Mixed matrix membranes, methods of making and using the same

Abstract

The application relates to the technical field of gas membrane separation, and discloses a mixed matrix membrane and a preparation method and application thereof. The mixed matrix membrane contains an ionic liquid modified covalent organic framework and a block polyether amide resin. The mixed matrix membrane has high permeability and excellent selectivity, is especially suitable for gas separation of carbon dioxide and methane, can maintain good overall performance under different temperatures and pressures, and has excellent thermal stability and good long-term operation stability without performance attenuation in long-term operation.

Description

Technical Field

[0001] This invention relates to the field of gas membrane separation technology, specifically to a mixed matrix membrane, its preparation method, and its application. Background Technology

[0002] With the rapid development of economic globalization and global industrialization, fossil fuels are widely used in both residential and industrial sectors. The combustion of fossil fuels produces large amounts of carbon dioxide, which is released into the atmosphere, causing severe greenhouse effects and other environmental problems. The efficient and rational development and application of renewable energy is an effective way to solve current environmental and energy problems. According to a United Nations resolution, renewable energy should account for 77% of global energy consumption by 2050. Biogas, also known as methane, is a low-carbon, environmentally friendly, clean, and renewable natural gas. However, untreated biogas contains large amounts of carbon dioxide, which not only severely reduces its calorific value but also corrodes transportation pipelines, causing economic losses. Therefore, it is essential to separate the carbon dioxide from biogas.

[0003] Currently, commonly used methods for carbon dioxide separation include adsorption, physical or chemical absorption, cryogenic distillation, hydration, and membrane separation. Among these, membrane separation has gained widespread commercial application due to its advantages of low cost, high efficiency, and minimal environmental pollution. Based on the membrane material, common gas separation membranes are mainly classified into three types: inorganic membranes, organic polymer membranes, and mixed matrix membranes. Generally, inorganic membranes have complex preparation processes and higher costs. While polymer membranes possess excellent mechanical properties and their fabrication process is simple and controllable, their separation performance is limited by a trade-off effect, making it impossible to simultaneously improve permeability and selectivity. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem that existing gas separation membranes cannot simultaneously achieve both high permeability and high selectivity, and to provide a hybrid matrix membrane, its preparation method, and its applications. This hybrid matrix membrane exhibits both high permeability and excellent selectivity, making it particularly suitable for the separation of carbon dioxide and methane gases. Furthermore, it maintains good overall performance under different temperatures and pressures, and its separation performance does not degrade during long-term operation, demonstrating excellent thermal stability and good long-term operational stability.

[0005] To achieve the above objectives, the present invention provides a hybrid matrix membrane containing an ionic liquid-modified covalent organic framework and a block polyether amide resin.

[0006] Preferably, the content of the ionic liquid-modified covalent organic framework is 0.1-20 parts by weight, more preferably 1-5 parts by weight, relative to 100 parts by weight of the block polyether amide resin.

[0007] Preferably, the ionic liquid-modified covalent organic framework is obtained by modifying the Dha Tab-COF framework with an ionic liquid.

[0008] Preferably, in the modification process, the mass ratio of the Dha Tab-COF framework to the ionic liquid is 1:(4-10), more preferably 1:(5-7).

[0009] Preferably, the ionic liquid is at least one selected from 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0010] Preferably, the thickness of the hybrid matrix membrane is 1.3-2.2 micrometers.

[0011] A second aspect of the present invention provides a method for preparing the hybrid matrix membrane described above, the method comprising the following steps:

[0012] (1) The covalent organic framework was modified with ionic liquid to obtain the covalent organic framework modified with ionic liquid;

[0013] (2) The ionic liquid-modified covalent organic framework is mixed with a block polyether amide resin solution, and the resulting mixture is coated on a porous base membrane, and then allowed to stand and dry.

[0014] Preferably, in step (1), the process of modifying the covalent organic framework with an ionic liquid includes the following steps:

[0015] S1: Vacuum treatment is performed on the covalent organic framework;

[0016] S2: Mix the ionic liquid with an organic solvent, and then mix the resulting mixture with a covalent organic framework that has been vacuum-treated;

[0017] S3: The mixture obtained after process S2 is centrifuged, and then the separated solids are washed and dried.

[0018] Preferably, the mass ratio of the covalent organic framework to the ionic liquid is 1:(4-10), more preferably 1:(5-7).

[0019] Preferably, the covalent organic framework is a Dha Tab-COF framework.

[0020] Preferably, the ionic liquid is at least one selected from 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0021] Preferably, in step (2), the mass ratio of the ionic liquid-modified covalent organic framework to the block polyether amide resin is (0.1-20):100, more preferably (1-5):100.

[0022] Preferably, the concentration of the block polyether amide resin solution is 2-10 wt%, more preferably 4-6 wt%.

[0023] Preferably, in step (2), the porous base membrane is a polyvinylidene fluoride membrane supported by polyester nonwoven fabric.

[0024] A third aspect of the present invention also provides the application of the hybrid matrix membrane described above in gas separation.

[0025] According to the present invention, the mixed matrix membrane uses an ionic liquid with high solubility for carbon dioxide to modify the covalent organic framework. The modified covalent organic framework not only greatly improves the permeability of carbon dioxide, but also enhances the gas separation capability. It can maintain good overall performance under different temperatures and pressures. During long-term operation, the separation performance of the mixed matrix membrane does not decay. It has excellent thermal stability and good long-term operational stability, and is particularly suitable for carbon dioxide gas separation, especially the separation of carbon dioxide and methane. Attached Figure Description

[0026] Figure 1 This is a surface morphology diagram of the mixed matrix film L1;

[0027] Figure 2 It is the surface morphology of the mixed matrix film D1;

[0028] Figure 3 This is a cross-sectional morphology diagram of the mixed matrix membrane L1;

[0029] Figure 4 This is the cross-sectional morphology of the mixed matrix film D1;

[0030] Figure 5 These are nitrogen adsorption-desorption curves of the Dha Tab-COF framework and the Dha Tab-COF framework modified with ionic liquid.

[0031] Figure 6 These are the XRD patterns of the Dha Tab-COF skeleton and the Dha Tab-COF skeleton modified with ionic liquid.

[0032] Figure 7 This is a pore size distribution diagram of the Dha Tab-COF framework and the Dha Tab-COF framework modified with ionic liquid.

[0033] Figure 8These are thermogravimetric images of the mixed matrix membrane D1, the mixed matrix membrane L1, and the ionic liquid;

[0034] Figure 9 These are images showing the long-term operational stability of the hybrid matrix membranes L1 and D2. Detailed Implementation

[0035] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0036] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0037] The hybrid matrix membrane of this invention contains an ionic liquid-modified covalent organic framework and a block polyether amide resin. The ionic liquid-modified covalent organic framework not only reduces the pore size from 1.1-2.3 nm to 1.0-2.2 nm, which is beneficial for improving gas sieving capacity, but also improves the solubility of carbon dioxide, thereby further enhancing the carbon dioxide separation capacity of the hybrid matrix membrane.

[0038] In the mixed matrix membrane of the present invention, the content of the ionic liquid modified covalent organic framework relative to 100 parts by weight of the block polyether amide resin can be 0.1-20 parts by weight, preferably 0.5-10 parts by weight, more preferably 1-5 parts by weight, and even more preferably 1.5-2.5 parts by weight.

[0039] In the hybrid matrix membrane of the present invention, in a preferred embodiment, the ionic liquid-modified covalent organic framework is obtained by modifying the Dha Tab-COF framework with an ionic liquid. The modified Dha Tab-COF framework is loaded with an ionic liquid that has high solubility for carbon dioxide, which can simultaneously improve the membrane's permeability and selectivity.

[0040] In the mixed matrix membrane of the present invention, during the modification process, the mass ratio of the Dha Tab-COF framework to the ionic liquid can be 1:(3-12), more preferably 1:(4-10), and even more preferably 1:(5-7).

[0041] In the hybrid matrix membrane described in this invention, the ionic liquid can be a common organic salt with high solubility for carbon dioxide. In a preferred embodiment, the ionic liquid is at least one selected from 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide.

[0042] In the hybrid matrix membrane described in this invention, the thickness of the hybrid matrix membrane can be 1.3-2.2 micrometers.

[0043] The method for preparing the hybrid matrix membrane of the present invention includes the following steps:

[0044] (1) The covalent organic framework was modified with ionic liquid to obtain the covalent organic framework modified with ionic liquid;

[0045] (2) The ionic liquid-modified covalent organic framework is mixed with a block polyether amide resin solution, and the resulting mixture is coated on a porous base membrane, and then allowed to stand and dry.

[0046] In the method described in this invention, step (1), the process of modifying the covalent organic framework with an ionic liquid, includes the following steps:

[0047] S1: Vacuum treatment is performed on the covalent organic framework;

[0048] S2: Mix the ionic liquid with an organic solvent, and then mix the resulting mixture with a covalent organic framework that has been vacuum-treated;

[0049] S3: The mixture obtained after process S2 is centrifuged, and then the separated solids are washed and dried.

[0050] In the method described in this invention, in step S1, the covalent organic framework is preferably a Dha Tab-COF framework. The vacuum treatment conditions include: a temperature preferably of 90-120°C and a time preferably of 20-28 hours. After vacuum treatment, the covalent organic framework can expel the gas from the framework channels, allowing for better mixing with the ionic liquid.

[0051] In the method described in this invention, in step S1, the Dha Tab-COF skeleton can be prepared using conventional techniques in the art. In some specific embodiments, the preparation method of the Dha Tab-COF skeleton includes: dissolving the reactants 2,5-dihydroxy-terephthalaldehyde and 1,3,5-tris(4-aminophenyl)benzene in a molar ratio of 3:(1.5-2.5) in a mixed solution of n-butanol and 1,2-dichlorobenzene; adding acetic acid as a catalyst, wherein the volume ratio of n-butanol, 1,2-dichlorobenzene, and acetic acid is (4-6):(4-6):1; then sealing the mixture in an oxygen-free ampoule and reacting it at 115-125°C for 50-100 hours; finally, filtering and washing the obtained reaction product, extracting it with tetrahydrofuran using a Soxhlet extractor, and drying it to obtain the product Dha Tab-COF skeleton.

[0052] In the method described in this invention, in step S2, the mass ratio of the ionic liquid to the organic solvent can be 1:(20-30), preferably 1:(22-28). The mixing conditions for the ionic liquid and the organic solvent include: a temperature preferably of 25-35°C and a time preferably of 20-40 minutes. In a preferred embodiment, the mixed liquid and the covalent organic framework are mixed by ultrasonic treatment, and the mixing conditions include: a temperature preferably of 25-35°C and a time preferably of 0.5-1.5 hours.

[0053] In some specific embodiments, the centrifugal separation conditions in step S3 may include: centrifugation time of 1-5 minutes and rotation speed of 6000-1600 r / min. The solid washing conditions may include: using methanol as the washing agent and washing 4-8 times. The solid drying conditions may include: a temperature of 70-100℃ and a time of 10-14 hours.

[0054] The covalent organic framework modified with ionic liquid obtained by the above process not only has its pore size reduced from 1.1-2.3 nm to 1.0-2.2 nm, which is beneficial to improving its gas sieving capacity, but also has improved the solubility of carbon dioxide, thereby further enhancing the separation capacity of the mixed matrix membrane for carbon dioxide.

[0055] In the method described in this invention, in step (1), the mass ratio of the covalent organic framework to the ionic liquid can be 1:(3-12), preferably 1:(4-10), and more preferably 1:(5-7). The covalent organic framework is preferably the Dha Tab-COF framework. The ionic liquid can be a common organic salt with high solubility for carbon dioxide, preferably at least one of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide.

[0056] In the method described in this invention, in step (2), the mass ratio of the ionic liquid-modified covalent organic framework to the block polyether amide resin is preferably (0.1-20):100, more preferably (0.5-10):100; even more preferably (1-5):100, and most preferably (1.5-2.5):100.

[0057] In the method described in this invention, in step (2), the concentration of the block polyether amide resin solution can be 2-10 wt%, more preferably 4-6 wt%.

[0058] In the method described in this invention, in step (2), the block polyether amide resin solution can be prepared using conventional techniques in the art. In some specific embodiments, the preparation method of the block polyether amide resin solution includes: adding block polyether amide resin particles to an organic solvent and heating under reflux to dissolve them. Preferably, the block polyether amide resin particles are PEBAX-2533 particles.

[0059] In the method described in this invention, in step (2), the porous base membrane is preferably a polyvinylidene fluoride membrane supported by a polyester nonwoven fabric. In some specific embodiments, the thickness of the polyester nonwoven fabric is 90-110 micrometers, the thickness of the polyvinylidene fluoride layer is 30-40 micrometers, and the pore size of the polyvinylidene fluoride layer is in the range of 0.08-0.1 micrometers.

[0060] The present invention also provides the application of the hybrid matrix membrane described above in gas separation, particularly suitable for the gas separation of carbon dioxide and methane.

[0061] The following examples further illustrate the hybrid matrix membrane, its preparation method, and its application according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0062] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0063] Preparation Example 1

[0064] 24.9 mg of 2,5-dihydroxyterephthalaldehyde and 35.0 mg of 1,3,5-tris(4-aminophenyl)benzene were added to a heat-resistant glass tube, followed by the addition of 1 mL of 1,2-dichlorobenzene, 1 mL of n-butanol, and 0.2 mL of an aqueous acetic acid solution (6 mol / L) as catalysts. After sonication for 20 min, the heat-resistant glass tube was flame-sealed after three cycles of freezing and vacuuming at 77 K liquid nitrogen. The sealed glass tube was then reacted in an oven at 120 °C for 72 h. Finally, the product was collected by filtration, washed successively with acetone and tetrahydrofuran, and then extracted with anhydrous tetrahydrofuran at 85 °C for 48 h using a Soxhlet extract. The extract was then vacuum-dried at 100 °C for 12 h to obtain the Dha Tab-COF skeleton.

[0065] Example 1

[0066] (1) 100 mg of the Dha Tab-COF framework from Preparation Example 1 was placed in a glass bottle and treated under vacuum at 100 °C for 24 h to purge the gas from the pores. Subsequently, 0.6 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added to 15 g of methanol solution, stirred at room temperature for 30 min, and then transferred to an ultrasonically treated glass bottle, which was ultrasonically treated at 30 °C for 1 h. The resulting mixture was centrifuged at 8000 r / min for 2 min, and the centrifuged solid was washed 5 times with methanol to remove the ionic liquid from the outer surface of the Dha Tab-COF framework. Finally, the collected particles were dried at 80 °C for 12 h to obtain the ionic liquid-modified Dha Tab-COF framework.

[0067] (2) Dissolve 0.5g of PEBAX-2533 (block polyether amide resin particles, purchased from Colette Polymer (Shenzhen) Co., Ltd.) particles in 9.5g of n-butanol and reflux at 80℃ for 2h to obtain a 5wt% block polyether amide resin solution. Add 10mg of the Dha Tab-COF skeleton prepared in step (1) to the block polyether amide resin solution, sonicate at 30℃ for 30 minutes, and then stir at room temperature for 12 hours to mix. Coat the resulting mixture onto a polyvinylidene fluoride membrane supported by polyester nonwoven fabric, place at room temperature for 48h, and then transfer to a vacuum drying oven at 60℃ for 24h to continue drying, finally obtaining the mixed matrix membrane L1. The polyvinylidene fluoride membrane supported by polyester nonwoven fabric has a polyester nonwoven fabric as the support layer with a thickness of 100 micrometers and a polyvinylidene fluoride layer thickness of 35 micrometers. The pore size range of the polyvinylidene fluoride is 0.08-0.1 micrometers.

[0068] Example 2

[0069] (1) 100 mg of the Dha Tab-COF framework from Preparation Example 1 was placed in a glass bottle and treated under vacuum at 100 °C for 24 h to purge the gas from the pores. Subsequently, 0.6 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added to 15 g of methanol solution, stirred at room temperature for 30 min, and then transferred to an ultrasonically treated glass bottle, which was ultrasonically treated at 30 °C for 1 h. The resulting mixture was centrifuged at 8000 r / min for 2 min, and the centrifuged solid was washed 5 times with methanol to remove the ionic liquid from the outer surface of the Dha Tab-COF framework. Finally, the collected particles were dried at 80 °C for 12 h to obtain the ionic liquid-modified Dha Tab-COF framework.

[0070] (2) 0.5 g of PEBAX-2533 (block polyether amide resin particles, purchased from Colette Polymer (Shenzhen) Co., Ltd.) particles were dissolved in 9.5 g of n-butanol and refluxed at 80 °C for 2 h to obtain a 5 wt% block polyether amide resin solution. 5 mg of the modified Dha Tab-COF skeleton prepared in step (1) was added to the block polyether amide resin solution, sonicated at 30 °C for 30 min, and then stirred at room temperature for 12 h to mix. The resulting mixture was coated onto a polyvinylidene fluoride membrane supported by polyester nonwoven fabric, placed at room temperature for 48 h, and then transferred to a vacuum drying oven at 60 °C for 24 h to continue drying, finally obtaining the mixed matrix membrane L2. The polyvinylidene fluoride membrane supported by polyester nonwoven fabric uses polyester nonwoven fabric as the support layer, the thickness of the polyester nonwoven fabric is 100 μm, the thickness of the polyvinylidene fluoride layer is 35 μm, and the pore size range of the polyvinylidene fluoride is 0.08-0.1 μm.

[0071] Example 3

[0072] (1) 100 mg of the Dha Tab-COF framework from Preparation Example 1 was placed in a glass bottle and treated under vacuum at 100 °C for 24 h to purge the gas from the pores. Subsequently, 0.6 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added to 15 g of methanol solution, stirred at room temperature for 30 min, and then transferred to an ultrasonically treated glass bottle, which was ultrasonically treated at 30 °C for 1 h. The resulting mixture was centrifuged at 8000 r / min for 2 min, and the centrifuged solid was washed 5 times with methanol to remove the ionic liquid from the outer surface of the Dha Tab-COF framework. Finally, the collected particles were dried at 80 °C for 12 h to obtain the ionic liquid-modified Dha Tab-COF framework.

[0073] (2) Dissolve 0.5g of PEBAX-2533 (block polyether amide resin particles, purchased from Colette Polymer (Shenzhen) Co., Ltd.) particles in 9.5g of n-butanol and reflux at 80℃ for 2h to obtain a 5wt% block polyether amide resin solution. Add 15mg of the modified Dha Tab-COF skeleton prepared in step (1) to the block polyether amide resin solution, sonicate at 30℃ for 30 minutes, and then stir at room temperature for 12 hours to mix. Coat the resulting mixture onto a polyvinylidene fluoride membrane supported by polyester nonwoven fabric, place at room temperature for 48h, and then transfer to a vacuum drying oven at 60℃ for 24h to continue drying, finally obtaining the mixed matrix membrane L3. The polyvinylidene fluoride membrane supported by polyester nonwoven fabric has a polyester nonwoven fabric as the support layer with a thickness of 100 micrometers and a polyvinylidene fluoride layer thickness of 35 micrometers. The pore size range of the polyvinylidene fluoride is 0.08-0.1 micrometers.

[0074] Example 4

[0075] (1) 100 mg of the Dha Tab-COF framework from Preparation Example 1 was placed in a glass bottle and treated under vacuum at 100 °C for 24 h to purge the gas from the pores. Subsequently, 0.6 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added to 15 g of methanol solution, stirred at room temperature for 30 min, and then transferred to an ultrasonically treated glass bottle, which was ultrasonically treated at 30 °C for 1 h. The resulting mixture was centrifuged at 8000 r / min for 2 min, and the centrifuged solid was washed 5 times with methanol to remove the ionic liquid from the outer surface of the Dha Tab-COF framework. Finally, the collected particles were dried at 80 °C for 12 h to obtain the ionic liquid-modified Dha Tab-COF framework.

[0076] (2) Dissolve 0.5g of PEBAX-2533 (block polyether amide resin particles, purchased from Colette Polymer (Shenzhen) Co., Ltd.) particles in 9.5g of n-butanol and reflux at 80℃ for 2h to obtain a 5wt% block polyether amide resin solution. Add 20mg of the modified Dha Tab-COF skeleton prepared in step (1) to the block polyether amide resin solution, sonicate at 30℃ for 30 minutes, and then stir at room temperature for 12 hours to mix. Coat the resulting mixture onto a polyvinylidene fluoride membrane supported by polyester nonwoven fabric, place at room temperature for 48h, and then transfer to a vacuum drying oven at 60℃ for 24h to continue drying, finally obtaining the mixed matrix membrane L4. Wherein, the polyvinylidene fluoride membrane supported by polyester nonwoven fabric has a polyester nonwoven fabric as the support layer, the thickness of the polyester nonwoven fabric is 100 micrometers, the thickness of the polyvinylidene fluoride layer is 35 micrometers, and the pore size range of the polyvinylidene fluoride is 0.08-0.1 micrometers.

[0077] Example 5

[0078] (1) 100 mg of the Dha Tab-COF framework from Preparation Example 1 was placed in a glass bottle and treated under vacuum at 100 °C for 24 h to purge the gas from the pores. Subsequently, 0.6 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added to 15 g of methanol solution, stirred at room temperature for 30 min, and then transferred to an ultrasonically treated glass bottle, which was ultrasonically treated at 30 °C for 1 h. The resulting mixture was centrifuged at 8000 r / min for 2 min, and the centrifuged solid was washed 5 times with methanol to remove the ionic liquid from the outer surface of the Dha Tab-COF framework. Finally, the collected particles were dried at 80 °C for 12 h to obtain the ionic liquid-modified Dha Tab-COF framework.

[0079] (2) Dissolve 0.5g of PEBAX-2533 (block polyether amide resin particles, purchased from Colette Polymer (Shenzhen) Co., Ltd.) particles in 9.5g of n-butanol and reflux at 80℃ for 2h to obtain a 5wt% block polyether amide resin solution. Add 25mg of the modified Dha Tab-COF skeleton prepared in step (1) to the block polyether amide resin solution, sonicate at 30℃ for 30 minutes, and then stir at room temperature for 12 hours to mix. Coat the resulting mixture onto a polyvinylidene fluoride membrane supported by polyester nonwoven fabric, place at room temperature for 48h, and then transfer to a vacuum drying oven at 60℃ for 24h to continue drying, finally obtaining the mixed matrix membrane L5. Wherein, the polyvinylidene fluoride membrane supported by polyester nonwoven fabric has a polyester nonwoven fabric as the support layer, the thickness of the polyester nonwoven fabric is 100 micrometers, the thickness of the polyvinylidene fluoride layer is 35 micrometers, and the pore size range of the polyvinylidene fluoride is 0.08-0.1 micrometers.

[0080] Comparative Example 1

[0081] 0.5 g of PEBAX-2533 (block polyether amide resin particles, purchased from Colette Polymer (Shenzhen) Co., Ltd.) particles were dissolved in 9.5 g of n-butanol and refluxed at 80 °C for 2 h to obtain a 5 wt% block polyether amide resin solution. The block polyether amide resin solution was coated onto a polyvinylidene fluoride (PVDF) membrane, and after being left at room temperature for 48 h, it was transferred to a vacuum drying oven at 60 °C for another 24 h to obtain the final mixed matrix membrane D1. The PVDF membrane has a polyester nonwoven fabric support layer with a thickness of 100 μm, a PVDF layer thickness of 35 μm, and a PVDF pore size range of 0.08-0.1 μm.

[0082] Comparative Example 2

[0083] (1) Place 100 mg of the Dha Tab-COF skeleton from Preparation Example 1 in a glass bottle and treat it under vacuum at 100°C for 24 h to purge the gas from the pores.

[0084] (2) Dissolve 0.5g of PEBAX-2533 (block polyether amide resin particles, purchased from Colette Polymer (Shenzhen) Co., Ltd.) particles in 9.5g of n-butanol and reflux at 80℃ for 2h to obtain a 5wt% block polyether amide resin solution. Add 10mg of the modified Dha Tab-COF skeleton prepared in step (1) to the block polyether amide resin solution, sonicate at 30℃ for 30 minutes, and then stir at room temperature for 12 hours to mix. Coat the resulting mixture onto a polyvinylidene fluoride membrane supported by polyester nonwoven fabric, place at room temperature for 48h, and then transfer to a vacuum drying oven at 60℃ for 24h to continue drying, finally obtaining the mixed matrix membrane D2. The polyvinylidene fluoride membrane supported by polyester nonwoven fabric has a polyester nonwoven fabric as the support layer with a thickness of 100 micrometers and a polyvinylidene fluoride layer thickness of 35 micrometers. The pore size range of the polyvinylidene fluoride is 0.08-0.1 micrometers.

[0085] Test Example 1

[0086] The mixed matrix membrane was first frozen in liquid nitrogen for one hour, then quenched and sputtered with gold using tweezers, and finally the surface and cross-sectional morphology of the mixed matrix membrane were observed under a scanning electron microscope (Carl Zeiss, Germany, ZEISS type).

[0087] Figure 1 The image shows the surface morphology of the hybrid matrix membrane L1 in Example 1. As can be seen from the image, the membrane is dense and defect-free. Figure 2 The image shows the surface morphology of the mixed matrix membrane D1 prepared for Comparative Example 1. As can be seen from the image, the membrane exhibits a typical polymer membrane morphology, which is dense and defect-free. Figure 3The image shown is a cross-sectional morphology of the hybrid matrix membrane L1 in Example 1, with a separation layer thickness of 2.2 micrometers. Figure 4 The image shows the cross-sectional morphology of the mixed matrix membrane D1 prepared in Comparative Example 1. The cross-sectional image shows that the block polyether amide resin separation layer and the polyvinylidene fluoride support layer are tightly bonded and have a clear interface. The thickness of the block polyether amide resin separation layer is 0.8 micrometers.

[0088] Test Example 2

[0089] (1) Weigh 0.1g of the Dha Tab-COF skeleton prepared in Preparation Example 1 and 0.1g of the Dha Tab-COF skeleton modified by ionic liquid prepared in Example 1, and dry them in a vacuum environment at 100°C for 12 hours.

[0090] (2) Subsequently, the two samples were subjected to BET nitrogen adsorption-desorption tests at 77K liquid nitrogen. The test method was as follows: The specific surface area of ​​the Dha Tab-COF framework was determined using an N2 physical adsorption / desorption analyzer (Micromeritics, ASAP 2460, USA). Before the test, the Dha Tab-COF framework was degassed in a vacuum at 100℃ for 12 hours to remove residual moisture and organic solvents from the pores of the Dha Tab-COF framework.

[0091] Figure 5 Nitrogen adsorption-desorption curves were obtained for the Dha Tab-COF framework prepared in Example 1 and the ionic liquid-modified Dha Tab-COF framework prepared in Example 1. The images show that both are typical type IV isotherms, indicating that both the Dha Tab-COF framework and the modified Dha Tab-COF framework are mesoporous materials.

[0092] Test Example 3

[0093] The Dha Tab-COF framework was ground into a fine powder using a mortar and pestle. An X-ray diffractometer (Rigaku Corporation, D / max-2550X) was used to scan from 2° to 40° at a test wavelength of λ = 0.154059 nm, at a rate of 5° / min. The interlayer spacing and interchain spacing of the Dha Tab-COF framework were then calculated using the Bragg equation (λ = 2d sinθ).

[0094] Figure 6The XRD patterns of the Dha Tab-COF framework prepared in Example 1 and the Dha Tab-COF framework modified with ionic liquid in Example 1 are shown. The spectra reveal that the Dha Tab-COF framework exhibits high crystallinity. The positions of the diffraction peaks did not change after loading with the ionic liquid, indicating that the Dha Tab-COF framework maintains a complete crystal structure. However, the intensity of the diffraction peaks decreased, which is due to the disordered distribution of the ionic liquid within the Dha Tab-COF framework causing a change in its internal electron density.

[0095] Test Example 4

[0096] The test method for pore size distribution is the same as the test method for specific surface area in Test Example 2.

[0097] Figure 7 Pore ​​size distribution diagrams are shown for the Dha Tab-COF framework prepared in Example 1 and the ionic liquid-modified Dha Tab-COF framework prepared in Example 1. The calculated BET surface area of ​​the modified Dha Tab-COF framework is 150.9 m². 2 / g, compared to the original Dha Tab-COF framework of 601m 2 / g decreased. Density functional theory calculations showed that the pore size of the modified Dha Tab-COF framework was mainly distributed in the range of 1.0-2.2 nm, which was smaller than that of the original Dha Tab-COF framework (1.1-2.3 nm). The reduction in pore size will help improve gas sieving capacity.

[0098] Test Example 5

[0099] The thermal stability of the hybrid matrix membrane was determined using a thermal analyzer (TA Instruments, USA, TGA-2050). The temperature range was from room temperature to 800℃, with a heating rate of 10℃ / min. Homogeneous membranes were used in all thermal stability tests of the hybrid matrix membranes, excluding PVDF base membranes.

[0100] Figure 8 The thermogravimetric images shown are of the mixed matrix membrane D1 prepared in Comparative Example 1, the mixed matrix membrane L1 prepared in Example 1, and the ionic liquid. As can be seen from the figures, the mixed matrix membrane L1 remains stable even at temperatures up to 250°C, exhibiting excellent thermal stability.

[0101] Test Example 6

[0102] Figure 9The figures show the long-term operational stability of the mixed matrix membrane L1 prepared in Example 1 and the mixed matrix membrane D2 prepared in Comparative Example 2. Stability tests were conducted on both membranes for 20 days at an operating pressure of 2 bar and an operating temperature of 15°C. The figures show that the CO2 / CH4 separation performance of the membranes is relatively stable without degradation. Although the carbon dioxide permeability coefficient fluctuates slightly, it remains above 260 Barre, indicating that the Dha Tab-COF framework and the ionic liquid do not damage the polymer matrix. This confirms that the mixed matrix membrane of this invention has good long-term operational stability.

[0103] Test Example 7

[0104] The gas separation performance of the mixed matrix membranes in Examples 1-15 and Comparative Examples 1-2 was measured using a 50% / 50% (vol / vol) CO2 / CH4 feed gas at 15°C. H2 was used as the carrier gas at a flow rate of 40 mL / min, and the test gas flow rate was 20 mL / min. The pressure difference across the membrane was controlled at 2 bar using a back pressure valve. The results are shown in Table 1.

[0105] Table 1

[0106]

[0107] As shown in Table 1, within the preferred range, the hybrid matrix membranes of this invention exhibit a permeability coefficient of over 230 for carbon dioxide, while also demonstrating a selectivity of over 23 for both carbon dioxide and methane. This indicates that the hybrid matrix membrane possesses both excellent permeability and high selectivity. Specifically, this is because the pores of the Dha Tab-COF framework are reduced after modification with the ionic liquid. These pores provide additional channels for carbon dioxide transport, and the Dha Tab-COF framework and the ionic liquid within it have a higher affinity for carbon dioxide gas molecules, preferentially binding with them. This, to a certain extent, enhances the permeability and selectivity of the Dha Tab-COF framework for carbon dioxide, making it particularly suitable for the separation of carbon dioxide and methane gases.

[0108] Test Example 8

[0109] Under the conditions of an experimental temperature of 15-35℃, a constant feed pressure of 2 bar, H2 as the carrier gas, a carrier gas flow rate of 40 mL / min, and experimental gases CO2 and CH4 flow rates of 20 mL / min, the permeation and separation performance of the mixed matrix membrane L1 prepared in Example 1 were tested, and the results are shown in Table 2:

[0110] Table 2

[0111] serial number Temperature (°C) <![CDATA[CO2 Permeability Coefficient (Barrer)]]> <![CDATA[CH4 Permeability Coefficient (Barrer)]]> <![CDATA[CO2 / CH4 selectivity]]> L1 15 281 6.0 46.8 L1 20 288 6.5 43.9 L1 25 294 7.1 41.2 L1 30 296 7.4 39.8 L1 35 305 7.9 38.6 D1 15 203 19.7 10.3

[0112] As can be seen from Table 2, even with increased temperature, the carbon dioxide coefficient of the mixed matrix membrane in this invention remains above 280, and the CO2 / CH4 selectivity is above 35, which is far superior to the performance of the mixed matrix membrane in the comparative example, demonstrating the excellent thermal stability of the mixed matrix membrane in this invention.

[0113] Test Example 9

[0114] The experimental temperature was fixed at 15℃. H2 was used as the carrier gas with a flow rate of 40 mL / min, and CO2 and CH4 were used as experimental gases with a flow rate of 20 mL / min. The pressure difference across the membrane was adjusted to be within the range of 2-6 bar using a back pressure valve. The gas separation performance of the mixed matrix membrane L1 prepared in Example 1 was tested, and the results are shown in Table 3.

[0115] Table 3

[0116] serial number Pressure (bar) <![CDATA[CO2 Permeability Coefficient (Barrer)]]> <![CDATA[CH4 Permeability Coefficient (Barrer)]]> <![CDATA[CO2 / CH4 selectivity]]> L1 2 281 6.0 46.8 L1 3 188 8.5 22.1 L1 4 169 9.7 17.4 L1 5 165 10.1 16.3 L1 6 161 10.5 15.3 D1 2 203 19.7 10.3

[0117] As can be seen from Table 3, the CO2 / CH4 selectivity of the mixed matrix membrane decreases with increasing pressure. However, even under a high pressure of 6 bar, the CO2 / CH4 selectivity of the mixed matrix membrane in this invention is above 15, which is better than the overall performance of the mixed matrix membrane in the comparative example.

[0118] pass Figure 1-9 As can be seen from the results in Tables 1-3, the hybrid matrix membrane of the present invention, modified with ionic liquids to modify the covalent organic framework, exhibits both high permeability and excellent selectivity, making it particularly suitable for the separation of carbon dioxide and methane gases. Furthermore, the hybrid matrix membrane maintains good overall performance under different temperatures and pressures, and its separation performance does not degrade during long-term operation, demonstrating excellent thermal stability and good long-term operational stability.

[0119] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A hybrid matrix membrane, characterized in that, The mixed matrix membrane contains an ionic liquid-modified covalent organic framework and a block polyether amide resin, wherein the content of the ionic liquid-modified covalent organic framework is 0.1-20 parts by weight relative to 100 parts by weight of the block polyether amide resin. The covalent organic framework modified by the ionic liquid is obtained by modifying the Dha Tab-COF framework with ionic liquid. During the modification process, the mass ratio of the Dha Tab-COF framework to the ionic liquid is 1:(3-12). The ionic liquid is at least one of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt.

2. The hybrid matrix membrane according to claim 1, characterized in that, The content of the ionic liquid-modified covalent organic framework is 1-5 parts by weight relative to 100 parts by weight of the block polyether amide resin.

3. The hybrid matrix membrane according to claim 1 or 2, characterized in that, During the modification process, the mass ratio of the Dha Tab-COF framework to the ionic liquid is 1:(5-7).

4. The hybrid matrix membrane according to claim 1 or 2, characterized in that, The thickness of the hybrid matrix membrane is 1.3-2.2 micrometers.

5. A method for preparing a hybrid matrix membrane, characterized in that, The method includes the following steps: (1) The covalent organic framework was modified with ionic liquid to obtain the covalent organic framework modified with ionic liquid; (2) The ionic liquid-modified covalent organic framework is mixed with a block polyether amide resin solution, the resulting mixture is coated on a porous base membrane, and then allowed to stand and dry. In step (1), the process of modifying the covalent organic framework with ionic liquid includes the following steps: S1: Vacuum treatment is performed on the covalent organic framework; S2: Mix the ionic liquid with an organic solvent, and then mix the resulting mixture with a covalent organic framework that has been vacuum-treated; S3: The mixture obtained after process S2 is centrifuged, and the separated solids are then washed and dried. The mass ratio of the covalent organic framework to the ionic liquid is 1:(3-12). The covalent organic framework is the Dha Tab-COF framework; The ionic liquid is at least one of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt; In step (2), the mass ratio of the ionic liquid-modified covalent organic framework to the block polyether amide resin is (0.1-20):

100.

6. The method according to claim 5, characterized in that, The mass ratio of the covalent organic framework to the ionic liquid is 1:(5-7).

7. The preparation method according to claim 5 or 6, characterized in that, In step (2), the mass ratio of the ionic liquid-modified covalent organic framework to the block polyether amide resin is (1-5):

100.

8. The preparation method according to claim 5 or 6, characterized in that, The concentration of the block polyether amide resin solution is 2-10 wt%.

9. The preparation method according to claim 8, characterized in that, The concentration of the block polyether amide resin solution is 4-6 wt%.

10. The preparation method according to claim 5 or 6, characterized in that, In step (2), the porous base membrane is a polyvinylidene fluoride membrane supported by polyester nonwoven fabric.

11. The application of the hybrid matrix membrane according to any one of claims 1-4 in gas separation.

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