Covalent organic framework materials, method of making cof-based anion exchange membranes, and applications thereof
Patent Information
- Application Number
- CN202610976818.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-01
- Publication Date
- 2026-08-21
AI Technical Summary
[0005]鉴于上述现有技术中存在的问题，本发明要解决的技术问题是提供一种新的共价有机框架材料和COF基阴离子交换膜的制法，以解决传导效率低与稳定性差的问题
1、高效离子传导：本发明通过共价有机框架构建的有序离子通道结构，显著提升氢氧根离子传导效率，阴离子交换膜氢氧根离子电导率从130 mS/cm提升至180 mS/cm，解决了传统阴离子交换膜因无序结构导致的传导瓶颈问题。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of anion exchange membrane electrolysis for hydrogen production technology, specifically to a covalent organic framework material, a method for preparing a COF-based anion exchange membrane, and its applications. Background Technology
[0002] Anion exchange membrane electrolysis for hydrogen production is one of the core technologies for green hydrogen production, and the performance of its core component, the anion exchange membrane, directly affects the efficiency and lifespan of the electrolyzer. Traditional anion exchange membranes exhibit slow hydroxide ion conduction, while OH... - Conduction in traditional anion exchange membranes relies on ion cluster networks formed by microphase separation. However, this structure is random and disconnected, limiting the continuity of ion channels. Furthermore, traditional anion exchange membranes exhibit large swelling and poor dimensional stability, facing the dual challenges of chemical degradation and ionic conductivity decline under high alkalinity and high temperature conditions. In particular, cationic groups (such as quaternary ammonium salts) are prone to Hofmann elimination or nucleophilic substitution reactions in strongly alkaline environments, leading to membrane structural failure. Simultaneously, polymer backbones containing heteroatoms (such as O and S) in OH... - The membrane fractures under attack, significantly shortening its lifespan.
[0003] Covalent organic frameworks (COFs) are a class of crystalline porous materials linked by covalent bonds. Their ordered pore structure and customizable chemical environment provide an ideal platform for efficient ion transport. From 2020 to 2023, Professor Jiang Zhongyi's research group developed a series of quaternary ammonium functionalized side-chain COF membranes obtained by phase transfer polymerization. The anion exchange sites in these COFs are densely and orderly arranged along the channels within the framework. The influence of ionic group concentration on ion migration behavior was investigated, and the optimal COF membrane was found to be at 80 °C. o The hydroxide ion conductivity at C exceeds 300 mS / cm ( Advanced Materials 2020, 32 (36), 2001284; Angewandte Chemie International Edition 2021, 60 (32), 17638-17646; Journal of the American Chemical Society 2023, 145 (51), 27984-27992). In 2025, Professor Xu Hong's research group reported a 3D COF film exhibiting high conductivity (80). o The efficiency was 169 mS / cm at C, and 160 mW / cm was achieved in the H2 / O2 single-cell test. 2 peak power density ( Journal of the American Chemical Society 2025, 147(18), 15777-15786). Based on the above background, traditional AEMs suffer from limited hydroxide conduction due to chemical instability and disordered structure, while COFs materials can solve the problems of conduction efficiency and stability simultaneously through ordered pore design and chemical microenvironment regulation. However, the imine bonds and boron-oxygen bonds commonly found in covalent organic frameworks have poor basic stability, and there are relatively few types of covalent organic frameworks.
[0004] Therefore, those skilled in the art are dedicated to constructing covalent organic frameworks by employing carbon-carbon double bonds and introducing COFs into anion exchange membrane systems to build ordered ion channels and functionalized pore walls, which is a revolutionary path to break through existing conduction bottlenecks. Summary of the Invention
[0005] In view of the problems existing in the prior art, the technical problem to be solved by the present invention is to provide a new method for preparing covalent organic framework materials and COF-based anion exchange membranes, so as to solve the problems of low conductivity and poor stability.
[0006] To achieve the above-mentioned technical objectives, the present invention mainly adopts the following technical solutions: This invention discloses a method for preparing a covalent organic framework material, comprising the following steps: Step 1: Add Me3TOTA ClO4, DTA, BTA and alkaline catalyst to the reaction vessel, add solvent, sonicate to mix evenly, flash freeze, and after three flash freeze-pump-thaw cycles, the reactor is flame sealed under vacuum conditions, and then placed under heating conditions for reaction. Step 2: After the reaction in Step 1 is completed, the reactor is naturally cooled to room temperature, the solid product is collected, washed, and unreacted reactants and catalysts are removed. Then, it is heated and dried in a vacuum to obtain the covalent organic framework material.
[0007] In a preferred embodiment of the present invention, in step 1, the molar ratio of Me3TOTA ClO4 to the sum of DTA and BTA is 2:3.
[0008] In a preferred embodiment of the present invention, in step 1, the alkaline catalyst is CH3COOCs and the solvent is acetic acid.
[0009] In a preferred embodiment of the present invention, in step 1, the flash freezing conditions are: flash freezing is carried out under liquid nitrogen bath conditions at 77K; the reaction conditions are: at 150-200... o Under C conditions, the reaction takes 3-7 days.
[0010] In a preferred embodiment of the present invention, in step 2, the solid product is washed sequentially with N,N-dimethylformamide, water, methanol, acetone, tetrahydrofuran, and dichloromethane.
[0011] The present invention also discloses the application of a covalent organic framework material prepared by the above method in the preparation of COF-based anion exchange membranes.
[0012] This invention also discloses a method for preparing a COF-based anion exchange membrane, comprising the following steps: Step 3: Place the covalent organic framework material prepared by the above method in DMSO and sonicate it. Then mix it with a preheated DMSO solution of linear aromatic piperidine polymer, continue stirring, add iodomethane, and react in the dark at room temperature. Step 4: After the reaction in step 3 is completed, the reaction solution is added dropwise to ethyl acetate, the precipitate is collected, washed, and unreacted reactants are removed. Then, it is dried under vacuum to obtain the COFs grafted polymer. Step 5: Dissolve the COFs grafted polymer in an appropriate amount of DMSO, heat, dry the solvent, and then form a film. Step 6: Place the membrane prepared in Step 5 into a KOH solution and soak it to replace the negatively charged free ions with OH-. - Thus, a COF-based anion exchange membrane is obtained.
[0013] In a preferred embodiment of the present invention, in step 3, the linear aromatic piperidine polymer is poly(dibenzothiophene-terphenylpiperidine) or poly(1,3-diphenylazinepiperidine), and in step 6, the KOH solution concentration is 1 mol / L, and the soaking conditions are: at 80°C... o Soak in water at temperature C for 1-5 days.
[0014] The present invention also discloses a COF-based anion exchange membrane prepared by the above method.
[0015] The present invention also discloses the application of the COF-based anion exchange membrane described above in the electrolysis of water to produce hydrogen.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Highly efficient ion conduction: This invention significantly improves the conduction efficiency of hydroxide ions through the ordered ion channel structure constructed by the covalent organic framework. The hydroxide ion conductivity of the anion exchange membrane is increased from 130 mS / cm to 180 mS / cm, solving the conduction bottleneck problem caused by the disordered structure of traditional anion exchange membranes.
[0017] 2. Excellent chemical stability: The covalent organic framework provided by this invention achieves carbon-carbon double bond synthesis under the Aldol reaction mechanism through methyl reaction sites activated by carbocations. The rigid framework structure of the covalent organic framework formed by carbon-carbon double bond connection exhibits strong stability to harsh chemical environments (including boiling water, strong acids and bases, redox conditions). No significant degradation or structural damage was observed under alkaline conditions (no significant degradation after soaking in 1 mol / L KOH solution at 80°C for 5 days). It also has excellent thermogravimetric analysis performance and meets the requirements of high-temperature working conditions. Its stability far exceeds that of other reported crystalline porous materials such as zeolites, MOFs and other COFs.
[0018] 3. Good dimensional stability: The covalent organic framework provided by this invention has a rigid skeleton and grafting sites, which can stabilize the swelling of anion exchange membrane molecular chains in an alkaline environment. The swelling rate of anion exchange membrane is reduced from 30% to 15%, effectively controlling the swelling behavior of membrane materials in alkaline environment and greatly improving dimensional stability.
[0019] 4. Material System Innovation: This invention uses Me3TOTA, DTA, and BTA as monomers to synthesize covalent organic frameworks through reversible polymerization reactions. For the first time, it successfully synthesized covalent organic frameworks with TOTA, DTA, and BTA as the main components, realizing the successful synthesis of a variety of novel types of covalent organic frameworks and filling the gap in carbon-carbon double bond-linked COFs materials.
[0020] 5. Feasibility: The main raw materials Me3TOTA ClO4, DTA, and BTA are all commercially available chemicals with a stable supply chain. The synthesis process uses conventional reaction conditions (150-200). o C, 3-7 days), with low equipment requirements, simple post-processing, compatible with existing membrane material production processes, high reaction yield, good raw material utilization, good cost control space, and easy to scale up production.
[0021] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description
[0022] Figure 1 The COF-Br provided in Embodiment 1 of the present invention 25 A schematic diagram of the synthesis; Figure 2 The COF-Br provided in Embodiment 1 of the present invention 25 Powder X-ray diffraction (PXRD) pattern; Figure 3 The COF-Br provided in Embodiment 1 of the present invention 25 Solid-state nuclear magnetic resonance 13C CP / MAS NMR spectrum; Figure 4 The COF-Br provided in Embodiment 1 of the present invention 25 Scanning electron microscope (SEM) image; Figure 5 COF-ZS provided in Embodiment 1 of the present invention 25 SEM image of anion exchange membrane; Figure 6 COF-ZS provided in Embodiment 1 of the present invention 25 Thermogravimetric analysis (TGA) diagram of anion exchange membrane.
[0023] Figure 7 COF-ZS provided in Embodiment 1 of the present invention 25 Figure showing the conductivity results of hydroxide ions. Figure 8 COF-ZS provided in Embodiment 1 of the present invention 25 Figure showing the performance test results of anion exchange membrane water electrolysis device. Detailed Implementation
[0024] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.
[0025] The Me3TOTA ClO of this invention 4、 DTA and BTA have the following structures respectively:
[0026] Me3TOTA ClO4 was synthesized according to the literature method. Organic Letters 2024, 26 (24), 5125-5129), DTA and BTA were purchased from Jilin Zhongke Science and Technology Co., Ltd., with product numbers YSZC6478 and YSZC090 respectively.
[0027] The linear aromatic piperidine polymers described in this invention are poly(dibenzothiophene-terphenylpiperidine) or poly(1,3-diphenylazinepiperidine).
[0028] The poly(dibenzothiophene-terphenylpiperidine) used in this invention was synthesized according to the literature method. Angewandte Chemie International Edition 2024, 63(34), e202405738). The specific method was as follows: 1.48 g (6.43 mmol), dibenzothiophene (296.0 mg, 1.61 mmol), and 1-methyl-4-piperidinone (1.00 g, 8.84 mmol) were added to dichloromethane (10 ml). After stirring in an ice-water bath for 10 minutes, trifluoroacetic acid (1 ml) and trifluoromethanesulfonic acid (10 ml) were added dropwise sequentially. Then, at 0... o The mixture was stirred at C for 1 hour, then stirred at room temperature for 5 hours. The reaction was then terminated by adding 1 M potassium carbonate solution (400 ml). The resulting precipitate was washed until neutral and then dried. The polymer has the following structure:
[0029] The specific synthesis method of poly(1,3-diphenylazoperidine) used in this invention is as follows: 1,3-diphenylazoperidine (2.26 g, 8.06 mmol) and 1-methyl-4-piperidinone (1.00 g, 8.84 mmol) are added to dichloromethane (10 ml). After stirring in an ice-water bath for 10 minutes, trifluoroacetic acid (1 ml) and trifluoromethanesulfonic acid (10 ml) are added dropwise sequentially. Then, at 0... o The mixture was stirred at C for 1 hour, then stirred at room temperature for 5 hours. The reaction was then terminated by adding 1 M potassium carbonate solution (400 ml). The resulting precipitate was washed until neutral and then dried. The polymer has the following structure:
[0030] Example 1 COF-ZS 25 Synthesis
[0031] 1. (17.07 mg, 0.04 mmol) Me3TOTA ClO4, (6.54 mg, 0.015 mmol) DTA, (7.48 mg, 0.045 mmol) BTA, and an alkaline catalyst (CH3COOCs, 345.51 mg) were added to a reaction vessel, followed by 1.5 ml of acetic acid. The mixture was sonicated until homogeneous and then flash-frozen at 77 K (liquid nitrogen bath). After three flash-pump-thaw cycles, the reactor was flame-sealed under vacuum, reducing the pipe length to approximately 15 cm. The reactor was then placed at 150 °C. o Under C conditions, the reaction lasted for 3 days.
[0032] 2. After the reaction is complete, the reactor is allowed to cool naturally to room temperature. The solid product is collected and washed with N,N-dimethylformamide, water, methanol, acetone, tetrahydrofuran, and dichloromethane to remove unreacted reactants and catalyst. The product is then dried under vacuum to obtain COF-Br. 25 .
[0033] 3. Add 50 mg COF-Br 25 Place in 10 ml DMSO and sonicate for 2 hours, then mix with pre-treated 80 ml DMSO. o Mix 450 mg of poly(dibenzothiophene-terphenylpiperidine) (ZS) with 10 ml of DMSO solution heated and stirred for 2 hours at 80°C. o Stir for 3 days, add 1 ml of iodomethane, and stir in the dark at room temperature for 2 days.
[0034] 4. After the reaction is complete, the reaction solution is added dropwise to 100 ml of ethyl acetate, the precipitate is collected, and washed 3-5 times with ethyl acetate to remove unreacted reactants. The precipitate is then dried under vacuum to obtain COF-ZS. 25 .
[0035] 5. Take 300 mg of COF-ZS 25 Dissolve in 10 ml of DMSO at 80°C. o After heating at C for 6 hours to dry the solvent, a COF-based anion exchange membrane was formed.
[0036] 6. Place the membrane in a 1 mol / L KOH solution at 80°C. o Soaking at C for 5 days replaces the negatively charged free ions with OH-. - .
[0037] 7. The COF-based anion exchange membrane was used for ionic conductivity testing and anion exchange membrane water electrolysis device testing.
[0038] Results: A COF-based anion exchange membrane material with a thickness of 25 μm was obtained.
[0039] Example 2 COF-ZS 50 Synthesis
[0040] 1. (17.07 mg, 0.04 mmol) Me3TOTA ClO4, (13.08 mg, 0.03 mmol) DTA, (4.98 mg, 0.03 mmol) BTA, and an alkaline catalyst (CH3COOCs, 345.51 mg) were added to a reaction vessel, followed by 1.5 ml of acetic acid. The mixture was sonicated until homogeneous and then flash-frozen at 77 K (liquid nitrogen bath). After three flash-pump-thaw cycles, the reactor was flame-sealed under vacuum, reducing the pipe length to approximately 15 cm. The reactor was then placed at 150 °C. o Under C conditions, the reaction lasted for 3 days.
[0041] 2. After the reaction is complete, the reactor is allowed to cool naturally to room temperature. The solid product is collected and washed with N,N-dimethylformamide, water, methanol, acetone, tetrahydrofuran, and dichloromethane to remove unreacted reactants and catalyst. The product is then dried under vacuum to obtain COF-Br. 50 .
[0042] 3. Add 50 mg COF-Br 50 Place in 10 ml DMSO and sonicate for 2 hours, then mix with pre-treated 80 ml DMSO. o A solution of 450 mg ZS heated and stirred for 2 hours at 80 °C was mixed with 10 ml of DMSO solution. o Stir for 3 days, add 1 ml of iodomethane, and stir in the dark at room temperature for 2 days.
[0043] 4. After the reaction is complete, the reaction solution is added dropwise to 100 ml of ethyl acetate, the precipitate is collected, and washed 3-5 times with ethyl acetate to remove unreacted reactants. The precipitate is then dried under vacuum to obtain COF-ZS. 50 .
[0044] 5. Take 300 mg of COF-ZS 50 Dissolve in 10 ml of DMSO at 80°C. o After heating at C for 6 hours to dry the solvent, a COF-based anion exchange membrane was formed.
[0045] 6. Place the membrane in a 1 mol / L KOH solution at 80°C. o Soaking at C for 5 days replaces the negatively charged free ions with OH-. - .
[0046] 7. The COF-based anion exchange membrane was used for conductivity testing and testing of anion exchange membrane water electrolysis devices.
[0047] Results: A COF-based anion exchange membrane material with a thickness of 25 μm was obtained.
[0048] Example 3 COF-ZS 75 Synthesis
[0049] 1. (17.07 mg, 0.04 mmol) Me3TOTA ClO4, (19.63 mg, 0.045 mmol) DTA, (2.49 mg, 0.015 mmol) BTA, and an alkaline catalyst (CH3COOCs, 345.51 mg) were added to a reaction vessel, followed by 1.5 ml of acetic acid. The mixture was sonicated to ensure homogeneity and then flash-frozen at 77 K (liquid nitrogen bath). After three flash-pump-thaw cycles, the reactor was flame-sealed under vacuum, reducing the pipe length to approximately 15 cm. The reactor was then placed at 150 °C. o Under C conditions, the reaction lasted for 3 days.
[0050] 2. After the reaction is complete, the reactor is allowed to cool naturally to room temperature. The solid product is collected and washed with N,N-dimethylformamide, water, methanol, acetone, tetrahydrofuran, and dichloromethane to remove unreacted reactants and catalyst. The product is then dried under vacuum to obtain COF-Br. 75 .
[0051] 3. Add 50 mg COF-Br 75 Place in 10 ml DMSO and sonicate for 2 hours, then mix with pre-treated 80 ml DMSO. o A solution of 450 mg ZS heated and stirred for 2 hours at 80 °C was mixed with 10 ml of DMSO solution. o Stir for 3 days, add 1 ml of iodomethane, and stir in the dark at room temperature for 2 days.
[0052] 4. After the reaction is complete, the reaction solution is added dropwise to 100 ml of ethyl acetate, the precipitate is collected, and washed 3-5 times with ethyl acetate to remove unreacted reactants. The precipitate is then dried under vacuum to obtain COF-ZS. 75 .
[0053] 5. Take 300 mg of COF-ZS 75 Dissolve in 10 ml of DMSO at 80°C. o After heating at C for 6 hours to dry the solvent, a COF-based anion exchange membrane was formed.
[0054] 6. Place the membrane in a 1 mol / L KOH solution at 80°C. o Soaking at C for 5 days replaces the negatively charged free ions with OH-. - .
[0055] 7. The COF-based anion exchange membrane was used for conductivity testing and testing of anion exchange membrane water electrolysis devices.
[0056] Results: A COF-based anion exchange membrane material with a thickness of 25 μm was obtained.
[0057] Example 4 COF-PDAzP 25 Synthesis
[0058] 1. (17.07 mg, 0.04 mmol) Me3TOTA ClO4, (6.54 mg, 0.015 mmol) DTA, (7.48 mg, 0.045 mmol) BTA, and an alkaline catalyst (CH3COOCs, 345.51 mg) were added to a reaction vessel, followed by 1.5 ml of acetic acid. The mixture was sonicated until homogeneous and then flash-frozen at 77 K (liquid nitrogen bath). After three flash-pump-thaw cycles, the reactor was flame-sealed under vacuum, reducing the pipe length to approximately 15 cm. The reactor was then placed at 150 °C. o Under C conditions, the reaction lasted for 3 days.
[0059] 2. After the reaction is complete, the reactor is allowed to cool naturally to room temperature. The solid product is collected and washed with N,N-dimethylformamide, water, methanol, acetone, tetrahydrofuran, and dichloromethane to remove unreacted reactants and catalyst. The product is then dried under vacuum to obtain COF-Br. 25 .
[0060] 3. Add 50 mg COF-Br 25 Place in 10 ml DMSO and sonicate for 2 hours, then mix with pre-treated 80 ml DMSO. o A solution of 450 mg poly(1,3-diphenylazinepiperidine) (DAzP) heated and stirred for 2 hours at 80 °C was mixed with 10 ml of DMSO solution. o Stir for 3 days, add 1 ml of iodomethane, and stir in the dark at room temperature for 2 days.
[0061] 4. After the reaction is complete, add the reaction solution dropwise to 100 ml of ethyl acetate, collect the precipitate, and wash it 3-5 times with ethyl acetate to remove unreacted reactants. Then, dry the precipitate under vacuum to obtain COF-DAzP. 25 .
[0062] 5. Take 300 mg COF-DAzP 25 Dissolve in 10 ml of DMSO at 80°C. o After heating at C for 6 hours to dry the solvent, a COF-based anion exchange membrane was formed.
[0063] 6. Place the membrane in a 1 mol / L KOH solution at 80°C. o Soaking at C for 5 days replaces the negatively charged free ions with OH-. - .
[0064] 7. The COF-based anion exchange membrane was used for ionic conductivity testing and anion exchange membrane water electrolysis device testing.
[0065] Results: A COF-based anion exchange membrane material with a thickness of 25 μm was obtained.
[0066] Experimental Example 1: The COF-Br prepared in Example 1 25、 COF-ZS 25 Structural characterization
[0067] 1. COF-Br 25 The X-ray diffraction (PXRD) pattern is shown below. Figure 2 As shown, by Figure 2 It can be seen that COF-Br 25 In 3.3 o The presence of obvious diffraction peaks indicates that the material has good crystallinity and an ordered pore structure.
[0068] 2. COF-Br 25 nuclear magnetic resonance 13 CCP / MAS NMR spectra as follows Figure 3 As shown, by Figure 3 It can be seen that the characteristic chemical shift peaks correspond to the target structure, verifying the chemical structure of the material.
[0069] 3. COF-Br 25 Scanning electron microscope (SEM) image as shown Figure 4 As shown, by Figure 4 It can be seen that the sample exhibits a uniform granular morphology.
[0070] 4. COF-ZS 25 Scanning electron microscope (SEM) image as shown Figure 5 As shown, by Figure 5 It can be seen that the surface of the membrane sample exhibits a uniform and dense structure.
[0071] Experimental Example 2: COF-ZS prepared in Example 1 25 Thermogravimetric analysis of anion exchange membranes
[0072] Experimental method: Take an appropriate amount of sample and place it in a thermogravimetric analyzer. Under a nitrogen atmosphere, heat the sample from room temperature to 800℃ at a heating rate of 20℃ / min and record the mass change of the sample.
[0073] The results are as follows Figure 6As shown, by Figure 6 It can be seen that the mass loss of the membrane before 100℃ originates from the physical adsorption of water within the membrane. The mass loss at 200℃ is due to the degradation of cationic groups and long side chains, while the mass loss at 350~450℃ is attributed to the degradation of the polymer backbone. Crucially, the membrane shows no significant mass loss within a temperature range up to 180℃, demonstrating its excellent thermal stability.
[0074] Experimental Example 3: Hydroxide ion conductivity test and anion exchange membrane water electrolysis device test
[0075] Experimental method: The OH group was measured at different temperatures using the AC impedance method. - The ohmic impedance of the membrane was measured, and the ionic conductivity of the membrane was calculated using the ionic conductivity-impedance calculation formula. In the testing of the anion exchange membrane water electrolysis device, the COF-ZS prepared in Example 1 of this invention was used. 25 As anion exchange membranes, Pt / C and NiFe were used as cathode and anode catalysts, respectively, and the performance of the anion exchange membrane water electrolysis device was tested in 1 M KOH.
[0076] The hydroxide ion conductivity results are as follows: Figure 7 As shown, the anion exchange membrane exhibits high hydroxide ion conductivity throughout the test temperature range, and the conductivity increases with increasing temperature, reaching 80°C. o The hydroxide ion conductivity at C reaches 185.9 mS / cm. -1 .
[0077] Performance test results of the anion exchange membrane water electrolysis device are as follows: Figure 8 As shown, based on COF-ZS 25 The anion exchange membrane water electrolysis device exhibits excellent performance at 2 V and 80 o The current density reaches 1.73 A cm under condition C. -2 .
[0078] The COF-based anion exchange membrane provided by this invention has broad application prospects in green energy fields such as alkaline water electrolysis for hydrogen production, fuel cells, and electrochemical energy storage. With the deepening of the "dual-carbon" strategy, the market demand for efficient and stable anion exchange membrane materials is enormous. This invention not only solves the conductivity and stability problems of existing AEM materials but also provides a feasible path for the industrial production of high-performance ion exchange membranes, possessing significant technological transformation value and market competitiveness.
[0079] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. A method for preparing a covalent organic framework material, characterized in that, Includes the following steps: Step 1: Add Me3TOTA ClO4, DTA, BTA and alkaline catalyst to the reaction vessel, add solvent, sonicate to mix evenly, flash freeze, and after three flash freeze-pump-thaw cycles, the reactor is flame-sealed under vacuum conditions, and then placed under heating conditions for reaction. Step 2: After the reaction in Step 1 is completed, the reactor is naturally cooled to room temperature, the solid product is collected, washed, and unreacted reactants and catalysts are removed. Then, it is heated and dried in a vacuum to obtain the covalent organic framework material.
2. According to the preparation method of claim 1, in step 1, the molar ratio of Me3TOTA ClO4 to the sum of DTA and BTA is 2:
3.
3. According to the preparation method of claim 1, in step 1, the alkaline catalyst is CH3COOCs and the solvent is acetic acid.
4. The preparation method according to claim 1, wherein in step 1, the flash freezing conditions are: flash freezing is performed in a liquid nitrogen bath at 77K; and the reaction conditions are: at 150-200℃. o Under C conditions, the reaction takes 3-7 days.
5. According to the preparation method of claim 1, in step 2, the solid product is washed sequentially with N,N-dimethylformamide, water, methanol, acetone, tetrahydrofuran, and dichloromethane.
6. The application of the covalent organic framework material prepared by the method according to any one of claims 1-5 in the preparation of COF-based anion exchange membranes.
7. A method for preparing a COF-based anion exchange membrane, characterized in that, Includes the following steps: Step 3: Place the covalent organic framework material prepared by the method according to any one of claims 1-5 in DMSO and sonicate it. Then mix it with a DMSO solution of a preheated linear aromatic piperidine polymer, continue stirring, add iodomethane, and react in the dark at room temperature. Step 4: After the reaction in step 3 is completed, the reaction solution is added dropwise to ethyl acetate, the precipitate is collected, washed, and unreacted reactants are removed. Then, it is dried under vacuum to obtain the COFs grafted polymer. Step 5: Dissolve the COFs grafted polymer in an appropriate amount of DMSO, heat, dry the solvent, and then form a film. Step 6: Place the membrane prepared in Step 5 into a KOH solution and soak it to replace the negatively charged free ions with OH-. - Thus, a COF-based anion exchange membrane is obtained.
8. The preparation method according to claim 7, wherein in step 3, the linear aromatic piperidine polymer is poly(dibenzothiophene-terphenylpiperidine) or poly(1,3-diphenylazinepiperidine), and in step 6, the KOH solution concentration is 1 mol / L, and the soaking conditions are: at 80°C... o Soak in water at temperature C for 1-5 days.
9. The COF-based anion exchange membrane prepared by the method of claim 7.
10. The application of the COF-based anion exchange membrane as described in claim 9 in hydrogen production by water electrolysis.