Polyimide hollow fiber membrane for oxygen-enriched combustion scene and preparation method of polyimide hollow fiber membrane

Abstract

The invention relates to a polyimide hollow fiber membrane for an oxygen-enriched combustion scene and a preparation method of the polyimide hollow fiber membrane, and belongs to the technical field of separation membranes, and specifically, a membrane material of the hollow fiber membrane is formed by polymerizing naphthalene diamine, dianhydride and terephthaloyl chloride; the molar ratio of terephthaloyl chloride to dianhydride is (100: 1)-(70: 30), the fiber membrane is applied to gas separation in an oxygen-enriched combustion environment at the temperature of 80-150 DEG C, the oxygen concentration can be enriched from 21% to 30%-35%, and the fiber membrane has high O2 / N2 selectivity and high air permeability and also has excellent thermal stability and moisture resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of polyimide hollow fiber membrane for oxygen-enriched combustion scene and its preparation method, belong to separation membrane technical field. BACKGROUND

[0002] Oxygen-enriched combustion technology can significantly improve fuel combustion efficiency (energy saving rate reaches 10%-30%) by increasing the oxygen concentration in air from 21% to 25%-35%, while reducing nitrogen oxides (NO x ) emissions by more than 60%, and facilitating carbon dioxide capture and storage (CCS) in flue gas, which is one of the key technologies to achieve the "double carbon" goal. In the oxygen-enriched combustion system, the energy consumption and stability of the oxygen enrichment link directly determine the technical economy, so it is of great significance to develop oxygen separation materials that are efficient and resistant to harsh environments.

[0003] Currently, there are three main oxygen enrichment technologies: cryogenic separation method, which separates oxygen and nitrogen by low-temperature rectification, with oxygen purity up to 99.5% or more, but with high equipment investment and energy consumption, and only suitable for large centralized scenarios. Pressure swing adsorption (PSA) uses molecular sieves to separate oxygen and nitrogen based on their adsorption differences, with fast response speed, but short adsorbent life, moderate energy consumption, and limited pure oxygen production due to adsorption capacity. In contrast, membrane separation method separates oxygen and nitrogen based on the permeation difference of high molecular weight membranes, with the advantages of low energy consumption, compact equipment, and simple operation. However, traditional membrane materials have obvious shortcomings: poor temperature resistance (long-term use temperature <80 ℃), low O2 / N2 selectivity (separation factor <7), and easy aging in high temperature and high humidity environments (80-150 ℃, humidity >80%) of oxygen-enriched combustion scene, making it difficult to meet the long-term stable operation requirements.

[0004] Polyimide has become the core material for membrane separation method due to its excellent thermal stability and mechanical properties, but traditional polyimide has two major bottlenecks: one is that the molecular chain is tightly packed, resulting in low oxygen permeation coefficient and large membrane module volume; the other is that the chain segment is not flexible enough, and rigid collapse easily occurs at high temperatures, resulting in a sharp decrease in O2 / N2 selectivity with increasing temperature, with the separation factor dropping to less than 5 at 100 ℃. SUMMARY

[0005] To solve the technical problems existing in the prior art, the present application provides a kind of polyimide hollow fiber membrane for oxygen-enriched combustion scene and its preparation method, which has high O2 / N2 selectivity, high gas permeability, and also has excellent thermal stability and moisture resistance.

[0006] To achieve the above object, the technical scheme adopted by the present application is a kind of polyimide hollow fiber membrane for oxygen-enriched combustion scene, the membrane material of the hollow fiber membrane is polymerized by naphthalene diamine, dianhydride and terephthaloyl chloride;The molar ratio of terephthaloyl chloride and dianhydride is 100:1-70:30, the fiber membrane is applied in the gas separation of oxygen-enriched combustion environment with temperature of 80-150 ℃, and the oxygen concentration can be enriched from 21% to 30%-35%.

[0007] Preferably, the naphthalene diamine is one of 1,5-naphthalene diamine and 1,7-naphthalene diamine;The dianhydride is one of hexafluoro dianhydride, bisphenol A type diether dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0008] A kind of polyimide hollow fiber membrane for oxygen-enriched combustion scene preparation method, comprising the following steps,

[0009] S1, preparation of polyamide acid solution, control the total molar number of naphthalene diamine and the total molar number of dianhydride and terephthaloyl chloride and the ratio is 1:1, the solid content of reaction system is 15%-30%, naphthalene diamine is dissolved in N-methyl pyrrolidone under nitrogen protection, and dianhydride and terephthaloyl chloride are added in batches under 0-10 ℃ low temperature environment, stirring and reaction, to form polyamide acid solution;

[0010] S2, preparation of polyimide powder, polyamide acid solution is treated by chemical imidization with acetic anhydride and 3-methyl pyridine, then purified by precipitation and dried to obtain polyimide powder;

[0011] S3, preparation of hollow fiber membrane, dry-wet spinning process is used to prepare hollow fiber membrane.

[0012] Preferably, in the step S3, the dry-wet spinning process is as follows: polyimide powder is dissolved in N-methyl pyrrolidone solvent to prepare 15wt%-20wt% casting solution, after vacuum degassing, with 30% DMAc / water mixture as core liquid, the length of air section is controlled to 5-10 cm, and the membrane is formed in 25 ℃ deionized water coagulation bath, after water washing for 24 h to remove residual solvent, 60 ℃ vacuum drying for 12 h, and then 150-200 ℃ heat treatment for 2 h, finally the hollow fiber membrane with asymmetric structure is obtained.

[0013] Compared with the prior art, the present application has the following technical effects: the present application adopts naphthalene diamine, specific dianhydride and terephthaloyl chloride to prepare polyimide, which has obvious advantages compared with the traditional system. The rigid naphthalene ring of naphthalene diamine enhances the rigidity of the molecular chain through the conjugated π system, improves the thermal stability of the film, and the glass transition temperature Tg is greater than 300 DEG C, while reducing the chain segment movement at high temperature to maintain the O2 / N2 selectivity. The dianhydride adopts one of hexafluoro dianhydride, bisphenol A type diether dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride. The hexafluoroisopropyl in 6FDA gives the molecular chain hydrophobicity and free volume, which can improve the oxygen permeability; the ether bond of BPADA can increase the chain segment flexibility to balance the air permeability and mechanical properties; the ketone group of BTDA can enhance the intermolecular force to improve the aging resistance. The rigid benzene ring of terephthaloyl chloride as the third monomer can optimize the molecular chain packing density, ensure high oxygen permeability, and improve the O2 / N2 selectivity through size screening effect; the structure of "rigid skeleton-flexible connection-polarity regulation" formed by ternary copolymerization balances high permeability and high selectivity, improves film uniformity and mechanical strength, and can maintain long-time operation in 80-150 DEG C, high humidity and oxygen-rich combustion environment, and the aging resistance and plastic resistance are better than those of traditional materials. The gas separation membrane prepared by the present application can enrich the oxygen concentration from 21% to 30%-35% in the 80-150 DEG C, high humidity and oxygen-rich combustion environment, which provides an efficient solution for industrial oxygen-enriched combustion energy saving and carbon dioxide capture. DETAILED DESCRIPTION

[0014] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0015] Example 1

[0016] (1) 15.82g 1,5-naphthalene diamine was added to a three-necked flask which was pre-treated by drying, and 391.2mL NMP (solid content 15%) was added under the protection of high-purity nitrogen atmosphere, and stirred until completely dissolved. Then, the temperature of the reaction system was reduced to 0 DEG C and stabilized for 30min, 44.44g 6FDA was added in batches, and 0.18g TPC (6FDA:TPC=100:1) was added after stirring for 30min, and the stirring was continued at 0 DEG C for 24h to form a viscous polyamide acid solution. 90mL acetic anhydride and 10mL 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the reaction was completed after 24h. The reaction liquid was poured into deionized water for precipitation, and after filtration, it was washed with deionized water for 4 times, and vacuum dried at 80 DEG C for 24h to obtain polyimide.

[0017] (2) 15 g of polyimide powder was dissolved in 97.09 mL of NMP to prepare a 15 wt% casting solution, which was stirred at 60 °C for 48 h and vacuum degassed for 2 h. Dry-jet wet spinning was performed, with 30% DMAc / water mixture (volume ratio) as the core solution, 5 cm as the air gap length, and deionized water at 25 °C as the coagulation bath. The solidified fiber was washed with water for 24 h to remove residual solvent, vacuum dried at 60 °C for 12 h, and then heat treated at 150 °C for 2 h to obtain the finished membrane.

[0018] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester, with an O2 permeation coefficient of 42 Barrer and an O2 / N2 separation factor of 9.2.

[0019] Example 2

[0020] (1) 15.82 g of 1,7-naphthalenediamine was added to a three-necked flask which was previously subjected to drying treatment, and 242 mL of NMP (solid content 22.5%) was added under a high-purity nitrogen protective atmosphere, and stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to 5 °C and stabilized for 30 min, 37.52 g of BPADA was added in batches, and 2.75 g of TPC (6FDA:TPC = 85:15) was added after stirring for 30 min, and the stirring was continued at 5 °C for 24 h to form a viscous polyamide acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the reaction was completed after 24 h of chemical imidization. The reaction solution was poured into deionized water for precipitation, and after filtration, it was washed with deionized water for 4 times, and vacuum dried at 80 °C for 24 h to obtain polyimide.

[0021] (2) 17 g of polyimide powder was dissolved in 97.09 mL of NMP to prepare a 17 wt% casting solution, which was stirred at 60 °C for 48 h and vacuum degassed for 2 h. Dry-jet wet spinning was performed, with 30% DMAc / water mixture (volume ratio) as the core solution, 7 cm as the air gap length, and deionized water at 25 °C as the coagulation bath. The solidified fiber was washed with water for 24 h to remove residual solvent, vacuum dried at 60 °C for 12 h, and then heat treated at 180 °C for 2 h to obtain the finished membrane.

[0022] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester, with an O2 permeation coefficient of 35 Barrer and an O2 / N2 separation factor of 10.5.

[0023] Example 3

[0024] (1) 15.82 g of 1,7-naphthyldiamine was added to a pre-dried three-necked flask, and 242 mL of NMP (30% solid content) was added under a high-purity nitrogen atmosphere. The mixture was stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to 10 °C and stabilized for 30 min. 22.57 g of BTDA was added in portions, and after stirring for 30 min, 5.5 g of TPC (6FDA:TPC=70:30) was added. The mixture was stirred continuously at 10 °C for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the chemical imidization was completed after 24 h of reaction. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80 °C for 24 h to obtain polyimide.

[0025] (2) Dissolve 20g of polyimide powder in 97.09mL of NMP to prepare a 20wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 8cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 200℃ for 2h to obtain the finished film.

[0026] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester. Its O2 permeability coefficient was 28 Barrer and its O2 / N2 separation factor was 11.8.

[0027] Comparative Example 1 (compared to Example 1)

[0028] (1) 15.82 g of 1,5-naphthyldiamine was added to a pre-dried three-necked flask, and 322.3 mL of NMP (15% solid content) was added under a high-purity nitrogen atmosphere. The mixture was stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to 0 °C and stabilized for 30 min. 26.66 g of 6FDA was added in portions, and after stirring for 30 min, 7.32 g of TPC (6FDA:TPC=60:40) was added. The mixture was stirred continuously at 0 °C for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the chemical imidization was completed after 24 h of reaction. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80 °C for 24 h to obtain polyimide.

[0029] (2) Dissolve 15g of polyimide powder in 97.09mL of NMP to prepare a 15wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 5cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 150℃ for 2h to obtain the finished film.

[0030] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester. Excessive TPC caused excessive cross-linking of molecular chains and severe densification of membrane structure. The O2 permeability coefficient of the product was only 18 Barrer), and the O2 / N2 separation factor was 8.2.

[0031] Comparative Example 2 (compared to Example 1)

[0032] (1) 15.82 g of 1,5-naphthyldiamine was added to a pre-dried three-necked flask, and 392.9 mL of NMP (15% solid content) was added under a high-purity nitrogen atmosphere. The mixture was stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to 0 °C and stabilized for 30 min. 44.89 g of 6FDA was added in portions, without the addition of TPC (6FDA:TPC=100:0). The mixture was stirred continuously at 0 °C for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the chemical imidization was completed after 24 h of reaction. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80 °C for 24 h to obtain polyimide.

[0033] (2) Dissolve 15g of polyimide powder in 97.09mL of NMP to prepare a 15wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 5cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 150℃ for 2h to obtain the finished film.

[0034] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester. Due to the lack of TPC size sieving control, the molecular chain stacking uniformity was insufficient, the O2 / N2 separation factor was only 7.5, and the O2 permeability coefficient was 38 Barrer.

[0035] Comparative Example 3 (compared to Example 2)

[0036] (1) 15.82 g of 1,7-naphthyldiamine was added to a pre-dried three-necked flask, and 544.6 mL of NMP (10% solid content) was added under a high-purity nitrogen atmosphere. The mixture was stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to 5 °C and stabilized for 30 min. 37.52 g of BPADA was added in portions, and after stirring for 30 min, 2.75 g of TPC (6FDA:TPC=85:15) was added. The mixture was stirred continuously at 5 °C for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the chemical imidization was completed after 24 h of reaction. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80 °C for 24 h to obtain polyimide.

[0037] (2) Dissolve 17g of polyimide powder in 97.09mL of NMP to prepare a 17wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 7cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 180℃ for 2h to obtain the finished film.

[0038] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester. The reaction system was too dilute, the molecular chain growth was hindered, the viscosity of polyamic acid decreased, the O2 permeability coefficient of the product was 29 Barrer, and the O2 / N2 separation factor was 8.7.

[0039] Comparative Example 4 (compared to Example 3)

[0040] (1) 15.82 g of 1,7-naphthyldiamine was added to a pre-dried three-necked flask, and 121.7 mL of NMP (35% solid content) was added under a high-purity nitrogen atmosphere. The mixture was stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to 10 °C and stabilized for 30 min. 22.57 g of BTDA was added in portions, and after stirring for 30 min, 5.5 g of TPC (6FDA:TPC=70:30) was added. The mixture was stirred continuously at 10 °C for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the chemical imidization was completed after 24 h of reaction. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80 °C for 24 h to obtain polyimide.

[0041] (2) Dissolve 20g of polyimide powder in 97.09mL of NMP to prepare a 20wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 8cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 200℃ for 2h to obtain the finished film.

[0042] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester. The system viscosity was too high, the dianhydride and TPC were not dispersed evenly, the reaction was incomplete, and unreacted monomers remained in the polyimide powder. The O2 permeability coefficient of the product was 23 Barrer, and the O2 / N2 separation factor was 8.5.

[0043] Comparative Example 5 (compared to Example 1)

[0044] (1) 15.82 g of 1,5-naphthyldiamine was added to a pre-dried three-necked flask, and 391.2 mL of NMP (15% solid content) was added under a high-purity nitrogen atmosphere. The mixture was stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to -5℃ and stabilized for 30 min. 44.44 g of 6FDA was added in portions, and after stirring for 30 min, 0.18 g of TPC (6FDA:TPC=100:1) was added. The mixture was stirred continuously at -5℃ for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the chemical imidization was completed after 24 h of reaction. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80℃ for 24 h to obtain polyimide.

[0045] (2) Dissolve 15g of polyimide powder in 97.09mL of NMP to prepare a 15wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 5cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 150℃ for 2h to obtain the finished film.

[0046] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester. The low temperature during polymerization caused the reaction rate to be too slow, the monomer reaction was incomplete, and the molecular weight of polyimide was low. The O2 permeability coefficient of the product was 22 Barrer, and the O2 / N2 separation factor was 8.1.

[0047] Comparative Example 6 (compared to Example 2)

[0048] (1) 10.81 g of 4,4'-diaminodiphenyl ether (ODA, replacing naphthyldiamine) was added to a pre-dried three-necked flask. 242 mL of NMP (22.5% solid content) was added under a high-purity nitrogen atmosphere and stirred until completely dissolved. Subsequently, the reaction system temperature was lowered to 5 °C and stabilized for 30 min. 37.52 g of BPADA was added in batches, and after stirring for 30 min, 2.75 g of TPC (6FDA:TPC=85:15) was added. The mixture was stirred continuously at 5 °C for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the reaction was carried out for 24 h to complete the chemical imidization. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80 °C for 24 h to obtain polyimide.

[0049] (2) Dissolve 17g of polyimide powder in 97.09mL of NMP to prepare a 17wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 7cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 180℃ for 2h to obtain the finished film.

[0050] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N2 separation test on a gas separation tester. After ODA was used to replace naphthalene diamine, the product lacked the rigid skeleton of naphthalene ring, and the glass transition temperature (Tg) dropped to 265℃ (<300℃); the O2 permeability coefficient was 32 Barrer, and the O2 / N2 separation factor was 7.8.

[0051] Comparative Example 7 (compared to Example 3)

[0052] (1) 15.82 g of 1,7-naphthyldiamine was added to a pre-dried three-necked flask, and 242 mL of NMP (30% solid content) was added under a high-purity nitrogen atmosphere. The mixture was stirred until completely dissolved. Subsequently, the temperature of the reaction system was lowered to 10 °C and stabilized for 30 min. 22.57 g of BTDA was added in portions, and after stirring for 30 min, 5.5 g of TPC (6FDA:TPC=70:30) was added. The mixture was stirred continuously at 10 °C for 24 h to form a viscous polyamic acid solution. 90 mL of acetic anhydride and 10 mL of 3-methylpyridine (volume ratio 9:1) were added dropwise to the solution, and the chemical imidization was completed after 24 h of reaction. The reaction solution was poured into deionized water to precipitate the precipitate. After filtration, the precipitate was washed four times with deionized water and dried under vacuum at 80 °C for 24 h to obtain polyimide.

[0053] (2) Dissolve 20g of polyimide powder in 97.09mL of NMP to prepare a 20wt% casting solution. Stir at 60℃ for 48h and degas under vacuum for 2h. Use wet-dry spinning method, with the core solution being a 30% DMAc / water mixture (volume ratio), an air section length of 8cm, and deionized water at 25℃ in the coagulation bath. After curing, wash the fiber with water for 24h to remove residual solvent, vacuum dry at 60℃ for 12h, and then heat treat at 120℃ for 2h to obtain the finished film.

[0054] (3) The polyimide hollow fiber membrane prepared above was subjected to O2 / N separation test on a gas separation tester. Due to the decrease in heat treatment temperature, the membrane structure was not completely stable and the molecular chain arrangement was loose. The O2 / N separation factor of the product was 9.1.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A polyimide hollow fiber membrane for oxygen enriched combustion scenarios, characterized by: The membrane material of the hollow fiber membrane is polymerized by naphthalene diamine, dianhydride and terephthaloyl chloride; the molar ratio of the terephthaloyl chloride to the dianhydride is 100:1-70:30, the fiber membrane is applied in the gas separation in the oxygen-rich combustion environment with the temperature of 80-150℃, and the oxygen concentration can be enriched from 21% to 30%-35%.

2. The polyimide hollow fiber membrane for oxygen-enriched combustion scenario according to claim 1, characterized in that: The naphthalene diamine is one of 1,5-naphthalene diamine and 1,7-naphthalene diamine; the dianhydride is one of hexafluoro dianhydride, bisphenol A type diether dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

3. A method of making a polyimide hollow fiber membrane for oxygen- enriched combustion scenarios as claimed in claim 1, characterized by: The method comprises the following steps, S1, preparing a polyamide acid solution, controlling the total molar number of naphthalene diamine and the total molar number of dianhydride and terephthaloyl chloride to be 1:1, the solid content of the reaction system being 15%-30%, dissolving the naphthalene diamine in N-methyl pyrrolidone under nitrogen protection, and adding the dianhydride and terephthaloyl chloride in batches under the low-temperature environment of 0-10℃, stirring and reacting to form a polyamide acid solution; S2, preparing a polyimide powder, chemically imidizing the polyamide acid solution by acetic anhydride and 3-methyl pyridine, and then purifying and drying to obtain a polyimide powder; S3, preparing a hollow fiber membrane, and adopting a dry-wet spinning process to prepare the hollow fiber membrane.

4. A method of making a polyimide hollow fiber membrane for oxygen- enriched combustion applications according to claim 3, characterized in that: In the step S3, the dry-wet spinning process is as follows: dissolving the polyimide powder in N-methyl pyrrolidone solvent to prepare a 15wt%-20wt% casting solution, vacuum degassing, taking a 30% DMAc / water mixture as a core liquid, controlling the air section length to be 5-10cm, solidifying and forming in a 25℃ deionized water coagulation bath, removing residual solvents after water washing for 24h, vacuum drying at 60℃ for 12h, and then heat treating at 150-200℃ for 2h to finally obtain a hollow fiber membrane with an asymmetric structure.