A method for preparing a non-fluorine composite proton exchange membrane
By introducing covalent organic framework materials into sulfonated polyether ether ketone, a continuous hydrogen bond network and proton transport channels are formed, solving the conductivity and mechanical strength problems of non-fluorinated proton exchange membranes and realizing the preparation of high-performance composite membranes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- OFFSHORE OIL ENG CO LTD
- Filing Date
- 2026-02-09
- Publication Date
- 2026-06-02
Smart Images
Figure CN122124632A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer membrane technology, and particularly relates to a method for preparing a non-fluorine composite proton exchange membrane. Background Technology
[0002] As a core component of the proton exchange membrane electrolysis (PEMWE) system, the performance of the proton exchange membrane (PEM) directly determines the system's hydrogen production efficiency and service life.
[0003] An ideal proton exchange membrane must meet the following requirements: (1) good mechanical properties to maintain dimensional stability and prevent shortening of the electrolyzer life due to membrane aging or rupture; (2) high proton conductivity to ensure the system's energy conversion efficiency. Currently, the proton exchange membranes widely used in PEMWE are still mainly DuPont's perfluorosulfonic acid (Nafion) series membranes, but their high price, complex synthesis process, and poor environmental friendliness greatly limit the large-scale commercialization of PEMWE technology.
[0004] Sulfonated polyether ether ketone (SPEEK) has been widely studied as a non-fluorinated alternative to Nafion due to its low cost and ease of synthesis and processing. The proton conductivity of SPEEK membranes primarily depends on their ion exchange capacity, i.e., the content of sulfonic acid groups in the membrane. The hydrophilic region is responsible for proton transport, while the hydrophobic region provides mechanical support. As the ion exchange capacity increases, the hydrophilic region expands while the hydrophobic region correspondingly decreases, leading to a significant decline in the membrane's mechanical properties, creating a "trade-off" effect where proton conductivity and mechanical strength are difficult to balance. Furthermore, the increasingly porous network structure not only weakens mechanical strength but also reduces membrane density, thereby increasing the risk of gas permeation. A published patent (CN119725645A) attempts to incorporate surface-modified inorganic fillers into composite membranes; however, due to the lack of continuous proton conduction pathways in the fillers themselves, their effect on improving conductivity is limited. More seriously, inorganic fillers have poor compatibility with organic matrices and are prone to agglomeration, which not only disrupts proton transport channels and causes a sharp drop in conductivity, but also causes local stress concentration, significantly reducing the mechanical strength of the composite membrane.
[0005] Therefore, there is an urgent need to design a method for preparing a non-fluorine composite proton exchange membrane to solve the problems mentioned above. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing a non-fluorine composite proton exchange membrane, which has the advantages of high proton conductivity and mechanical properties. It solves the problem in the prior art that after the proton transport channel is damaged, the conductivity drops sharply and local stress concentration occurs, which significantly reduces the mechanical strength of the composite membrane.
[0007] To achieve the above objectives, the specific technical solution of the non-fluorine composite proton exchange membrane preparation method of the present invention is as follows: A method for preparing a non-fluorinated composite proton exchange membrane involves using sulfonated polyether ether ketone as the main component, adding sulfonated covalent organic framework material as a filler, and preparing the membrane by casting after thorough mixing. Sulfonated covalent organic framework nanosheets were synthesized by phase transfer polymerization. They were then thoroughly mixed with sulfonated polyether ether ketone at a solute mass ratio of 0.02 to 0.1:1, and sulfonated polyether ether ketone or sulfonated covalent organic framework composite films were prepared by casting.
[0008] Furthermore, the preparation of sulfonated covalent organic framework materials includes: Dissolve 0.15 mmol of 2,5-diaminobenzenesulfonic acid or 4,4'-diamino-3,3'-biphenyldisulfonic acid and 0.1 mmol of trialdehyde phloroglucinol in 30 mL of deionized water and 20 mL of octanoic acid, respectively. An octanoic acid solution of trialdehyde phloroglucinol was added above an aqueous solution of 2,5-diaminobenzenesulfonic acid or 4,4'-diamino-3,3'-biphenyldisulfonic acid. The mixture was allowed to stand for 3 days. The lower dark red solution was then dialyzed in dimethyl sulfoxide to remove impurities, yielding a sulfonated covalent organic framework dispersion.
[0009] Furthermore, the preparation of sulfonated polyether ether ketone includes: Commercially available polyetheretherketone granules were dried at 100°C under vacuum for 24 hours to remove moisture. Dry polyether ether ketone (12 g) was added granules by granules to concentrated sulfuric acid (100 mL), and the reaction was carried out in a constant temperature water bath. The mixture was mechanically stirred at 25°C for 2.5 hours, and then the temperature was raised to 50°C. After continuous mechanical stirring for 5-8 hours, the reaction product was slowly poured into mechanically stirred deionized water to obtain white filamentous sulfonated polyether ether ketone. The sulfonated polyether ether ketone was washed with a large amount of deionized water until pH=7.0, and then dried to obtain a yellow sulfonated polyether ether ketone with a sulfonation degree of 50~70%.
[0010] Furthermore, the preparation of the composite membrane includes: The sulfonated covalent organic framework material dispersion was mixed with sulfonated polyether ether ketone (200 mg) at a solute mass ratio of 0.02~0.1:1. Dimethyl sulfoxide was added to prepare a 5 mL mixed solution. The mixture was stirred at room temperature for 24 h. The mixture was sonicated for 15 min before and after stirring. The solution was then filtered through a filter cloth to obtain the film-forming solution. Composite membranes were prepared by casting, in which the film-forming liquid was dropped onto a film-laying plate and kept at 60°C for 24 hours to obtain sulfonated polyether ether ketone or sulfonated covalent organic framework material composite membranes.
[0011] Furthermore, the molar ratio of 2,5-diaminobenzenesulfonic acid or 4,4'-diamino-3,3'-biphenyldisulfonic acid and 0.1 mmol trialdehyde phloroglucinol is 3:2.
[0012] Furthermore, the mass ratio of the solute in the sulfonated covalent organic framework to the sulfonated polyether ether ketone is 0.02~0.1:1.
[0013] Furthermore, the mass concentration of the sulfonated polyether ether ketone solution is 40 mg / mL.
[0014] The method for preparing the non-fluorine composite proton exchange membrane of the present invention has the following advantages: A composite membrane was prepared by synthesizing a sulfonated covalent organic framework material and incorporating it into a sulfonated polyether ether ketone matrix. The covalent organic framework material and the polymer form a continuous hydrogen bond network and high-speed proton transport channels, improving proton conductivity. The abundant hydrogen bonds and electrostatic interactions between the covalent organic framework material and the polymer effectively enhance the mechanical strength of the membrane. Furthermore, the composite membrane exhibits excellent performance in proton exchange membrane water electrolysis for hydrogen production. Attached Figure Description
[0015] Figure 1 This is a schematic diagram showing the proton conductivity of the composite membrane prepared in this invention; Figure 2 This is a schematic diagram illustrating the mechanical strength of the composite membrane prepared according to the present invention. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0017] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.
[0018] The following is a reference to the appendix. Figure 1 To be continued Figure 2 The present invention describes a method for preparing a non-fluorine composite proton exchange membrane.
[0019] The non-fluorinated composite proton exchange membrane preparation method of the present invention uses sulfonated polyether ether ketone as the main body, adds sulfonated covalent organic framework material as filler, and prepares it by casting method after thorough mixing. Sulfonated covalent organic framework nanosheets were synthesized using phase transfer polymerization. These nanosheets were then thoroughly mixed with sulfonated polyether ether ketone (PEE ketone) at a solute-to-mass ratio of 0.02–0.1:1. The resulting composite films of sulfonated PEE ketone or sulfonated covalent organic framework materials were prepared by casting. The main steps include: S1. Preparation of sulfonated covalent organic framework material: 0.15 mmol of 2,5-diaminobenzenesulfonic acid (Pa-SO3H) / 4,4'-diamino-3,3'-biphenyl disulfonic acid (Bd-(SO3H)2) and 0.1 mmol of trialdehyde phloroglucinol (Tp) were dissolved in 30 mL of deionized water and 20 mL of octanoic acid, respectively. The octanoic acid solution of Tp was added above the aqueous solution of Pa-SO3H / Bd-(SO3H)2. The reaction was allowed to stand for 3 days. The lower dark red solution was taken and dialyzed in dimethyl sulfoxide to remove impurities, and a sulfonated covalent organic framework dispersion was obtained.
[0020] The molar ratio of 2,5-diaminobenzenesulfonic acid (Pa-SO3H) / 4,4'-diamino-3,3'-biphenyldisulfonic acid (Bd-(SO3H)2) and 0.1 mmol trialdehyde phloroglucinol (Tp) is 3:2.
[0021] S2. Preparation of sulfonated polyether ether ketone: Commercially available polyether ether ketone granules were dried under vacuum at 100°C for 24 hours to remove moisture, etc. The dried polyether ether ketone (12 g) was added granule by granule to concentrated sulfuric acid (100 mL), and the reaction was carried out in a constant temperature water bath. The mixture was mechanically stirred at 25°C for 2.5 hours, then the temperature was raised to 50°C, and the mixture was mechanically stirred for 5-8 hours. The reaction product was then slowly poured into mechanically stirred deionized water to obtain white filamentous sulfonated polyether ether ketone.
[0022] The sulfonated polyether ether ketone was washed with a large amount of deionized water until pH=7.0. After drying, a yellow sulfonated polyether ether ketone was obtained with a sulfonation degree of 50-70%.
[0023] S3. Preparation of composite membrane: The SCOF dispersion from S1 and SPEEK (200 mg) from S2 were mixed at a solute mass ratio of 0.02~0.1:1. Dimethyl sulfoxide (DMSO) was added to prepare a 5 mL mixed solution. The mixture was stirred at room temperature for 24 h, and sonicated for 15 min before and after stirring. The solution was then filtered through a filter cloth to obtain the membrane-building solution. The composite membrane was prepared by casting. The membrane-building solution was dropped onto a casting plate and kept at 60℃ for 24 hours to obtain the SPEEK / SCOF composite membrane.
[0024] The mass ratio of the solute in the sulfonated covalent organic framework to the sulfonated polyether ether ketone is 0.02~0.1:1; the mass concentration of the sulfonated polyether ether ketone solution is 40 mg / mL.
[0025] Example 1: Preparation of a composite membrane based on a covalent organic framework, the steps are as follows: S1. Preparation of sulfonated covalent organic framework materials: Tp (0.1 mmol) and Pa-SO3H (0.15 mmol) were dissolved in octanoic acid and deionized water, respectively.
[0026] The Pa-SO3H solution was slowly added to the beaker, followed by the slow dropwise addition of the Tp solution to the upper layer of the aqueous phase. The reaction was allowed to stand at room temperature for 3 days.
[0027] After the reaction was completed, the lower layer of sulfonated COF nanosheet dispersion was dialyzed in deionized water for 3 days to completely remove unreacted Tp and Pa-SO3H monomers, and TpPa-SO3H nanosheet dispersion was obtained.
[0028] S2. Preparation of sulfonated polyether ether ketone (PEEK) material: Dry PEEK particles were added one by one to concentrated sulfuric acid and reacted in a constant temperature water bath. The mixture was mechanically stirred at room temperature and heated to 50 °C. After continuous mechanical stirring for 5.5 h, the reaction product was slowly poured into mechanically stirred deionized water to obtain white filamentous SPEEK. The SPEEK was washed with a large amount of deionized water until pH=7.0 and dried to obtain yellow SPEEK.
[0029] S3. Preparation of composite membrane: Using N,N-dimethylformamide (DMF) as solvent, a casting solution is prepared with a mass fraction of SPEEK:SCOF of 0.02. The casting solution is magnetically stirred at room temperature until SPEEK is completely dissolved. Then, the casting solution is spread on a specially made glass plate mold. The glass plate is placed in an oven to dry until the solvent is completely evaporated, and finally the SPEEK / SCOF composite membrane is obtained.
[0030] Example 2: Preparation of a composite membrane based on a covalent organic framework. The preparation process is basically the same as in Example 1; the only difference is that the mass ratio of SPEEK to SCOF in S3 is 0.04, and the composite membrane is finally obtained.
[0031] Example 3: Preparation of a composite membrane based on a covalent organic framework. The preparation process is basically the same as in Example 1; the only difference is that the mass ratio of SPEEK to SCOF in S3 is 0.06, and the final composite membrane is obtained.
[0032] Example 4: Preparation of a composite membrane based on a covalent organic framework. The preparation process is basically the same as in Example 1; the only difference is that the mass ratio of SPEEK to SCOF in S3 is 0.08, and the final composite membrane is obtained.
[0033] Example 5: Preparation of a composite membrane based on a covalent organic framework. The preparation process is basically the same as in Example 1; the only difference is that the mass ratio of SPEEK to SCOF in S3 is 0.1, and the composite membrane is finally obtained.
[0034] Comparative example: The specific steps for preparing sulfonated polyetheretherketone (PEEK) films are as follows: S1. Preparation of sulfonated polyether ether ketone (PEEK) material: First, dry PEEK particles were added one by one to concentrated sulfuric acid and reacted in a constant temperature water bath. The mixture was mechanically stirred at room temperature and heated to 50°C. After continuous mechanical stirring for 5.5 h, the reaction product was slowly poured into mechanically stirred deionized water to obtain white filamentous SPEEK. The SPEEK was washed with a large amount of deionized water until pH=7.0 and dried to obtain yellow SPEEK.
[0035] S2. Preparation of composite membrane: Add 5 mL of dimethyl sulfoxide (DMSO) to 200 mg SPEEK to prepare casting solution. Stir the casting solution magnetically at room temperature until SPEEK is completely dissolved. Then, spread the casting solution on a specially made glass plate mold. Place the glass plate in an oven to dry until the solvent is completely evaporated, and finally obtain the SPEEK membrane.
[0036] like Figure 1 As shown, Figure 1 The graph shows the change in proton conductivity of the membrane with temperature. With the incorporation of covalent organic framework materials, the proton conductivity of the membrane is significantly improved.
[0037] This invention provides a method for preparing a non-fluorinated composite proton exchange membrane based on a covalent organic framework. The materials used are easy to synthesize, the preparation process is simple, and the operation is relatively convenient. Membrane performance is mainly evaluated through its proton conductivity and mechanical properties. Sulfonated polyetheretherketone (PEEK) is the most commonly used proton conduction membrane; its proton conductivity depends on the degree of sulfonation. Higher sulfonation results in higher proton conductivity, but excessively high sulfonation leads to a significant increase in water absorption, which in turn significantly reduces the membrane's mechanical strength and affects its service life.
[0038] In the preparation method of this invention, by introducing a covalent organic framework, a more continuous hydrogen bond network and an efficient proton transport path are formed between the covalent organic framework material and the polymer chain segments, ultimately resulting in a high-performance composite film with improved proton conductivity and mechanical strength.
[0039] In this invention, through comparison of Examples 1-5 and the comparative examples, it can be concluded that the introduction of a covalent organic framework significantly improves the proton conductivity and mechanical strength of the membrane. The covalent organic framework forms a more continuous hydrogen bond network and efficient proton transport channels with the polymer, resulting in a significant increase in proton conductivity. Furthermore, the rigid and ordered skeleton of the covalent organic framework enhances the mechanical strength of the polymer matrix, leading to higher mechanical strength in the composite membrane.
[0040] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing a non-fluorine composite proton exchange membrane, characterized in that, The product is prepared by casting after thorough mixing of sulfonated polyether ether ketone as the main component and sulfonated covalent organic framework material as the filler. Sulfonated covalent organic framework nanosheets were synthesized by phase transfer polymerization. They were then thoroughly mixed with sulfonated polyether ether ketone at a solute mass ratio of 0.02 to 0.1:1, and sulfonated polyether ether ketone or sulfonated covalent organic framework composite films were prepared by casting.
2. The method for preparing a non-fluorine composite proton exchange membrane according to claim 1, characterized in that, Preparation of sulfonated covalent organic framework materials includes: Dissolve 0.15 mmol of 2,5-diaminobenzenesulfonic acid or 4,4'-diamino-3,3'-biphenyldisulfonic acid and 0.1 mmol of trialdehyde phloroglucinol in 30 mL of deionized water and 20 mL of octanoic acid, respectively. An octanoic acid solution of trialdehyde phloroglucinol was added above an aqueous solution of 2,5-diaminobenzenesulfonic acid or 4,4'-diamino-3,3'-biphenyldisulfonic acid. The mixture was allowed to stand for 3 days. The lower dark red solution was then dialyzed in dimethyl sulfoxide to remove impurities, yielding a sulfonated covalent organic framework dispersion.
3. The method for preparing a non-fluorine composite proton exchange membrane according to claim 1, characterized in that, The preparation of sulfonated polyether ether ketone includes: Commercially available polyetheretherketone granules were dried at 100°C under vacuum for 24 hours to remove moisture. Dry polyether ether ketone (12 g) was added granules by granules to concentrated sulfuric acid (100 mL), and the reaction was carried out in a constant temperature water bath. The mixture was mechanically stirred at 25°C for 2.5 hours, and then the temperature was raised to 50°C. After continuous mechanical stirring for 5-8 hours, the reaction product was slowly poured into mechanically stirred deionized water to obtain white filamentous sulfonated polyether ether ketone. The sulfonated polyether ether ketone was washed with a large amount of deionized water until pH=7.0, and then dried to obtain a yellow sulfonated polyether ether ketone with a sulfonation degree of 50~70%.
4. The method for preparing a non-fluorine composite proton exchange membrane according to claim 1, characterized in that, The preparation of composite membranes includes: The sulfonated covalent organic framework material dispersion was mixed with sulfonated polyether ether ketone (200 mg) at a solute mass ratio of 0.02~0.1:
1. Dimethyl sulfoxide was added to prepare a 5 mL mixed solution. The mixture was stirred at room temperature for 24 h. The mixture was sonicated for 15 min before and after stirring. The solution was then filtered through a filter cloth to obtain the film-forming solution. Composite membranes were prepared by casting, in which the film-forming liquid was dropped onto a film-laying plate and kept at 60°C for 24 hours to obtain sulfonated polyether ether ketone or sulfonated covalent organic framework material composite membranes.
5. The method for preparing a non-fluorine composite proton exchange membrane according to claim 2, characterized in that, The molar ratio of 2,5-diaminobenzenesulfonic acid or 4,4'-diamino-3,3'-biphenyldisulfonic acid and 0.1 mmol trialdehyde phloroglucinol is 3:
2.
6. The method for preparing a non-fluorine composite proton exchange membrane according to claim 4, characterized in that, The mass ratio of the solute in the sulfonated covalent organic framework to the sulfonated polyether ether ketone is 0.02~0.1:
1.
7. The method for preparing a non-fluorine composite proton exchange membrane according to claim 4, characterized in that, The mass concentration of the sulfonated polyether ether ketone solution is 40 mg / mL.