Polybenzimidazole mixed matrix hollow fiber membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of gas separation membrane materials, in particular to a polybenzimidazole mixed matrix hollow fiber membrane and a preparation method and application thereof.The preparation method comprises the steps that amino silane modified filling particles are taken and dispersed in a solvent, ultrasonic treatment is conducted to obtain a filling particle solution, pretreated polybenzimidazole is added into the filling particle solution, stirring is conducted for 8-12 h at the temperature of 60-80 DEG C, and the polybenzimidazole mixed matrix hollow fiber membrane is obtained; then carrying out vacuum defoaming for 4-8 hours to obtain a modified membrane casting solution; the preparation method comprises the following steps: adding N-methyl-2-pyrrolidone into ethanol to obtain a core solution; pouring the modified membrane casting solution and the core solution into a spinning tank for spinning, filling nitrogen until the air pressure is 0.02-0.03 MPa, controlling the flow velocity ratio of the modified membrane casting solution to the core solution to be 3: (1-2), simultaneously extruding from a spinning nozzle, entering a water coagulating bath, collecting by a wire winding wheel to obtain polybenzimidazole mixed matrix hollow fibers, soaking and drying to obtain the polybenzimidazole mixed matrix hollow fiber membrane. The fiber membrane has excellent helium permeability and helium selectivity, and can be used for helium separation and purification.

Description

Technical Field

[0001] The invention relates to the technical field of gas separation membrane materials, and in particular to a polybenzimidazole mixed matrix hollow fiber membrane and a preparation method and application thereof. Background Art

[0002] Helium is one of the inert gases on Earth. It has special properties such as low surface tension, strong thermal conductivity, and extremely low viscosity. It is widely used in medical, military, semiconductor manufacturing and other fields. It is called the "chip in gas" and is an important resource related to national security and the development of high-tech industries. Helium is mainly distributed in the mantle, rocks, air and natural gas. Extracting He from natural gas is currently the only way to utilize He as a resource. The main technologies for helium purification are cryogenic distillation and pressure swing adsorption. The helium concentration in my country is relatively low. Using these two technologies to purify helium will consume huge energy and have high production costs. In recent years, with the development of membrane technology, membranes with high separation performance have gradually been used in helium purification, providing a promising alternative for natural gas helium separation and has good application prospects.

[0003] Compared with traditional separation technology, membrane separation technology has many advantages, but it also has many defects, such as the "trade-off" effect and poor stability. The literature [Separation and Purification Technology 237 (2020) 116347] reported a hollow fiber membrane prepared by filling polybenzimidazole with ZIF-8, which achieved an increase in gas flux, with an H2 flux of 107 GPU and an H2 / CO2 selectivity of 18. The flux performance of this material is relatively excellent, but the gas selectivity is low and the commercial application value is low. Chinese patent CN117654291A discloses a homogeneous hollow fiber polybenzimidazole separation membrane and its preparation method and application. Polybenzimidazole is prepared in situ using monoacid as solvent. The H2 flux reaches 33 GPU, the H2 / N2 selectivity is 228, and the H2 / CH4 selectivity is 293. This material has a high selectivity, but its flux is low. Chinese patent CN115703044A discloses the structure, preparation method and application of a heterocyclic polybenzimidazole gas separation membrane, which is used for helium extraction, hydrogen separation and CO2 capture and separation. The material is prepared by ionization reaction modification and composite with polyacid. The hydrogen flux is 1310 Barre and the H2 / CO2 selectivity is 20 at room temperature. The material has high flux but low selectivity.

[0004] Therefore, the existing separation membranes used for helium separation and purification have the problems of low gas flux and poor selectivity, and it is difficult to take both into account at the same time. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a polybenzimidazole mixed matrix hollow fiber membrane and a preparation method and application thereof, so as to at least solve the problems of low gas flux and poor selectivity of existing separation membranes used for helium separation and purification, and the difficulty in taking both into account at the same time.

[0006] The present invention solves the above technical problems by the following technical means:

[0007] A first aspect of an embodiment of the present invention provides a method for preparing a polybenzimidazole mixed matrix hollow fiber membrane, comprising the following steps:

[0008] The aminosilane modified filling particles are dispersed in a solvent, and ultrasonic treatment is performed for 30 to 60 minutes to obtain a filling particle solution, and the pretreated polybenzimidazole is added to the filling particle solution, and stirred at 60 to 80° C. for 8 to 12 hours, and then vacuum degassing is performed for 4 to 8 hours to obtain a modified casting solution;

[0009] Adding N-methyl-2-pyrrolidone to ethanol, mixing and stirring to obtain a core liquid;

[0010] The modified casting liquid and core liquid are poured into a spinning tank for spinning, and nitrogen is filled to a pressure of 0.02-0.03 MPa. The flow rate ratio of the modified casting liquid and the core liquid is controlled to be 3:(1-2), and they are extruded from the spinneret at the same time and enter a water coagulation bath. The fibers are then collected through a winding wheel to obtain polybenzimidazole mixed matrix hollow fibers, which are successively soaked in water, and alternately soaked in n-hexane and ethanol, and dried naturally to obtain polybenzimidazole mixed matrix hollow fiber membranes.

[0011] In combination with the first aspect, in some embodiments, the mass ratio of the aminosilane modified filler particles to the polybenzimidazole is 1:(10-15), and the pretreatment of the polybenzimidazole is to vacuum dry the polybenzimidazole at 100-120° C. for 8-12 hours.

[0012] In combination with the first aspect, in some embodiments, the preparation method of the aminosilane-modified filling particles is as follows:

[0013] The filling particles are dispersed in a mixed solution of deionized water, ethanol and ammonia water, and ultrasonically treated at 40-60°C for 1-2 hours. Then, aminosilane is added dropwise under stirring, and the mixture is stirred at room temperature for 8-12 hours. The mixture is centrifuged, and the obtained solid product is washed with ethanol for 3-5 times, and then vacuum dried at 60-80°C for 12-24 hours to obtain aminosilane-modified filling particles.

[0014] In combination with the first aspect, in some embodiments, the mass ratio of the filling particles to the aminosilane is 1:(1-3), and the filling particles are any one of SiO2, TiO2, and Al2O3.

[0015] In combination with the first aspect, in some embodiments, the mass ratio of the filling particles, deionized water, ethanol and ammonia water is 1:(1-2):(30-40):(2-4).

[0016] In combination with the first aspect, in some embodiments, the mass ratio of the aminosilane-modified filler particles to the solvent is 1:(55-70), and the solvent is N-methyl-2-pyrrolidone or chloroform.

[0017] In combination with the first aspect, in some embodiments, the mass ratio of the ethanol to N-methyl-2-pyrrolidone is 1:(10-15), and the N-methyl-2-pyrrolidone is added to the ethanol and mixed and stirred for 1-2 hours.

[0018] In combination with the first aspect, in some embodiments, the temperature of the spinneret is 40-60° C., the temperature of the water coagulation bath is 28-33° C., and the distance between the spinneret and the water coagulation bath is 8-9 cm.

[0019] A second aspect of an embodiment of the present invention provides a polybenzimidazole mixed matrix hollow fiber membrane, wherein the polybenzimidazole mixed matrix hollow fiber membrane is prepared by the preparation method described in the first aspect.

[0020] The third aspect of the embodiments of the present invention provides the use of the polybenzimidazole mixed matrix hollow fiber membrane described in the second aspect in helium purification.

[0021] In the preparation method of the polybenzimidazole mixed matrix hollow fiber membrane of the present invention, aminosilane-grafted SiO2, TiO2, and Al2O3 filling particles are designed to be added to the polybenzimidazole hollow fiber membrane. The addition of the filling particles will destroy the arrangement of the polymer chains, expand the interface space, and increase the gas flux, thereby improving the gas transmission efficiency. Aminosilane gives the filling particles good dispersibility, improves the affinity between the filler and the polymer, avoids the formation of non-selective gaps, and retains the excellent selectivity of the membrane itself.

[0022] The polybenzimidazole mixed matrix hollow fiber membrane prepared by the present invention has both excellent helium permeability and helium selectivity, and the helium flux can reach up to 349GPU, and the corresponding He / CH4 and He / N2 selectivity can reach 375 and 392 respectively, and can be used for helium separation and purification. In addition, the polybenzimidazole mixed matrix hollow fiber membrane prepared by adding aminosilane modified filling particles to polybenzimidazole has excellent long-term separation stability, and the separation performance is still excellent after running for 450 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a graph showing the separation stability test results of the polybenzimidazole mixed matrix hollow fiber membrane prepared in Example 3;

[0024] Figure 2 This is a graph showing the separation stability test results of the polybenzimidazole fiber membrane prepared in Comparative Example 1. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0027] The English letters in the present invention are interpreted as follows:

[0028] NMP: N-methyl-2-pyrrolidone.

[0029] Existing separation membranes for helium purification either have the problem of low gas flux or poor gas selectivity, and it is difficult to take into account both high flux and better selectivity. To this end, the present invention proposes a method for preparing a polybenzimidazole mixed matrix hollow fiber membrane, adding SiO2, TiO2, and Al2O3 filling particles modified by aminosilane grafting to polybenzimidazole. The addition of aminosilane-modified filling particles will destroy the arrangement of polybenzimidazole polymer chains and expand the interface space, thereby improving gas transmission efficiency; at the same time, aminosilane gives the filling particles good dispersibility, improves the affinity between the filling particles and the polybenzimidazole polymer, avoids the formation of non-selective gaps, and retains the excellent selectivity of the polybenzimidazole membrane itself.

[0030] The method for preparing the polybenzimidazole mixed matrix hollow fiber membrane of the present invention comprises the following steps:

[0031] The aminosilane modified filling particles are dispersed in a solvent, and ultrasonic treatment is performed for 30 to 60 minutes to obtain a filling particle solution, and the pretreated polybenzimidazole is added to the filling particle solution, and stirred at 60 to 80° C. for 8 to 12 hours, and then vacuum degassing is performed for 4 to 8 hours to obtain a modified casting solution;

[0032] Add ethanol and N-methyl-2-pyrrolidone in a mass ratio of 1:(10-15) and stir for 1-2 hours to obtain a core liquid;

[0033] The modified casting liquid and core liquid are poured into the spinning tank for spinning, and nitrogen is filled to a pressure of 0.02-0.03 MPa. The flow rate ratio of the modified casting liquid and the core liquid is controlled to be 3:(1-2), and they are extruded from the spinneret at the same time, enter the water coagulation bath, and then collected by the winding wheel to obtain the polybenzimidazole mixed matrix hollow fiber, which is successively soaked in water, and alternately soaked in n-hexane and ethanol, and dried naturally to obtain the polybenzimidazole mixed matrix hollow fiber membrane. The spinneret temperature is set to 40-60°C, and the water coagulation bath temperature is set to 28-33°C. A small distance between the spinneret and the water coagulation bath will result in more defects in the fiber membrane, while a large distance between the spinneret and the water coagulation bath will make the membrane filaments compact, resulting in a low fiber flux, so the distance between the spinneret and the water coagulation bath is set to 8-9 cm.

[0034] The mass ratio of aminosilane modified filler particles to polybenzimidazole is 1:(10-15), and the pretreatment of polybenzimidazole is to vacuum dry the polybenzimidazole at 100-120° C. for 8-12 hours. Drying pretreatment of polybenzimidazole can remove moisture contained in the raw materials and effectively avoid defects in subsequent membrane fibers.

[0035] The preparation method of aminosilane modified filling particles is as follows:

[0036] The filling particles are dispersed in a mixed solution of deionized water, ethanol and ammonia water, and ultrasonically treated at 40-60°C for 1-2 hours, and then aminosilane is added dropwise under stirring, and the reaction is stirred at room temperature for 8-12 hours, centrifuged, and the obtained solid product is washed with ethanol for 3-5 times, and then vacuum dried at 60-80°C for 12-24 hours to obtain aminosilane-modified filling particles. In order to improve the helium selectivity and flux of the fiber membrane and strengthen the binding between the filling particles and the subsequent polybenzimidazole, the mass ratio of the filling particles to the aminosilane is set to 1: (1-3), and the filling particles are any one of SiO2, TiO2, and Al2O3; the mass ratio between the filling particles, deionized water, ethanol and ammonia water is 1: (1-2): (30-40): (2-4); the mass ratio of the aminosilane-modified filling particles to the solvent is 1: (55-70), and the solvent is N-methyl-2-pyrrolidone or chloroform.

[0037] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0038] Example 1

[0039] The preparation method of the polybenzimidazole mixed matrix hollow fiber membrane of this embodiment is as follows:

[0040] (1) Preparation of aminosilane modified filler particles

[0041] 5 g of SiO2 particles were dispersed in a mixed solution of 5 g of deionized water, 150 g of ethanol and 20 g of ammonia water, and ultrasonically treated at 60°C for 2 h. Then, 5 g of aminosilane was added dropwise under stirring, and the mixture was stirred at room temperature for 8 h, and then centrifuged. The obtained solid product was washed with ethanol three times, and then vacuum dried at 60°C for 12 h to obtain aminosilane-modified SiO2 particles.

[0042] (2) Preparation of modified casting solution

[0043] 2 g of aminosilane-modified SiO2 particles were dispersed in 110 g of NMP and ultrasonically treated for 30 min to obtain a filling particle solution. 20 g of polybenzimidazole was then vacuum dried at 100 °C for 8 h, added to the filling particle solution, stirred at 60 °C for 8 h, and finally vacuum degassed for 4 h to obtain a modified casting solution.

[0044] (3) Preparation of core liquid

[0045] 90 g of NMP was added to 9 g of ethanol, and the mixture was mixed and stirred for 1 h to obtain a core liquid.

[0046] (4) Spinning and weaving into membrane

[0047] The modified casting liquid and core liquid are poured into a spinning tank for spinning, and nitrogen is filled to 0.02MPa. The flow rate of the modified casting liquid and the core liquid is controlled to be 3:1. At the same time, they are extruded from the spinneret and enter a 28°C water coagulation bath. The temperature of the spinneret is 40°C, and the height of the spinneret from the water coagulation bath is 8cm. The polybenzimidazole mixed matrix hollow fiber is collected by a winding wheel, and then soaked in water for 1 day, and then soaked alternately in n-hexane and ethanol twice, each time for 30 minutes, and finally naturally dried for 2 days to obtain a polybenzimidazole mixed matrix hollow fiber membrane.

[0048] Example 2

[0049] The preparation method of the polybenzimidazole mixed matrix hollow fiber membrane of this embodiment is as follows:

[0050] (1) Preparation of aminosilane modified filler particles

[0051] 5 g of TiO2 particles were dispersed in a mixed solution of 10 g of deionized water, 200 g of ethanol and 10 g of ammonia water, and ultrasonically treated at 40°C for 1 h. Then, 15 g of aminosilane was added dropwise under stirring, and the mixture was stirred at room temperature for 12 h. The mixture was then centrifuged and the solid product was washed 5 times with ethanol and then vacuum dried at 80°C for 12 h to obtain aminosilane-modified TiO2 particles.

[0052] (2) Preparation of modified casting solution

[0053] 2 g of aminosilane-modified TiO2 particles were dispersed in 140 g of chloroform and ultrasonically treated for 60 min to obtain a filling particle solution. 30 g of polybenzimidazole was vacuum dried at 120 ° C for 12 h, then added to the filling particle solution, stirred at 80 ° C for 12 h, and finally vacuum degassed for 8 h to obtain a modified casting solution.

[0054] (3) Preparation of core liquid

[0055] 135 g of NMP was added to 9 g of ethanol, and the mixture was mixed and stirred for 2 h to obtain a core liquid.

[0056] (4) Spinning and weaving into membrane

[0057] The modified casting liquid and core liquid are poured into a spinning tank for spinning, and nitrogen is filled to 0.03MPa. The flow rate of the modified casting liquid and the core liquid is controlled to be 3:2, and they are extruded from the spinneret at the same time and enter a 33°C water coagulation bath. The spinneret temperature is 60°C, and the spinneret is 9cm away from the water coagulation bath. The polybenzimidazole mixed matrix hollow fiber is collected by a winding wheel, and then soaked in water for 2 days, and alternately soaked in n-hexane and ethanol for 3 times, each time for 60 minutes, and finally naturally dried for 3 days to obtain a polybenzimidazole mixed matrix hollow fiber membrane.

[0058] Example 3

[0059] The preparation method of the polybenzimidazole mixed matrix hollow fiber membrane of this embodiment is as follows:

[0060] (1) Preparation of aminosilane modified filler particles

[0061] 5g Al2O3 particles were dispersed in a mixed solution of 5g deionized water, 200g ethanol and 20g ammonia water, and ultrasonically treated at 40°C for 1h. Then 10g aminosilane was added dropwise under stirring, and the mixture was stirred at room temperature for 12h, then centrifuged and washed with ethanol 5 times. Finally, the aminosilane-modified Al2O3 was vacuum dried at 80°C for 12h to obtain aminosilane-modified Al2O3 particles.

[0062] (2) Preparation of modified casting solution

[0063] 2 g of aminosilane-modified Al2O3 particles were dispersed in 130 g of NMP and ultrasonicated for 60 min to obtain a filling particle solution. 30 g of polybenzimidazole was then vacuum dried at 120°C for 12 h and then added to the filling particle solution. The mixture was stirred at 80°C for 12 h and finally vacuum degassed for 8 h to obtain a modified casting solution.

[0064] (3) Preparation of core liquid

[0065] 135 g of NMP was added to 9 g of ethanol, and the mixture was mixed and stirred for 2 h to obtain a core liquid.

[0066] (4) Spinning and weaving into membrane

[0067] The modified casting liquid and core liquid are poured into a spinning tank, filled with nitrogen to 0.03MPa, the flow rate of the modified casting liquid and the core liquid is controlled to be 3:2, and they are extruded from the spinneret at the same time and enter a 30°C water coagulation bath. The spinneret temperature is 60°C, and the spinneret is 8cm above the water coagulation bath. The polybenzimidazole mixed matrix hollow fiber is collected by a winding wheel, and then soaked in water for 2 days, and alternately soaked in n-hexane and ethanol for 3 times, each time for 60 minutes, and finally naturally dried for 2 days to obtain a polybenzimidazole mixed matrix hollow fiber membrane.

[0068] Example 4

[0069] The preparation method of the polybenzimidazole mixed matrix hollow fiber membrane of this embodiment is as follows:

[0070] (1) Preparation of aminosilane modified filler particles

[0071] 5g Al2O3 particles were dispersed in a mixed solution of 5g deionized water, 200g ethanol and 20g ammonia water, and ultrasonically treated at 40°C for 1h. Then 10g aminosilane was added dropwise under stirring, and the mixture was stirred at room temperature for 12h, then centrifuged and washed with ethanol 5 times. Finally, the aminosilane-modified Al2O3 was vacuum dried at 80°C for 12h to obtain aminosilane-modified Al2O3 particles.

[0072] (2) Preparation of modified casting solution

[0073] 2 g of aminosilane-modified Al2O3 particles were dispersed in 130 g of NMP and ultrasonicated for 60 min to obtain a filling particle solution. 20 g of polybenzimidazole was then vacuum dried at 120°C for 12 h and then added to the filling particle solution. The mixture was stirred at 80°C for 12 h and finally vacuum degassed for 8 h to obtain a modified casting solution.

[0074] (3) Preparation of core liquid

[0075] 135 g of NMP was added to 9 g of ethanol, and the mixture was mixed and stirred for 2 h to obtain a core liquid.

[0076] (4) Spinning and weaving into membrane

[0077] The modified casting liquid and core liquid are poured into a spinning tank, filled with nitrogen to 0.03MPa, the flow rate of the modified casting liquid and the core liquid is controlled to be 3:2, and they are extruded from the spinneret at the same time and enter a 30°C water coagulation bath. The spinneret temperature is 60°C, and the spinneret is 8cm above the water coagulation bath. The polybenzimidazole mixed matrix hollow fiber is collected by a winding wheel, and then soaked in water for 2 days, and alternately soaked in n-hexane and ethanol for 3 times, each time for 60 minutes, and finally naturally dried for 2 days to obtain a polybenzimidazole mixed matrix hollow fiber membrane.

[0078] Example 5

[0079] The preparation method of the polybenzimidazole mixed matrix hollow fiber membrane of this embodiment is as follows:

[0080] (1) Preparation of aminosilane modified filler particles

[0081] 5g Al2O3 particles were dispersed in a mixed solution of 5g deionized water, 200g ethanol and 20g ammonia water, and ultrasonically treated at 40°C for 1h. Then 10g aminosilane was added dropwise under stirring, and the mixture was stirred at room temperature for 12h, then centrifuged and washed with ethanol 5 times. Finally, the aminosilane-modified Al2O3 was vacuum dried at 80°C for 12h to obtain aminosilane-modified Al2O3 particles.

[0082] (2) Preparation of modified casting solution

[0083] 2 g of aminosilane-modified Al2O3 particles were dispersed in 130 g of NMP and ultrasonicated for 60 min to obtain a filling particle solution. 40 g of polybenzimidazole was then vacuum dried at 120°C for 12 h and then added to the filling particle solution. The mixture was stirred at 80°C for 12 h and finally vacuum degassed for 8 h to obtain a modified casting solution.

[0084] (3) Preparation of core liquid

[0085] 135 g of NMP was added to 9 g of ethanol, and the mixture was mixed and stirred for 2 h to obtain a core liquid.

[0086] (4) Spinning and weaving into membrane

[0087] The modified casting liquid and core liquid are poured into a spinning tank, filled with nitrogen to 0.03MPa, the flow rate of the modified casting liquid and the core liquid is controlled to be 3:2, and they are extruded from the spinneret at the same time and enter a 30°C water coagulation bath. The spinneret temperature is 60°C, and the spinneret is 8cm above the water coagulation bath. The polybenzimidazole mixed matrix hollow fiber is collected by a winding wheel, and then soaked in water for 2 days, and alternately soaked in n-hexane and ethanol for 3 times, each time for 60 minutes, and finally naturally dried for 2 days to obtain a polybenzimidazole mixed matrix hollow fiber membrane.

[0088] Comparative Example 2

[0089] The preparation method of the polybenzimidazole fiber membrane of this embodiment is as follows:

[0090] (1) Preparation of casting solution

[0091] 20 g of polybenzimidazole was vacuum dried at 100° C. for 8 h, then added into 110 g of NMP, stirred at 60° C. for 8 h, and finally vacuum degassed for 4 h to obtain a casting solution.

[0092] (2) Preparation of core liquid

[0093] 90 g of NMP was added to 9 g of ethanol, and the mixture was mixed and stirred for 1 h to obtain a core liquid.

[0094] (3) Spinning and weaving into film

[0095] The casting liquid and the core liquid are poured into a spinning tank for spinning, and nitrogen is filled to 0.02MPa. The flow rate of the casting liquid and the core liquid is controlled to be 3:1, and they are extruded from the spinneret at the same time and enter a 28°C water coagulation bath. The temperature of the spinneret is 40°C, and the height of the spinneret from the water coagulation bath is 8cm. The polybenzimidazole fiber is collected by a winding wheel, and then soaked in water for 1 day, and then soaked alternately in n-hexane and ethanol twice, each time for 30 minutes, and finally naturally dried for 2 days to obtain a polybenzimidazole fiber membrane.

[0096] The fiber membranes prepared in Examples 1-5 and Comparative Examples 1-2 were used as test samples to perform the following performance tests:

[0097] The fiber membrane samples prepared in each example were respectively encapsulated in a membrane assembly with epoxy resin, and the test pressure was 1 MPa and the temperature was room temperature. The gas flux and selectivity were distributed and tested. The test gases were CH4, He, CO2 and N2. The test results are shown in Table 1. The long-term separation stability of the fiber membranes of Example 3 and Comparative Example 1 was also tested. The test results are shown in Table 1. Figure 1-2 .

[0098]

[0099] Table 1

[0100] It can be seen from the data in Table 1 that the hollow fiber membranes prepared in Examples 1 to 5 have excellent helium permeability and helium selectivity, with a maximum helium flux of 349 GPU, and corresponding He / CH4 and He / N2 selectivities of 375 and 392, respectively. In Comparative Example 1, aminosilane was not added, and the helium flux dropped to 136 GPU, and the He / CH4 and He / N2 selectivities were only 88 and 93. In Comparative Example 2, no filler particles were added, and the helium flux was only 32 GPU, and the He / CH4 and He / N2 selectivities were only 142 and 157, indicating that the addition of aminosilane improved the affinity between the filler and the polymer, avoided the formation of non-selective voids, and retained the excellent selectivity of the membrane itself, while the introduction of SiO2, TiO2, and Al2O3 improved the transmission efficiency of helium.

[0101] Recombination Figure 1 and Figure 2The comparison shows that the filling particles modified with aminosilane have excellent long-term separation stability, and the separation performance is still excellent after 450 hours of operation. However, the hollow fiber membrane without the addition of aminosilane has poor separation stability and a significant decrease in helium selectivity, which indicates that aminosilane is between the filling particles and the polymer, and can play a role in connecting and stabilizing the polymer chains, thereby improving the overall stability of the fiber membrane.

[0102] In summary, the polybenzimidazole mixed matrix hollow fiber membrane prepared by the preparation method of the present invention can be applied to helium purification.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention. The techniques, shapes, and structural parts not described in detail in the present invention are all known technologies.

Claims

1. A method for preparing a polybenzimidazole mixed matrix hollow fiber membrane, characterized in that: The following steps are involved: The aminosilane modified filling particles are dispersed in a solvent, and ultrasonic treatment is performed for 30 to 60 minutes to obtain a filling particle solution, and the pretreated polybenzimidazole is added to the filling particle solution, and stirred at 60 to 80° C. for 8 to 12 hours, and then vacuum degassing is performed for 4 to 8 hours to obtain a modified casting solution; Adding N-methyl-2-pyrrolidone to ethanol, mixing and stirring to obtain a core liquid; The modified casting liquid and core liquid are poured into a spinning tank for spinning, and nitrogen is filled to a pressure of 0.02-0.03 MPa. The flow rate ratio of the modified casting liquid and the core liquid is controlled to be 3:(1-2), and they are extruded from the spinneret at the same time and enter a water coagulation bath. The fibers are then collected through a winding wheel to obtain polybenzimidazole mixed matrix hollow fibers, which are successively soaked in water, and alternately soaked in n-hexane and ethanol, and dried naturally to obtain polybenzimidazole mixed matrix hollow fiber membranes.

2. The method for preparing a polybenzimidazole mixed matrix hollow fiber membrane according to claim 1, characterized in that: The mass ratio of the aminosilane modified filling particles to the polybenzimidazole is 1:(10-15), and the pretreatment of the polybenzimidazole is to vacuum dry the polybenzimidazole at 100-120° C. for 8-12 hours.

3. The method for preparing a polybenzimidazole mixed matrix hollow fiber membrane according to claim 2, characterized in that: The preparation method of the aminosilane modified filling particles is as follows: The filling particles are dispersed in a mixed solution of deionized water, ethanol and ammonia water, and ultrasonically treated at 40-60°C for 1-2 hours. Then, aminosilane is added dropwise under stirring, and the mixture is stirred at room temperature for 8-12 hours. The mixture is centrifuged, and the obtained solid product is washed with ethanol for 3-5 times, and then vacuum dried at 60-80°C for 12-24 hours to obtain aminosilane-modified filling particles.

4. The method for preparing a polybenzimidazole mixed matrix hollow fiber membrane according to claim 3, characterized in that: The mass ratio of the filling particles to the aminosilane is 1:(1-3), and the filling particles are any one of SiO2, TiO2, and Al2O3.

5. The method for preparing a polybenzimidazole mixed matrix hollow fiber membrane according to claim 4, characterized in that: The mass ratio of the filling particles, deionized water, ethanol and ammonia water is 1:(1-2):(30-40):(2-4).

6. The method for preparing a polybenzimidazole mixed matrix hollow fiber membrane according to claim 1, characterized in that: The mass ratio of the aminosilane modified filling particles to the solvent is 1:(55-70), and the solvent is N-methyl-2-pyrrolidone or chloroform.

7. The method for preparing a polybenzimidazole mixed matrix hollow fiber membrane according to claim 1, characterized in that: The mass ratio of the ethanol to N-methyl-2-pyrrolidone is 1:(10-15), and the N-methyl-2-pyrrolidone is added to the ethanol and mixed and stirred for 1-2 hours.

8. The method for preparing a polybenzimidazole mixed matrix hollow fiber membrane according to claim 1, characterized in that: The temperature of the spinneret is 40-60° C., the temperature of the water coagulation bath is 28-33° C., and the distance between the spinneret and the water coagulation bath is 8-9 cm.

9. A polybenzimidazole mixed matrix hollow fiber membrane, characterized in that: The polybenzimidazole mixed matrix hollow fiber membrane is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the polybenzimidazole mixed matrix hollow fiber membrane according to claim 9 in helium purification.

Images