Cross-linked polyaryl anion exchange membrane and preparation method thereof
By using a cross-linked polyaryl anion exchange membrane with a non-ether bond backbone design and cross-linked structure, the problems of insufficient chemical stability and mechanical strength of existing membranes are solved, and high-efficiency hydrogen production through water electrolysis is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-09
- Publication Date
- 2026-04-03
AI Technical Summary
Existing anion exchange membranes have shortcomings in terms of chemical stability, mechanical strength, and ionic conductivity, which limits their application in alkaline membrane electrolyzers.
A cross-linked polyaryl anion exchange membrane was prepared by using an ether-free main chain design and cross-linked structure through acid-catalyzed polymerization, functionalization modification and flat-plate casting method to form a microphase separation structure to improve chemical stability and mechanical strength.
It achieves high ionic conductivity (≥125mS/cm), high mechanical properties (tensile stress >30MPa), and maintains good electrolysis performance at 80℃ (current density ≥2.4A/cm2), making it suitable for water electrolysis hydrogen production technology.
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Figure CN121779684A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of anion exchange membranes, and more particularly to a cross-linked polyaryl anion exchange membrane and its preparation method. Background Technology
[0002] With the increasing global demand for clean energy and sustainable development, hydrogen energy has attracted much attention as an environmentally friendly and efficient energy form. Traditional hydrogen production methods, such as natural gas cracking, coal gasification, methanol cracking, and photocatalytic oxidation, suffer from high energy consumption, severe environmental pollution, and complex processes. In contrast, water electrolysis for hydrogen production offers advantages such as high efficiency, cleanliness, and renewability, enabling zero carbon emissions in the hydrogen production process. Among various water electrolysis technologies, alkaline membrane electrolysis is particularly noteworthy due to its high electrolysis efficiency and high hydrogen purity. This technology allows low-concentration alkaline water or pure water as the electrolyte, resulting in less corrosion to the electrolysis equipment and outperforming traditional alkaline aqueous solution electrolysis for hydrogen production. Anion exchange membranes, as a core component of alkaline membrane electrolyzers, conduct hydroxide anions and isolate the positive and negative electrodes; their performance directly affects the electrolysis efficiency and lifespan of the electrolyzer. However, current anion exchange membranes on the market still have some shortcomings in terms of chemical stability, mechanical strength, and ionic conductivity, limiting their practical application in alkaline membrane electrolyzers.
[0003] Traditional polyarylene ether anion exchange membranes contain ether bonds, which are prone to degradation under high temperature and strong alkaline conditions, leading to main chain breakage and reduced mechanical properties. Furthermore, existing anion exchange membranes generally suffer from insufficient mechanical strength, making them susceptible to breakage or perforation during long-term use, further affecting the stable operation of the electrolyzer.
[0004] Therefore, there is an urgent need to develop a novel anion exchange membrane with excellent chemical stability, mechanical strength, and high ionic conductivity to efficiently adapt to the harsh environment of water electrolysis for hydrogen production. Summary of the Invention
[0005] In view of the shortcomings of the above-mentioned technologies, the present invention provides a cross-linked polyaryl anion exchange membrane to solve the problems of insufficient performance of existing anion exchange membranes in terms of chemical stability, mechanical strength and ionic conductivity.
[0006] To address the aforementioned shortcomings, the inventors of this application conceived of improving the chemical and mechanical stability of the anion exchange membrane material through an ether-free main chain design and the introduction of a cross-linked structure. Simultaneously, the cross-linked polyaryl anion exchange membrane, prepared using acid-catalyzed polymerization, functionalization modification, and flat-plate casting, exhibits a simple preparation process, low cost, and excellent performance, effectively meeting the practical application requirements of water electrolysis for hydrogen production. The prepared anion exchange membrane possesses a side-chain structure, which promotes polymer self-assembly and the formation of a microphase separation structure, thereby achieving high ionic conductivity and ensuring high electrolysis efficiency in the water electrolysis hydrogen production process.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A cross-linked polyaryl anion exchange membrane, wherein the chemical structural formula of the anion exchange membrane is as follows:
[0009]
[0010] Where x:y = 0.01 to 5, and m is 5 to 200. It is any of the following aryl groups:
[0011]
[0012] Another aspect of the present invention is to provide a method for preparing a cross-linked polyaryl anion exchange membrane as described above, the method comprising the following steps:
[0013] S1: Benzene-containing monomers and 7-bromo-1,1,1-trifluoroheptane-2-one were dissolved in dichloromethane, followed by the dropwise addition of a certain amount of trifluoromethanesulfonic acid. The reaction was carried out at 0–60 °C for 2–48 hours. The product was poured into a precipitant to precipitate, filtered, washed, and dried to obtain the unfunctionalized polymer, the structural formula of which is shown below.
[0014]
[0015] S2: Dissolve the unfunctionalized polymer obtained in step S1 in an organic solvent, add a certain amount of alkaline substance, stir at room temperature to 60°C for 0 to 12 hours, then cool to room temperature, add a certain proportion of functionalizing reagent and crosslinking agent, and continue the reaction for 0 to 48 hours to obtain a functionalized polymer solution.
[0016] S3: Centrifuge the functionalized polymer solution obtained in step S2 to obtain a pure supernatant, then coat it onto a plate by casting, and dry it at room temperature to 100°C for 5 to 48 hours. After the solvent evaporates, a film is formed. At room temperature, immerse the obtained film in potassium hydroxide solution or sodium hydroxide solution for a certain time to convert the anions into hydroxide ions, and obtain the cross-linked polyaryl anion exchange membrane.
[0017] As a preferred technical solution, the benzene-containing monomer is any one or a mixture of two of the following:
[0018]
[0019] As a preferred technical solution, the precipitant is at least one selected from ethanol, methanol, propanol, water, aqueous solution of sodium hydroxide, and aqueous solution of potassium hydroxide.
[0020] As a preferred technical solution, the alkaline substance is at least one selected from potassium carbonate, sodium carbonate, cesium carbonate, lithium hydroxide, sodium hydroxide, and potassium hydroxide.
[0021] As a preferred technical solution, the organic solvent is at least one of N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylformamide.
[0022] As a preferred technical solution, the functionalizing reagent is an aqueous solution of trimethylamine or a solution of trimethylamine alcohol.
[0023] As a preferred technical solution, the crosslinking agent is N,N-dimethyl-1-(4-vinylphenyl)methylamine.
[0024] As a preferred technical solution, the mass ratio of the crosslinking agent to the functionalizing reagent is (0.01~100):(0.01~100).
[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0026] The cross-linked polyaryl anion exchange membrane provided by this invention has a main chain containing only carbon and hydrogen atoms, exhibiting strong chemical stability and thus ensuring stable operation of the alkaline membrane electrolyzer. The side chain structure promotes polymer self-assembly, forming a microphase separation structure, resulting in a membrane with high ionic conductivity (≥125 mS / cm, 80℃). The introduced cross-linking structure improves the dimensional stability (swelling rate ≤15%, 80℃) and mechanical properties (tensile stress >30 MPa) of the membrane material. When the anion exchange membrane is assembled into an electrolyzer, it exhibits ≥2.4 A / cm at 80℃ and 1.8V. 2 High current density performance.
[0027] The cross-linked polyaryl anion exchange membrane provided by this invention is prepared through acid-catalyzed polymerization, functionalization, and flat-plate casting. Its preparation process is simple, low-cost, and has excellent performance, enabling large-scale production. Attached Figure Description
[0028] Figure 1 This is a physical image of the cross-linked polyaryl anion exchange membrane prepared in Example 1 of the present invention.
[0029] Figure 2 This is a schematic diagram showing the relationship between the ionic conductivity and temperature of the cross-linked polyaryl anion exchange membrane prepared in Example 1 of the present invention. Detailed Implementation
[0030] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.
[0031] Example 1
[0032] This embodiment provides a cross-linked polyaryl anion exchange membrane, with the following chemical structural formula:
[0033]
[0034] The preparation method of the cross-linked polyaryl anion exchange membrane in this embodiment includes the following steps:
[0035] S1: Dissolve m-terphenyl (2.30 g) and 7-bromo-1,1,1-trifluoroheptane-2-one (2.47 g) in dichloromethane, then add 9 mL of trifluoromethanesulfonic acid dropwise, react at 0 °C for 24 hours, pour the product into methanol to precipitate, filter, wash and dry the product to obtain the unfunctionalized polymer.
[0036] S2: Dissolve the unfunctionalized polymer obtained in step S1 in the organic solvent dimethyl sulfoxide, add potassium carbonate (0.6 g), stir at 60 °C for 1 hour, then cool to room temperature, add N,N-dimethyl-1-(4-vinylphenyl)methylamine (0.08 g) and a 28% trimethylamine ethanol solution (4 mL), and continue the reaction for 12 hours to obtain a functionalized polymer solution;
[0037] S3: The functionalized polymer solution obtained in step S2 is centrifuged to obtain a pure supernatant, which is then coated onto a glass plate by casting and dried at 100°C for 15 hours. After the solvent evaporates, a film is formed. At room temperature, the resulting membrane is immersed in a 1 mol / L potassium hydroxide solution for 48 hours to convert anions into hydroxide ions, thus obtaining the cross-linked polyaryl anion exchange membrane. Figure 1 As shown.
[0038] Test results show that the ionic conductivity of the anion exchange membrane in this embodiment is 135 mS / cm at 80℃ (e.g., Figure 2As shown, the swelling ratio is 12%, and the tensile stress is 31.5 MPa. When the anion exchange membrane of this embodiment is immersed in 1M NaOH solution at 80°C for 1000 hours, the ionic conductivity decreases by only 3.5%. When the anion exchange membrane of this embodiment is assembled into an alkaline membrane electrolyzer, the current density reaches 3.0 A / cm² at 80°C and 1.8V. 2 .
[0039] Example 2
[0040] This embodiment provides a cross-linked polyaryl anion exchange membrane, with the following chemical structural formula:
[0041]
[0042] The preparation method of the cross-linked polyaryl anion exchange membrane in this embodiment includes the following steps:
[0043] S1: Biphenyl (1.54 g) and 7-bromo-1,1,1-trifluoroheptane-2-one (2.47 g) were dissolved in dichloromethane, followed by the addition of 10 mL of trifluoromethanesulfonic acid. The mixture was reacted at 25 °C for 6 hours. The product was poured into water to precipitate, filtered, washed, and dried to obtain the unfunctionalized polymer.
[0044] S2: Dissolve the unfunctionalized polymer obtained in step S1 in the organic solvent N-methylpyrrolidone, add potassium carbonate (0.2 g), stir at room temperature for 2 hours, then cool to room temperature, add N,N-dimethyl-1-(4-vinylphenyl)methylamine (0.16 g) and 28% trimethylamine ethanol solution (3 mL), and continue the reaction for 24 hours to obtain a functionalized polymer solution;
[0045] S3: Centrifuge the functionalized polymer solution obtained in step S2 to obtain a pure supernatant, then coat it onto a glass plate by casting, dry it at 60°C for 24 hours, and form a film after the solvent evaporates; at room temperature, immerse the obtained film in a 1 mol / L potassium hydroxide solution for 48 hours to convert the anions into hydroxide ions, and obtain the cross-linked polyaryl anion exchange membrane.
[0046] Test results show that the anion exchange membrane of this embodiment has an ionic conductivity of 125 mS / cm, a swelling ratio of 15%, and a tensile stress of 30.2 MPa at 80℃. Immersing the anion exchange membrane of this embodiment in 80℃, 1M NaOH solution for 1000 hours only resulted in a 4.2% decrease in ionic conductivity. When the anion exchange membrane of this embodiment is assembled into an alkaline membrane electrolyzer, a current density of 2.6 A / cm² is achieved at 80℃ and 1.8V. 2 .
[0047] Example 3
[0048] This embodiment provides a cross-linked polyaryl anion exchange membrane, with the following chemical structural formula:
[0049]
[0050] The preparation method of the cross-linked polyaryl anion exchange membrane in this embodiment includes the following steps:
[0051] S1: Dissolve terphenyl (2.30 g) and 7-bromo-1,1,1-trifluoroheptane-2-one (2.47 g) in dichloromethane, then add 10 mL of trifluoromethanesulfonic acid. React at 30 °C for 12 hours. Pour the product into ethanol to precipitate, filter, wash and dry the product to obtain the unfunctionalized polymer.
[0052] S2: Dissolve the unfunctionalized polymer obtained in step S1 in the organic solvent dimethyl sulfoxide, add potassium carbonate (0.5 g), stir at room temperature for 2 hours, then cool to room temperature, add N,N-dimethyl-1-(4-vinylphenyl)methylamine (0.32 g) and 28% trimethylamine ethanol solution (5 mL), and continue the reaction for 12 hours to obtain a functionalized polymer solution;
[0053] S3: Centrifuge the functionalized polymer solution obtained in step S2 to obtain a pure supernatant, then coat it onto a glass plate by casting, dry it at 80°C for 12 hours, and form a film after the solvent evaporates; at room temperature, immerse the obtained film in a 1 mol / L potassium hydroxide solution for 48 hours to convert the anions into hydroxide ions, and obtain the cross-linked polyaryl anion exchange membrane.
[0054] Test results show that the anion exchange membrane of this embodiment has an ionic conductivity of 131 mS / cm, a swelling ratio of 13%, and a tensile stress of 30.4 MPa at 80℃. Immersing the anion exchange membrane of this embodiment in 80℃, 1M NaOH solution for 1000 hours only resulted in a 3.1% decrease in ionic conductivity. When the anion exchange membrane of this embodiment was assembled into an alkaline membrane electrolyzer, a current density of 2.4 A / cm² was achieved at 80℃ and 1.8V. 2 .
[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.
Claims
1. A cross-linked polyaryl anion exchange membrane, characterized in that, The chemical structural formula of the anion exchange membrane is: Where x:y = 0.01 to 5, and m is 5 to 200. It is any of the following aryl groups:
2. A method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 1, characterized in that, The preparation method includes the following steps: S1: Dissolve benzene-containing monomer and 7-bromo-1,1,1-trifluoroheptane-2-one in dichloromethane, then add a certain amount of trifluoromethanesulfonic acid dropwise, react at 0-60℃ for 2-48 hours, pour the product into a precipitant to precipitate, filter, wash and dry the product to obtain the unfunctionalized polymer. S2: Dissolve the unfunctionalized polymer obtained in step S1 in an organic solvent, add a certain amount of alkaline substance, stir at room temperature to 60°C for 0.5 to 12 hours, then cool to room temperature, add a certain proportion of functionalizing reagent and crosslinking agent, and continue the reaction for 0.5 to 48 hours to obtain a functionalized polymer solution. S3: Centrifuge the functionalized polymer solution obtained in step S2 to obtain a pure supernatant, then coat it onto a plate by casting, and dry it at room temperature to 100°C for 5 to 48 hours. After the solvent evaporates, a film is formed. At room temperature, immerse the obtained film in potassium hydroxide solution or sodium hydroxide solution for a certain time to convert the anions into hydroxide ions, and obtain the cross-linked polyaryl anion exchange membrane.
3. The method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 2, characterized in that, The benzene-containing monomer is any one or a mixture of two of the following:
4. The method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 2, characterized in that, The precipitant is at least one of ethanol, methanol, propanol, water, aqueous sodium hydroxide solution, and aqueous potassium hydroxide solution.
5. The method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 2, characterized in that, The alkaline substance is at least one of potassium carbonate, sodium carbonate, cesium carbonate, lithium hydroxide, sodium hydroxide, and potassium hydroxide.
6. The method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 2, characterized in that, The organic solvent is at least one of N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylformamide.
7. The method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 2, characterized in that, The functionalizing reagent is an aqueous solution of trimethylamine or a solution of trimethylamine alcohol.
8. The method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 2, characterized in that, The crosslinking agent is N,N-dimethyl-1-(4-vinylphenyl)methylamine.
9. The method for preparing the cross-linked polyaryl anion exchange membrane as described in claim 2, characterized in that, The mass ratio of the crosslinking agent to the functionalizing reagent is (0.01–100):(0.01–100).