A multi-network ion gel mixed matrix membrane for gas separation and its preparation method and application

Abstract

The present invention discloses a multi-network ion gel mixed matrix membrane for gas separation, and a preparation method and application thereof. The membrane is prepared by a one-step process and comprises a first network with a flexible structure formed by a block copolymer and a multifunctional cross-linking agent, a second network with a rigid structure formed by a polyionic liquid monomer, a cross-linking agent capable of undergoing free radical reaction, and a photoinitiator, and a physically bonded brittle cross-linked network formed between inorganic nanofillers as a sacrificial network. This gives the membrane structure a structural characteristic of being easily broken under load to dissipate energy, thereby improving the mechanical properties of the gel mixed matrix membrane. The high porosity and high specific surface area of ​​the inorganic nanofillers are utilized to construct channels for efficient rapid transmission of gas molecules, thereby improving the gas permeability coefficient. The membrane has good separation effect in the separation application of nitrogen and carbon dioxide mixed gases.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation and carbon neutralization, and in particular to a multi-network ion gel mixed matrix membrane for gas separation, a preparation method thereof, and applications thereof. Background Art

[0002] Since the beginning of the Industrial Revolution, global greenhouse gas emissions have continued to increase, the greenhouse effect has become increasingly severe, and climate change has become a serious challenge we must face. CO2 is the most abundant greenhouse gas in the atmosphere, accounting for over 70% of global greenhouse gas emissions. Therefore, CO2 separation and capture is necessary. Among the many CO2 separation and capture technologies, membrane separation, as a high-tech method, has attracted much attention in the field of CO2 separation. Compared with other traditional CO2 separation technologies, membrane separation offers advantages such as low energy consumption, low cost, small footprint, no pollution, and simple process, making it a promising CO2 capture technology.

[0003] Among them, inorganic porous membranes require demanding preparation conditions, are costly, and are difficult to produce defect-free on a large scale, making industrial production difficult. Compared to inorganic porous membranes, polymer homogeneous membranes offer a simpler preparation process, lower cost, and are amenable to large-scale production. However, homogeneous membranes often have low CO2 solubility and poor gas permeability. In the search for more efficient and cost-effective CO2 capture technologies, mixed-matrix membranes (MMMs) have emerged as a promising option. They combine the advantages of inorganic and polymeric membranes, utilizing two materials with different transport properties to synergistically combine the ease of polymer processing with the excellent gas separation performance of porous fillers. Currently, a variety of nanofillers of varying types and structures have been used to prepare MMMs. However, poor compatibility between the inorganic filler and the polymer matrix results in reduced selectivity for the CO2 / N2 gas pair, and interfacial defects lead to poor mechanical properties of the MMMs, severely hindering their application. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-network ion gel mixed matrix membrane for gas separation that has both high CO2 permeability coefficient and high CO2 / N2 selectivity and excellent mechanical properties.

[0005] Another object of the present invention is to provide a method for preparing the multi-network ion gel mixed matrix membrane for gas separation.

[0006] Another object of the present invention is to provide an application of the multi-network ion gel mixed matrix membrane for gas separation.

[0007] To this end, the technical solution of the present invention is as follows:

[0008] A multi-network ion gel mixed matrix membrane for gas separation, the preparation steps are as follows:

[0009] S1. Adding an inorganic nanofiller to a free ionic liquid and uniformly dispersing the inorganic nanofiller and soaking it in the free ionic liquid by ultrasonic dispersion;

[0010] S2, mixing a block copolymer and a multifunctional cross-linking agent for forming a first network having a flexible structure, and a polyionic liquid monomer, a cross-linking agent capable of undergoing a free radical reaction, and a photoinitiator for forming a second network having a rigid structure to form a composite mixture; wherein the block copolymer and the polyionic liquid monomer are the polymer matrix of the membrane structure;

[0011] S3. Add the composite mixture prepared in step S2 to the free ionic liquid and mix them evenly; pour the mixed solution between quartz plates, first heat it at 90°C to 150°C for 3h to 7h, and then irradiate it under ultraviolet light for 3h to 6h to obtain a multi-network ion gel mixed matrix membrane.

[0012] Preferably, in step S1, the inorganic nanofiller is ZIF-8, UIO-66, PMFI, MCM-41 or SiO2.

[0013] Preferably, in step S1, the free ionic liquid is 1-ethyl-3-methylimidazolinium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium dicyanamide, 1,3-dimethylimidazolium tetrafluoroborate or 1,3-dimethylimidazolium hexafluorophosphate.

[0014] Preferably, in step S1, the amount of inorganic nanofiller used is 1% to 20% of the total weight of the block copolymer and the polyionic liquid; the amount of free ionic liquid used is 60% of the total weight of the block copolymer and the polyionic liquid.

[0015] Preferably, in step S1, the ultrasonic dispersion time is 120 min to 200 min.

[0016] Preferably, in step S2, the block copolymer is O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2).

[0017] Preferably, in step S2, the polyionic liquid monomer is 1-vinyl-imidazole bis(trifluoromethanesulfonyl)imide salt, 1-vinyl-3-ethylimidazole bis(trifluoromethanesulfonyl)imide salt or 1-vinyl-3-butylimidazole tetrafluoroborate.

[0018] Preferably, in step S2, the multifunctional cross-linking agent is trimethylolpropane triglycidyl ether, pentaerythritol glycidyl ether, glycerol triglycidyl ether or 1,4-butanediol glycidyl ether.

[0019] Preferably, in step S2, the crosslinking agent capable of undergoing free radical reaction is divinylbenzene, 1,3-divinyltetramethyldisiloxane or N,N′-methylenebisacrylamide; the photoinitiator is 2-hydroxy-2-methylphenylacetone, 1-hydroxy-cyclohexyl-phenyl ketone, benzophenone or 4-dimethylamino-ethyl benzoate.

[0020] Preferably, in step S2, the amount of polyionic liquid is 0.2 to 2.4 times the weight of the block copolymer; the amount of the multifunctional cross-linking agent is 0.2 to 0.6 times the weight of the block copolymer; the amount of the free radical reaction agent is 0.1 to 0.6 times the weight of the polyionic liquid; and the amount of the photoinitiator is 0.06 to 0.12 times the weight of the polyionic liquid.

[0021] A multi-network ion gel mixed matrix membrane for gas separation prepared by the preparation method of the multi-network ion gel mixed matrix membrane for gas separation.

[0022] An application of the multi-network ion gel mixed matrix membrane for gas separation as described above is specifically used for separating a mixed gas of nitrogen and carbon dioxide.

[0023] Compared with the prior art, the multi-network ion gel mixed matrix membrane for gas separation includes a first network with a flexible structure formed by a block copolymer and a multifunctional cross-linking agent, a second network with a rigid structure formed by a polyionic liquid monomer, a cross-linking agent capable of undergoing free radical reaction, and a photoinitiator, and a physically bonded brittle cross-linked network formed between inorganic nanofillers distributed between the first and second networks as a sacrificial network; the sacrificial network is formed by physically bonded brittle cross-links between inorganic nanofillers, which gives the membrane structure a structural characteristic that it can easily break under load to dissipate energy, thereby significantly improving the mechanical properties of the gel mixed matrix membrane. ; At the same time, the membrane structure utilizes the high porosity and high specific surface area of ​​the inorganic nanofiller itself to construct a channel for the rapid transmission of efficient gas molecules in the membrane structure, further improving the gas permeability coefficient; on the other hand, the inorganic nanofiller is added in the form of dispersion in the free ionic liquid, which can greatly improve the interface compatibility and reduce the generation of interface defects, thereby realizing the preparation of a multi-network ion gel mixed matrix membrane with both gas separation characteristics and mechanical properties; in addition, the multi-network ion gel mixed matrix membrane for gas separation is prepared by a one-step method, the preparation method is simple, the reaction conditions are easy to control, the production cost is low, and it has good market application and promotion prospects. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to specific examples, but the following examples are by no means intended to limit the present invention in any way.

[0025] In the following examples and comparative examples, all raw materials were purchased from commercially available products; among them, O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol was produced by Shanghai Aladdin Biochemical Technology Co., Ltd.; ZIF-8 was produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.; UIO-66 was produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.; MCM-41 was produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.; SiO2 was produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.; PMFI was produced by Clariant Chemical Technology (Shanghai) Co., Ltd.

[0026] Example 1

[0027] A method for preparing a multi-network ion gel mixed matrix membrane is prepared by the following steps:

[0028] S1. Take 12 mg, 36 mg, 60 mg, 120 mg, and 240 mg (i.e., 1 wt%, 3 wt%, 5 wt%, 10 wt%, and 20 wt% based on the weight of the polymer matrix) of ZIF-8, respectively, and add them to 1.83 g of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, followed by ultrasonic dispersion for 120 min to uniformly disperse the nanofiller and soak it in the free ionic liquid;

[0029] S2, respectively weighing 0.76 g of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2) and 0.16 g of trimethylolpropane triglycidyl ether for forming a flexible first network, and 0.46 g of 1-vinyl-imidazole bis(trifluoromethanesulfonyl)imide salt, 0.09 g of divinylbenzene and 0.04 g of 2-hydroxy-2-methylphenylacetone for forming a rigid second network, and mixing them uniformly to form a composite mixture;

[0030] S3, the substances obtained in step S1 and step S2 were mixed evenly, poured between the quartz plates, and placed in a 120°C oven for heating for 6 hours, and then irradiated with ultraviolet light (wavelength 365nm, 1100μW / cm 2 ) was irradiated for 5 h to achieve a one-step preparation of an ion gel mixed matrix membrane for gas separation.

[0031] Example 2

[0032] A method for preparing a multi-network ion gel mixed matrix membrane is prepared by the following steps:

[0033] S1. 120 mg (i.e., 10 wt% based on the weight of the polymer matrix) of ZIF-8, UIO-66, PMFI, MCM-41, and SiO2 were added to 1.83 g of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, followed by ultrasonic dispersion for 120 min to uniformly disperse the nanofillers and infiltrate them into the ILs.

[0034] S2, respectively weighing 0.76 g of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2) and 0.16 g of trimethylolpropane triglycidyl ether for forming a flexible first network, and 0.46 g of 1-vinyl-imidazole bis(trifluoromethanesulfonyl)imide salt, 0.09 g of divinylbenzene and 0.04 g of 2-hydroxy-2-methylphenylacetone for forming a rigid second network, and mixing them uniformly to form a composite mixture;

[0035] S3, the substances obtained in step S1 and step S2 were mixed evenly, poured between the quartz plates, and placed in a 120°C oven for heating for 6 hours, and then irradiated with ultraviolet light (wavelength 365nm, 1100μW / cm 2 ) was irradiated for 5 h to achieve a one-step preparation of an ion gel mixed matrix membrane for gas separation.

[0036] Example 3

[0037] A method for preparing a multi-network ion gel mixed matrix membrane is prepared by the following steps:

[0038] S1. 120 mg (i.e., 10 wt% based on the weight of the polymer matrix) of ZIF-8 was added to 1.83 g of 1-ethyl-3-methylimidazolium dicyanamide (ILs), followed by ultrasonic dispersion for 90 min to uniformly disperse the nanofiller and infiltrate it into the ILs.

[0039] S2, respectively weighing 0.56 g of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2) and 0.26 g of pentaerythritol glycidyl ether for forming a flexible first network, and 0.66 g of 1-vinyl-3-ethylimidazole bistrifluoromethanesulfonyl imide salt, 0.12 g of 1,3-divinyltetramethyldisiloxane and 0.08 g of 1-hydroxy-cyclohexyl-phenyl ketone for forming a rigid second network, and mixing them uniformly to form a composite mixture;

[0040] S3, the substances obtained in step S1 and step S2 were mixed evenly, poured between the quartz plates, and placed in a 90°C oven for heating for 3 hours, and then subjected to ultraviolet light (wavelength of 365nm, 1100μW / cm 2 ) was irradiated for 4 h to achieve a one-step preparation of ion gel mixed matrix membrane for gas separation.

[0041] Example 4

[0042] A method for preparing a multi-network ion gel mixed matrix membrane is prepared by the following steps:

[0043] S1. 60 mg (i.e., 5 wt% based on the weight of the polymer matrix) of UIO-66 was added to 1.83 g of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, followed by ultrasonic dispersion for 150 min to uniformly disperse the nanofiller and infiltrate it into the ILs.

[0044] S2, respectively weighing 0.36 g of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2) and 0.20 g of pentaerythritol glycidyl ether for forming a flexible first network, and 0.86 g of 1-vinyl-3-ethylimidazole bistrifluoromethanesulfonyl imide salt, 0.12 g of 1,3-divinyltetramethyldisiloxane and 0.06 g of 1-hydroxy-cyclohexyl-phenyl ketone for forming a rigid second network, and mixing them uniformly to form a composite mixture;

[0045] S3, the substances obtained in step S1 and step S2 were mixed evenly, poured between the quartz plates, and placed in a 150°C oven to heat for 7 hours, and then subjected to ultraviolet light (wavelength of 365nm, 1100μW / cm 2 ) for 3 h to achieve a one-step preparation of an ion gel mixed matrix membrane for gas separation.

[0046] Example 5

[0047] A method for preparing a multi-network ion gel mixed matrix membrane is prepared by the following steps:

[0048] S1. Take 240 mg (i.e., 20 wt% based on the weight of the polymer matrix) of PMFI and add it to 1.83 g of 1-ethyl-3-methylimidazolium dicyanamide (ILs), followed by ultrasonic dispersion for 150 min to uniformly disperse the nanofiller and infiltrate it into the ILs;

[0049] S2, respectively weighing 0.96 g of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2) and 0.56 g of trimethylolpropane triglycidyl ether for forming a flexible first network, and 0.26 g of 1-vinyl-3-ethylimidazole bistrifluoromethanesulfonyl imide salt, 0.15 g of divinylbenzene and 0.02 g of 2-hydroxy-2-methylphenylacetone for forming a rigid second network, and mixing them uniformly to form a composite mixture;

[0050] S3, the substances obtained in step S1 and step S2 were mixed evenly, poured between the quartz plates, and placed in a 110°C oven for heating for 4 hours, and then subjected to ultraviolet light (wavelength of 365nm, 1100μW / cm 2 ) was irradiated for 6 h to achieve a one-step preparation of an ion gel mixed matrix membrane for gas separation.

[0051] Comparative Example 1

[0052] A method for preparing a single-network ion gel mixed matrix membrane is prepared by the following steps:

[0053] S1. 8 mg, 23 mg, 38 mg, 76 mg, and 152 mg (i.e., 1 wt%, 3 wt%, 5 wt%, 10 wt%, and 20 wt% based on the weight of the polymer matrix) of ZIF-8 were added to 1.14 g of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, followed by ultrasonic dispersion for 120 min to uniformly disperse the nanofiller and infiltrate it into the ILs.

[0054] S2. Weigh 0.76 g of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2) and 0.16 g of trimethylolpropane triglycidyl ether for forming a flexible first network, and mix them evenly to form a composite mixture.

[0055] S3, the substances obtained in step S1 and step S2 were mixed evenly, poured between the quartz plates, and placed in a 120°C oven for heating for 6 hours, and then subjected to ultraviolet light (wavelength of 365nm, 1100μW / cm 2 ) was irradiated for 5 h to achieve a one-step preparation of an ion gel mixed matrix membrane for gas separation.

[0056] In addition, the applicant also tried to replace the composition used to form the first network in step S2 of Comparative Example 1 with a composition for forming the second network. However, since the second network itself is a rigid network, the ion gel mixed matrix membrane prepared using it alone is too rigid and has no practical value.

[0057] Comparative Example 2

[0058] A method for preparing a double-network ion gel mixed matrix membrane is prepared by the following steps:

[0059] S1. Weigh 0.76 g of O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (NH2-PPG-PEG-PPG-NH2) and 0.16 g of trimethylolpropane triglycidyl ether for forming a flexible first network, and 0.46 g of 1-vinyl-imidazole bis(trifluoromethanesulfonyl)imide salt for forming a flexible second network, add 0.09 g of divinylbenzene, add 0.04 g of 2-hydroxy-2-methylphenylacetone, and mix well to form a composite mixture;

[0060] S2. Add the composite mixture prepared in step S1 to 1.83 g of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide as a free ionic liquid, and stir to form a composite mixed solution;

[0061] S3, pour the compound mixture prepared in step S2 between the quartz plates, heat it in a 120°C oven for 6 hours, and then irradiate it with ultraviolet light (wavelength 365nm, 1100μW / cm 2 ) was irradiated for 5 h to achieve a one-step preparation of an ion gel mixed matrix membrane for gas separation.

[0062] Performance testing:

[0063] (1) Gas separation performance test of multi-network ion gel mixed matrix membrane

[0064] The gas permeability of the DN ion gel gas separation membranes prepared in some examples was tested using a gas permeometer (CLASSIC 216 Beiyang Equipment). The test temperature was 25°C, the test pressure was 2 atm, and the N2 test was performed first, followed by the CO2 test.

[0065] When the pressure on the downstream side of the membrane changes steadily, the slope of the pressure-time curve can be used to calculate the gas permeability coefficient.

[0066]

[0067] Where P is the permeability coefficient of the gas (unit is Barrer, 1 Barrer = 10 -10 cm 3 (STP)cm -1 s -1 cm Hg -1), V is the volume of the downstream side of the membrane (in cm3), l is the thickness of the membrane (in cm), and A represents the effective test area of ​​the membrane (in cm 2 ), T is the test temperature (K), p2 is the test pressure upstream of the membrane (in psi), and (dp / dt) refers to the slope of the curve of the pressure change on the downstream side of the membrane with the test time when the gas is steadily permeating the membrane. The diffusion coefficient D of the gas in the membrane is obtained by the time-lag method and is calculated as follows: Where θ is the time lag obtained by extrapolation from the downstream pressure curve measured under steady state. The permeability coefficient is equal to the solubility coefficient multiplied by the diffusion coefficient, thus obtaining the solubility coefficient S, which is calculated as follows:

[0068] The gas permeability of the multi-network ion gel mixed matrix membrane prepared in Example 1 and the single-network ion gel mixed matrix membranes prepared in Comparative Examples 1 and 2 was tested; the specific gas permeability test results are shown in Table 1 below.

[0069] Table 1:

[0070] Test Case <![CDATA[P CO2 ]]> <![CDATA[P CO2 / P N2 ]]> <![CDATA[D CO2 ]]> <![CDATA[D CO2 / D N2 ]]> <![CDATA[S CO2 ]]> <![CDATA[S CO2 / S N2 ]]> Example 1 (1 wt%) 588 27 172.4 0.54 3.41 50.0 Example 1 (3 wt%) 719 23 223.3 0.30 3.22 76.7 Example 1 (5 wt%) 606 28 172.2 0.49 3.52 57.1 Example 1 (10 wt%) 311 34 86.4 0.62 3.60 54.8 Example 1 (20 wt%) 336 32 95.7 0.78 3.51 41.1 Comparative Example 1 (1 wt%) 300 28 87.9 0.54 3.41 51.9 Comparative Example 1 (3 wt%) 440 22 141.9 0.30 3.10 73.3 Comparative Example 1 (5 wt%) 515 23 160.9 0.51 3.20 45.1 Comparative Example 1 (10 wt%) 315 22 95.5 0.58 3.30 37.9 Comparative Example 1 (20 wt%) 329 23 91.4 0.37 3.60 62.2 Comparative Example 2 (0 wt%) 280 21 89.7 0.35 3.12 60.0

[0071] P:10 -10 cm 3 (STP)cm -1 s -1 cmHg -1 ;D:10 -8 cm 2 s -1 ;S:10 -2 cm 3 (STP)cm -3 cmHg -1 .

[0072] From the test results in Table 1, it can be seen that the CO2 gas permeability coefficients P of the five multi-network ion gel mixed matrix membranes prepared in Example 1 are higher than those of the single-network ion gel mixed matrix membranes prepared in Comparative Example 1 and Comparative Example 2. CO2 The significant improvement indicates that the multi-network ion gel mixed matrix membrane of the present application has a faster separation effect, which improves the separation efficiency of the membrane; and according to the ratio of the permeability coefficient of CO2 gas to the permeability coefficient of N2 gas P CO2 / P N2 The test results show that Example 1 improves the membrane separation effect and still maintains a good separation ability of nitrogen and carbon dioxide mixed gas, and further improves it on some membranes.

[0073] The gas permeation properties of the multi-network ion gel mixed matrix membranes prepared in Examples 2 to 5 were tested, and the gas permeation properties thereof are shown in Table 2.

[0074] Table 2:

[0075]

[0076]

[0077] P:10 -10 cm 3 (STP)cm -1 s -1 cmHg -1 ;D:10 -8 cm 2 s -1 ;S:10 -2 cm 3 (STP)cm -3 cmHg -1 ;

[0078] It can be seen from the test results in Table 2 that the multi-network ion gel mixed matrix membranes prepared in Examples 2 to 5, when using different types of inorganic nanofillers to form sacrificial networks, can maintain the same performance as the membrane product in Example 1, that is, they have both good separation efficiency and separation effect.

[0079] (2) Mechanical properties test of multi-network ion gel mixed matrix membrane

[0080] A precision electronic universal testing machine (AGS-X, SHIMADZU, Japan) was used to study the mechanical strength and properties of MMMs with a maximum load of 50 N and a test speed of 10 mm / min.

[0081] The mechanical properties of the multi-network ion gel mixed matrix membrane prepared in Example 1 and the single-network ion gel mixed matrix membranes prepared in Comparative Examples 1 and 2 were tested. The specific mechanical property test results are shown in Table 3 below.

[0082] Table 3:

[0083]

[0084] It can be seen from the test results in Table 3 that the five multi-network ion gel mixed matrix membranes prepared in Example 1 have significant improvements in tensile strength, elongation at break, Young's modulus and toughness compared to the single-network ion gel mixed matrix membranes prepared in Comparative Examples 1 and 2, indicating that the present application can achieve a significant improvement in the mechanical properties of the membrane product under the mutual cooperation of the first network with a rigid structure, the second network with a flexible structure and the sacrificial network formed by the inorganic nanofiller.

[0085] The mechanical properties of the multi-network ion gel mixed matrix membranes prepared in Examples 2 to 5 were tested, and the mechanical properties are shown in Table 4.

[0086] Table 4:

[0087]

[0088] It can be seen from the test results in Table 4 that the multi-network ion gel mixed matrix membranes prepared in Examples 2 to 5 can maintain the same performance as the membrane product of Example 1 when different types of inorganic nanofillers are used to form a sacrificial network. That is, compared with the ion gel membrane without the addition of nanoparticles, the mixed matrix membrane can significantly improve the mechanical properties of the membrane.

Claims

1. A method for preparing a multi-network ion gel mixed matrix membrane for gas separation, characterized in that: The preparation steps are as follows: S1. Adding an inorganic nanofiller to a free ionic liquid and uniformly dispersing and soaking the inorganic nanofiller in the free ionic liquid by ultrasonic dispersion; wherein the inorganic nanofiller is ZIF-8, UIO-66, PMFI, MCM-41 or SiO2; S2. Mixing a block copolymer and a multifunctional cross-linking agent for forming a first network, and a polyionic liquid monomer, a cross-linking agent capable of undergoing a free radical reaction, and a photoinitiator for forming a second network to form a composite mixture; wherein the block copolymer is O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol; and the polyionic liquid monomer is 1-vinyl-imidazole bis(trifluoromethanesulfonyl imide), 1-vinyl-3-ethylimidazole bis(trifluoromethanesulfonyl imide), or 1-vinyl-3-butylimidazole tetrafluoroborate; S3. Add the composite mixture prepared in step S2 to the free ionic liquid and mix them evenly; pour the mixed solution between quartz plates, first heat it at 90°C to 150°C for 3h to 7h, and then irradiate it under ultraviolet light for 3h to 6h to obtain a multi-network ion gel mixed matrix membrane.

2. The method for preparing a multi-network ion gel mixed matrix membrane for gas separation according to claim 1, characterized in that: In step S1 , the free ionic liquid is 1-ethyl-3-methylimidazolinium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium dicyanamide, 1,3-dimethylimidazolium tetrafluoroborate or 1,3-dimethylimidazolium hexafluorophosphate.

3. The method for preparing a multi-network ion gel mixed matrix membrane for gas separation according to claim 1, characterized in that: In step S1, the amount of inorganic nanofiller used is 1% to 20% of the total weight of the block copolymer and the polyionic liquid; the amount of free ionic liquid used is 60% of the total weight of the block copolymer and the polyionic liquid.

4. The method for preparing a multi-network ion gel mixed matrix membrane for gas separation according to claim 1, characterized in that: In step S1 , the ultrasonic dispersion time is 120 min to 200 min.

5. The method for preparing a multi-network ion gel mixed matrix membrane for gas separation according to claim 1, characterized in that: In step S2 , the multifunctional cross-linking agent is trimethylolpropane triglycidyl ether, pentaerythritol glycidyl ether, glycerol triglycidyl ether or 1,4-butanediol glycidyl ether.

6. The method for preparing a multi-network ion gel mixed matrix membrane for gas separation according to claim 1, characterized in that: In step S2, the crosslinking agent capable of undergoing free radical reaction is divinylbenzene, 1,3-divinyltetramethyldisiloxane or N,N′-methylenebisacrylamide; the photoinitiator is 2-hydroxy-2-methylphenylacetone, 1-hydroxy-cyclohexyl-phenyl ketone, benzophenone or 4-dimethylamino-ethyl benzoate.

7. The method for preparing a multi-network ion gel mixed matrix membrane for gas separation according to claim 1, characterized in that: In step S2, the amount of polyionic liquid used is 0.2 to 2.4 times the weight of the block copolymer; the amount of multifunctional cross-linking agent used is 0.2 to 0.6 times the weight of the block copolymer; the amount of free radical reaction-initiating agent used is 0.1 to 0.6 times the weight of the polyionic liquid; and the amount of photoinitiator used is 0.06 to 0.12 times the weight of the polyionic liquid. 8 . A multi-network ion gel mixed matrix membrane for gas separation prepared by the method for preparing a multi-network ion gel mixed matrix membrane for gas separation according to any one of claims 1 to 7 .

9. Use of the multi-network ion gel mixed matrix membrane for gas separation according to claim 8, characterized in that: Used to separate mixed gases of nitrogen and carbon dioxide.

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