Polybenzimidazole mixed matrix hollow fiber membrane and its preparation method and application

Abstract

The present invention relates to the technical field of gas separation membrane materials, and more particularly to polybenzimidazole mixed matrix hollow fiber membrane and its preparation method and application, preparation method includes: taking aminosilane modified filling particles and being dispersed in a solvent to ultrasonically obtain a filling particle solution, pretreated polybenzimidazole is added to the filling particle solution, stirred at 60-80 DEG C for 8-12h, then vacuum deaeration for 4-8h, to obtain modified casting solution; N-methyl-2-pyrrolidone is added to ethanol to obtain core liquid; Modified casting solution and core liquid are poured into a spinning pot for spinning, and it is 0.02-0.03MPa to be filled with nitrogen to an air pressure, and the flow rate ratio of the modified casting solution and core liquid is controlled to be 3:(1-2), and simultaneously extruded from a spinneret, enters a water coagulation bath, then collected by a winding wheel to obtain polybenzimidazole mixed matrix hollow fiber, soaked, dried, and obtained polybenzimidazole mixed matrix hollow fiber membrane. The fiber membrane of the present invention has excellent helium permeability and helium selectivity simultaneously, and can be used for helium separation and purification.

Description

Technical Field

[0001] The present 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. Background Art

[0002] Helium is one of the inert gases on Earth. It has special properties such as low surface tension, high thermal conductivity, and extremely low viscosity. It is widely used in the fields of medicine, military industry, semiconductor manufacturing, etc. 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 amounts of energy and have high production costs. In recent years, with the development of membrane technology, membranes with high separation performance have gradually been used for 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 ZIF-8 with polybenzimidazole, which achieved an increase in gas flux. The H2 flux reached 107 GPU and the H2 / CO2 selectivity was 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 monoprotic acid as a solvent. The H2 flux reaches 33 GPU, the H2 / N2 selectivity is 228, and the H2 / CH4 selectivity is 293. This material has 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 polyacids. 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 its preparation method and application, 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 through 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 filler particles are dispersed in a solvent and ultrasonically treated for 30 to 60 minutes to obtain a filler particle solution. The pretreated polybenzimidazole is added to the filler particle solution, stirred at 60 to 80° C. for 8 to 12 hours, and then vacuum degassed for 4 to 8 hours to obtain a modified casting solution.

[0009] Add N-methyl-2-pyrrolidone to ethanol, mix and stir 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). The modified casting liquid and the core liquid are extruded from the spinneret at the same time and enter a water coagulation bath. The fibers are then collected on 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 polybenzimidazole is 1:(10-15), and the pretreatment of 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 filler particles is as follows:

[0013] The filling particles are dispersed in a mixed solution of deionized water, ethanol and ammonia water, ultrasonically treated at 40-60°C for 1-2 hours, and then aminosilane is added dropwise under stirring. The mixture is stirred at room temperature for 8-12 hours and centrifuged. The obtained solid product is washed with ethanol 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 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 the embodiments of the present invention provides a polybenzimidazole mixed matrix hollow fiber membrane, which is prepared by the preparation method described in the first aspect.

[0020] A 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] The present invention's method for preparing a polybenzimidazole mixed-matrix hollow fiber membrane employs the incorporation of aminosilane-grafted SiO2, TiO2, and Al2O3 filler particles into the polybenzimidazole hollow fiber membrane. The addition of these filler particles disrupts the alignment of polymer chains, expands interfacial space, and increases gas flux, thereby improving gas transmission efficiency. The aminosilane imparts excellent dispersibility to the filler particles, enhancing the affinity between the filler and the polymer, preventing the formation of nonselective voids and preserving the membrane's excellent selectivity.

[0022] The polybenzimidazole mixed-matrix hollow fiber membrane prepared by the present invention exhibits both 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, making it suitable for helium separation and purification. Furthermore, the polybenzimidazole mixed-matrix hollow fiber membrane prepared by adding aminosilane-modified filler particles to polybenzimidazole exhibits excellent long-term separation stability, maintaining excellent separation performance after 450 hours of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 3 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] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] In the embodiments of this 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 this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

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

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

[0029] Existing separation membranes used for helium purification suffer from either low gas flux or poor gas selectivity, making it difficult to achieve both high flux and superior selectivity. To address this issue, the present invention proposes a method for preparing a polybenzimidazole mixed-matrix hollow fiber membrane. Aminosilane-grafted SiO2, TiO2, and Al2O3 filler particles are added to the polybenzimidazole. The addition of the aminosilane-modified filler particles disrupts the arrangement of the polybenzimidazole polymer chains, expanding the interfacial space and thereby improving gas transmission efficiency. At the same time, the aminosilane imparts good dispersibility to the filler particles, enhancing the affinity between the filler particles and the polybenzimidazole polymer, preventing the formation of non-selective voids and retaining 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 filler particles are dispersed in a solvent and ultrasonically treated for 30 to 60 minutes to obtain a filler particle solution. The pretreated polybenzimidazole is added to the filler particle solution, stirred at 60 to 80° C. for 8 to 12 hours, and then vacuum degassed 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 solution and core solution were poured into a spinning pot, filled with nitrogen to a pressure of 0.02-0.03 MPa. The flow rate ratio of the modified casting solution to the core solution was controlled at 3:(1-2). The fibers were extruded simultaneously from the spinneret and entered into a water coagulation bath. The fibers were then collected on a winding wheel to obtain polybenzimidazole mixed-matrix hollow fibers. These fibers were then soaked in water, then alternately soaked in n-hexane and ethanol, and dried naturally to obtain polybenzimidazole mixed-matrix hollow fiber membranes. The spinneret temperature was set at 40-60°C, and the water coagulation bath temperature was set at 28-33°C. A smaller distance between the spinneret and the water coagulation bath resulted in more fiber membrane defects, while a larger distance between the spinneret and the water coagulation bath resulted in dense membrane fibers and lower fiber flux. Therefore, the distance between the spinneret and the water coagulation bath was set at 8-9 cm.

[0034] The mass ratio of aminosilane-modified filler particles to polybenzimidazole is 1:(10-15). The polybenzimidazole is pretreated by vacuum drying at 100-120°C for 8-12 hours. Drying the polybenzimidazole pretreatment removes moisture from the raw material, effectively preventing defects in the subsequent membrane filaments.

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

[0036] The filler particles are dispersed in a mixed solution of deionized water, ethanol, and ammonia, ultrasonically treated at 40-60°C for 1-2 hours, and then aminosilane is added dropwise with stirring. The reaction is stirred at room temperature for 8-12 hours, centrifuged, and the resulting solid product is washed 3-5 times with ethanol. The product is then vacuum-dried at 60-80°C for 12-24 hours to obtain aminosilane-modified filler particles. To improve the helium selectivity and flux of the fiber membrane and enhance the bonding between the filler particles and the subsequent polybenzimidazole, the mass ratio of the filler particles to the aminosilane is set at 1:(1-3). The filler particles are any one of SiO2, TiO2, and Al2O3. The mass ratio of the filler particles to deionized water, ethanol, and ammonia is 1:(1-2):(30-40):(2-4). 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.

[0037] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to 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 filling particles

[0041] 5g of SiO2 particles were dispersed in a mixture of 5g of deionized water, 150g of ethanol, and 20g of ammonia water and ultrasonically treated at 60°C for 2h. Then, 5g of aminosilane was added dropwise with stirring, and the mixture was stirred at room temperature for another 8h. The reaction was then centrifuged, and the resulting solid product was washed three times with ethanol and then vacuum-dried at 60°C for 12h 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 and then added to the filling particle solution. The mixture was 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 stirred for 1 h to obtain a core liquid.

[0046] (4) Spinning and weaving into film

[0047] The modified casting liquid and core liquid were poured into a spinning tank for spinning, nitrogen was filled to 0.02 MPa, the flow rate of the modified casting liquid and the core liquid was controlled to be 3:1, and they were extruded from the spinneret at the same time and entered a 28°C water coagulation bath. The temperature of the spinneret was 40°C, and the height of the spinneret from the water coagulation bath was 8 cm. The polybenzimidazole mixed matrix hollow fiber was 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 dried naturally 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 filling 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, ultrasonically treated at 40 ° C for 1 h, and then 15 g of aminosilane was added dropwise under stirring. The reaction was stirred at room temperature for 12 h and then centrifuged. 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 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.

[0054] (3) Preparation of core liquid

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

[0056] (4) Spinning and weaving into film

[0057] The modified casting liquid and core liquid were poured into a spinning tank for spinning, and nitrogen was filled to 0.03 MPa. The flow rate of the modified casting liquid and the core liquid was controlled to be 3:2. They were extruded from the spinneret at the same time and entered a 33°C water coagulation bath. The spinneret temperature was 60°C, and the height of the spinneret from the water coagulation bath was 9 cm. The polybenzimidazole mixed matrix hollow fiber was obtained by collecting it through a winding wheel. It was then soaked in water for 2 days, and alternately soaked in n-hexane and ethanol 3 times, each time for 60 minutes. Finally, it was 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 filling particles

[0061] 5g of Al2O3 particles were dispersed in a mixture of 5g of deionized water, 200g of ethanol, and 20g of ammonia water and ultrasonically treated at 40°C for 1 hour. Then, 10g of aminosilane was added dropwise with stirring. The mixture was stirred at room temperature for another 12 hours, then centrifuged and washed five times with ethanol. Finally, the aminosilane-modified Al2O3 was dried in a vacuum at 80°C for 12 hours 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 stirred for 2 h to obtain a core liquid.

[0066] (4) Spinning and weaving into film

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

[0071] 5g of Al2O3 particles were dispersed in a mixture of 5g of deionized water, 200g of ethanol, and 20g of ammonia water and ultrasonically treated at 40°C for 1 hour. Then, 10g of aminosilane was added dropwise with stirring. The mixture was stirred at room temperature for another 12 hours, then centrifuged and washed five times with ethanol. Finally, the aminosilane-modified Al2O3 was dried in a vacuum at 80°C for 12 hours 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 stirred for 2 h to obtain a core liquid.

[0076] (4) Spinning and weaving into film

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

[0081] 5g of Al2O3 particles were dispersed in a mixture of 5g of deionized water, 200g of ethanol, and 20g of ammonia water and ultrasonically treated at 40°C for 1 hour. Then, 10g of aminosilane was added dropwise with stirring. The mixture was stirred at room temperature for another 12 hours, then centrifuged and washed five times with ethanol. Finally, the aminosilane-modified Al2O3 was dried in a vacuum at 80°C for 12 hours 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 stirred for 2 h to obtain a core liquid.

[0086] (4) Spinning and weaving into film

[0087] The modified casting liquid and core liquid were poured into a spinning tank, filled with nitrogen to 0.03 MPa, and the flow rate of the modified casting liquid and the core liquid was controlled to be 3:2. They were extruded from the spinneret at the same time and entered a 30°C water coagulation bath. The spinneret temperature was 60°C, and the height of the spinneret from the water coagulation bath was 8 cm. The polybenzimidazole mixed matrix hollow fiber was collected by a winding wheel, and then soaked in water for 2 days, and soaked alternately in n-hexane and ethanol for 3 times, each time for 60 minutes, and finally dried naturally 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 to 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 stirred for 1 h to obtain a core liquid.

[0094] (3) Spinning and weaving into film

[0095] The casting liquid and core liquid are poured into a spinning tank for spinning, and nitrogen is filled to 0.02 MPa. The flow rate of the 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 8 cm. 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 dried naturally 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 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 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] As can be seen from the data in Table 1, 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. Compared with Example 1, in which no aminosilane was added, the helium flux dropped to 136 GPU, and the He / CH4 and He / N2 selectivities were only 88 and 93. Compared with Example 2, in which no filler particles were added, the helium flux was only 32 GPU, and the He / CH4 and He / N2 selectivities were only 142 and 157. This indicates that the addition of aminosilane enhances the affinity between the filler and the polymer, avoids the formation of non-selective voids, and retains the excellent selectivity of the membrane itself, while the introduction of SiO2, TiO2, and Al2O3 enhances 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. This shows that aminosilane is located 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 used in helium purification.

[0103] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and such modifications or equivalents shall be encompassed by the claims of the present invention. Any techniques, shapes, and structures not described in detail herein are well known.

Claims

1. A method for preparing a polybenzimidazole mixed matrix hollow fiber membrane, characterized in that: The following steps are involved: The aminosilane-modified filler particles are dispersed in a solvent and ultrasonically treated for 30 to 60 minutes to obtain a filler particle solution. The pretreated polybenzimidazole is added to the filler particle solution, stirred at 60 to 80° C. for 8 to 12 hours, and then vacuum degassed for 4 to 8 hours to obtain a modified casting solution. Add N-methyl-2-pyrrolidone to ethanol, mix and stir 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). The modified casting liquid and the core liquid are extruded from the spinneret at the same time and enter a water coagulation bath. The fibers are then collected on 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, wherein: 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, ultrasonically treated at 40-60°C for 1-2 hours, and then aminosilane is added dropwise under stirring. The mixture is stirred at room temperature for 8-12 hours and centrifuged. The obtained solid product is washed with ethanol 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, wherein: 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, wherein: 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, wherein: 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.

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