A gas separation membrane and a method of making the same

Abstract

The application relates to the technical field of gas separation membranes, in particular to a gas separation membrane and a preparation method thereof. The gas separation membrane comprises a base film layer, a transition layer, a filter skin layer and a separation skin layer in sequence; the base film layer is made of polysulfone or polyvinylidene fluoride, the transition layer is made of polyimide, the filter skin layer is made of a polybenzimidazole derivative, and the separation skin layer is made of silicone rubber; the preparation method comprises the following steps: firstly, preparing the base film layer; secondly, forming a polyimide film on the base film layer; and thirdly, successively coating a polybenzimidazole derivative and silicone rubber on the polyimide film to form the gas separation membrane. The prepared gas separation membrane adopts a base film with high temperature resistance and good toughness as a supporting structure, the combination degree of the base film and the filter skin layer is improved by coating the polyimide, and finally, the separation skin layer is arranged on the surface of the filter skin layer, so that the prepared gas separation membrane has high mechanical strength and air permeability, the preparation process is simple, and the gas separation membrane is easy to popularize and use in industry.

Description

Technical Field

[0001] This invention relates to the field of gas separation membrane technology, and in particular to a gas separation membrane and its preparation method. Background Technology

[0002] Gas membrane separation is a process that separates components in a gas mixture by utilizing the difference in their permeation rates across a membrane under the influence of a pressure difference. Components that permeate quickly accumulate on the permeate side, while those that permeate slowly accumulate on the retentate side. Gas membrane separation technology has attracted increasing attention due to its advantages such as simple process, low energy consumption, high separation efficiency, and no environmental pollution. Gas separation membranes can be classified into porous and non-porous (dense membranes) types. Based on material properties, they are mainly divided into three categories: polymeric materials, inorganic materials, and polymer-inorganic composite materials. Currently, inorganic membranes exhibit better gas separation performance, while polymeric gas separation membranes offer advantages such as low manufacturing cost, strong structural controllability, and good film-forming properties.

[0003] However, inorganic membranes with good gas separation performance are hampered in industrial applications due to their high price and poor modeling. Conversely, the better the gas permeability of polymeric gas separation membranes, the lower their strength. Furthermore, simplifying the gas separation membrane preparation process is crucial. Chinese invention patent CN110404423A discloses a high-performance polyimide hollow fiber membrane and its preparation method and application, using a dry-wet spinning method to prepare the polyimide hollow fiber membrane. This method requires high-temperature annealing of the nascent fiber membrane to near its glass transition temperature, making the operation relatively complex and demanding on environmental equipment. Chinese invention patent CN110270231A discloses a MOF-derived gas separation membrane and its preparation method and application. Its preparation process repeatedly uses toxic organic solvents such as NMP, requires a high-temperature environment when processing MOF materials, and utilizes ultrasonic stirring technology when mixing with polymer solutions. This results in high production costs, complex operation, and significant environmental pollution. Since gas separation membranes are selective membranes, their mechanical strength must be able to withstand a certain pressure difference. Therefore, there is an urgent need to develop membrane materials with high mechanical strength and good gas permeability, as well as simple and effective membrane manufacturing processes, to further promote the development of membrane gas separation technology. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a gas separation membrane and its preparation method, based on existing gas separation membranes.

[0005] On one hand, the present invention provides a gas separation membrane, which sequentially comprises a base membrane layer, a transition layer, a filter layer and a separation layer; wherein, the base membrane layer comprises polysulfone or polyvinylidene fluoride, the transition layer comprises polyimide, the filter layer comprises a polybenzimidazole derivative, and the separation layer comprises silicone rubber.

[0006] Furthermore, the thickness of the base film layer is 8μm-12μm, the thickness of the transition layer is 1μm-3μm, the thickness of the filter layer is 0.3μm-0.8μm, and the thickness of the separation layer is 0.05μm-0.15μm.

[0007] Furthermore, the base membrane layer is a hollow microfiltration membrane, a hollow ultrafiltration membrane, or a hollow fiber ultrafiltration membrane, and the pore size of the base membrane layer is 30nm-500nm.

[0008] Furthermore, the polyimide is prepared by reacting dianhydride and diamine.

[0009] Furthermore, the dianhydride is selected from one of 6FDA, PMDA, BPDA, and BTDA, wherein the structural formula of 6FDA is:

[0010]

[0011] The structural formula of PMDA is:

[0012]

[0013] The structural formula of BPDA is:

[0014]

[0015] The structural formula of BTDA is:

[0016]

[0017] Further, the diamine is selected from one or more of PABZ, TAB-p-AB, i-PABZ, TAB-m-AB, DP, DAB-p-AB, and DAB-m-AB, wherein the structural formula of PABZ (5-amino-2-4-(aminobenzyl)benzimidazole) is:

[0018]

[0019] The structural formula of TAB-p-AB(2-2'-bis-p-aminophenyl-2-6-aminobenzimidazole) is:

[0020]

[0021] The structural formula of i-PABZ (5-amino-2-3-(aminobenzene)benzimidazole) is:

[0022]

[0023] The structural formula of TAB-m-AB(2-2'-bis-m-aminophenyl-2-6-aminobenzimidazole) is:

[0024]

[0025] The structural formula of DP(2,2'-p-benzylbis(5-aminobenzimidazole)) is:

[0026]

[0027] The structural formula of DAB-p-AB (2-2'-bis-p-aminophenyl-5-5'-dibenzimidazole) is:

[0028]

[0029] The structural formula of DAB-m-AB(2-2'-bis-m-aminophenyl-5-5'-dibenzimidazole) is:

[0030]

[0031] Furthermore, the polybenzimidazole derivative is a nitrogen-substituted isobutyl-modified polybenzimidazole derivative or a tert-butyl-modified polybenzimidazole derivative.

[0032] Furthermore, silicone rubber includes one or more of polysiloxane, polyurethane, polyphenylsulfone, and polypropylene.

[0033] Furthermore, the gas is a mixture of hydrogen and carbon dioxide or a mixture of oxygen and nitrogen.

[0034] On the other hand, the present invention also provides a method for preparing a gas separation membrane, comprising the following preparation steps:

[0035] (1) Preparation of the base film layer by phase separation method;

[0036] (2) Dissolve polyimide in DMAc to obtain a polyimide solution with a concentration of 2%-10%, and then form a film on the base film layer to obtain composite film one;

[0037] (3) Dissolve the polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 1%-2.5%, then form it on composite membrane one, dry it, and then expose it to steam to obtain composite membrane two.

[0038] (4) Dissolve silicone rubber completely in γ-butyrolactone to prepare a mixed solution with a concentration of 1‰-5‰, and then form the mixed solution onto the composite membrane to obtain a gas separation membrane.

[0039] Furthermore, the film-forming method in step (2) is coating, spin coating, dip coating, or scraping.

[0040] Furthermore, the film formation method in step (3) is dip coating, the drying treatment is microwave drying, the drying temperature is 75℃-90℃, the drying time is 8min-12min, and the exposure time in steam is 5s-10s.

[0041] Furthermore, the film formation method in step (4) is dip coating, and the dip coating temperature is 60℃-70℃.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] 1. The gas separation membrane prepared by this invention firstly uses a high-temperature resistant and tough base membrane as the supporting structure of the entire separation membrane, laying a good foundation for high-pressure gas separation; secondly, a polyimide transition layer is coated on the base membrane, which can protect the base membrane on the one hand, and improve the bonding between the base membrane and the filter skin layer on the other hand, thereby improving the gas permeability of the separation membrane and thus improving the gas separation coefficient; finally, a separation skin layer is set, and silicone rubber is coated on the surface of the filter skin layer to reduce the defects generated by the polybenzimidazole derivative polymer in the filter skin layer during the film formation process, thereby further improving the separation coefficient of the membrane, ultimately resulting in the prepared gas having high mechanical strength and permeability, good gas permeability selectivity, and excellent thermal and chemical stability.

[0044] 2. The gas separation membrane of the present invention is prepared by re-coating to form a composite gas separation membrane. The high-flux coating on the outer layer does not affect the gas flux of the inner separation layer. The preparation process is simple, easy to operate, and low in cost, making it easy to promote and use in industry. Detailed Implementation

[0045] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0046] In this invention, unless otherwise stated, all materials used are commercially available.

[0047] In this invention, unless otherwise stated, experimental methods without specific conditions are generally performed under conventional conditions or according to the manufacturer's recommended usage conditions.

[0048] Example 1

[0049] This embodiment provides a gas separation membrane, the preparation steps of which are as follows:

[0050] (1) A hollow fiber ultrafiltration membrane with a pore size of 200 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0051] (2) The polyimide prepared by 6FDA and PABZ was dissolved in DMAc to prepare a polyimide solution with a concentration of 2.5%. The solution was then spin-coated onto the base film layer obtained in step (1) to form a film with a thickness of 2 μm, thus obtaining composite film one.

[0052] (3) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%, and then coat it onto the composite membrane obtained in step (2) by dip coating. Then, dry it at 80°C for 10 min by microwave drying, and then expose it to steam for 8 s. The final film thickness is 0.5 μm, and the composite membrane is obtained.

[0053] (4) Dissolve polydimethylsiloxane silicone rubber completely in r-butyrolactone to prepare a mixed solution with a concentration of 3‰. Then, by dip coating, the mixed solution is deposited onto the composite membrane obtained in step (3) at 65°C with a film thickness of 0.1μm to obtain a gas separation membrane.

[0054] The gas separation membrane prepared in this embodiment was subjected to H2 / CO2 gas permeability testing at 35℃ and 0.50MPa, in accordance with the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas permeating through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas is stably permeating. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0055] Example 2

[0056] This embodiment provides a gas separation membrane, which differs slightly from Embodiment 1 in the preparation process and raw materials. The preparation steps are as follows:

[0057] (1) A hollow fiber ultrafiltration membrane with a pore size of 30 nm and a thickness of 9 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0058] (2) The polyimide prepared by PMDA and TAB-p-AB is dissolved in DMAc to prepare a polyimide solution with a concentration of 2%. The solution is then formed on the base film layer obtained in step (1) by a doctor blade. The film thickness is 1 μm, and a composite film is obtained.

[0059] (3) Dissolve the tert-butyl modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 1.8%. Then, apply the polymer solution to the composite membrane obtained in step (2) by dip coating. Then, microwave dry it at 90°C for 12 min and expose it to steam for 5 s. The final film thickness is 0.4 μm, and the composite membrane is obtained.

[0060] (4) The polydimethylsiloxane rubber is completely dissolved in γ-butyrolactone to prepare a mixed solution with a concentration of 5‰. Then, the mixed solution is dip-coated at 60°C onto the composite membrane 2 obtained in step (3) with a film thickness of 0.05μm to obtain a gas separation membrane.

[0061] The gas separation membrane prepared in this embodiment was subjected to H2 / CO2 gas permeability testing at 35℃ and 0.50MPa, in accordance with the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas permeating through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas is stably permeating. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0062] Example 3

[0063] This embodiment provides a gas separation membrane, the preparation steps of which are as follows:

[0064] (1) A hollow microfiltration membrane with a pore size of 500 nm and a thickness of 11 μm was prepared by conventional phase separation method and used as the base membrane layer;

[0065] (2) The polyimide prepared by BTDA, i-PABZ and DP is dissolved in DMAc to prepare a 5% polyimide solution. The solution is then coated onto the base film layer obtained in step (1) to form a film with a thickness of 3 μm, thus obtaining composite film one.

[0066] (3) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%. Then, the polymer solution is dip-coated onto the composite membrane obtained in step (2). The membrane is then dried at 80°C for 10 min by microwave drying and then exposed to steam for 9 s. The final film thickness is 0.6 μm, and the composite membrane is obtained.

[0067] (4) The polydimethylsiloxane rubber is completely dissolved in γ-butyrolactone to prepare a mixed solution with a concentration of 2‰. Then, the mixed solution is dip-coated at 70°C onto the composite membrane obtained in step (3) with a film thickness of 0.08 μm to obtain a gas separation membrane.

[0068] The gas separation membrane prepared in this embodiment was subjected to H2 / CO2 gas permeability testing at 35℃ and 0.50MPa, in accordance with the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas permeating through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas is stably permeating. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0069] Example 4

[0070] This embodiment provides a gas separation membrane, the preparation steps of which are as follows:

[0071] (1) A hollow microfiltration membrane with a pore size of 250 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer;

[0072] (2) The polyimide prepared by PMDA and TAB-m-AB and DAB-p-AB is dissolved in DMAc to prepare a polyimide solution with a concentration of 2%. The solution is coated onto the base film layer obtained in step (1) to form a film with a thickness of 2 μm, thus obtaining composite film one.

[0073] (3) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 1%, and then coat it onto the composite membrane obtained in step (2) by dip coating. Then, dry it at 75°C for 8 min by microwave drying, and then expose it to steam for 5 s. The final film thickness is 0.3 μm, and the composite membrane is obtained.

[0074] (4) The polysiloxane silicone rubber is completely dissolved in r-butyrolactone to prepare a mixed solution with a concentration of 1‰. Then, the mixed solution is dip-coated at 70°C onto the composite membrane obtained in step (3) with a film thickness of 0.11μm to obtain a gas separation membrane.

[0075] The gas separation membrane prepared in this embodiment was subjected to H2 / CO2 gas permeability testing at 35℃ and 0.50MPa, in accordance with the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas permeating through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas is stably permeating. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0076] Example 5

[0077] This embodiment provides a gas separation membrane, the preparation steps of which are as follows:

[0078] (1) A hollow microfiltration membrane with a pore size of 400 nm and a thickness of 8 μm was prepared by conventional phase separation method and used as the base membrane layer;

[0079] (2) The polyimide prepared by BPDA and DAB-m-AB, TAB-p-AB, i-PABZ is dissolved in DMAc to prepare a polyimide solution with a concentration of 8%. The solution is then spin-coated onto the base film layer obtained in step (1) to form a film with a thickness of 2 μm, thus obtaining composite film one.

[0080] (3) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 1.5%. Then, the polymer solution is dip-coated onto the composite membrane obtained in step (2). The membrane is then dried at 90°C for 12 min by microwave drying and then exposed to steam for 9 s. The final film thickness is 0.7 μm, and the composite membrane is obtained.

[0081] (4) Dissolve polyurethane silicone rubber completely in γ-butyrolactone to prepare a mixed solution with a concentration of 5‰. Then, by dip coating, the mixed solution is deposited onto the composite membrane 2 obtained in step (3) at 60°C with a film thickness of 0.12μm to obtain a gas separation membrane.

[0082] The gas separation membrane prepared in this embodiment was subjected to H2 / CO2 gas permeability testing at 35℃ and 0.50MPa, in accordance with the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas permeating through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas is stably permeating. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient.H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0083] Example 6

[0084] This embodiment provides a gas separation membrane, the preparation steps of which are as follows:

[0085] (1) A hollow microfiltration membrane with a pore size of 350 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0086] (2) The polyimide prepared by BTDA and TAB-m-AB, DP, DAB-p-AB is dissolved in DMAc to prepare a 10% polyimide solution. The solution is then dip-coated onto the base film layer obtained in step (1) to form a film with a thickness of 3 μm, thus obtaining composite film one.

[0087] (3) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2.5%. Then, apply the polymer solution to the composite membrane obtained in step (2) by dip coating. Then, dry it at 75°C for 8 min by microwave drying and expose it to steam for 10 s. The final film thickness is 0.8 μm, and the composite membrane is obtained.

[0088] (4) Dissolve polyphenylsulfone silicone rubber completely in γ-butyrolactone to prepare a mixed solution with a concentration of 3‰. Then, by dip coating, the mixed solution is deposited onto the composite membrane 2 obtained in step (3) at 65°C with a film thickness of 0.15μm to obtain a gas separation membrane.

[0089] The gas separation membrane prepared in this embodiment was subjected to H2 / CO2 gas permeability testing at 35℃ and 0.50MPa, in accordance with the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas permeating through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas is stably permeating. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0090] Comparative Example 1

[0091] This comparative example provides a gas separation membrane, which differs from Example 1 mainly in that: the gas separation membrane prepared in this comparative example consists of a base membrane layer, a separation layer, a transition layer, and a filter layer in that order, and its preparation steps are as follows:

[0092] (1) A hollow fiber ultrafiltration membrane with a pore size of 200 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0093] (2) The polydimethylsiloxane silicone rubber was completely dissolved in γ-butyrolactone to prepare a mixed solution with a concentration of 2‰. Then, the mixed solution was dip-coated onto the base film layer obtained in step (1) at 65°C to obtain a composite film with a thickness of 0.1 μm.

[0094] (3) Dissolve the polyimide prepared by 6FDA and PABZ in DMAc to prepare a 5% polyimide solution, and spin-coat it onto the composite film one obtained in step (2) with a film thickness of 2μm to obtain composite film two.

[0095] (4) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%. Then, apply the polymer solution to the composite membrane obtained in step (3) by dip coating. Then, dry it at 80°C for 10 min by microwave drying and expose it to steam for 8 s. The final film thickness is 0.5 μm, and a gas separation membrane is obtained.

[0096] The gas separation membrane prepared in this comparative example was tested for H2 / CO2 gas permeability at 35℃ and 0.50MPa according to the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas passing through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas permeates stably. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0097] Comparative Example 2

[0098] This comparative example provides a gas separation membrane, which differs from Example 1 mainly in that: the gas separation membrane prepared in this comparative example consists of a base membrane layer, a filter layer, a separation layer, and a transition layer in that order, and its preparation steps are as follows:

[0099] (1) A hollow fiber ultrafiltration membrane with a pore size of 200 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0100] (2) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%. Then, the polymer solution is dip-coated onto the base film layer obtained in step (1). The solution is then dried at 80°C for 10 min by microwave drying and then exposed to steam for 8 s. The final film thickness is 0.5 μm, and the composite film is obtained.

[0101] (3) Dissolve polydimethylsiloxane rubber completely in r-butyrolactone to prepare a mixed solution with a concentration of 2‰. Then, by dip coating, the mixed solution is deposited onto the composite membrane one obtained in step (2) at 65°C with a film thickness of 0.1μm to obtain composite membrane two.

[0102] (4) The polyimide prepared by 6FDA and PABZ is dissolved in DMAc to prepare a polyimide solution with a concentration of 5%. The solution is then spin-coated onto the composite membrane obtained in step (3) to form a film with a thickness of 2 μm, thus obtaining a gas separation membrane.

[0103] The gas separation membrane prepared in this comparative example was tested for H2 / CO2 gas permeability at 35℃ and 0.50MPa according to the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas passing through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas permeates stably. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0104] Comparative Example 3

[0105] This comparative example provides a gas separation membrane, which differs from Example 1 mainly in that the gas separation membrane prepared in this comparative example does not contain a base membrane layer, and its preparation steps are as follows:

[0106] (1) The polyimide prepared by 6FDA and PABZ was dissolved in DMAc to prepare a polyimide solution with a concentration of 5%. A hollow fiber membrane with a film thickness of 2μm was obtained by conventional wet spinning process.

[0107] (2) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%, and then coat it onto the hollow fiber membrane obtained in step (1) by dip coating. Then dry it at 80°C for 10 min by microwave drying, and then expose it to steam for 8 s. The final film thickness is 0.5 μm, and composite membrane one is obtained.

[0108] (3) Dissolve polydimethylsiloxane rubber completely in γ-butyrolactone to prepare a mixed solution with a concentration of 2‰. Then, by dip coating, the mixed solution is deposited onto the composite membrane obtained in step (2) at 65°C with a film thickness of 0.1 μm to obtain a gas separation membrane.

[0109] The gas separation membrane prepared in this comparative example was tested for H2 / CO2 gas permeability at 35℃ and 0.50MPa according to the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas passing through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas permeates stably. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0110] Comparative Example 4

[0111] This comparative example provides a gas separation membrane, which differs from Example 1 mainly in that the gas separation membrane prepared in this comparative example does not contain a transition layer, and its preparation steps are as follows:

[0112] (1) A hollow fiber ultrafiltration membrane with a pore size of 200 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0113] (2) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%. Then, the polymer solution is dip-coated onto the base film layer obtained in step (1). The solution is then dried at 80°C for 10 min by microwave drying and then exposed to steam for 8 s. The final film thickness is 0.5 μm, and the composite film is obtained.

[0114] (3) Dissolve polydimethylsiloxane rubber completely in γ-butyrolactone to prepare a mixed solution with a concentration of 2‰. Then, by dip coating, the mixed solution is deposited onto the composite membrane obtained in step (2) at 65°C with a film thickness of 0.1 μm to obtain a gas separation membrane.

[0115] The gas separation membrane prepared in this comparative example was tested for H2 / CO2 gas permeability at 35℃ and 0.50MPa according to the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas passing through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas permeates stably. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0116] Comparative Example 5

[0117] This comparative example provides a gas separation membrane, which differs from Example 1 mainly in that the gas separation membrane prepared in this comparative example does not contain a separation skin layer, and its preparation steps are as follows:

[0118] (1) A hollow fiber ultrafiltration membrane with a pore size of 200 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0119] (2) The polyimide prepared by 6FDA and PABZ is dissolved in DMAc to prepare a polyimide solution with a concentration of 5%. The solution is then spin-coated onto the base film layer obtained in step (1) to form a film with a thickness of 2 μm, thus obtaining composite film one.

[0120] (3) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%. Then, apply the polymer solution to the composite membrane obtained in step (2) by dip coating. Then, dry it at 80°C for 10 min by microwave drying and expose it to steam for 8 s. The final film thickness is 0.5 μm, and a gas separation membrane is obtained.

[0121] The gas separation membrane prepared in this comparative example was tested for H2 / CO2 gas permeability at 35℃ and 0.50MPa according to the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas passing through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas permeates stably. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0122] Comparative Example 6

[0123] This comparative example provides a gas separation membrane, which differs from Example 1 mainly in that the gas separation membrane prepared in this comparative example does not contain a transition layer and a separation skin layer. Its preparation steps are as follows:

[0124] (1) A hollow fiber ultrafiltration membrane with a pore size of 200 nm and a thickness of 10 μm was prepared by conventional phase separation method and used as the base membrane layer.

[0125] (2) Dissolve the isobutyl-modified polybenzimidazole derivative in formic acid to prepare a polymer solution with a concentration of 2%. Then, the polymer solution is dip-coated onto the base film layer obtained in step (1). The solution is then dried at 80°C for 10 min by microwave drying and then exposed to steam for 8 s. The final film thickness is 0.5 μm, and a gas separation membrane is obtained.

[0126] The gas separation membrane prepared in this comparative example was tested for H2 / CO2 gas permeability at 35℃ and 0.50MPa according to the standard GB / T 40260-2021 "Test Method for Gas Permeability Performance of Polymer Membrane Materials". The permeability coefficient P1 was used to characterize the permeability, which represents the volume of gas passing through a unit area of ​​sample per unit time under standard conditions at a constant temperature and unit pressure difference when the gas permeates stably. The adsorption selectivity of H2 / CO2, S1 = P, was calculated based on the permeability coefficient. H2 / P CO2 The results are shown in Table 1. The O2 / N2 gas permeability performance was tested at 35℃ and 0.50MPa, characterized by the permeability coefficient P2, and the gas adsorption selectivity S2 was calculated. The results are shown in Table 2.

[0127] Table 1 H2 / CO2 gas separation performance

[0128]

[0129] Table 2 O2 / N2 gas separation performance

[0130]

[0131]

[0132] As can be seen from the results in Tables 1 and 2, the gas separation membrane prepared by this invention achieves a high gas permeability coefficient and H2 / CO2 and O2 / N2 separation coefficients through the sequential arrangement of each layer and the synergistic effect of the interlayer structure, resulting in good gas separation effect and high separation efficiency. In Comparative Example 1, compared to Example 1, the separation skin layer is placed in the second position, and the filter skin layer is placed on the outermost layer. Due to the lack of protection from the separation skin layer, the gas permeability coefficient decreases significantly. In Comparative Example 2, compared to Example 1, the filter skin layer is placed in the second position, lacking a transition layer between its inner layer and the base membrane, and being covered by two membrane layers, further exacerbating the decrease in gas permeability. In Comparative Example 3, due to the lack of a base membrane layer as a framework, subsequent film formation performance is poor, resulting in poor gas permeability. Comparative Example 4 does not include a transition layer, and its filter skin layer lacks a transition layer connection with the base membrane. Comparative Example 5 does not include a separation skin layer, failing to effectively compensate for the defects generated during filter skin layer film formation. In Comparative Example 6, the filter skin layer is formed directly on the base membrane framework, and its filter skin layer lacks protection. Therefore, it can be seen that when the arrangement of membranes is changed or the structure is reduced, the overall structure changes and the interaction between them also changes, resulting in a significant decrease in gas permeability and gas selectivity.

[0133] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. A gas separation membrane, characterized in that, It consists of, in sequence, a base membrane layer, a transition layer, a filter layer, and a separation layer; The base membrane layer comprises polysulfone or polyvinylidene fluoride, the transition layer comprises polyimide, the filter layer comprises a polybenzimidazole derivative, and the separation layer comprises silicone rubber. The polybenzimidazole derivative is a nitrogen-substituted isobutyl-modified polybenzimidazole derivative or a tert-butyl-modified polybenzimidazole derivative.

2. The gas separation membrane according to claim 1, characterized in that, The base membrane layer is a hollow microfiltration membrane or a hollow fiber ultrafiltration membrane, and the pore size of the base membrane layer is 30nm-500nm.

3. The gas separation membrane according to claim 1, characterized in that, The polyimide is prepared by reacting dianhydride and diamine.

4. The gas separation membrane according to claim 3, characterized in that, The dianhydride is selected from one of 6FDA, PMDA, BPDA, and BTDA.

5. The gas separation membrane according to claim 3, characterized in that, The diamine is selected from one or more of PABZ, TAB-p-AB, i-PABZ, TAB-m-AB, 2,2'-p-benzylbis(5-aminobenzimidazole), DAB-p-AB, and DAB-m-AB.

6. The gas separation membrane according to claim 1, characterized in that, The silicone rubber includes polysiloxane.

7. The gas separation membrane according to claim 1, characterized in that, The gas is a mixture of hydrogen and carbon dioxide or a mixture of oxygen and nitrogen.

8. The method for preparing the gas separation membrane according to any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Preparation of the base film layer by phase separation method; (2) Dissolve polyimide in DMAc to obtain a polyimide solution with a concentration of 2%-10%, and then form a film on the base film layer to obtain composite film one; (3) Dissolve the polybenzimidazole derivative in formic acid to obtain a polymer solution with a concentration of 1%-2.5%, then form a film on the first composite membrane, dry it and expose it to steam to obtain the second composite membrane; (4) The silicone rubber is completely dissolved in γ-butyrolactone to obtain a mixed solution with a concentration of 1‰-5‰. The mixed solution is then deposited onto the composite membrane to obtain a gas separation membrane.

9. The method for preparing the gas separation membrane according to claim 8, characterized in that, The drying temperature in step (3) is 75℃-90℃.

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