on the surface to evaporate. The standing time does not need to be too long; in some embodiments, the standing time can be 0.5 to 2 minutes.

[0044] In some embodiments, in the solution containing diamine monomer and acid absorbent described in step S2, the concentration of the diamine monomer is 0.2~10 g / L, for example 0.5 g / L, 0.8 g / L, 1 g / L, 2 g / L, 2.5 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, or 10 g / L. In the method described in this invention, if the concentration of the diamine monomer is too high, the interfacial polymerization of the diamine monomer with the acyl chloride will result in excessively high polymer crosslinking degree and membrane thickness, thereby reducing the CO2 permeation performance of the prepared composite membrane; if the concentration of the diamine monomer is too low, the polymer crosslinking degree will decrease, the membrane thickness will decrease, leading to reduced CO2 selectivity, and may even cause unstable interfacial polymerization and failure to form a membrane. In order to ensure that the prepared composite membrane has both excellent permeation and separation properties, and to further improve the performance of the composite membrane, in a preferred embodiment, the concentration of the diamine monomer in the solution containing the diamine monomer and the acid absorbent in step S2 is 2~5 g / L.

[0045] In the method described in this invention, to facilitate better polymerization of the diamine monomer and the acyl chloride, the two end groups of the main molecular chain of the diamine monomer can be primary amine groups. In some embodiments, the diamine monomer containing ether oxygen segments and having ≥2 ether oxygen bonds is 2,2'-(ethylenedioxy)bis(ethylamine) and / or O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol, preferably O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol. The molecular weight of O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol can be 400-1000. For example, O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol can be ED-600 and / or ED-900.

[0046] In this invention, preferably, the solution containing the diamine monomer and the acid absorbent is an aqueous solution. The inventors have found that the higher the molecular weight of the diamine monomer in the aqueous solution, the weaker its ability to diffuse from the homogeneous aqueous solution to the oil-water interface, and the weaker the reactivity of the amino group with the acyl chloride. However, a high molecular weight of the diamine monomer in the aqueous solution can provide a higher density of ether oxygen segments within the membrane, which is beneficial for the membrane's affinity for CO2 molecules. Furthermore, using a higher molecular weight inorganic phase monomer can result in a relatively soft and porous membrane structure, which is beneficial for improving CO2 permeation performance. Therefore, in order to obtain a separation membrane with excellent permeation and separation performance, and to further improve the performance of the composite membrane, in a preferred embodiment, the molecular weight of O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 600.

[0047] In a more preferred embodiment, the acyl chloride in the acyl chloride solution is isophthaloyl chloride and / or trimesoyl chloride, and the molecular weight of O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 600. The composite membrane prepared using this preferred embodiment has superior performance.

[0048] In one embodiment, when the acyl chloride is trimesoyl pyromellitic chloride and the diamine monomer is O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol, the basic structural equation for the reaction between the acyl chloride and the diamine monomer is as follows:

[0049]

[0050] .

[0051] In this invention, the acid absorbent serves to absorb hydrogen chloride generated from the reaction of acyl chloride and diamine monomer. In some embodiments, the concentration of the acid absorbent in the solution containing the diamine monomer and the acid absorbent in step S2 is 0.2~1.6 g / L. In this invention, the acid absorbent can be a common alkaline substance in the art. In some embodiments, the acid absorbent can be selected from at least one of sodium hydroxide, sodium bicarbonate, and sodium carbonate.

[0052] In some embodiments, the reaction time of the interfacial polymerization reaction in step S2 can be 10 s to 2 min, for example, 10 s, 20 s, 30 s, 40 s, 50 s, 1 min, 1.5 min, or 2 min. In order to further improve the permeation performance and separation performance of the composite membrane to a higher level at the same time, in some preferred embodiments, the reaction time of the interfacial polymerization reaction in step S2 is 10 s to 1 min.

[0053] In the method described in this invention, the method further includes: after the interfacial polymerization reaction is completed, taking out the obtained product and rinsing its surface with deionized water.

[0054] In this invention, the product obtained from the interfacial polymerization reaction undergoes thermal crosslinking during drying in step S3. This thermal crosslinking causes the small-molecule oligomers to re-crosslink, forming a denser polymer network. In some embodiments, the drying temperature in step S3 can be 40–80°C, and the drying time can be 5–20 min. To further improve the performance of the composite membrane, in a more preferred embodiment, the drying temperature in step S3 is 45–60°C.

[0055] In a preferred embodiment, the method for preparing the composite membrane includes the following steps:

[0056] S1. Using a polysulfone ultrafiltration membrane coated with a polydimethylsiloxane interlayer as the base membrane, the base membrane is immersed in an acyl chloride solution with a concentration of 2-2.5 g / L, then removed and allowed to stand. The acyl chloride in the acyl chloride solution is isophthaloyl chloride and / or trimesoyl chloride.

[0057] S2. The product obtained in step S1 is immersed in a solution containing diamine monomer and acid absorbent for interfacial polymerization reaction for 10s to 1min. After removal, its surface is rinsed with water. The diamine monomer is O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol with a molecular weight of 500-600, and the concentration of the diamine monomer is 2-5g / L.

[0058] S3. The product obtained in step S2 is dried and thermally crosslinked at 45~60℃.

[0059] The composite membrane prepared by this preferred embodiment exhibits the best performance; for the CO2 / N2 system, the separation membrane achieves a CO2 permeation rate of up to 1591.7 GPU and a separation factor of up to 78.55. Figure 1 As shown, the composite membrane prepared by this preferred embodiment includes a polymer support layer, an intermediate layer covering the surface of the polymer support layer, and a separation layer located on the surface of the intermediate layer.

[0060] The experimental conditions of this invention are easy to control, and the resulting ether-rich oxygen-segmented polyamide membrane exhibits excellent film-forming properties. The prepared composite membrane demonstrates excellent permeability selectivity and high repeatability. This preparation process can be used for scale-up production to mass-produce CO2 separation composite membranes.

[0061] This invention also provides a composite membrane prepared by the method described above. This composite membrane is an ether-rich oxygen-segment polyamide composite membrane, exhibiting excellent permeation and separation properties.

[0062] This invention also provides a composite membrane prepared by the method described above and its application as a carbon dioxide separation membrane. The ether-rich oxygen-segmented polyamide membrane composite membrane provided by this invention exhibits excellent CO2 separation performance and has strong application prospects.

[0063] The following examples further illustrate the preparation method of the composite membrane, the composite membrane itself, and its application as a carbon dioxide separation membrane. These examples are implemented based on the technical solution of this invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of this invention is not limited to the following examples.

[0064] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0065] In the following embodiments:

[0066] ED-600 with a molecular weight of 600 was purchased from Adamas, and its structural formula is as follows: Where (x+z) is approximately 3.6 and y is approximately 9;

[0067] ED-900, with a molecular weight of 900, was purchased from Adamas. Its structural formula is as follows: , where (x+z) is approximately 6 and y is approximately 12.5.

[0068] Example 1

[0069] S1. Take a base membrane coated with a polydimethylsiloxane interlayer on a polysulfone ultrafiltration membrane, immerse it in a 0.5 g / L solution of pyromellitic trimethylol chloride in n-heptane for 1 min, and then remove it and let it stand for 1 min.

[0070] S2. The membrane product obtained in step S1 is immersed in an aqueous solution containing 2,2'-(ethylenedioxy)bis(ethylamine) and sodium hydroxide for 30 s. After rinsing, the surface is rinsed with deionized water. The molecular weight of 2,2'-(ethylenedioxy)bis(ethylamine) is 148, the concentration of 2,2'-(ethylenedioxy)bis(ethylamine) in the aqueous solution is 0.8 g / L, and the concentration of sodium hydroxide is 0.5 g / L.

[0071] S3. Place the membrane product obtained in step S2 into a 40°C oven to dry and thermally crosslink for 10 min.

[0072] Example 2

[0073] S1. Take a base membrane coated with a polydimethylsiloxane interlayer on a polyethersulfone ultrafiltration membrane, immerse it in a 2.1 g / L solution of pyromellitic trimethylol chloride in n-heptane for 30 seconds, and then remove it and let it stand for 1 minute.

[0074] S2. The membrane product obtained in step S1 is immersed in an aqueous solution containing ED-600 and sodium hydroxide for 1 min. After rinsing, the surface is rinsed with deionized water. The molecular weight of ED-600 is 600, the concentration of ED-600 in the aqueous solution is 2.5 g / L, and the concentration of sodium hydroxide is 1.0 g / L.

[0075] S3. Place the membrane product obtained in step S2 into a 60°C oven to dry and thermally crosslink for 15 min.

[0076] Example 3

[0077] S1. Take a base membrane coated with a polydimethylsiloxane interlayer on a polyacrylonitrile ultrafiltration membrane, immerse it in a 4.5 g / L hexane solution of adipyl chloride for 1.5 min, and then let it stand for 1 min.

[0078] S2. The membrane product obtained in step S1 is immersed in an aqueous solution containing ED-900 and sodium bicarbonate and reacted for 1.5 min. After removal, its surface is rinsed with deionized water. The molecular weight of ED-900 is 900, the concentration of ED-900 in the aqueous solution is 6.0 g / L, and the concentration of sodium bicarbonate is 1.6 g / L.

[0079] S3. Place the membrane product obtained in step S2 into an 80°C oven to dry and thermally crosslink for 5 min.

[0080] Example 4

[0081] S1. Take a base membrane coated with a polydimethylsiloxane interlayer on a polysulfone ultrafiltration membrane, immerse it in a cyclohexane solution of 1.9 g / L terephthaloyl chloride for 10 seconds, and then let it stand for 1 minute.

[0082] S2. The membrane product obtained in step S1 is immersed in an aqueous solution containing ED-600 and sodium bicarbonate for 2 minutes. After rinsing, the surface is rinsed with deionized water. The molecular weight of ED-600 is 600, the concentration of ED-600 in the aqueous solution is 2.5 g / L, and the concentration of sodium bicarbonate is 1.2 g / L.

[0083] S3. Place the membrane product obtained in step S2 into a 55°C oven to dry and thermally crosslink for 12 min.

[0084] Example 5

[0085] S1. Take a base membrane coated with a polydimethylsiloxane interlayer on a polyethersulfone ultrafiltration membrane, immerse it in a 2.0 g / L isophthaloyl chloride n-pentane solution for 2 min, and then take it out and let it stand for 1 min.

[0086] S2. The membrane product obtained in step S1 is immersed in an aqueous solution containing ED-600 and sodium hydroxide and reacted for 10 seconds. After removal, its surface is rinsed with deionized water. The molecular weight of ED-600 is 600, the concentration of ED-600 in the aqueous solution is 2.5 g / L, and the concentration of sodium hydroxide is 0.75 g / L.

[0087] S3. Place the membrane product obtained in step S2 into a 45°C oven to dry and thermally crosslink for 20 min.

[0088] Example 6

[0089] S1. Take a base membrane coated with a polydimethylsiloxane interlayer on a polysulfone ultrafiltration membrane, immerse it in a 2.2 g / L solution of pyromellitic trimethylol chloride in hexane for 10 s, and then remove it and let it stand for 1 min.

[0090] S2. The membrane product obtained in step S1 is immersed in an aqueous solution containing ED-600 and sodium bicarbonate for 2 min. After rinsing, the surface is rinsed with deionized water. The molecular weight of ED-600 is 600, the concentration of ED-600 in the aqueous solution is 2.5 g / L, and the concentration of sodium bicarbonate is 1.0 g / L.

[0091] S3. Place the membrane product obtained in step S2 into a 65°C oven to dry and thermally crosslink for 10 min.

[0092] Comparative Example 1

[0093] The method of Example 1 was implemented, except that in step S2, 2,2'-(ethylenedioxy)bis(ethylamine) at a concentration of 0.8 g / L was replaced with piperazine at a concentration of 1.0 g / L.

[0094] The specific operation process includes:

[0095] S1. Take a base membrane coated with a polydimethylsiloxane interlayer on a polysulfone ultrafiltration membrane, immerse it in a 0.5 g / L solution of pyromellitic trimethylol chloride in n-heptane for 1 min, and then remove it and let it stand for 1 min.

[0096] S2. The membrane product obtained in step S1 is immersed in an aqueous solution containing piperazine and sodium hydroxide for 30 seconds. After rinsing, the surface is rinsed with deionized water. The concentration of piperazine in the aqueous solution is 1.0 g / L and the concentration of sodium hydroxide is 1.0 g / L.

[0097] S3. Place the membrane product obtained in step S2 into a 40°C oven to dry and thermally crosslink for 20 min.

[0098] Test case

[0099] The separation membrane was tested in a CO2 / N2 mixed gas system (CO2 to N2 volume ratio 15:85), with the feed gas pressure set at 0.20 MPa and the test temperature at 25℃. The composition of the permeate gas was analyzed by gas chromatography calibrated using the external standard method, and the CO2 permeability and separation factor of the separation membrane were calculated. The results are shown in Table 1.

[0100] Table 1

[0101]

[0102] Note: 1 The permeation rate is the CO2 gas permeability, measured in GPUs.

[0103] 2 The separation factor is the ratio of CO2 gas permeability to N2 gas permeability.

[0104] As shown in Table 1, under the CO2 / N2 system, compared with Comparative Example 1, the composite membrane prepared by the method described in this embodiment of the invention has higher CO2 permeability and separation factor. The separation membrane has a maximum CO2 permeability of 1591.7 GPU and a maximum separation factor of 78.55.

[0105] Table 2 lists several commonly used polymer membranes worldwide, along with their CO2 permeation rates and separation factors.

[0106] Table 2

[0107]

[0108] As can be seen from the results in Table 2, the ether-rich oxygen-chain polyamide membrane composite membrane prepared by the method described in the embodiments of the present invention has excellent CO2 separation performance and strong application prospects.

[0109] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a composite membrane, characterized in that, The method includes the following steps: S1. The base film is immersed in an acyl chloride solution. The base film includes a polymer support layer and an intermediate layer covering the surface of the polymer support layer. The intermediate layer is a polydimethylsiloxane layer and / or its derivative layer. The acyl chloride in the acyl chloride solution has two carbonyl chloride functional groups and / or three carbonyl chloride functional groups. The concentration of the acyl chloride in the acyl chloride solution is 0.4~5 g / L. S2. The product obtained in step S1 is immersed in a solution containing a diamine monomer and an acid absorbent to carry out an interfacial polymerization reaction. The concentration of the diamine monomer in the solution containing the diamine monomer and the acid absorbent is 2~5 g / L. The diamine monomer is 2,2'-(ethylenedioxy)bis(ethylamine) and / or O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol, and the molecular weight of O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 600. S3. Dry the product obtained in step S2.

2. The method according to claim 1, characterized in that, In step S1, the polymer support layer is made of at least one of polysulfone, polyacrylonitrile, and polyethersulfone.

3. The method according to claim 1 or 2, characterized in that, In step S1, the acyl chloride in the acyl chloride solution is selected from at least one of terephthaloyl chloride, isophthaloyl chloride, trimesoyl chloride, glutaryl chloride, and adipyl chloride.

4. The method according to claim 1, characterized in that, In step S1, the concentration of acyl chloride in the acyl chloride solution is 2-2.5 g / L.

5. The method according to claim 1 or 4, characterized in that, In step S1, the solvent of the acyl chloride solution is selected from at least one of n-pentane, n-hexane, n-heptane, and cyclohexane.

6. The method according to claim 1, characterized in that, In step S1, the soaking time is 10 seconds to 2 minutes.

7. The method according to claim 1, characterized in that, In the solution containing diamine monomer and acid absorbent described in step S2, the concentration of the acid absorbent is 0.2~1.6 g / L.

8. The method according to claim 1, characterized in that, The acid absorbent is selected from at least one of sodium hydroxide, sodium bicarbonate, and sodium carbonate.

9. The method according to claim 1, characterized in that, In step S2, the reaction time of the interfacial polymerization reaction is 10 s to 2 min.

10. The method according to claim 9, characterized in that, In step S2, the reaction time of the interfacial polymerization reaction is 10 s to 1 min.

11. The method according to claim 1, characterized in that, In step S3, the drying temperature is 40~80℃; the drying time is 5~20 min.

12. The composite membrane prepared by the method according to any one of claims 1-11.

13. The application of the composite membrane according to claim 12 as a carbon dioxide separation membrane.

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