A modified sulfonated polyether ether ketone proton exchange membrane, a preparation method and application thereof

Abstract

The application discloses a modified sulfonated polyether ether ketone proton exchange membrane and a preparation method and application thereof. The modified sulfonated polyether ether ketone proton exchange membrane comprises sulfonated polyether ether ketone with a sulfonation degree of 85-90% and triazine biphenyl compounds with isocyanate groups; and the mass ratio of the sulfonated polyether ether ketone and the triazine biphenyl compounds with isocyanate groups is 100:(5-10). The proton exchange membrane is prepared by modifying the sulfonated polyether ether ketone with the triazine biphenyl compounds with isocyanate groups, and the mechanical strength and the dimensional stability of the high-sulfonation-degree polyether ether ketone proton exchange membrane can be effectively improved, the vanadium ion permeation rate is reduced, and the comprehensive use performance is good under the condition of keeping good proton conductivity. The proton exchange membrane can be used for a hydrogen fuel cell or a hydrogen production electrolytic cell.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane technology, specifically to a modified sulfonated polyether ether ketone proton exchange membrane, its preparation method, and its applications. Background Technology

[0002] With the development of clean energy technologies such as fuel cells, hydrogen energy, and water electrolysis for hydrogen production, the proton exchange membrane (PEM), as a core component of fuel cells, directly determines the overall efficiency and lifespan of the fuel cell. Currently, the most widely used PEMs on the market are mainly represented by perfluorosulfonic acid resins (such as Nafion). However, the high cost of perfluorosulfonic acid resins has always been one of the main factors hindering the commercialization of fuel cells. In recent years, sulfonated polyether ether ketone (SPEEK) has emerged as a low-cost PEM material, achieving high proton conductivity in the hydrated state. However, it also presents some problems. For example, while increasing the degree of sulfonation can enhance proton conductivity, it also increases water absorption. Excessive water absorption and swelling can exacerbate vanadium ion penetration. Conversely, decreasing the degree of sulfonation reduces proton transport sites and lowers proton conductivity. Therefore, how to avoid increasing vanadium ion penetration and reducing mechanical strength due to excessive sulfonation, while simultaneously ensuring the proton conductivity of the SPEEK membrane, has become a pressing technical problem for the industry. Summary of the Invention

[0003] In view of the problems existing in the background art, the purpose of the present invention is to provide a modified sulfonated polyether ether ketone proton exchange membrane. This proton exchange membrane is modified by sulfonated polyether ether ketone with triazine biphenyl compounds containing isocyanate groups. While maintaining good proton conductivity, it can effectively improve the mechanical strength and dimensional stability of high-sulfonated polyether ether ketone proton exchange membranes, reduce vanadium ion permeability, and has better comprehensive performance.

[0004] To achieve the above objectives, in a first aspect, the present invention provides a modified sulfonated polyether ether ketone proton exchange membrane, comprising sulfonated polyether ether ketone with a sulfonation degree of 85-90% and a triazine biphenyl compound with an isocyanate group; wherein the mass ratio of the sulfonated polyether ether ketone to the triazine biphenyl compound with an isocyanate group is 100:(5-10).

[0005] Preferably, the method for preparing the triazine biphenyl compound with isocyanate group includes the following steps: (1) In a reaction vessel, 1 mol of 4-hydroxybiphenyl-4-nitrile is dissolved in 1 L of dichloromethane at a molar ratio. Under the protection of an inert gas, 1 mol of ZnCl2 is added dropwise while maintaining the temperature at 0°C in an ice-water bath. The mixture is stirred continuously until the liquid phase is homogeneous. Then, the temperature is slowly raised to room temperature and reacted for 16 h. Ammonia is added dropwise to adjust the pH value to neutral. The crude product is obtained by filtration. (2) The crude product is washed with deionized water and acetone is used. Purification was carried out by recrystallization and vacuum drying to obtain 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine; (3) The 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine from step (2) was dissolved in 800 mL of N,N'-dimethylformamide, and the temperature was controlled at 80-90 °C under nitrogen protection. 0.3 mol of toluene diisocyanate was added dropwise, and the reaction was maintained for 2-3 h. The solvent was removed to obtain triazine biphenyl compounds with isocyanate groups.

[0006] Secondly, the present invention also provides a method for preparing a modified sulfonated polyether ether ketone proton exchange membrane, comprising the following steps: (1) weighing sulfonated polyether ether ketone, triazine biphenyl compound with isocyanate group and organic solvent according to mass ratio and adding them to a three-necked beaker, heating and stirring under nitrogen protection to fully dissolve them, and obtaining a high-viscosity mixture; (2) scraping the high-viscosity mixture onto the surface of a glass plate, then placing it in a vacuum drying oven to dry to constant weight, restoring normal pressure and cooling to room temperature, taking it out, peeling it off, and obtaining the modified sulfonated polyether ether ketone proton exchange membrane.

[0007] Preferably, the organic solvent is one of N,N'-dimethylformamide, N,N'-dimethylacetamide, and dimethyl sulfoxide.

[0008] Preferably, the mass ratio of the sulfonated polyether ether ketone, the triazine biphenyl compound with isocyanate group, and the organic solvent is 100:(5-10):300.

[0009] Preferably, the heating temperature in step (1) is 110-120℃ and the stirring time is 10-12h.

[0010] Preferably, the drying temperature in step (2) is 120°C, the vacuum degree is 0.1 MPa, and the drying time is 24 h.

[0011] Thirdly, the present invention also provides an application of a modified sulfonated polyether ether ketone proton exchange membrane, which can be used as a membrane in hydrogen fuel cells or hydrogen electrolyzers.

[0012] Fourthly, the present invention also provides a hydrogen fuel cell comprising the above-described modified sulfonated polyether ether ketone proton exchange membrane.

[0013] The beneficial effects of this invention are as follows: The triazine biphenyl compounds with isocyanate groups prepared in this invention have a three-dimensional symmetrical rigid structure and high thermal stability. Furthermore, the isocyanate groups on the benzene ring undergo a graft crosslinking reaction with the sulfonic acid groups of sulfonated polyether ether ketone under heating, forming a three-dimensional network in structure and increasing the crosslinking density. This results in high-sulfonation polyether ether ketone exhibiting better mechanical properties and mechanical stability while maintaining suitable proton conductivity. Moreover, the triazine biphenyl structure and sulfonyl groups present in the resin can significantly reduce vanadium ion permeability, resulting in good overall performance. Detailed Implementation

[0014] To make the above-mentioned objects, features and advantages of the invention more apparent and understandable, the specific embodiments of the invention are described in detail below.

[0015] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0016] First, a modified sulfonated polyether ether ketone proton exchange membrane according to a first aspect of the present invention is described, comprising sulfonated polyether ether ketone with a sulfonation degree of 85-90% and a triazine biphenyl compound with an isocyanate group; wherein the mass ratio of the sulfonated polyether ether ketone to the triazine biphenyl compound with an isocyanate group is 100:(5-10).

[0017] In one embodiment, the preparation method of triazine biphenyl compounds with isocyanate groups includes the following steps: (1) In a reaction vessel, 1 mol of 4-hydroxybiphenyl-4-nitrile is dissolved in 1 L of dichloromethane at a molar ratio. Under the protection of an inert gas and at 0°C in an ice-water bath, 1 mol of ZnCl2 is added dropwise. The mixture is stirred continuously until the liquid phase is homogeneous. Then, the temperature is slowly raised to room temperature and reacted for 16 h. Ammonia is added dropwise to adjust the pH value to neutral. The crude product is obtained by filtration. (2) The crude product is washed with deionized water and then subjected to acetone treatment. The ketone was purified by recrystallization and dried under vacuum to obtain 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine; (3) The 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine from step (2) was dissolved in 800 mL of N,N'-dimethylformamide. Under nitrogen protection, the temperature was controlled at 80-90 °C, and 0.3 mol of toluene diisocyanate was added dropwise. The reaction was maintained for 2-3 h, and the solvent was removed to obtain triazine biphenyl compounds with isocyanate groups.

[0018] Secondly, a method for preparing a modified sulfonated polyether ether ketone proton exchange membrane according to the present invention is described, comprising the following steps: (1) weighing sulfonated polyether ether ketone, triazine biphenyl compound with isocyanate group and organic solvent according to mass ratio and adding them to a three-necked beaker, heating and stirring under nitrogen protection to fully dissolve them, and obtaining a high-viscosity mixture; (2) scraping the high-viscosity mixture onto the surface of a glass plate, then placing it in a vacuum drying oven to dry to constant weight, restoring normal pressure and cooling to room temperature, taking it out, peeling it off, and obtaining the modified sulfonated polyether ether ketone proton exchange membrane.

[0019] In one embodiment, the organic solvent is one of N,N'-dimethylformamide, N,N'-dimethylacetamide, and dimethyl sulfoxide.

[0020] In one embodiment, the mass ratio of sulfonated polyether ether ketone, triazine biphenyl compound with isocyanate group and organic solvent is 100:(5-10):300.

[0021] In one embodiment, the heating temperature in step (1) is 110-120°C and the stirring time is 10-12h.

[0022] In one embodiment, the drying temperature in step (2) is 120°C, the vacuum degree is 0.1 MPa, and the drying time is 24 h.

[0023] Furthermore, the application of the modified sulfonated polyether ether ketone proton exchange membrane according to the present invention can be described, and it can be used as a membrane in a hydrogen fuel cell or a hydrogen electrolyzer.

[0024] Finally, a hydrogen fuel cell according to the present invention is described, comprising the above-described modified sulfonated polyether ether ketone proton exchange membrane.

[0025] To more clearly demonstrate the technical solution and its effects provided by the present invention, the modified sulfonated polyether ether ketone proton exchange membrane and its preparation method provided by the present invention will be described in detail below with reference to specific embodiments.

[0026] Example 1 1. Preparation of triazine biphenyl compounds with isocyanate groups (1) In a reaction vessel, 1 mol of 4-hydroxybiphenyl-4-nitrile was dissolved in 1 L of dichloromethane. Under the protection of an inert gas, 1 mol of ZnCl2 was added dropwise while maintaining the temperature at 0°C in an ice-water bath. The mixture was stirred until the liquid phase was homogeneous. Then, the temperature was slowly raised to room temperature and reacted for 16 h. Ammonia was added dropwise to adjust the pH value to neutral. The crude product was obtained by filtration. (2) The crude product was washed with deionized water, purified by recrystallization with acetone, and dried under vacuum to obtain 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine; (3) Dissolve the 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine from step (2) in 800 mL of N,N'-dimethylformamide, control the temperature at 80 °C under nitrogen protection, add 0.3 mol of toluene diisocyanate dropwise, maintain the reaction for 2 h, remove the solvent, and obtain triazine biphenyl compounds with isocyanate groups.

[0027] 2. Film formation (1) Weigh 100 parts of sulfonated polyether ether ketone with a sulfonation degree of 85%, 5 parts of triazine biphenyl compound with isocyanate group and 300 parts of organic solvent according to the mass ratio, add them to a three-necked beaker, heat the temperature to 110℃ and stir for 10h to fully dissolve them to obtain a high viscosity mixture. (2) The high viscosity mixture is scraped onto the surface of a glass plate and then placed in a vacuum drying oven to dry to constant weight. The drying temperature is 120°C, the vacuum degree is 0.1MPa, and the drying time is 24h. After restoring to normal pressure and cooling to room temperature, it is taken out and peeled off to obtain a modified sulfonated polyether ether ketone proton exchange membrane with a thickness of 20μm.

[0028] Example 2 1. Preparation of triazine biphenyl compounds with isocyanate groups (1) In a reaction vessel, 1 mol of 4-hydroxybiphenyl-4-nitrile was dissolved in 1 L of dichloromethane. Under the protection of an inert gas, 1 mol of ZnCl2 was added dropwise while maintaining the temperature at 0°C in an ice-water bath. The mixture was stirred until the liquid phase was homogeneous. Then, the temperature was slowly raised to room temperature and reacted for 16 h. Ammonia was added dropwise to adjust the pH value to neutral. The crude product was obtained by filtration. (2) The crude product was washed with deionized water, purified by recrystallization with acetone, and dried under vacuum to obtain 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine; (3) Dissolve the 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine from step (2) in 800 mL of N,N'-dimethylformamide, control the temperature at 90 °C under nitrogen protection, add 0.3 mol of toluene diisocyanate dropwise, maintain the reaction for 3 h, remove the solvent, and obtain triazine biphenyl compounds with isocyanate groups.

[0029] 2. Film formation (1) Weigh 100 parts of sulfonated polyether ether ketone with a sulfonation degree of 90%, 10 parts of triazine biphenyl compound with isocyanate group and 300 parts of organic solvent according to the mass ratio, add them to a three-necked beaker, heat the temperature to 120℃ and stir for 12h to fully dissolve them to obtain a high viscosity mixture. (2) The high viscosity mixture is scraped onto the surface of a glass plate and then placed in a vacuum drying oven to dry to constant weight. The drying temperature is 120°C, the vacuum degree is 0.1MPa, and the drying time is 24h. After restoring to normal pressure and cooling to room temperature, it is taken out and peeled off to obtain a modified sulfonated polyether ether ketone proton exchange membrane with a thickness of 20μm.

[0030] Example 3 1. Preparation of triazine biphenyl compounds with isocyanate groups (1) In a reaction vessel, 1 mol of 4-hydroxybiphenyl-4-nitrile was dissolved in 1 L of dichloromethane. Under the protection of an inert gas, 1 mol of ZnCl2 was added dropwise while maintaining the temperature at 0°C in an ice-water bath. The mixture was stirred until the liquid phase was homogeneous. Then, the temperature was slowly raised to room temperature and reacted for 16 h. Ammonia was added dropwise to adjust the pH value to neutral. The crude product was obtained by filtration. (2) The crude product was washed with deionized water, purified by recrystallization with acetone, and dried under vacuum to obtain 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine; (3) Dissolve the 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine from step (2) in 800 mL of N,N'-dimethylformamide, control the temperature at 85 °C under nitrogen protection, add 0.3 mol of toluene diisocyanate dropwise, maintain the reaction for 2.5 h, remove the solvent, and obtain triazine biphenyl compounds with isocyanate groups.

[0031] 2. Film formation (1) Weigh 100 parts of sulfonated polyether ether ketone with a sulfonation degree of 88%, 8 parts of triazine biphenyl compound with isocyanate group and 300 parts of organic solvent according to the mass ratio, add them to a three-necked beaker, heat at 115°C and stir for 11 hours to fully dissolve, and obtain a high viscosity mixture. (2) The high viscosity mixture is scraped onto the surface of a glass plate and then placed in a vacuum drying oven to dry to constant weight. The drying temperature is 120°C, the vacuum degree is 0.1MPa, and the drying time is 24h. After restoring to normal pressure and cooling to room temperature, it is taken out and peeled off to obtain a modified sulfonated polyether ether ketone proton exchange membrane with a thickness of 20μm.

[0032] Comparative Example 1 Except for the absence of triazine biphenyl compounds with isocyanate groups, the process was the same as in Example 3.

[0033] Performance testing 1. Swelling rate and water absorption rate: The swelling rate and water absorption rate (25℃) of the proton exchange membrane are the percentage changes in length and mass of the membrane in the wet state relative to the dry state. The dry state is the initial state, and the wet state is the state of the membrane after being immersed in deionized water at room temperature for 24 hours.

[0034] 2. Mechanical strength: At room temperature, dumbbell-shaped specimen, 10mm wide and 35mm long, tensile speed of universal testing machine is 5mm / min.

[0035] 3. Proton transfer rate: Using the Solatron 1260 electrochemical workstation, with a frequency range of 0.1 Hz to 1 MHz and a voltage amplitude of 10 mV, the proton transfer rate ρ = distance D between the working electrode and the counter electrode / (membrane impedance R × effective membrane area S × 10⁻⁶). 7 ).

[0036] 4. Vanadium ion permeability: H-type diffusion cell (effective area 1.77 cm²) 2 The diffusion cell contained 50 mL of 1.5 M MgSO4 / 3.0 M H2SO4 solution on one side and the same volume of 1.5 M MgSO4 / 3.0 M H2SO4 solution on the other side. Samples were taken from the MgSO4 / H2SO4 solution every 24 hours, and the absorbance was measured at 762 nm using a UV-Vis spectrophotometer. VO2+ was determined using a standard absorbance / concentration curve. 2+ The concentration of vanadium is used to calculate the vanadium permeation rate according to standards.

[0037] The test results are shown in Table 1.

[0038] Table 1 As can be seen from the examples and comparative data, the present invention modifies sulfonated polyether ether ketone by adding triazine biphenyl compounds with isocyanate groups to sulfonated polyether ether ketone with high sulfonation degree. While maintaining good proton conductivity, it can effectively improve the mechanical strength and dimensional stability of high sulfonated polyether ether ketone proton exchange membranes, reduce vanadium ion permeability, and has good comprehensive performance.

[0039] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A modified sulfonated polyetheretherketone proton exchange membrane, characterized in that, The compound comprises sulfonated polyether ether ketone with a sulfonation degree of 85-90% and triazine biphenyl compounds with isocyanate groups; the mass ratio of the sulfonated polyether ether ketone to the triazine biphenyl compound with isocyanate groups is 100:(5-10); the preparation method of the triazine biphenyl compound with isocyanate groups includes the following steps: (1) In a reaction vessel, 1 mol of 4-hydroxybiphenyl-4-nitrile was dissolved in 1 L of dichloromethane. Under the protection of an inert gas, 1 mol of ZnCl2 was added dropwise while maintaining the temperature at 0°C in an ice-water bath. The mixture was stirred until the liquid phase was homogeneous. Then, the temperature was slowly raised to room temperature and reacted for 16 h. Ammonia was added dropwise to adjust the pH value to neutral. The crude product was obtained by filtration. (2) The crude product was washed with deionized water, purified by recrystallization with acetone, and dried under vacuum to obtain 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine; (3) Dissolve the 2,4,6-tris(4'-hydroxybiphenyl)-1,3,5-triazine from step (2) in 800 mL of N,N'-dimethylformamide, control the temperature at 80-90 °C under nitrogen protection, add 0.3 mol of toluene diisocyanate dropwise, maintain the reaction for 2-3 h, remove the solvent, and obtain triazine biphenyl compounds with isocyanate groups.

2. The method for preparing the modified sulfonated polyether ether ketone proton exchange membrane as described in claim 1, characterized in that, Includes the following steps: (1) Weigh sulfonated polyether ether ketone, triazine biphenyl compound with isocyanate group and organic solvent according to the mass ratio and add them to a three-necked beaker. Heat and stir under nitrogen protection to fully dissolve and obtain a high viscosity mixture. (2) The high viscosity mixture is scraped onto the surface of a glass plate, then placed in a vacuum drying oven to dry to constant weight, restored to normal pressure and cooled to room temperature, then taken out and peeled off to obtain a modified sulfonated polyether ether ketone proton exchange membrane.

3. The method for preparing the modified sulfonated polyether ether ketone proton exchange membrane as described in claim 2, characterized in that, The organic solvent is one of N,N'-dimethylformamide, N,N'-dimethylacetamide, and dimethyl sulfoxide.

4. The method for preparing the modified sulfonated polyether ether ketone proton exchange membrane as described in claim 2, characterized in that, The mass ratio of the sulfonated polyether ether ketone, the triazine biphenyl compound with isocyanate group, and the organic solvent is 100:(5-10):

300.

5. The method for preparing the modified sulfonated polyether ether ketone proton exchange membrane as described in claim 2, characterized in that, The heating temperature in step (1) is 110-120℃, and the stirring time is 10-12h.

6. The method for preparing the modified sulfonated polyether ether ketone proton exchange membrane as described in claim 2, characterized in that, The drying temperature in step (2) is 120°C, the vacuum degree is 0.1 MPa, and the drying time is 24 h.

7. The application of the modified sulfonated polyether ether ketone proton exchange membrane as described in claim 1, or the application of the modified sulfonated polyether ether ketone proton exchange membrane prepared by any one of claims 2-6, characterized in that, It can be used as a membrane in hydrogen fuel cells or hydrogen electrolyzers.

8. A hydrogen fuel cell, characterized in that, This includes the modified sulfonated polyether ether ketone proton exchange membrane as described in claim 1 or the modified sulfonated polyether ether ketone proton exchange membrane prepared by any one of the preparation methods in claims 2-6.

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