Enhanced anion exchange membrane for hydrogen production through water electrolysis and preparation method of enhanced anion exchange membrane

Abstract

The invention discloses an enhanced anion-exchange membrane for hydrogen production through water electrolysis and a preparation method of the enhanced anion-exchange membrane. The enhanced anion exchange membrane is composed of polymer resin A (side chain functionalized poly (p-terphenyl piperidine) polymer) and a base material modified by a semi-interpenetrating polymer (SIPN). The polymer resin takes alkali-resistant polyterphenyl piperidine as a main chain and is laterally grafted with a quaternary ammonium cation alkyl side chain containing a hydrophilic group, transmission sites of OH <-> are increased under the condition that the functionalization degree of the main chain is certain, and a microphase separation form is effectively constructed through interaction of the hydrophobic polymer main chain and the hydrophilic functionalized alkyl side chain, so that the polymer resin is prepared. The ionic conductivity of the membrane is greatly improved. According to a semi-interpenetrating network structure formed based on SIPN, high-molecular resin and a base material are tightly combined, and the problem that a composite membrane in the market is too high in gas permeability is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of anion exchange membrane materials, and particularly relates to a preparation method and application of an enhanced anion exchange membrane for hydrogen production by water electrolysis. Background Art

[0002] With the depletion of fossil energy, hydrogen, as a green and clean energy source, has gradually come into the public view. Water electrolysis can directly utilize the remaining renewable energy, so it is considered one of the most promising hydrogen production methods. Currently, low-temperature electrolysis is mainly divided into alkaline water electrolysis (AWE), proton exchange membrane water electrolysis (PEMWE), and anion exchange membrane water electrolysis (AEMWE). AWE has been widely used in industrial applications, but the low current density (<500 mA cm -2 ) limits its development, especially in realizing the utilization of fluctuating and highly intermittent renewable energy. In contrast, PEMWE and AEMWE based on the "zero-gap" structure achieved through ion exchange membranes can provide higher working current densities than AWE. However, PEMWE largely relies on the use of platinum group metal (PGM)-based materials, resulting in high hydrogen production costs. In recent years, AEMWE has become a cost-effective alternative to PEMWE due to the use of inexpensive platinum-group metal-free materials.

[0003] As the core component of AEMWE, anion exchange membranes (AEMs) currently have problems such as difficulty in balancing ion conductivity and dimensional stability and poor alkaline stability, which seriously restrict the widespread application and commercialization of this technology. Efficient ion conductivity is crucial for the process of hydrogen production by water electrolysis, which directly affects electrolysis efficiency and energy consumption. However, in actual applications, the ion conductivity of many AEMs is difficult to meet the requirements of efficient hydrogen production. A class of polymer-based anion exchange membranes mentioned in Chinese patent CN 109280198 B has certain innovations in membrane preparation process and structural design, but the ion conductivity performance is poor in actual use. In the process of hydrogen production by water electrolysis, the lower ion conductivity increases the ion transmission resistance, resulting in the electrolyzer needing to apply a higher voltage to maintain a certain current density, thereby increasing energy consumption. However, high ion conductivity may cause the membrane to absorb water excessively and swell. For example, Chinese patent CN 116487665 A mentions that when the ion conductivity of the anion exchange membrane is improved, the ion exchange groups in the membrane will attract more water molecules, resulting in excessive expansion of the membrane structure. Excessive water absorption and swelling will not only cause a significant change in the size of the membrane, destroy the compatibility between the membrane and components such as electrodes, and affect the normal operation of the entire water electrolysis system, but will also reduce the mechanical strength of the membrane, increase the risk of membrane perforation, and thus shorten the service life of the membrane. At the same time, the swelling process may destroy the originally ordered ion transmission channels in the membrane, causing the ion conductivity to decline, and unable to meet the requirements of efficient hydrogen production for ion conduction, which seriously restricts the widespread application and performance improvement of anion exchange membranes in the field of water electrolysis hydrogen production.

[0004] In view of the problems of anion exchange membranes in ion conductivity and dimensional stability, it is urgent to develop an anion exchange membrane with better performance. Summary of the invention

[0005] In order to solve the above problems, the present invention selects polyterphenyl piperidine with excellent rigidity and chemical stability as the polymer skeleton, and uses the N atom of piperidone on its main chain to graft quaternary ammonium cationic alkyl side chains with hydrophilic groups. This design increases the OH without increasing the functionalization degree of the main chain. -Conduction sites. Constructing an alkyl spacer between the hydrophobic polymer backbone and the hydrophilic functionalized side chains can effectively promote the formation of a clear microphase-separated morphology. Additionally, selecting the SIPN-modified substrate as the reinforcing material, the presence of SIPN significantly enhances the adhesion between the polymer and the substrate, effectively solving the problem of increased gas permeability caused by voids between the polymer and the substrate. The SIPN-substrate reduces the water absorption and swelling of the membrane while enhancing the mechanical properties. Finally, the purpose of improving the hydroxide ion conductivity and maintaining dimensional stability is achieved. The "trade-off" problem between ion conductivity and dimensional stability commonly existing in anion exchange membranes on the market is successfully solved. Through innovative structural design and preparation processes, the present invention is expected to solve the above problems and inject new vitality into the development of efficient and safe water electrolysis hydrogen production technology.

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method and application for an enhanced anion exchange membrane for water electrolysis hydrogen production. In view of the problems commonly existing in anion exchange membranes, such as low ion conductivity, poor mechanical properties and dimensional stability, the present invention provides a preparation method for an enhanced anion exchange membrane for water electrolysis hydrogen production with a simple process and capable of mass production, thereby being able to significantly improve the long-term high-performance hydrogen production of alkaline anion exchange membrane electrolyzers.

[0007] To achieve the purpose of this invention, the present invention adopts the following technical solutions: An enhanced anion exchange membrane for water electrolysis hydrogen production, the components of the enhanced anion exchange membrane include a polymer resin A and a semi-interpenetrating polymer SIPN-modified substrate.

[0008] Further, the polymer resin A is a side-chain functionalized poly(p-terphenylpiperidine) polymer, having the structure shown by the following formula: Wherein, n = 2 - 5; x, y and z represent the proportions of the polymer units in the polymer chain segment, and their values are between 0 - 100%, and the sum of x, y and z is 100%.

[0009] Further, the preparation method of the side-chain functionalized poly(p-terphenylpiperidine) polymer includes the following steps: (1) Uniformly disperse p-terphenyl and N-methyl-4-piperidone in dichloromethane. Subsequently, drop the catalyst. After the reaction ends, precipitate the mixed liquid in a NaOH solution, filter the obtained product, wash it to neutrality, collect it and dry it in an 80 °C oven to obtain Polymer 1.

[0010] (2) Add the polymer 1 in (1) into DMSO, add a small amount of TFA to promote dissolution. After stirring or sonicating to dissolve at room temperature, add the haloalcohol and the catalyst N,N-diisopropylethylamine. During the reaction, add potassium carbonate in portions. Use potassium carbonate as an acid scavenger to deprotonate the polymer, which can enable the smooth progress of the Menkshutkin reaction between the polymer and the haloalcohol. After the reaction, precipitate the resulting product with ethyl acetate. Put the obtained solid into an oven and dry it at 80 °C to obtain polymer 2.

[0011] (3) Dissolve polymer 2 in (2) in DMSO, add 2,3-epoxypropyltrimethylammonium chloride (EPTAC) and the catalyst boron trifluoride diethyl etherate. The reaction temperature is 50 - 70 °C, and the reaction time is 12 - 60 h. After the reaction, cool the reaction solution, add methyl iodide to completely quaternize the remaining piperidine. The reaction temperature is from room temperature to 45 °C, and the reaction time is 12 - 60 h, and the reaction needs to be carried out in the dark. After the reaction, wash the precipitate reaction solution with ethyl acetate. Dry the obtained solid to obtain the final product polymer 3 (i.e., the side-chain functionalized poly(p-terphenyl)piperidine polymer).

[0012] Further, in the reaction described in step (1), the catalyst is a combination of trifluoroacetic acid TFA and trifluoromethanesulfonic acid TFSA, and the volume ratio of the two is 1:(8 - 15); Further, in the reaction described in step (1), the molar ratio of p-terphenyl, N-methyl-4-piperidone to trifluoroacetic acid TFA is 1:(1 - 3):(1 - 2); Further, the temperature of the reaction described in step (1) is 0 °C, and the time is 1 - 12 h.

[0013] Further, in the reaction described in step (2), the haloalcohol selected is ω-haloalcohol, where ω represents that the halogen atom is at the ω position of the alcohol hydroxyl group, that is, the terminal position far from the hydroxyl group, including any one of 2-bromoethanol, 3-bromo-1-propanol, 4-bromo-1-butanol, and 5-bromo-1-pentanol; Further, in the reaction described in step (2), the molar ratio of polymer 1, haloalcohol, potassium carbonate and TFA is 1:(1 - 3):(0.2 - 1.2):(0.5 - 1); Further, in the reaction described in step (2), the molar ratio of N,N-diisopropylethylamine to polymer 1 is (0.3 - 0.7):1; Further, the temperature of the reaction described in step (2) is 60 - 90 °C, and the time is 12 - 60 h.

[0014] In the present invention, polymer 2 with different degrees of quaternization reaction is obtained by adjusting the addition amount of halohydrin and potassium carbonate in step (2). The grafting ratio in this step affects the degree of ring-opening reaction with EPTAC in step (3) due to the steric effect. The average number of functional groups on each structural unit is calculated based on the degree of these two steps.

[0015] Further, the molar ratio of polymer 2 to EPTAC in the reaction in step (3) is 1:(0.5-3); Furthermore, in the reaction in step (3), the molar ratio of boron trifluoride ether to polymer 2 is (0.3-0.7):1; Furthermore, the molar ratio of polymer 2 to methyl iodide in the reaction in step (3) is 1:(1-3); Furthermore, in the reaction described in step (3), the temperature for the reaction with EPTAC is 50-70°C, the reaction time is 12-60 h, the temperature for the reaction with iodomethane is room temperature to 45°C, the reaction time is 12-60 h, and the reaction needs to be shielded from light.

[0016] Furthermore, the preparation method of the enhanced anion exchange membrane comprises the following steps: Polyethylene oxide (PEO) is dissolved in a mixture of N,N-dimethylformamide and acetone, and then branched polyethyleneimine (PEI) and bisphenol A diglycidyl ether (DGEBA) are added and reacted at 30-60 °C for 12-36 h. -NH2 in PEI undergoes a ring-opening reaction with the epoxy groups in DGEBA to form a cross-linked network, which is entangled with PEO to form a SIPN solution. Then, the substrate is immersed in the SIPN solution, taken out and dried after a period of time; polymer 3 is dissolved in dimethyl sulfoxide to obtain a polymer solution, and the polymer solution is coated on the surface of the obtained substrate to form a composite film.

[0017] Further, the mass ratio of PEO, PEI and DGEBA is (15-30):1:(1-5); Furthermore, the solid content of the SIPN solution is 0.01-0.05 g / mL.

[0018] In the present invention, by adjusting the solid content of PEO, PEI and DGEBA in the solvent, the solid content determines the amount of SIPN loaded on the substrate. When the solid content is too low, the SIPN loaded on the substrate is too small, and the amount of amino groups is insufficient to react with -CH2Br in the polymer. As a result, the interaction between the two is not obvious. On the contrary, if the solid content is too high, the original structure of the polymer will be destroyed, which will have a negative impact on the performance of the membrane.

[0019] Further, the substrate includes any one of polytetrafluoroethylene, polyphenylene sulfide, polyether ether ketone, polyethylene, and polypropylene-based wire mesh, woven fabric, or non-woven fabric; Further, the thickness of the substrate is 5 - 100 μ m Further, the soaking time of the substrate in the SIPN solution is 1 - 12 h, and the soaking temperature is 25 - 55 °C.

[0020] Further, the mass fraction of the polymer 3 in the polymer solution is 10 - 25 wt%; Further, the compounding of the polymer solution and the substrate into a film includes the following steps: laying the substrate flat on a fixing device, then coating the polymer solution on the surface of the substrate, and drying to obtain the enhanced anion exchange membrane for water electrolysis hydrogen production; The fixing device includes any one of a stretching fixing device, an adsorption fixing device, or a splint fixing device; The coating method is doctor blade coating; The drying method includes any one of heat drying, microwave drying, or ultraviolet drying; The temperature of the heat drying is 60 - 100 °C.

[0021] Further, before use, the enhanced anion exchange membrane for water electrolysis hydrogen production needs to be soaked in an alkali solution to replace all the anions therein with hydroxide ions. The alkali solution includes sodium hydroxide solution or potassium hydroxide solution, with a concentration of 1 - 2 mol / L, the soaking temperature is 50 - 80 °C, and the time is 24 - 60 h.

[0022] In the present invention, polytriphenylpiperidine with excellent rigidity and chemical stability is selected as the polymer backbone. Using the N atom of piperidone on the main chain, haloalcohol is grafted through the Menshutkin reaction, and then epoxy ring-opening reaction occurs between the hydroxyl group and 2,3-epoxypropyltrimethylammonium chloride to obtain a polymer with triphenylpiperidine as the main chain and hydrophilic alkyl groups with quaternary ammonium cations as the side chains. The ether bond spacer chain formed by epoxy ring-opening in the side chain has an electron-donating effect on the one hand, reducing the attack of OH - on the piperidine cation and the quaternary ammonium cation. On the other hand, the good interaction between the ether bond and water molecules is beneficial to expanding the ion conduction region in the channel, thus being beneficial to OH -Transport through the Grotthuss mechanism. In addition, a substrate modified with SIPN is selected as the support reinforcing material to obtain an enhanced anion exchange membrane for hydrogen production by water electrolysis. Combining the excellent strength and dimensional stability of the substrate itself, the mechanical strength and dimensional stability of the film are improved, and finally an enhanced anion exchange membrane for hydrogen production by water electrolysis with stable dimensions, high mechanical strength, high ionic conductivity, good alkali stability and electrolysis performance is obtained.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing an enhanced anion exchange membrane for hydrogen production by water electrolysis. First, its preparation process is simple and easy to achieve mass production; second, the prepared composite polymer alkaline anion exchange membrane has an ionic conductivity of more than 120 mS / cm in an 80 °C, 1 M KOH electrolyte, enabling high-performance hydrogen production in an alkaline anion exchange membrane electrolyzer; finally, the prepared composite polymer alkaline anion exchange membrane has excellent ionic conductivity, mechanical properties, dimensional stability, alkali stability and electrochemical properties, and can meet the requirements of hydrogen production in an alkaline anion exchange membrane electrolyzer under long-term high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1H NMR spectrum of the quaternization product of the side-chain functionalized polyarylpiperidine polymer described in Example 1; Figure 2 Polarization curves of the electrolyzers assembled with the anion exchange membranes provided in Examples 1-5 and Comparative Examples 1-3; Figure 3 Stability performance diagram of the electrolyzer assembled with the enhanced anion exchange membrane provided in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The technical solution of the present invention will be further described below by combining the drawings and specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0026] Example 1 This example provides a method for preparing an enhanced anion exchange membrane for hydrogen production by water electrolysis, and the method includes the following steps: (1) 1 g of p-terphenyl and 0.7 mL of N-methyl-4-piperidone were uniformly dispersed in 5 mL of dichloromethane. Subsequently, a mixed solution of 0.5 mL of TFA and 5.8 mL of TFSA was slowly added dropwise, and the reaction was continued at 0 °C for 6 h. After the reaction was completed, the mixed liquid was precipitated in a 5 M NaOH solution, washed to neutral, and dried in an 80 °C oven for 24 h to obtain Polymer 1.

[0027] (2) First, weigh 1 g of Polymer 1 and add it to 15 mL of DMSO. Add 200 μ μL of TFA to promote dissolution. After stirring and dissolving at room temperature, add 1 eq. of 2-bromoethanol and 0.5 eq. of N,N-diisopropylethylamine according to the molar ratio of Polymer 1. During the reaction, add 0.5 eq. of potassium carbonate in four portions, and raise the temperature to 80 °C and react for 24 h. Then stop heating, precipitate the resulting product with ethyl acetate, collect it and place it in an oven to dry at 80 °C for 24 h to obtain Polymer 2.

[0028] (3) Weigh 1 g of Polymer 2 and add it to 20 mL of DMSO. After complete dissolution, add 1.5 eq. of EPTAC and 100 μ μL of boron trifluoride diethyl etherate according to the molar ratio of Polymer 2. Raise the temperature to 60 °C and react for 24 h. After the reaction solution is cooled to 40 °C, add 800 μ μL of methyl iodide and react for 24 h under light-shielded conditions to completely quaternize the remaining piperidine. After the reaction, wash the precipitation reaction solution with ethyl acetate. Collect and dry to obtain the final side-chain functionalized polyarylpiperidine Polymer 3.

[0029] The structural formula of Polymer 3 is: (4) Dissolve 0.5 g of PEO in a mixed solution of 25 mL of N,N-dimethylformamide and 5 mL of acetone. Then add 0.03 g of PEI and 0.06 g of DGEBA. The solid content of the solution is 0.02 g / mL. React at 50 °C for 24 h to obtain a SIPN solution. Immerse the PPS substrate for 1.5 h and then take it out and dry it at 60 °C. Mix Polymer 3 and dimethyl sulfoxide to obtain a polymer solution, where the mass fraction of the polymer is 15 wt%. Lay the SIPN-substrate flat on the stretching and fixing device, and then use a squeegee to achieve double-sided scraping and filling of the polymer solution. The dosage of the polymer solution per square centimeter on one side of the PPS substrate is 0.025 mL. Heat and dry at 80 °C to obtain the enhanced anion exchange membrane for water electrolysis hydrogen production. Immerse the above enhanced membrane in a potassium hydroxide solution with a concentration of 1.0 mol / L, where the immersion temperature is 80 °C and the time is 24 h, and change the alkali solution every 8 h. Then the enhanced anion exchange membrane of hydroxide type for water electrolysis hydrogen production can be obtained.

[0030] Example 2 This example provides a method for preparing an enhanced anion exchange membrane for water electrolysis hydrogen production, and the method includes the following steps: (1) 1 g of p-terphenyl and 0.7 mL of N-methyl-4-piperidone were evenly dispersed in 5 mL of dichloromethane. Subsequently, a mixed solution of 0.5 mL of TFA and 5.8 mL of TFSA was slowly added dropwise, and the reaction was continuously carried out at 0 °C for 6 h. After the reaction was completed, the mixed liquid was precipitated in 5M NaOH solution, washed to neutrality, and dried in an oven at 80 °C for 24 h to obtain Polymer 1.

[0031] (2) First, 1 g of Polymer 1 was weighed and added to 15 mL of DMSO. 200 μ μL of TFA was added to promote dissolution. After ultrasonic dissolution at room temperature, 2 eq. of 2-bromoethanol and 0.5 eq. of N,N-diisopropylethylamine were added according to the molar ratio of Polymer 1. During the reaction, 0.5 eq. of potassium carbonate was added in four portions, and the temperature was raised to 80 °C for reaction for 24 h. Then the heating was stopped, and the resulting product was precipitated with ethyl acetate, collected and dried in an oven at 80 °C for 24 h to obtain Polymer 2.

[0032] (3) 1 g of Polymer 2 was weighed and added to 20 mL of DMSO. After complete dissolution, 1.5 eq. of EPTAC and 100 μ μL of boron trifluoride diethyl etherate were added according to the molar ratio of Polymer 2. The temperature was raised to 60 °C for reaction for 24 h. After the reaction solution was cooled to 40 °C, 800 μ μL of methyl iodide was added, and the reaction was carried out for 24 h under light-shielded conditions to completely quaternize the remaining piperidine. After the reaction was completed, the reaction solution was washed with ethyl acetate. The final side-chain functionalized polyarylpiperidine Polymer 3 was obtained after collection and drying.

[0033] The structural formula of Polymer 3 is: (4) Dissolve 0.5 g of PEO in a mixed solution of 25 mL of N,N-dimethylformamide and 5 mL of acetone. Then add 0.03 g of PEI and 0.06 g of DGEBA. The solid content of the solution is 0.02 g / mL. React at 50 °C for 24 h to obtain a SIPN solution. Immerse the PPS substrate for 1.5 h and then take it out and dry it at 60 °C. Mix polymer 3 and dimethyl sulfoxide, where the mass fraction of the polymer in dimethyl sulfoxide is 15 wt% to obtain a polymer solution. Lay the SIPN-substrate flat on a stretching and fixing device, and then use a scraper to achieve bilateral scraping and filling of the polymer solution. The dosage of the polymer solution per square centimeter on one side of the PPS substrate is 0.025 mL. After heating and drying at 80 °C, the enhanced anion exchange membrane for hydrogen production by water electrolysis is obtained. Immerse the above enhanced membrane in a sodium hydroxide solution with a concentration of 1.0 mol / L, where the immersion temperature is 80 °C and the time is 24 h, and change the alkali solution every 8 h. Then the enhanced anion exchange membrane of hydroxide type for hydrogen production by water electrolysis can be obtained.

[0034] Example 3 This example provides a method for preparing an enhanced anion exchange membrane for hydrogen production by water electrolysis, and the method includes the following steps: (1) Uniformly disperse 1 g of p-terphenyl and 0.7 mL of N-methyl-4-piperidone in 5 mL of dichloromethane. Subsequently, slowly dropwise add a mixed solution of 0.5 mL of TFA and 5.8 mL of TFSA, and continuously react at 0 °C for 6 h. After the reaction is completed, precipitate the mixed liquid in 5M NaOH solution, wash it until neutral, and dry it in an oven at 80 °C for 24 h to obtain polymer 1.

[0035] (2) First, weigh 1 g of polymer 1 and add it to 15 mL of DMSO. Add 200 μ μL of TFA to promote dissolution. After stirring and dissolving at room temperature, add 2 eq. of 2-bromoethanol and 0.5 eq. of N,N-diisopropylethylamine according to the molar ratio of polymer 1. During the reaction, add 1 eq. of potassium carbonate in four portions and heat up to 80 °C for reaction for 24 h. Then stop heating, precipitate the generated product with ethyl acetate, collect it and put it in an oven to dry at 80 °C for 24 h to obtain polymer 2.

[0036] (3) Weigh 1 g of polymer 2 and add it to 20 mL of DMSO. After complete dissolution, add 1.5 eq. of EPTAC and 100 μ μL of boron trifluoride diethyl etherate according to the molar ratio of polymer 2. Heat up to 60 °C for reaction for 24 h. After the reaction solution is cooled to 40 °C, add 800 μL-iodomethane was reacted for 24 h under light-shielded conditions to completely quaternize the remaining piperidine. After the reaction, the precipitation reaction solution was washed with ethyl acetate. After collection and drying, the final side-chain functionalized polyarylpiperidine polymer 3 was obtained.

[0037] The structural formula of polymer 3 is: (4) 0.5 g of PEO was dissolved in a mixed solution of 25 mL of N,N-dimethylformamide and 5 mL of acetone. Then, 0.03 g of PEI and 0.06 g of DGEBA were added. The solid content of the solution was 0.02 g / mL. The reaction was carried out at 50 °C for 24 h to obtain a SIPN solution. The PPS substrate was immersed for 1.5 h and then taken out and dried at 60 °C. Polymer 3 and dimethyl sulfoxide were mixed, and the mass fraction of the polymer in dimethyl sulfoxide was 15 wt% to obtain a polymer solution. The SIPN-substrate was laid flat on a stretching and fixing device, and then the polymer solution was filled by double-sided scraping with a squeegee. The amount of the polymer solution used per square centimeter on one side of the PPS substrate was 0.025 mL. After heating and drying at 80 °C, the enhanced anion exchange membrane for water electrolysis to produce hydrogen was obtained. The above enhanced membrane was soaked in a potassium hydroxide solution with a concentration of 1.0 mol / L, where the soaking temperature was 80 °C and the time was 24 h, and the alkali solution was replaced every 8 h. Thus, the hydroxide-type enhanced anion exchange membrane for water electrolysis to produce hydrogen was obtained.

[0038] Example 4 This example provides a method for preparing an enhanced anion exchange membrane for water electrolysis to produce hydrogen, and the method includes the following steps: (1) 1 g of p-terphenyl and 0.7 mL of N-methyl-4-piperidone were uniformly dispersed in 5 mL of dichloromethane. Subsequently, a mixed solution of 0.5 mL of TFA and 5.8 mL of TFSA was slowly added dropwise, and the reaction was continuously carried out at 0 °C for 6 h. After the reaction ended, the mixed liquid was precipitated in 5M NaOH solution, washed to neutrality, and dried in an 80 °C oven for 24 h to obtain polymer 1.

[0039] (2) First, 1 g of polymer 1 was weighed and added to 15 mL of DMSO, and 200 μ L of TFA was added to promote dissolution. After stirring and dissolving at room temperature, 1 eq. of 2-bromoethanol and 0.5 eq. of N,N-diisopropylethylamine were added according to the molar ratio of polymer 1. During the reaction, 0.5 eq. of potassium carbonate was added in four portions, and the temperature was raised to 80 °C and the reaction was carried out for 24 h. Then, the heating was stopped, and the generated product was precipitated with ethyl acetate, collected and dried in an 80 °C oven for 24 h to obtain polymer 2.

[0040] (3) Weigh 1 g of Polymer 2 and add it to 20 mL of DMSO. After complete dissolution, add 1.5 eq. of EPTAC and 100 μ mL of boron trifluoride diethyl etherate. Heat the mixture to 60 °C and react for 24 h. After the reaction solution is cooled to 40 °C, add 800 μ mL of methyl iodide and react for 24 h under light-shielded conditions to completely quaternize the remaining piperidine. After the reaction, wash the precipitate reaction solution with ethyl acetate. After collection and drying, the final side-chain functionalized polyarylpiperidine polymer 3 is obtained.

[0041] The structural formula of Polymer 3 is: (4) Dissolve 0.25 g of PEO in a mixed solution of 25 mL of N,N-dimethylformamide and 5 mL of acetone. Then add 0.015 g of PEI and 0.03 g of DGEBA. The solid content of the solution is 0.01 g / mL. React at 50 °C for 24 h to obtain a SIPN solution. Immerse the PPS substrate for 1.5 h and then take it out and dry it at 60 °C. Mix Polymer 3 and dimethyl sulfoxide, where the mass fraction of the polymer in dimethyl sulfoxide is 15 wt% to obtain a polymer solution. Lay the SIPN-substrate flat on a stretching and fixing device, and then use a squeegee to achieve double-sided scraping and filling of the polymer solution. The dosage of the polymer solution per square centimeter on one side of the PPS substrate is 0.025 mL. After heating and drying at 80 °C, the enhanced anion exchange membrane for hydrogen production by water electrolysis is obtained. Immerse the above enhanced membrane in a potassium hydroxide solution with a concentration of 1.0 mol / L, where the immersion temperature is 80 °C and the time is 24 h, and change the alkali solution every 8 h. The hydroxide-type enhanced anion exchange membrane for hydrogen production by water electrolysis can be obtained.

[0042] Example 5 This example provides a method for preparing an enhanced anion exchange membrane for hydrogen production by water electrolysis, and the method includes the following steps: (1) Uniformly disperse 1 g of p-terphenyl and 0.7 mL of N-methyl-4-piperidone in 5 mL of dichloromethane. Subsequently, slowly dropwise add a mixed solution of 0.5 mL of TFA and 5.8 mL of TFSA, and continuously react at 0 °C for 6 h. After the reaction, precipitate the mixed liquid in 5 M NaOH solution, wash it to neutral, and dry it in an 80 °C oven for 24 h to obtain Polymer 1.

[0043] (2) First, weigh 1 g of Polymer 1 and add it to 15 mL of DMSO, and add 200 μL TFA promotes dissolution. After stirring and dissolving at room temperature, 1 eq. of 2-bromoethanol and 0.5 eq. of N,N-diisopropylethylamine are added according to the molar ratio of polymer 1. During the reaction, 0.5 eq. of potassium carbonate is added in four portions, and the temperature is raised to 80 °C for reaction for 24 h. Then the heating is stopped, and the resulting product is precipitated with ethyl acetate, collected and placed in an oven for drying at 80 °C for 24 h to obtain polymer 2.

[0044] (3) Weigh 1 g of polymer 2 and add it to 20 mL of DMSO. After complete dissolution, 1.5 eq. of EPTAC and 100 μ L of boron trifluoride diethyl etherate are added according to the molar ratio of polymer 1. The temperature is raised to 60 °C for reaction for 24 h. After the reaction solution is cooled to 40 °C, 800 μ L of methyl iodide is added, and the reaction is carried out for 24 h under light-shielded conditions to completely quaternize the remaining piperidine. After the reaction is completed, the precipitate reaction solution is washed with ethyl acetate. After collection and drying, the final side-chain functionalized polyarylpiperidine polymer 3 is obtained.

[0045] The structural formula of polymer 3 is: (4) Dissolve 0.75 g of PEO in a mixed solution of 25 mL of N,N-dimethylformamide and 5 mL of acetone, then add 0.045 g of PEI and 0.09 g of DGEBA. The solid content of the solution is 0.03 g / mL, and the reaction is carried out at 50 °C for 24 h to obtain a SIPN solution. The PPS substrate is immersed for 1.5 h and then taken out and dried at 60 °C. Polymer 3 and dimethyl sulfoxide are mixed, and the mass fraction of the polymer in dimethyl sulfoxide is 15 wt% to obtain a polymer solution. The SIPN-substrate is laid flat on a stretching fixing device, and then the polymer solution is filled by double-sided scraping with a scraper. The dosage of the polymer solution per square centimeter on one side of the PPS substrate is 0.025 mL. After heating and drying at 80 °C, the enhanced anion exchange membrane for hydrogen production by water electrolysis is obtained. The above enhanced membrane is immersed in a potassium hydroxide solution with a concentration of 1.0 mol / L, the immersion temperature is 80 °C, and the time is 24 h, and the alkali solution is replaced every 8 h. The enhanced anion exchange membrane of hydroxide type for hydrogen production by water electrolysis can be obtained.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that in the comparative example, polymer 1 undergoes a quaternization reaction with 1.5 eq. of methyl iodide, that is, no functionalized side chain is grafted.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that the polymer solution obtained in step (4) is directly cast into a film without using the SIPN-PPS substrate. The amount of the polymer solution used per square centimeter of the casting area is 0.05 mL, and a homogeneous film is finally obtained. Other conditions are the same as those in Example 1.

[0048] Comparative Example 3 The difference between this comparative example and Example 1 is that the substrate is not modified with SIPN, and other conditions are the same as those in Example 1.

[0049] Test conditions The enhanced anion exchange membranes for water electrolysis hydrogen production provided in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to performance tests. The test methods are as follows: (1) Ion exchange capacity: The IEC of the anion exchange membrane sample was measured by the back titration method. The fully dried anion exchange membrane was soaked in 1 mol L -1 NaOH solution at room temperature for 48 h to ensure that the anions in the membrane after the quaternization process were fully converted by OH - . A certain mass of the membrane sample was taken, and the residual OH on the surface was rinsed off with deionized water - . Then, it was soaked in 0.01 mol L -1 HCl solution at room temperature for 48 h to fully neutralize the OH in the membrane with acid - . Then, the membrane was taken out, and the remaining HCl solution was titrated with 0.01 mol L -1 NaOH solution, and the pH meter was used to accurately judge the titration end point. The volume of the NaOH solution consumed during the test was recorded. The ion exchange capacity (IEC) of the anion exchange membrane can be calculated by the formula: IEC = (C1V1 - C2V2) / m dry , where: C1 and C2 represent the concentrations of the standard solutions of HCl and NaOH respectively, V1 and V2 represent the volumes of the standard solutions of HCl and NaOH respectively, and m dry is the weight of the dried anion sample membrane.

[0050] (2) Water absorption and swelling ratio: The membrane in the OH - form was cut into pieces of 30 mm * 30 mm in size and soaked in deionized water at 80 °C for 24 h to make it in a fully hydrated state. Then, the membrane sample was taken out, and the residual water on the membrane surface was gently wiped off with filter paper, and its weight was weighed and the length and width of the membrane were measured to obtain the wet weight (m wet ) and the wet size length (L wet). Then place the membrane in a vacuum drying oven at 80 °C and dry it until the weight is constant. At this time, weigh the membrane again to obtain the dry weight (m dry ), and measure the length and width of the membrane to obtain the dry-state length (L dry ) of the membrane. The water uptake (WU) and swelling ratio (SR) of the anion sample membrane can be calculated by the formula: WU = (m wet - m dry ) / m dry * 100%, SR = (L wet - L dry ) / L dry * 100%.

[0051] (3) Ionic conductivity Use an electrochemical workstation to test the OH - conductivity of the membrane. Clamp the membrane sample in the form of OH - with a size of 30 mm * 30 mm on the ionic conductivity test fixture, connect the fixture to the electrochemical workstation, and the test is carried out under two-electrode alternating current. The frequency of the alternating current is 1 Hz - 100 kHz. The Nyquist curve of the anion exchange membrane at different temperatures is measured, and the impedance R of the membrane can be obtained after fitting. The test process of the membrane in the form of OH - is protected by nitrogen to avoid the influence of CO2 on the test results. Test the ionic conductivity of OH - of the membrane at 80 °C. The ionic conductivity of the anion exchange membrane can be calculated by the formula (2 - 7): σ = L / (R * S), where σ is the ionic conductivity (mS cm -1 ) of the sample membrane, L represents the thickness (cm) of the membrane, R is the resistance (Ω) inside the membrane, and S is the contact area (cm -2 ) between the electrode and the membrane.

[0052] (4) Tensile strength and elongation at break Use an electronic universal testing machine to test the tensile strength and elongation at break of the membrane in a fully wetted state to evaluate the mechanical properties of the membrane. Cut the anion exchange membrane sample into rectangular splines with a length of 8 cm and a width of 2 cm, and the test is carried out at room temperature with a tensile rate of 3 mm / min -1 .

[0053] Assemble the electrolytic cells provided in Examples 1 to 5 and Comparative Examples 1 to 3 with the enhanced anion exchange membranes having covalent connection interfaces for performance testing. The anode and cathode catalysts are NiFe / NF and NiCoP / NF respectively. Test the alkaline membrane polarization curve in 1M KOH solution at 80 °C.

[0054] The test results are shown in Table 1 as follows: Table 1 a OH - Form film, 80 °C.

[0055] It can be seen from Table 1 that based on the above test results, Example 1 is a preferred technical solution. Table 1 shows that its ion conductivity, tensile strength and elongation at break are optimal. Figure 2 This indicates that the electrolytic cell assembled by the method has a smaller polarization. Figure 3 It shows that the electrolytic cell assembled has good stability, so Example 1 has good comprehensive performance. Secondly, by adjusting the solid content of PEO, PEI and PEGDGE in the solvent, the solid content of the solution and the loading amount of SIPN on PPS are appropriate. The solid content determines the amount of SIPN loaded on the substrate. When the solid content is too low, the SIPN loaded on the substrate is too small, and the interaction between the two is not obvious. On the contrary, if the solid content is too high, it will destroy the original organic structure of the polymer. Both situations ultimately lead to poor film-forming performance; finally, Comparative Example 1 shows that the introduction of a flexible side chain structure inhibits the entanglement of polymer molecular chains, plays a role similar to that of a plasticizer, reduces the tensile strength of the film, and increases the elongation at break of the film. It shows that the structural design strategy of combining hydrophilic alkyl side chains with hydrophobic ether-free main chains is a feasible way to improve the comprehensive performance of AEM. Comparative Examples 2 and 3 show that after the polymer solution is composited with the SIPN-modified substrate to form a film, the enhanced film tensile strength and dimensional stability are significantly better than the corresponding performance parameters of the homogeneous film and the composite membrane without SIPN modification, indicating that this method can effectively improve the mechanical properties of the film.

[0056] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An enhanced anion exchange membrane for hydrogen production by water electrolysis, characterized in that, The components of the enhanced anion exchange membrane include a polymer resin A and a substrate modified with semi-interpenetrating polymer SIPN; The polymer resin A is a side-chain functionalized poly(p-terphenylpiperidine) polymer with the structure shown by the following formula: where n = 2 - 5; x, y, and z represent the proportions of the polymer units in the polymer chain segment, and their values are between 0 - 100%, and the sum of x, y, and z is 100%.

2. The enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 1, wherein The preparation method of the side-chain functionalized poly(p-terphenylpiperidine) polymer includes the following steps: (1) p-Terphenyl and N-methyl-4-piperidone are evenly dispersed in dichloromethane, and then the catalyst is dropped in. After the reaction ends, the mixed liquid is precipitated in NaOH solution, the filtered product is washed to neutrality, collected and dried in an oven at 80 °C to obtain Polymer 1; (2) Polymer 1 is added to DMSO, and trifluoroacetic acid TFA is added to promote dissolution. After stirring or ultrasonic dissolution at room temperature, a haloalcohol and the catalyst N,N-diisopropylethylamine are added. During the reaction, the acid-binding agent potassium carbonate is added in portions; after the reaction ends, the resulting product is precipitated with ethyl acetate, and the obtained solid is dried in an oven at 80 °C to obtain Polymer 2; (3) Polymer 2 is dissolved in DMSO, 2,3-epoxypropyltrimethylammonium chloride EPTAC and the catalyst boron trifluoride diethyl etherate are added, the reaction temperature is 50 - 70 °C, and the reaction time is 12 - 60 h; after the reaction ends, the reaction solution is cooled, and methyl iodide is added to continue the reaction, the reaction temperature is from room temperature to 45 °C, and the reaction time is 12 - 60 h, and the reaction needs to be carried out in the dark; after the reaction ends, the precipitate reaction solution is washed with ethyl acetate, and the obtained solid is dried to obtain the side-chain functionalized poly(p-terphenylpiperidine) polymer.

3. The enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 2, wherein, In step (1), the catalyst is a combination of trifluoroacetic acid TFA and trifluoromethanesulfonic acid TFAS, and the volume ratio of the two is 1:(8 - 15); In step (1), the molar ratio of p-terphenyl, N-methyl-4-piperidone to trifluoroacetic acid TFA is 1:(1 - 3):(1 - 2); In step (1), the reaction temperature is 0 °C, and the reaction time is 1 - 12 h.

4. An enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 2, characterized in that, In step (2), the haloalcohol includes any one of 2-bromoethanol, 3-bromo-1-propanol, 4-bromo-1-butanol, 5-bromo-1-pentanol; In step (2), the molar ratio of Polymer 1, haloalcohol, potassium carbonate, and TFA is 1:(1 - 3):(0.2 - 1.2):(0.5 - 1); In step (2), the molar ratio of N,N-diisopropylethylamine to Polymer 1 is (0.3 - 0.7):1; In step (2), the reaction temperature is 60 - 90 °C, and the reaction time is 12 - 60 h.

5. The enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 2, wherein, In step (3), the molar ratio of Polymer 2 and EPTAC is 1:(0.5 - 3); In step (3), the molar ratio of boron trifluoride diethyl etherate to Polymer 2 is (0.3 - 0.7):1; In step (3), the molar ratio of Polymer 2 and methyl iodide is 1:(1 - 3).

6. The preparation method of an enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 1, characterized in that, The preparation method of the enhanced anion exchange membrane includes the following steps: Polyethylene oxide (PEO) is dissolved in a mixed solution of N,N-dimethylformamide and acetone. Subsequently, branched polyethyleneimine (PEI) and bisphenol A diglycidyl ether (DGEBA) are added, and the reaction is carried out at 30 - 60 °C for 12 - 36 h to form a semi-interpenetrating polymer network (SIPN) solution. Then, the substrate is immersed in the SIPN solution and taken out and dried after a period of time. The high molecular resin A is dissolved in DMSO to obtain a polymer solution, and the polymer solution is coated on the surface of the obtained substrate to form a composite film.

7. The preparation method of an enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 6, characterized in that, The mass ratio of PEO, PEI, and DGEBA is (15 - 30):1:(1 - 5); The solid content of the SIPN solution is 0.01 - 0.05 g / mL.

8. The preparation method of an enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 6, characterized in that, The substrate includes any one of wire meshes, woven fabrics, and non-woven fabrics made of polytetrafluoroethylene, polyphenylene sulfide, polyether ether ketone, polyethylene, and polypropylene; The thickness of the base material is 5-100 μ m; The immersion time of the substrate in the SIPN solution is 1 - 12 h, and the immersion temperature is 25 - 55 °C.

9. The preparation method of an enhanced anion exchange membrane for hydrogen production by water electrolysis according to claim 6, characterized in that, The mass fraction of the high molecular resin A in the polymer solution is 10 - 25 wt%.

10. According to the preparation method of an enhanced anion exchange membrane for hydrogen production by water electrolysis described in claim 6, before use, the enhanced anion exchange membrane for hydrogen production by water electrolysis needs to be immersed in an alkali solution to replace all the anions therein with hydroxide ions. The alkali solution includes sodium hydroxide solution or potassium hydroxide solution, with a concentration of 1 - 2 mol / L, an immersion temperature of 50 - 80 °C, and a time of 24 - 60 h.

Images