A polyamide-imide hollow fiber gas separation membrane, its preparation method and application

Abstract

This invention discloses a polyamide-imide hollow fiber gas separation membrane, its preparation method, and its applications. The invention introduces highly soluble acyl chloride groups into a highly crystalline polyimide system to prepare a polyamide-imide gas separation membrane. While ensuring gas separation performance and mechanical properties, the solubility of the polymer is improved, avoiding the use of phenolic solvents. The obtained polyamide-imide is then spun to produce a hollow fiber membrane. This membrane exhibits advantages such as high strength and resistance to plasticization during gas separation, good thermal stability, and improved permeability while maintaining good selectivity for CO2 / N2 and CO2 / CH4, playing an important role in CO2 removal from flue gas and biogas.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer membrane separation technology, and particularly relates to a polyamide-imide hollow fiber gas separation membrane, a preparation method and application. The gas separation membrane is a polyamide-imide hollow fiber gas separation membrane with good solubility and mechanical strength. The present application relates to the manufacture and use of aromatic polyamide-imides. The present application also relates to an asymmetric structure hollow fiber gas separation membrane, which has good permeability, strong CO2 plasticization resistance, good solubility and high mechanical properties. The present application further relates to a CO2 gas separation method using the aforementioned gas separation membrane. BACKGROUND

[0002] With the increasingly serious global warming problem, how to reduce CO2 emissions has become an important problem in environmental protection. CO2 is produced by the combustion of fossil fuels, and how to purify CO2 in flue gas has become the key to controlling CO2 emissions.

[0003] Biogas is mainly composed of methane, but the presence of carbon dioxide impurities will reduce the calorific value of biogas, increase transportation costs, and limit the application of biogas (International Journal of Hydrogen Energy, 2021, 46(11):21318-21337).

[0004] The key to the above two problems lies in the separation of carbon dioxide. In recent years, membrane technology has played an increasingly important role in the field of CO2 separation. Because it does not involve phase change, the energy consumption required for membrane separation of carbon dioxide is low, which can effectively meet the growing demand for carbon dioxide gas separation (Chemical Engineering Journal, 2021, 411:128468).

[0005] In recent years, polyimide, especially polyimide gas separation membrane based on 6FDA-DABA system, has been widely studied and applied in the field of methane and carbon dioxide separation due to its high selectivity, good thermal stability and chemical stability. But the molecular weight of 6FDA-DABA system polyimide is low, and the mechanical property is poor, which seriously limits its application in hollow fiber membrane field.

[0006] The introduction of aromatic and highly crystalline dianhydride and diamine monomers can solve the above problems. However, the introduction of high-rigidity diamine monomers will also reduce the solubility of the polymer, which can only be dissolved in phenolic solvents, limiting the application range of polyimide hollow fiber membranes.

[0007] The present application prepares a polyamide-imide gas separation membrane with good solubility and high mechanical strength by adding acyl chloride monomers, solving the problem of poor solubility of high mechanical strength polyimide.

[0008] Polyamide-imide (PAI) has both the excellent mechanical properties of polyamide and the high thermal stability and solvent resistance of polyimide. Suat Hong Goh research team proved that the water vapor separation capacity of polyamide-imide is much stronger than that of polyamide and polyimide under the same operating conditions (Journal of Membrane Science, 2021, 318 (1-2): 217-226). At present, there are few studies on the preparation of gas separation membranes by polyamide-imide.

[0009] In order to meet the requirements of industrial and life practical application, a hollow fiber gas separation membrane for CO2 separation with high permeability, high selectivity, plasticizing resistance and excellent mechanical properties is synthesized. The polyamide-imide gas separation membrane is prepared in the present application. The gas separation membrane has good separation selectivity, high mechanical strength and excellent plasticizing resistance. SUMMARY

[0010] The application discloses a polyamide-imide hollow fiber gas separation membrane, a preparation method and application. The application is an application of a plasticizing-resistant hollow fiber gas separation membrane with good solubility and mechanical properties in flue gas and biogas CO2 removal. The polyamide-imide gas separation membrane is prepared by introducing acyl chloride groups with good solubility into a crystalline polyimide system. The gas separation membrane has excellent mechanical properties and high CO2 / CH4 selectivity, and plays an important role in flue gas and biogas CO2 removal.

[0011] To achieve the above object, the technical scheme adopted by the application is as follows:

[0012] The polyimide gas separation membrane of the application is made of a polyamide-imide polymer, and the polyamide-imide polymer has the structure shown in general formula I:

[0013] (I)

[0014] wherein n represents the degree of polymerization of the different components of the polymer, n is an integer from 50 to 200, x, y, z are independently integers from 0 to 100, x+y+z = 100 (optionally, x, y and z are not all zero); the weight average molecular weight of the polymer is from 100000 to 300000. For example, n is 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195 or 200. For example, x is 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100. For example, y is 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100. For example, z is 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100.

[0015] Further, the weight average molecular weight of the polymer is from 100000 to 300000, for example, the weight average molecular weight of the polymer is 100000, 110000, 120000, 130000, 140000, 150000, 160000, 170000, 180000, 190000, 200000, 210000, 220000, 230000, 240000, 250000, 260000, 270000, 280000, 290000 or 300000.

[0016] R1in general formula (I) comprises one or more of the following structures:

[0017]

[0018] R2group comprises any one or more of the following structures:

[0019]

[0020] R3group is one or more of the following groups:

[0021] .

[0022] The polyamide-imide hollow fiber gas separation membrane is a polyamide-imide hollow fiber gas separation membrane with good solubility and mechanical strength. In the preparation method of the gas separation membrane, an acyl chloride monomer is involved in copolymerization to improve the solubility of the polymer and ensure the successful polymerization.

[0023] The preparation method of the polyamide-imide hollow fiber gas separation membrane as described above is prepared by a two-step method. First, a polyamide and polyimide copolymer is synthesized, the copolymer is used for spinning, and then the prepared hollow fiber membrane is heat treated to obtain a polyamide and polyimide copolymer hollow fiber membrane.

[0024] Further, the preparation method as described above comprises the following steps:

[0025] (1). At -10~-15℃, DABA, 6FDA, crystalline diamine monomer and crystalline dianhydride monomer, and acyl chloride monomer are dissolved in N,N-dimethylacetamide (DMAC), the molar ratio of the monomers is diamine monomer:acyl chloride monomer+dianhydride monomer=1~1.1:1~1.1, the solid content of the solution is 15-20wt%, and the solution is stirred and dissolved at -10~-15℃; wherein the monomers consist of DABA, 6FDA, crystalline diamine monomer and crystalline dianhydride monomer, and acyl chloride monomer, the crystalline diamine monomer is monomer A, the crystalline dianhydride monomer is monomer B, and the acyl chloride monomer is monomer C;

[0026] (2). After the monomers are completely dissolved in the solvent, the stirring speed is increased, the polymer viscosity rises after the polymerization reaction starts, and it presents a gel state; at this time, DMAC is continuously added to continuously dilute the solid content of the solution, so that the solid is re-dissolved to continue the polymerization reaction, and DMAC is continuously added step by step until the whole solution no longer presents a gel state, at which time the solid content of the solution is 5-8wt%; the molar ratio of diamine and dianhydride in the reaction system is kept at 1~1.1:1~1.1;

[0027] The monomer A is selected from any one or more of the following compounds:

[0028] 2,2'-diaminobiphenyl, 2,2',5,5'-tetraaminobiphenyl, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 2,3,5,6-tetramethyl-1,4-diaminobenzene, 3,6-diaminocarbazole, 3,6-diamino-9-ethylcarbazole, 4,6-diamino-2-phenylindole hydrochloride, and 4,4'-diaminodiphenyl sulfide;

[0029] The monomer B is selected from any one or more of the following compounds:

[0030]

[0031] said monomer C is selected from any one or more of the following compounds:

[0032]

[0033] (3). After dilution of the solution, it is colorless, clear and transparent, and the reaction is carried out for 14-18 h; after being raised to room temperature, pyridine and acetic anhydride are added for chemical ring closure, and the reaction is continued for 20-24 h; the viscosity of the solution is controlled, and the viscosity at 100°C is 150-200 poise;

[0034] (4). The rotational viscosity of the solution is controlled, the obtained polymer solution is filtered, then extruded through a hollow fiber membrane spinning nozzle, and the extruded hollow fiber body is passed through a N2 atmosphere, followed by phase inversion in a coagulation bath of an ethanol aqueous solution at a temperature of -10 to -5°C to obtain a wet fiber; the wet fiber is immersed in ethanol at a temperature of 50-60°C for 2-3 hours, and then immersed in isooctane at a temperature of 65-75°C for 3-5 hours to remove the solvent in the fiber; the fiber is completely dried at a temperature of 100-120°C, and then heat treated at 320-350°C for 15-20 h to obtain a finished hollow fiber membrane.

[0035] Specifically, the preparation method of the polyamide-imide hollow fiber gas separation membrane according to the present application comprises the following steps:

[0036] (1). At -10°C, first, the monomers DABA (3,5-diaminobenzoic acid), 6FDA (hexafluoro dianhydride), a high-crystallinity diamine monomer (monomer A) and a high-crystallinity dianhydride monomer (monomer B), and an acyl chloride monomer (monomer C) are dissolved in N,N-dimethylacetamide (DMAC) under a N2 atmosphere for about 10 minutes, the molar ratio of the monomers is diamine monomer:acyl chloride monomer+dianhydride monomer=1:1, the solid content of the solution is 15-20 wt%, and the solution is stirred and dissolved at -10°C.

[0037] (2). After the monomers are completely dissolved in the solvent, the stirring speed is increased, the polymer viscosity rises after the polymerization reaction starts, and a gel state is presented. At this time, DMAC is continuously added to continuously dilute the solid content of the solution, so that the solid is re-dissolved to continue the polymerization reaction, and DMAC is continuously added step by step until the solution as a whole no longer presents a gel state, at which time the solid content of the solution is 5-8 wt%. The molar ratio of the diamine and the dianhydride in the reaction system is maintained at 1:1.

[0038] In the above preparation method, the monomer A is selected from any one or more of the following compounds:

[0039] 2,2'-diaminodiphenyl, 2,2',5,5'-tetrachlorodiaminodiphenyl, p-diaminodiphenyl, 4,4'-diamino-2,2'-dimethyl-1,1 '-biphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 3,6-diaminocarbazole, 3,6-diamino-9-ethylcarbazole, 4,6-diamino-2-phenylindole hydrochloride, 4,4'-diaminodiphenyl sulfide.

[0040] said monomer B is selected from any one or more of the following compounds:

[0041]

[0042] said monomer C is selected from any one or more of the following compounds:

[0043]

[0044] (3). The solution is diluted to a colorless clear transparent state, and the reaction is continued for 14 h. The solution is raised to room temperature, and pyridine and acetic anhydride are added to chemically close the ring, and the reaction is continued for 24 h. The viscosity of the solution is controlled, and at 100°C, the viscosity is about 200 poise.

[0045] (4). A polyimide solution is filtered through a 500 mesh metal screen, then extruded through a hollow fiber membrane spinning nozzle, and the extruded hollow fiber body is passed through a N2 atmosphere, and then phase inversion is carried out in a coagulation bath of a specific solid content (25 wt%) ethanol aqueous solution at a temperature of -5°C to produce a wet fiber. The wet fiber is immersed in ethanol at a temperature of 50°C for 2 hours, and then immersed in isooctane at a temperature of 70°C for 3 hours to remove the solvent in the fiber. Complete drying is carried out at a temperature of 100°C, and then heat treatment is carried out at a specific temperature (320-350°C), and the treatment time is increased from 20 h at 320°C to 1 h at 350°C to obtain a finished hollow fiber membrane.

[0046] Method for measuring the CO2 flux and selectivity of the hollow fiber membrane in the embodiments of the present application:

[0047] A permeation performance evaluation element having an effective length of 20 mm is prepared using about 10 hollow fiber membranes, a stainless steel tube, and an epoxy resin-based adhesive, and the element is inserted into a stainless steel container to prepare a pencil-like assembly. The temperature is controlled to be constant at 35°C, and pure CO2 gas is input at a fixed rate to the outside of the hollow fibers of the pencil-like assembly, with the gas before the hollow fiber membrane element being the upstream gas and the gas passing through the element being the downstream gas. The upstream gas pressure is controlled to be constant, and the downstream gas pressure is measured over time. The CO2 permeation flux is calculated by a formula; the CH4 permeation flux is measured in the same way. The CO2 / CH4 selectivity is obtained by comparing the two.

[0048] The pure gas in the above method is replaced by a CH4 / CO2 mixed gas containing 50% CH4, and the same method is used to test the mixed gas flux, and the proportion of the two gases in the mixed gas is determined to obtain the CO2 / CH4 selectivity of the mixed gas.

[0049] The viscosity in the present application is rotational viscosity.

[0050] Measurement of rotational viscosity (i.e., rotational viscosity):

[0051] The rotational viscosity of the polyamide solution is measured at a temperature of 100°C using a rotational viscometer (Germany proRheo R180 rotational viscosity tester) (rotor shear rate: 1.75 / s).

[0052] The application of the hollow fiber gas separation membrane prepared from the polyamide-imide provided by the present application includes the following aspects:

[0053] The hollow fiber gas separation membrane prepared from the polyamide-imide is applied to the CO2 removal of high-pollution flue gas and biogas in industry.

[0054] About 1000-10000 hollow fiber membranes prepared by the method of the present application are bundled; the two sides of the fiber bundle are fixed in the tube plate by resin, and the opening is kept at one end of the two ends of the fiber, and the gas inlet is maintained, and the assembly of the membrane module is completed in this way. Then the membrane module is connected to a container provided with a mixed gas inlet, a permeated gas outlet and a non-permeated gas outlet, so that the space inside the hollow fiber membrane is isolated from the space outside the hollow fiber membrane. In such a gas separation membrane assembly, the mixed gas is input from the mixed gas guide inlet to the inside or the space in communication with the outside of the hollow fiber membrane, but not limited to this. When the mixed gas contacts the hollow fiber membrane, the specific gas components contained in the mixed gas selectively permeate the membrane. The permeable gas is discharged from the permeable gas outlet, and the non-permeable gas that does not permeate the membrane is discharged from the non-permeable gas outlet. In this way, gas separation is achieved. The element of the gas separation membrane assembly is prepared in this way.

[0055] The element is inserted into a stainless steel container to make a membrane separation assembly. The flue gas or biogas material to be separated is passed into the hollow fiber gas separation membrane outside at a pressure of 300 psi. The flue gas or biogas after CO2 removal is obtained at the product gas outlet.

[0056] The beneficial results of the present application are:

[0057] (1) The polyamide-imide hollow fiber gas separation membrane has good solubility and high mechanical properties. It is a gas separation membrane with high CO2 / CH4 selectivity and excellent CO2 plasticization resistance.

[0058] (2) The prepared polymer has good solubility and film-forming properties, and can be dissolved in one or more polar solvents such as NMP, DMF, DMAc and DMSO at room temperature.

[0059] (3) The obtained hollow fiber gas separation membrane has good thermal stability and mechanical properties, and the glass transition temperature can reach about 350℃, and the tensile strength can reach more than 12MPa.

[0060] (4) The gas separation membrane is applied to the removal of CO2 from biogas and flue gas, and has excellent gas selectivity and permeation flux.

[0061] (5) The gas separation membrane is applied to CO2 separation membrane. After 100h of pure CO2 gas treatment at a pressure of 500psi, the permeability decreases by about 15%, and no plasticization phenomenon occurs, indicating that the gas separation membrane can be operated stably for a long time under high feed pressure. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 The permeation flux and selectivity change diagram of the polymer membrane prepared in Example 1 under different feed pressures in pure gas conditions.

[0063] Figure 2 The thermogravimetric curve of the polymer membrane prepared in Example 4.

[0064] Figure 3 The tensile strength curve of the polymer membrane prepared in Example 4 and the comparative example.

[0065] Figure 4 The solubility of the polymer prepared in Example 4. DETAILED DESCRIPTION

[0066] The technical solutions of the present application will be described in detail below through specific examples, but it should be clear that these examples are used for illustration, but not to limit the scope of the present application.

[0067] Example 1:

[0068] (1). At -10°C, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is TFDB:DABA:6FDA:BPDA:TPC=4:6:2:2:6, the solid content of the solution is 20wt%, and the solution is stirred and dissolved at -10°C.

[0069] (2). After the monomers are completely dissolved in the solvent, the stirring speed is increased, the polymer viscosity rises rapidly after the polymerization reaction starts, and the solution presents a gel state. At this time, continue to add DMAC to continuously dilute the solid content of the solution, so that the solid is re-dissolved to continue the polymerization reaction, and DMAC is continuously added step by step until the solution as a whole no longer presents a gel state, at this time the solid content of the solution is 8wt%.

[0070] (3). After the solution is diluted, it presents a colorless, clear and transparent state, and the reaction is carried out for 14h. The viscosity of the solution is controlled, and when the temperature is increased to 100°C, the viscosity is about 200 poise. The polymer obtained has a weight average molecular weight of about 250000. n represents the polymerization degree of different components of the polymer, and n is about 200.

[0071] (4). The obtained polymer solution is filtered with a 500-mesh metal screen, then extruded through a hollow fiber membrane spinning nozzle (1000μm circular aperture, 300μm circular hole gap width, 350μm center hole diameter), and the extruded hollow fiber body is passed through an N2 atmosphere, and then phase inversion is carried out in a coagulation bath of a specific solid content (25%) ethanol aqueous solution at a temperature of -5°C to obtain a wet fiber. The wet fiber is immersed in ethanol at a temperature of 50°C for 2 hours, and then immersed in isooctane at a temperature of 70°C for 3 hours to remove the solvent in the fiber. After being dried at a temperature of 100°C, heat treatment is carried out at a specific temperature (350°C) for 10h to obtain a hollow fiber membrane with an outer diameter size of about 500μm, an inner diameter size of about 400μm, and a membrane thickness of about 70μm.

[0072] The obtained hollow fiber gas separation membrane is applied to the removal of CO2 in flue gas and biogas.

[0073] About 105 of the hollow fiber membranes prepared by the method of the present application are bundled together; the hollow fibers are tightly packed (about 50% of the packing ratio), and the two ends of the fiber bundle are embedded in a thermosetting polymer epoxy resin and fixed in a tube sheet, and an opening is made at one end of the two ends of the fibers to maintain the gas inlet, and the assembly of the membrane module is completed in this way. Then the membrane module is connected to a container provided with a mixed gas inlet, a permeable gas outlet and a non-permeable gas outlet, so that the space inside the hollow fiber membrane is isolated from the space outside the hollow fiber membrane. In such a gas separation membrane module, the mixed gas is input from the mixed gas inlet to the space inside or in communication with the outside of the hollow fiber membrane, but not limited to this. When the mixed gas comes into contact with the hollow fiber membrane, the specific gas components contained in the mixed gas will selectively permeate the membrane. The permeable gas is discharged from the permeable gas outlet, and the non-permeable gas that does not permeate the membrane is discharged from the non-permeable gas outlet. In this way, a gas separation element is prepared.

[0074] The element is inserted into a stainless steel container to make a membrane separation module. The flue gas or biogas material to be separated is introduced into the hollow fiber gas separation membrane outside the hole side at a pressure of 300 psi, and the CO2-removed flue gas or biogas is obtained at the product gas outlet.

[0075] Example Two:

[0076] Under the condition of -10℃, first, the DABA (3,5-diaminobenzoic acid), terephthaloyl chloride (TPC), 6FDA, 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) are dissolved in N,N-dimethylacetamide (DMAC) under N2 atmosphere for about 10 minutes, and the molar ratio of the monomers is TFDB:DABA:BPDA:6FDA:TPC=3:7:2:2:6, and the solid content of the solution is 20wt%, and the solution is dissolved under the condition of -10℃ stirring. The remaining experimental steps and application steps are the same as in Example One. The weight average molecular weight of the polymer is about 250000. n represents the polymerization degree of different components of the polymer, and n is about 200.

[0077] Example Three:

[0078] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 2,2',5,5'-tetra-chloro-diphenylamine in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 2,2',5,5'-tetra-chloro-diphenylamine:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0079] Example four:

[0080] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 2,2',5,5'-tetra-chloro-diphenylamine in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 2,2',5,5'-tetra-chloro-diphenylamine:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0081] Example five:

[0082] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 2,2',5,5'-tetra-chloro-diphenylamine in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 2,2',5,5'-tetra-chloro-diphenylamine:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0083] Example six:

[0084] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 2,2',5,5'-tetra-chloro-diphenylamine in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 2,2',5,5'-tetra-chloro-diphenylamine:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0085] Example Seven:

[0086] DABA, 1,2,4,5-benzene tetracarboxylic dianhydride (PMDA), terephthaloyl chloride (TPC), 6FDA, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl were dissolved in N,N-dimethylacetamide (DMAC) under N2atmosphere for about 10 minutes at -10°C, the mole ratio of monomers was 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl:DABA:6FDA:PMDA:TPC=4:6:2:2:6, the solid content of solution was 20wt%, and the solution was stirred at -10°C. The rest of the experimental steps and application steps were the same as Example One. The weight average molecular weight of the polymer was about 250000. n represents the polymerization degree of different components of the polymer, and n was about 200.

[0087] Example Eight:

[0088] DABA, terephthaloyl chloride (TPC), 6FDA, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl were dissolved in N,N-dimethylacetamide (DMAC) under N2atmosphere for about 10 minutes at -10°C, the mole ratio of monomers was 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl:DABA:6FDA:TPC=3:7:3:7, the solid content of solution was 20wt%, and the solution was stirred at -10°C. The rest of the experimental steps and application steps were the same as Example One. The weight average molecular weight of the polymer was about 250000. n represents the polymerization degree of different components of the polymer, and n was about 200.

[0089] Example Nine:

[0090] DABA, terephthaloyl chloride (TPC), 6FDA, 4,4'-diamino-3,3'-dimethylbiphenyl were dissolved in N,N-dimethylacetamide (DMAC) under N2atmosphere for about 10 minutes at -10°C, the mole ratio of monomers was 4,4'-diamino-3,3'-dimethylbiphenyl:DABA:6FDA:TPC=4:6:3:7, the solid content of solution was 20wt%, and the solution was stirred at -10°C. The rest of the experimental steps and application steps were the same as Example One. The weight average molecular weight of the polymer was about 250000. n represents the polymerization degree of different components of the polymer, and n was about 200.

[0091] Example Ten:

[0092] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 4,4'-diamino-3,3'-dimethylbiphenyl in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 4,4'-diamino-3,3'-dimethylbiphenyl:DABA:6FDA:TPC=3:7:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0093] Example eleven:

[0094] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 1,2,4,5-benzene tetracarboxylic dianhydride (PMDA), 2,3,5,6-tetramethyl-1,4-diaminobenzene in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 2,3,5,6-tetramethyl-1,4-diaminobenzene:DABA:6FDA:PMDA:TPC=4:6:2:2:6, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0095] Example twelve:

[0096] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 2,3,5,6-tetramethyl-1,4-diaminobenzene in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 2,3,5,6-tetramethyl-1,4-diaminobenzene:DABA:6FDA:TPC=3:7:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0097] Example thirteen:

[0098] Under the condition of -10°C, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 3,6-diaminocarbazole in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 3,6-diaminocarbazole:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10°C. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0099] Example fourteen:

[0100] Under the condition of -10°C, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 3,6-diaminocarbazole in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 3,6-diaminocarbazole:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10°C. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0101] Example fifteen:

[0102] Under the condition of -10°C, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 3,6-diaminocarbazole in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 3,6-diaminocarbazole:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10°C. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0103] Example sixteen:

[0104] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 3,3',4,4'-diphenyltetracarboxylic dianhydride (BPDA), 3,6-diamino-9-ethylcarbazole in N,N-dimethylacetamide (DMAC), the mole ratio of monomers is 3,6-diamino-9-ethylcarbazole:DABA:6FDA:BPDA:TPC=3:7:2:2:6, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0105] Example seventeen:

[0106] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 4,4'-diaminodiphenyl sulfide in N,N-dimethylacetamide (DMAC), the mole ratio of monomers is 4,4'-diaminodiphenyl sulfide:DABA:6FDA:TPC=4:6:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0107] Example eighteen:

[0108] Under the condition of -10℃, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 4,4'-diaminodiphenyl sulfide in N,N-dimethylacetamide (DMAC), the mole ratio of monomers is 4,4'-diaminodiphenyl sulfide:DABA:6FDA:TPC=3:7:3:7, the solid content of solution is 20wt%, stirring and dissolving under the condition of -10℃. The rest of experimental steps and application steps are the same as example one. The weight average molecular weight of polymer is about 250000. n represents the polymerization degree of different components of the polymer, n is about 200.

[0109] Example nineteen:

[0110] Under the condition of -10°C, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 1,2,4,5-benzene tetracarboxylic dianhydride (PMDA), 4,6-diamino-2-phenylindole hydrochloride in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 4:6:2:2:6, the solid content of the solution is 20wt%, and stirring dissolving under the condition of -10°C. The rest of the experimental steps and application steps are the same as Example One. The weight average molecular weight of the polymer is about 250000. n represents the polymerization degree of different components of the polymer, and n is about 200.

[0111] Example Twenty:

[0112] Under the condition of -10°C, first purging for about 10 minutes under N2 atmosphere, then dissolving DABA, terephthaloyl chloride (TPC), 6FDA, 4,6-diamino-2-phenylindole hydrochloride in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is 3:7:3:7, the solid content of the solution is 20wt%, and stirring dissolving under the condition of -10°C. The rest of the experimental steps and application steps are the same as Example One. The weight average molecular weight of the polymer is about 250000. n represents the polymerization degree of different components of the polymer, and n is about 200.

[0113] Comparative Example:

[0114] In this example, 6FDA-DABA system polymer is used as a comparative example: DABA and 6FDA are dissolved in p-chlorophenol at room temperature, the molar ratio of monomers is 6FDA:DABA=1:1, and the solid content of the solution is 18wt%. The rest of the experimental steps and application steps are the same as Example One.

[0115] Table 1 is a comparison of the performance of the polymer membranes prepared in all examples and comparative examples. Table 1 shows the gas permeation performance of different examples and comparative examples. It can be seen that, compared with the pure 6FDA-DABA system, after adding acyl chloride monomers and aromatic monomers, the permeation flux of the gas separation membrane can be greatly improved while maintaining the selectivity at a high level.

[0116] Figure 1 The permeation flux and selectivity change diagram of the polymer membrane prepared in Example One under different feed pressures in pure gas conditions. From Figure 1 It can be seen that the gas separation membrane after adding acyl chloride monomers still has good plasticization resistance and will not be plasticized under 600psi feed pressure, proving that the membrane can be operated stably for a long time under high feed pressure.

[0117] Figure 2 The thermal gravimetric curve of the polymer film prepared in Example 4 is shown in Figure 4. Figure 2 The high temperature resistance of the film of the present application can be clearly seen in the thermal gravimetric curve, which starts to gradually lose weight above 400℃, indicating that the film prepared in the present application can remain stable at high temperature of 400℃, and can meet almost all harsh application temperatures.

[0118] Figure 3 The tensile strength curve of the polymer film prepared in Example 4 and the comparative example. Figure 3 It is shown that after adding acyl chloride, the mechanical properties of the film are not significantly reduced, which can ensure most gas separation conditions.

[0119] Figure 4 The solubility of the polymer prepared in Example 4. Figure 4 The solubility of the polymer after adding acyl chloride monomer is shown, and the solvent used in the figure is DMAC, and the solubility of the polymer is very excellent, avoiding the use of phenolic solvents.

[0120] The tensile strength test method used in the experiment is the national standard: GB / T 1040.2-2006 test standard. The test instrument used is CMT4502 double-column floor electronic universal testing machine, produced by Shanghai Jelu Instrument and Meter Co., Ltd. The test process is single hollow fiber membrane tensile test, and the tensile speed in the test is 50mm / min.

[0121] Table 1

[0122]

[0123] Some parts of the present application are not described in detail, which belong to the known technology of those skilled in the art. The above-described examples are only used to describe the preferred embodiments of the present application, and the preferred examples do not describe all the details and do not limit the application to the specific embodiments described. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A polyamide-imide hollow fiber gas separation membrane, characterized by, The gas separation membrane is made of a polyamide-imide polymer, and the molecular structure of the polymer is shown in general formula (I): wherein n represents the polymerization degree of different components of the polymer, n is an integer of 50-200, x, y, and z are respectively integers of 0-100, x, y, and z are not all 0, and x+y+z=100; the weight average molecular weight of the polymer is between 100000-300000; R1 in general formula (I) comprises one or more of the following structures: R2 groups comprise any one or more of the following structures: R3 groups are one or more of the following groups: 。 2. The method for producing a polyamide-imide hollow fiber gas separation membrane according to claim 1, characterized by, The acyl chloride monomer is involved in copolymerization.

3. The process for producing a polyamide-imide hollow fiber gas separation membrane as claimed in claim 1, characterized by, The polyamide-imide copolymer hollow fiber membrane is prepared by a two-step method, i.e., first, a polyamide-imide copolymer is synthesized, the copolymer is used for spinning, and then the obtained hollow fiber membrane is subjected to heat treatment to obtain the polyamide-imide copolymer hollow fiber membrane.

4. The production method according to claim 3, wherein The method comprises the following steps: (1). At -10 ~ -15℃, DABA, 6FDA, crystalline diamine monomer, and crystalline dianhydride monomer, and acyl chloride monomer are dissolved in N,N-dimethylacetamide (DMAC), the molar ratio of the monomers is diamine monomer:acyl chloride monomer+dianhydride monomer=1~1.1:1~1.1, the solid content of the solution is 15-20wt%, and the solution is stirred and dissolved at -10 ~ -15℃; wherein the monomers consist of DABA, 6FDA, crystalline diamine monomer, crystalline dianhydride monomer, and acyl chloride monomer, the crystalline diamine monomer is monomer A, the crystalline dianhydride monomer is monomer B, and the acyl chloride monomer is monomer C; (2). After the monomers are completely dissolved in the solvent, the stirring speed is increased, the polymer viscosity rises after the polymerization reaction starts, and a gel state is presented; at this time, DMAC is continuously added to continuously dilute the solid content of the solution, so that the solid is re-dissolved to continue the polymerization reaction, and DMAC is continuously added step by step until the whole solution no longer presents a gel state, at which time the solid content of the solution is 5-8wt%; the molar ratio of the diamine and the dianhydride in the reaction system is kept at 1~1.1:1~1.1; wherein the monomer A is selected from any one or more of the following compounds: 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2',5,5'-tetrachlorodiaminobenzene, p-diaminobiphenyl, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 2,3,5,6-tetramethyl-1,4-diaminobenzene, 3,6-diaminocarbazole, 3,6-diamino-9-ethylcarbazole, 4,6-diaminophenylindole hydrochloride, and 4,4'-diaminodiphenyl sulfide; the monomer B is selected from any one or more of the following compounds: the monomer C is selected from any one or more of the following compounds: (3). The solution is colorless, clear and transparent after dilution, and the reaction is carried out for 14-18 h; the temperature is raised to room temperature, pyridine and acetic anhydride are added for chemical ring closure, and the reaction is continued for 20-24 h; the viscosity of the solution is controlled, and the viscosity is 150-200 poise at 100°C; the amount of pyridine added is 110%-120% of the total moles of dianhydride monomers, and the amount of acetic anhydride added is 1000%-1100% of the total moles of dianhydride monomers; (4). The obtained polymer solution is filtered, then extruded through a hollow fiber membrane spinning nozzle, and the extruded hollow fiber body is passed through a N2 atmosphere, followed by phase inversion in an ethanol aqueous solution coagulation bath at a temperature of -10 to -5°C to obtain a wet fiber; the wet fiber is immersed in ethanol at a temperature of 50-60°C for 2-3 hours, and then immersed in isooctane at a temperature of 65-75°C for 3-5 hours to remove the solvent in the fiber; complete drying is carried out at a temperature of 100-120°C, and then heat treatment is carried out at 320-350°C for 15-20 h to obtain a finished hollow fiber membrane.

5. The production method according to claim 3, wherein Comprising the following steps: (1). At -10°C, first purged under N2 atmosphere for about 10 minutes, then the monomers DABA, 6FDA, crystalline diamine monomer and crystalline dianhydride monomer, and acyl chloride monomer are dissolved in N,N-dimethylacetamide (DMAC), the molar ratio of monomers is diamine monomer: acyl chloride monomer + dianhydride monomer = 1:1, and the solid content of the solution is 15-20wt%, and the solution is stirred and dissolved at -10°C; (2). After the monomers are completely dissolved in the solvent, the stirring speed is increased, the polymer viscosity rises after the polymerization reaction starts, and a gel state is presented; at this time, the solid content of the solution is continuously diluted by continuously adding DMAC to make the solid re-dissolve and continue the polymerization reaction, and DMAC is continuously added until the whole solution is no longer in a gel state, at which time the solid content of the solution is 5-8wt%; the molar ratio of diamine and dianhydride in the reaction system is maintained at 1:1; In the above preparation method, the monomer A is selected from any one or more of the following compounds: 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2',5,5'-tetrachlorodiaminobiphenyl, p-diaminobiphenyl, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 2,3,5,6-tetramethyl-1,4-diaminobenzene, 3,6-diaminocarbazole, 3,6-diamino-9-ethylcarbazole, 4,6-diamino-2-phenylindole hydrochloride, 4,4'-diaminodiphenyl sulfide; The monomer B is selected from any one or more of the following compounds: The monomer C is selected from any one or more of the following compounds: (3). The solution is colorless, clear and transparent after dilution, and the reaction is carried out for 14 h; the temperature is raised to room temperature, pyridine and acetic anhydride are added for chemical ring closure, and the reaction is continued for 24 h; the viscosity of the solution is controlled, and the viscosity is 200 poise at 100°C; (4). The rotational viscosity of the solution was controlled, the resulting polymer solution was filtered with a 500-mesh metal screen, then extruded through a hollow fiber membrane spinning nozzle, and the extruded hollow fiber body was passed through a N2 atmosphere, followed by phase inversion in a coagulation bath of 25 wt% ethanol aqueous solution at a temperature of -5°C to produce a wet fiber; The wet fiber was immersed in ethanol at a temperature of 50°C for 2 hours, then immersed in isooctane at a temperature of 70°C for 3 hours to remove the solvent in the fiber; dried thoroughly at a temperature of 100°C, then heat treated at 320-350°C.

6. The production method according to claim 4, wherein In step (2), the reaction temperature is -10°C.

7. The production method according to claim 4, wherein In step (2), the reaction time is 20-24h.

8. Use of the polyamide-imide hollow fiber gas separation membrane of claim 1 or the hollow fiber gas separation membrane prepared by the method of any one of claims 2-7, characterized in that: (1) the gas separation membrane is used for removal of CO2 in flue gas and biogas; and / or (2) the gas separation membrane is used for removal of CO2 from N2.

9. Use according to claim 8, wherein the compound is ###0008### The use is for flue gas removal in thermal power generation, steelmaking, aluminum electrolysis, natural gas exploitation and / or biogas purification in biogas generation devices.

Images