Preparation method of composite membrane, composite membrane and application of composite membrane as carbon dioxide separation membrane

Abstract

The invention 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 membrane in an acyl chloride solution; s2, a product obtained in the step S1 is soaked in a solution containing a diamine monomer and an acid absorbent for interfacial polymerization reaction, the diamine monomer contains ether oxygen chain segments, and the number of ether oxygen bonds is larger than or equal to 2; and S3, drying the product obtained in the step S2. The method comprises the following steps: soaking a base membrane in an acyl chloride solution to uniformly spread acyl chloride on the surface of the base membrane, and then soaking the base membrane in a solution of a diamine monomer rich in ether-oxygen chain segments, so that the acyl chloride and the diamine monomer rich in ether-oxygen chain segments are subjected to interfacial polymerization reaction to obtain the ether-oxygen chain segment-rich polyamide composite membrane with excellent permeability and separation performance.

Description

Technical Field

[0001] The invention relates to the technical field of gas separation membrane materials, and in particular to a preparation method of a composite membrane, the composite membrane and application of the composite membrane as a carbon dioxide separation membrane. Background Art

[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 energy 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, the destruction of the ecosystem, and a serious threat to 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 the advantages of low fixed investment, simple operation, low energy consumption and small footprint, and has good development prospects in the field of CO2 separation. The polymer membrane currently used for gas separation has the advantages of good mechanical stability, easy scale-up, and low cost and availability, and has received widespread attention from researchers.

[0003] However, the permeability or separation performance of polymer membranes currently used for gas separation is poor, which limits their practical application prospects. Therefore, there is an urgent need to study separation membranes with better performance. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of poor permeability or separation performance of polymer membranes for gas separation in the prior art, and to provide a method for preparing a composite membrane, a composite membrane, and an application of the composite membrane in a carbon dioxide separation membrane. The method comprises soaking a base membrane in an acyl chloride solution so that the acyl chloride is evenly spread on the surface of the base membrane, and then soaking the base membrane in a solution of a diamine monomer rich in ether oxygen segments, so that the acyl chloride and the diamine monomer rich in ether oxygen segments react by interfacial polymerization, thereby obtaining an ether oxygen segment-rich polyamide composite membrane with excellent permeability and separation performance.

[0005] In order to achieve the above object, the present invention provides a method for preparing a composite film in a first aspect, the method comprising the following steps:

[0006] S1, soaking the basement membrane in an acyl chloride solution;

[0007] 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 segment, and the number of ether oxygen bonds is ≥2;

[0008] S3, drying the product obtained in step S2.

[0009] Preferably, in step S1, the base film comprises 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 a derivative layer thereof.

[0010] Preferably, the material of the polymer support layer is selected from 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 adipoyl chloride.

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

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

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

[0016] Preferably, in the solution containing the diamine monomer and the acid absorbent in step S2, the concentration of the diamine monomer is 0.2 to 10 g / L, preferably 2 to 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 the diamine monomer and the acid absorbent 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 10 s to 2 min, preferably 10 s to 1 min.

[0022] Preferably, in step S3, the drying temperature is 40 to 80°C, preferably 45 to 60°C, and the drying time is 5 to 20 minutes.

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

[0024] The third aspect of the present invention provides a composite membrane prepared by the method described above and the use of the composite membrane described above 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 comprises soaking the base membrane in an acyl chloride solution so that the acyl chloride is evenly spread on the surface of the base membrane, and then soaking the obtained product in a solution of a diamine monomer rich in ether oxygen segments, so that the acyl chloride and the diamine monomer rich in ether oxygen segments react by interfacial polymerization, and the obtained ether oxygen segment-rich polyamide composite membrane has good permeability and separation performance.

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

[0028] (3) The composite membrane prepared by the present invention was tested with a mixed gas (CO2 / N2 15 / 85). The results showed that the composite membranes prepared by the present invention had good CO2 permeation rate and separation factor. In a preferred embodiment, by regulating the molecular weight of the diamine monomer and the concentrations of the diamine monomer and the acyl chloride, the composite membrane prepared by interfacial polymerization had better permeability 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 chloride at a concentration of 2.1 g / L had the best performance. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 2 This is a scanning electron microscope image of the surface structure of the composite membrane prepared in Example 2, which proves that after the ultrafiltration membrane is coated with a silicone rubber intermediate layer, a polyamide separation layer rich in ether oxygen segments can be polymerized at its surface interface. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

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

[0034] S1, soaking the basement membrane in an acyl chloride solution;

[0035] 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 segment, and the number of ether oxygen bonds is ≥2;

[0036] S3, drying the product obtained in step S2.

[0037] In the method described in the present invention, the inventors of the present invention found that by soaking the base membrane in acyl chloride in a specific order so that the acyl chloride is evenly spread on the surface of the base membrane, and then soaking the obtained 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 properties. A polyamide separation layer is formed on the surface of the composite membrane due to the polymerization reaction.

[0038] In the present invention, the base membrane can be a common polymer membrane in the art. In a more preferred embodiment, the base membrane described 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 a derivative layer thereof; in the present invention, the surface of the polymer support layer is coated with a polydimethylsiloxane layer and / or a derivative layer thereof to prevent the formed polyamide separation layer from penetrating into the pores of the polymer support layer and causing a sudden drop in performance. In some embodiments, the material of the polymer support layer can be selected from at least one of polysulfone, polyacrylonitrile and polyethersulfone. Preferably, the polymer support layer is an ultrafiltration membrane whose material is selected from polysulfone, polyacrylonitrile or polyethersulfone.

[0039] In the present 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 adipoyl 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 of step S1 can be 0.4-5g / L, such as 0.5g / L, 1g / L, 1.5g / L, 2g / L, 2.5g / L, 3g / L, 3.5g / L, 4g / L, 4.5g / L or 5g / L. In the method described in the present invention, if the concentration of acyl chloride in the acyl chloride solution is too high, when the acyl chloride and the diamine monomer are interfacially polymerized, the polymer cross-linking degree and the membrane thickness will be too high, thereby reducing the CO2 permeability of the prepared composite membrane; if the concentration of acyl chloride in the acyl chloride solution is too low, the polymer cross-linking degree will be reduced, the membrane thickness will be reduced, and the CO2 selectivity will be reduced, and even the interfacial polymerization film formation will be unstable and unable to form a film. In order to make the prepared composite membrane have excellent permeability and separation performance at the same time, and further improve the performance of the composite membrane, in a preferred embodiment, the concentration of acyl chloride in the acyl chloride solution is 2-2.5g / L.

[0041] In the present invention, the acyl chloride solution may be an organic solution. The solvent of the acyl chloride solution may be a conventional choice in the art; in some embodiments, the solvent of the acyl chloride solution may 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 10s to 2min, such as 10s, 30s, 1min, 1.5min or 2min. In the present invention, the soaking time in step S1 can be sufficient as long as the acyl chloride can be evenly spread on the surface of the base film.

[0043] In the present invention, the method further comprises: after the base film is soaked in the acyl chloride solution, the base film is taken out and allowed to stand to allow the solution on the surface to evaporate. The standing time does not need to be too long, and 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 in step S2, the concentration of 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 the present invention, if the concentration of diamine monomer is too high, when the diamine monomer and the acyl chloride are interfacially polymerized, the polymer crosslinking degree and the membrane thickness will be too high, thereby reducing the CO2 permeability of the prepared composite membrane; if the concentration of diamine monomer is too low, the polymer crosslinking degree will be reduced, the membrane thickness will be reduced, and the CO2 selectivity will be reduced, and even the interfacial polymerization film will be unstable and unable to form a film. In order to make the prepared composite membrane have excellent permeability and separation performance and further improve the performance of the composite membrane, in a preferred embodiment, in the solution containing diamine monomer and acid absorbent in step S2, the concentration of the diamine monomer is 2-5 g / L.

[0045] In the method of the present invention, in order to make the diamine monomer and the acyl chloride polymerize better, the two end groups of the molecular main chain of the diamine monomer can be primary amine groups. In some embodiments, the diamine monomer containing an ether oxygen segment and the number of ether oxygen bonds ≥ 2 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. Among them, the molecular weight of O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol can be 400-1000, and exemplarily, O,O'-di(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol can be ED-600 and / or ED-900.

[0046] In the present invention, preferably, the solution containing the diamine monomer and the acid absorbent is an aqueous solution. The inventors found that the higher the molecular weight of the diamine monomer in the aqueous solution, the weaker its ability to diffuse from the uniform aqueous solution to the oil-water interface, and the weaker the reactivity of the amino group with the acyl chloride; however, the high molecular weight of the diamine monomer in the aqueous solution can provide a higher ether oxygen segment density in the membrane, which is beneficial to the affinity of the membrane to the CO2 molecule, and the use of a relatively high molecular weight inorganic phase monomer can obtain a relatively soft and loose membrane structure, which is beneficial to the improvement of CO2 permeability. Therefore, in order to obtain a separation membrane with excellent permeability and separation performance, and 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'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 600. The composite membrane prepared by this preferred embodiment has better performance.

[0048] In one embodiment, when the acyl chloride is trimesoyl 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] In the present invention, the function of the acid absorbent is to absorb the hydrogen chloride generated by the reaction of the acyl chloride and the diamine monomer. In some embodiments, in the solution containing the diamine monomer and the acid absorbent in step S2, the concentration of the acid absorbent is 0.2 to 1.6 g / L. In the present invention, the acid absorbent can be an alkaline substance commonly found in the art. In some embodiments, the acid absorbent can be selected from at least one of sodium hydroxide, sodium bicarbonate and sodium carbonate.

[0051] In some embodiments, the reaction time of the interfacial polymerization reaction in step S2 can be 10s to 2min, such as 10s, 20s, 30s, 40s, 50s, 1min, 1.5min or 2min. In order to further improve the permeability and separation performance of the composite membrane to a higher level, in some preferred embodiments, the reaction time of the interfacial polymerization reaction in step S2 is 10s to 1min.

[0052] In the method described in the present invention, the method further comprises: after the interfacial polymerization reaction is completed, taking out the obtained product and washing its surface with deionized water.

[0053] In the present invention, the product obtained by the interfacial polymerization reaction undergoes thermal crosslinking while being dried in step S3, and the thermal crosslinking causes the small molecule oligomers to re-crosslink to form a denser polymer network. In some embodiments, the drying temperature in step S3 can be 40 to 80°C and the time is 5 to 20 minutes. In order to further improve the performance of the composite membrane, in a more preferred embodiment, the drying temperature in step S3 is 45 to 60°C.

[0054] In a more preferred embodiment, the method for preparing the composite film comprises the following steps:

[0055] S1, using a polysulfone ultrafiltration membrane coated with a polydimethylsiloxane intermediate layer as a base membrane, soaking the base membrane in an acyl chloride solution with a concentration of 2-2.5 g / L, taking it out and letting it stand, wherein the acyl chloride in the acyl chloride solution is isophthaloyl chloride and / or trimesoyl chloride;

[0056] S2, soaking the product obtained in step S1 in a solution containing a diamine monomer and an acid absorbent for interfacial polymerization reaction for 10 seconds to 1 minute, taking it out and rinsing its surface with water, wherein 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 2-5 g / L;

[0057] S3, drying the product obtained in step S2 at 45-60°C and thermally cross-linking.

[0058] The composite membrane prepared by this preferred embodiment has the best performance. For the CO2 / N2 system, the CO2 permeation rate of the separation membrane can reach up to 1591.7 GPU, and the separation factor can reach up to 78.55. Figure 1 As shown, the composite membrane prepared by this preferred embodiment includes a polymer support layer, an intermediate layer coated on the surface of the polymer support layer, and a separation layer located on the surface of the intermediate layer.

[0059] The experimental conditions of the invention are easy to control, the obtained ether oxygen segment-rich polyamide membrane has excellent film-forming property, the prepared composite membrane has excellent permeability selectivity and high repeatability. The preparation process can be used for scaled-up production and batch preparation of CO2 separation composite membranes.

[0060] The present invention also provides a composite membrane prepared by the method described above. The composite membrane is an ether oxygen segment-rich polyamide composite membrane, which has good permeability and separation performance.

[0061] The present invention also provides a composite membrane prepared by the method described above and the use of the composite membrane described above as a carbon dioxide separation membrane. The ether oxygen segment-rich polyamide membrane composite membrane provided by the present invention has excellent CO2 separation performance and has strong application prospects.

[0062] The following examples further illustrate the preparation method of the composite membrane of the present invention, the composite membrane, and the application of the composite membrane as a carbon dioxide separation membrane. The examples are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0063] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0064] In the following embodiments:

[0065] ED-600 with a molecular weight of 600 was purchased from Adamas Company and its structural formula is Among them, (x+z) is about 3.6, y is about 9;

[0066] ED-900 with a molecular weight of 900 was purchased from Adamas Company and its structural formula is Among them, (x+z) is approximately 6 and y is approximately 12.5.

[0067] Example 1

[0068] S1. Take a base membrane coated with a polydimethylsiloxane intermediate layer on a polysulfone ultrafiltration membrane, soak it in a 0.5 g / L trimesoyl chloride n-heptane solution for 1 min, then take it out and let it stand for 1 min;

[0069] S2, soaking the membrane product obtained in step S1 in an aqueous solution containing 2,2'-(ethylenedioxy)bis(ethylamine) and sodium hydroxide for reaction for 30 seconds, taking it out and rinsing its surface with deionized water, wherein 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;

[0070] S3. The membrane product obtained in step S2 is placed in a 40° C. oven for drying and thermal cross-linking for 10 min.

[0071] Example 2

[0072] S1. Take a base membrane coated with a polydimethylsiloxane intermediate layer on a polyethersulfone ultrafiltration membrane, soak it in a 2.1 g / L n-heptane solution of trimesoyl chloride for 30 seconds, then take it out and let it stand for 1 minute;

[0073] S2, soaking the membrane product obtained in step S1 in an aqueous solution containing ED-600 and sodium hydroxide for reaction for 1 min, taking it out and washing its surface with deionized water, wherein 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;

[0074] S3. The membrane product obtained in step S2 is placed in a 60° C. oven for drying and thermal cross-linking for 15 min.

[0075] Example 3

[0076] S1. Take a base membrane coated with a polydimethylsiloxane intermediate layer on a polyacrylonitrile ultrafiltration membrane, soak it in a 4.5 g / L hexane solution of adipoyl chloride for 1.5 min, then take it out and let it stand for 1 min;

[0077] S2, soaking the membrane product obtained in step S1 in an aqueous solution containing ED-900 and sodium bicarbonate for reaction for 1.5 minutes, taking it out and washing its surface with deionized water, wherein 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;

[0078] S3. The membrane product obtained in step S2 is placed in an oven at 80° C. and dried and thermally cross-linked for 5 minutes.

[0079] Example 4

[0080] S1. Take a base membrane coated with a polydimethylsiloxane intermediate layer on a polysulfone ultrafiltration membrane, soak it in a 1.9 g / L cyclohexane solution of terephthaloyl chloride for 10 seconds, then take it out and let it stand for 1 minute;

[0081] S2, soaking the membrane product obtained in step S1 in an aqueous solution containing ED-600 and sodium bicarbonate for 2 minutes, taking it out and washing its surface with deionized water, wherein 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;

[0082] S3. The membrane product obtained in step S2 is placed in a 55°C oven for drying and thermal cross-linking for 12 minutes.

[0083] Example 5

[0084] S1. Take a base membrane coated with a polydimethylsiloxane intermediate layer on a polyethersulfone ultrafiltration membrane, soak it in a 2.0 g / L n-pentane solution of isophthaloyl chloride for 2 minutes, then take it out and let it stand for 1 minute;

[0085] S2, soaking the membrane product obtained in step S1 in an aqueous solution containing ED-600 and sodium hydroxide for reaction for 10 seconds, taking it out and washing its surface with deionized water, wherein 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;

[0086] S3. The membrane product obtained in step S2 is placed in a 45°C oven for drying and thermal cross-linking for 20 minutes.

[0087] Example 6

[0088] S1. Take a base membrane coated with a polydimethylsiloxane intermediate layer on a polysulfone ultrafiltration membrane, soak it in a 2.2 g / L hexane solution of trimesoyl chloride for 10 seconds, then take it out and let it stand for 1 minute;

[0089] S2, soaking the membrane product obtained in step S1 in an aqueous solution containing ED-600 and sodium bicarbonate for 2 minutes, taking it out and washing its surface with deionized water, wherein 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;

[0090] S3. The membrane product obtained in step S2 is placed in a 65° C. oven for drying and thermal cross-linking for 10 min.

[0091] Comparative Example 1

[0092] The method of Example 1 was followed, except that in step S2, 0.8 g / L of 2,2'-(ethylenedioxy)bis(ethylamine) was replaced with 1.0 g / L of piperazine.

[0093] The specific operation process includes:

[0094] S1. Take a base membrane coated with a polydimethylsiloxane intermediate layer on a polysulfone ultrafiltration membrane, soak it in a 0.5 g / L trimesoyl chloride n-heptane solution for 1 min, then take it out and let it stand for 1 min;

[0095] S2, soaking the membrane product obtained in step S1 in an aqueous solution containing piperazine and sodium hydroxide for reaction for 30 seconds, taking it out and washing its surface with deionized water, wherein the concentration of 2,2'-(ethylenedioxy)bis(ethylamine) in the aqueous solution is 1.0 g / L, and the concentration of sodium hydroxide is 1.0 g / L;

[0096] S3. The membrane product obtained in step S2 is placed in a 40° C. oven for drying and thermal cross-linking for 20 min.

[0097] Test Case

[0098] The separation membrane was placed in a CO2 / N2 mixed gas system (the volume ratio of CO2 to N2 was 15:85) for testing, the feed gas pressure was set to 0.20 MPa, and the test temperature was 25°C. The composition of the permeate gas was analyzed using a gas chromatograph calibrated by the external standard method, and the CO2 permeability and separation factor of the separation membrane were calculated, and the results are shown in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] Note: 1 The permeation rate is the CO2 gas permeability, and the unit is GPU;

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

[0104] As shown in Table 1, under the CO2 / N2 system, the composite membrane prepared by the method described in the embodiment of the present invention has a higher CO2 permeability and separation factor than that of Comparative Example 1. The CO2 permeability of the separation membrane can reach up to 1591.7 GPU, and the separation factor can reach up to 78.55.

[0105] Table 2 lists several polymer membranes that are widely used worldwide and their CO2 permeation rates and separation factors.

[0106] Table 2

[0107]

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

[0109] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a composite film, characterized in that: The method comprises the following steps: S1, soaking the basement membrane 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 segment, and the number of ether oxygen bonds is ≥2; S3, drying the product obtained in step S2.

2. The method according to claim 1, characterized in that In step S1, the base film 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 a derivative layer thereof; Preferably, the material of the polymer support layer is selected from 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 has two carbonyl chloride functional groups and / or three carbonyl chloride functional groups; 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 adipoyl chloride.

4. The method according to any one of claims 1 to 3, characterized in that: In step S1, the concentration of acyl chloride in the acyl chloride solution is 0.4-5 g / L, preferably 2-2.5 g / L; Preferably, the solvent of the acyl chloride solution is at least one selected from n-pentane, n-hexane, n-heptane and cyclohexane.

5. The method according to any one of claims 1 to 4, characterized in that: In step S1, the soaking time is 10s to 2min.

6. The method according to any one of claims 1 to 5, characterized in that: In the solution containing the diamine monomer and the acid absorbent in step S2, the concentration of the diamine monomer is 0.2 to 10 g / L, preferably 2 to 5 g / L; 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; More preferably, the molecular weight of O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 400-1000, preferably 600.

7. The method according to any one of claims 1 to 6, characterized in that: In the solution containing the diamine monomer and the acid absorbent in step S2, the concentration of the acid absorbent is 0.2 to 1.6 g / L; Preferably, the acid absorbent is selected from at least one of sodium hydroxide, sodium bicarbonate and sodium carbonate.

8. The method according to any one of claims 1 to 7, characterized in that: In step S2, the reaction time of the interfacial polymerization reaction is 10 s to 2 min, preferably 10 s to 1 min.

9. The method according to any one of claims 1 to 8, characterized in that: In step S3, the drying temperature is 40 to 80°C, preferably 45 to 60°C, and the drying time is 5 to 20 minutes.

10. A composite membrane prepared by the method according to any one of claims 1 to 9.

11. Use of the composite membrane prepared by the method according to any one of claims 1 to 9 and the composite membrane according to claim 10 as a carbon dioxide separation membrane.

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