Cross-linked polybenzimidazole resin and preparation method and application of anion exchange membrane of cross-linked polybenzimidazole resin
By optimizing the chemical structure of polybenzimidazole and carrying out cross-linking reaction, a high-performance cross-linked polybenzimidazole resin and its anion exchange membrane were prepared, which solved the problems of single structure, poor solubility and low performance of polybenzimidazole, and achieved higher mechanical properties, ion conductivity and alkali resistance, and was suitable for a variety of high-performance applications.
Patent Information
- Application Number
- CN202510340604.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2025-06-24
AI Technical Summary
The existing polybenzimidazole has a single structure, poor solubility, and the mechanical properties, ion conductivity and alkali resistance of the anion exchange membrane are not high, which limits its application in the fields of electrolytic water and fuel cells.
By optimizing the chemical structure of polybenzimidazole, grafting and crosslinking reactions, a crosslinked polybenzimidazole resin and anion exchange membrane and its anion exchange membrane were prepared.
It improves the mechanical properties and heat resistance of polybenzimidazole resin, enhances the ion conductivity and mechanical properties of the anion exchange membrane, overcomes the shortcomings of traditional process preparation, and is suitable for fuel cells, electrolytic water or flow batteries.
Smart Images
Figure CN120192528A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of high-performance polymer resins and their ion exchange membranes, and relates to a preparation method and application of a cross-linked polybenzimidazole resin and its anion exchange membrane. Background Art
[0002] Hydrogen has a high energy density and only emits water vapor and heat during use, so it is a clean fuel. Electrolysis of water has received extensive attention in the field of hydrogen production due to advantages such as pure gas products, environmental protection, and sustainability. Among them, anion exchange membrane water electrolysis is a hot research topic.
[0003] The anion exchange membrane, the core component of anion exchange membrane water electrolysis (AEMWE), largely determines the performance, cost, and lifespan of the electrolyzer. The anion exchange membrane acts as a separator to isolate the cathode chamber and the anode chamber, preventing the gases generated at both poles from crossing; secondly, the anion exchange membrane is responsible for ion exchange and ion transport, ensuring the performance of anion exchange membrane water electrolysis. Currently, there is a constraint problem between the ionic conductivity and mechanical properties of the anion exchange membrane, which limits the commercial application of AEMWE. Therefore, it is of great significance to develop anion exchange membranes with high ionic conductivity and good mechanical properties.
[0004] Polybenzimidazole resin (PBI) has excellent chemical stability, thermal stability, and mechanical properties, and is also a preferred material for anion exchange membranes in applications such as aerospace, automotive ships, transportation, and other industries. Polybenzimidazole can remain stable in harsh environments (such as high-temperature and strong-acid environments), showing excellent chemical resistance and thermal stability. However, the aromatic structure in the polybenzimidazole structural unit gives it strong rigidity, and its elongation at break and solubility need to be improved to meet the actual requirements of water electrolysis. Secondly, when the ionic conductivity of the polybenzimidazole ion membrane increases, it often causes an increase in water absorption and excessive swelling. Therefore, introducing a cross-linking system to inhibit swelling is beneficial to the application of polybenzimidazole ion membranes in fields such as anion exchange membrane water electrolysis, fuel cells, and separation membranes. Summary of the Invention
[0005] The technical problem to be solved by the present invention is the problem of the existing single structure and poor solubility of polybenzimidazole; the mechanical properties, ionic conductivity, and alkali resistance of the polybenzimidazole anion exchange membrane are not high. In order to overcome the above deficiencies and defects, the present invention provides a preparation method and application of a cross-linked polybenzimidazole resin and its anion exchange membrane. The present invention optimizes the chemical structure of polybenzimidazole, grafting and cross-linking reactions to prepare polybenzimidazole resins and their ion exchange membranes with excellent mechanical properties, improved solubility, and good chemical stability, and tests the performance of the anion exchange membrane.
[0006] To achieve the above technical effects, the technical solution of the present invention is:
[0007] A preparation method of a crosslinked polybenzimidazole resin, in which a polybenzimidazole resin is obtained by copolymerization of an aromatic tetraamine and a dicarboxylic acid; and the crosslinked polybenzimidazole resin is obtained by reacting the polybenzimidazole resin with a crosslinking agent. The method includes the following steps:
[0008] Weigh an equimolar ratio of an aromatic tetraamine and a dicarboxylic acid and dissolve them in polyphosphoric acid. Under the protection of an inert gas, heat the mixture to 120 - 210 °C and react until a viscous polybenzimidazole solution is obtained; cool the reaction solution and precipitate it in deionized water, wash it with water, and dry it to obtain the polybenzimidazole resin; prepare a 0.5 - 20 wt% solution of the polybenzimidazole in a solvent, add 0.5 - 5 wt% of an initiator or no initiator, then add a crosslinking agent and react at 20 - 120 °C for 0.5 - 30 h, precipitate, filter, and dry to obtain the crosslinked polybenzimidazole resin.
[0009] A preparation method of a crosslinked polybenzimidazole anion exchange membrane, using the crosslinked polybenzimidazole resin prepared by the above method, includes the following steps:
[0010] Step 1: Dissolve the crosslinked polybenzimidazole resin in a solvent, use NaOH as a catalyst, add bromoalkane-1-methylpiperidine salt, and react at 50 - 120 °C for 5 - 70 h, precipitate, wash, and dry to obtain ammonium polybenzimidazole;
[0011] Step 2: Prepare a 0.5 - 20 wt% solution of the ammonium polybenzimidazole in a solvent, then add a crosslinking agent, and the mass fraction of the crosslinking agent in the ammonium polybenzimidazole solution is 2 - 50 wt%. React at 20 - 120 °C for 0.5 - 30 h to obtain a casting solution, then cast it on a clean substrate. After drying the membrane, transfer it to 1 - 2 M KOH for ion exchange to obtain the crosslinked polybenzimidazole anion exchange membrane.
[0012] The aromatic tetraamine is one or a mixture of two or more of the following compounds:
[0013]
[0014] The dicarboxylic acid is one or a mixture of two or more of the following compounds:
[0015]
[0016] Where p is a positive integer from 2 to 18.
[0017] The initiator is a peroxide, an azo compound, or a photoinitiator.
[0018] In the preparation methods of crosslinked polybenzimidazole resin and crosslinked polybenzimidazole anion exchange membrane, the solvent is one or more mixtures of dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylacetamide.
[0019] In the preparation methods of crosslinked polybenzimidazole resin and crosslinked polybenzimidazole anion exchange membrane, the crosslinking agent is one or more mixtures of the following compounds:
[0020]
[0021] Among them, R1 and R2 are Cl or Br, and R1 and R2 are the same or different; j is a positive integer from 2 to 10; h is a positive integer from 1 to 8; k is a positive integer from 1 to 10.
[0022] The application of the crosslinked polybenzimidazole resin prepared by a preparation method of crosslinked polybenzimidazole resin in aerospace, automotive ships, transportation, and other industries.
[0023] The crosslinked polybenzimidazole anion exchange membrane prepared by a preparation method of crosslinked polybenzimidazole anion exchange membrane is used for ion exchange membrane electrolysis of water, fuel cells, or membrane separation.
[0024] Advantages of the present invention:
[0025] The crosslinked polybenzimidazole resin prepared by the present invention has excellent mechanical properties and heat resistance, and has important applications in aerospace, automotive ships, transportation, and other industries; the prepared crosslinked polybenzimidazole anion exchange membrane has high ion conductivity and good mechanical properties, overcomes the disadvantages of the polybenzimidazole anion exchange membrane prepared by traditional processes, effectively improves the comprehensive performance of the polybenzimidazole anion exchange membrane, and can be used in fields such as fuel cells, electrolysis of water, or flow batteries. Description of the drawings
[0026] Figure 1 It is the hydrogen nuclear magnetic spectrum of the polybenzimidazole resin prepared in Example 1.
[0027] Figure 2 It is the Fourier transform infrared spectrum curve of the crosslinked polybenzimidazole anion exchange membrane prepared in Example 1, and the test conditions are: the number of scans is 32 times, the resolution is 4 cm -1 , and the range is 400 - 4000 cm -1 ;
[0028] Figure 3 It is the relationship curve between the OH - ion conductivity and temperature of the crosslinked polybenzimidazole anion exchange membrane prepared in Example 1;
[0029] Figure 4 The stress-strain curve of the crosslinked polybenzimidazole anion exchange membrane prepared in Example 1, the test conditions are: at room temperature, the stretching speed is set at 2 mm / min;
[0030] Figure 5 The thermogravimetric analysis curve of the crosslinked polybenzimidazole anion exchange membrane prepared in Example 1, the test conditions are: in a nitrogen atmosphere, the heating rate is 10 °C / min, and the test range is 50 - 800 °C. Detailed implementation manners
[0031] The following further illustrates the detailed implementation manners of the present invention in combination with the attached drawings and technical solutions.
[0032] Example 1
[0033] Under nitrogen protection, 1 mol of aromatic tetraamine ((c) in the aromatic tetraamine given in the invention content part), 0.4 mol of 1,4-naphthalenedicarboxylic acid, 0.6 mol of 1,4-cyclohexanedicarboxylic acid and polyphosphoric acid are added to the reactor, and the temperature is raised to 120 °C - 180 °C for 24 h to obtain a viscous polybenzimidazole solution. The reaction solution is poured into deionized water for precipitation, washed repeatedly, and dried to obtain polybenzimidazole; the polybenzimidazole is dissolved in dimethyl sulfoxide to obtain a 10 wt% solution, with or without a small amount of azobisisobutyronitrile, and then the metered crosslinking agent (b) is added and reacted at 60 °C for 1 h, precipitated, filtered, and dried to obtain a crosslinked polybenzimidazole resin.
[0034] Weigh 1 mol of the polybenzimidazole in the example and add it to the reactor, add dimethyl sulfoxide and 1 mol of sodium hydroxide, 1.8 mol of 1-(6-bromohexane)-1-methylpiperidine, and raise the temperature to 100 °C for reaction for 15 h,
[0035] Precipitate in ether, wash, and dry under vacuum to obtain ammonium polybenzimidazole;
[0036] Weigh 1 mol of ammonium polybenzimidazole and dissolve it in dimethyl sulfoxide, add 0.5 mol of 1,6-dibromohexane ((a) in the crosslinking agent given in the invention content part, and j = 6) to the solution, stir and cast a film, dry at 50 °C, and then transfer it to 1 M KOH for exchange to obtain a crosslinked polybenzimidazole anion exchange membrane.
[0037] The structure of the crosslinked polybenzimidazole anion exchange membrane obtained in this example is as follows:
[0038]
[0039] Spectrum analysis:
[0040] Figure 1 is the proton nuclear magnetic resonance spectrum of the polybenzimidazole resin obtained in this example. As shown in the figure, Figure 1 the characteristic peak of the solvent DMSO-d6 is at 2.50 ppm, and the characteristic peak of H2O is at 3.40 ppm. The characteristic peaks of the protons on the benzimidazole benzene ring and the naphthalene monomer appear at 7.72 - 9.32 ppm, the characteristic peak of N-H on the imidazole ring appears at the low field of 13.2 ppm, and the characteristic peaks of the protons of the cyclohexane monomer appear at 2.7 ppm and 1.2 ppm.
[0041] Figure 2 is the infrared spectroscopy (FT-IR) characterization result of the cross-linked polybenzimidazole anion exchange membrane in this example. First, the absorption peak appearing at 3400 cm -1 is attributed to the N-H bond on the imidazole ring of polybenzimidazole, and the absorption peak at 3100 cm -1 is the stretching vibration peak of the unsaturated C-H of the benzene ring on the 1,4-naphthalenedicarboxylic acid and 3,3'-diaminobenzidine monomers, while the absorption peaks appearing at 2960 cm -1 and 2840 cm -1 are the stretching vibration peaks of the methylene on the alkyl side chain.
[0042] Figure 3 is the variation curve of the OH - conductivity of the cross-linked polybenzimidazole anion exchange membrane with temperature in this example. The hydroxide ion conductivity is an important parameter for evaluating the anion exchange membrane. As the temperature rises from 20 °C to 80 °C, the OH - of the cross-linked anion exchange membrane increases from 23.04 mS cm -1 to 83.35 mS cm -1 . This cross-linked anion exchange membrane has a relatively high OH - conductivity and can meet the application of the anion exchange membrane electrolyzer.
[0043] Figure 4 is the stress-strain curve of the cross-linked anion exchange membrane at room temperature in this example. The tensile strength of the cross-linked polybenzimidazole anion exchange membrane obtained in this example is 71 MPa, and the elongation at break is 38%, indicating that this cross-linked anion exchange membrane has good mechanical properties and can effectively support its effective operation in the electrolysis of water by the anion exchange membrane.
[0044] Figure 5 is the thermogravimetric analysis curve of the cross-linked anion exchange membrane in this example. When the mass loss is 5 wt%, the thermogravimetric temperature is 240 °C, which can meet the operating temperature of the anion exchange membrane electrolyzer.
[0045] Example 2
[0046] Under nitrogen protection, 1 mol of aromatic tetraamine ((a) in the aromatic tetraamines given in the section of the invention content) and 1 mol of 1,4-naphthalenedicarboxylic acid and polyphosphoric acid were added to a reactor, and the temperature was raised to 210 °C for reaction for 12 h to obtain polybenzimidazole. The solution was poured into deionized water for precipitation, washed repeatedly, and dried to obtain polybenzimidazole.
[0047] 1 mol of polybenzimidazole was weighed and added to a reactor, N,N-dimethylacetamide was added, 1.2 mol of sodium hydroxide and 1.2 mol of 1-(6-bromobutane)-1-methylpiperidine were added, the temperature was raised to 50 °C for reaction for 20 h, and it was precipitated in ether, washed, and dried in vacuo to obtain ammonium polybenzimidazole;
[0048] 1 mol of ammonium polybenzimidazole was weighed and dissolved in dimethyl sulfoxide, 0.2 mol of 1,6-dibromobutane ((a) in the crosslinking agent given in the section of the invention content and j = 4) was added to the solution, stirred and cast into a film, and dried at 60 °C to obtain a crosslinked polybenzimidazole anion exchange membrane.
[0049] Example 3
[0050] Under nitrogen protection, 1 mol of aromatic tetraamine ((d) in the aromatic tetraamines given in the section of the invention content) and 0.4 mol of 1,4-naphthalenedicarboxylic acid and polyphosphoric acid were added to a reactor, and the temperature was raised to 170 °C for reaction for 24 h to obtain polybenzimidazole. The reaction solution was poured into deionized water for precipitation, washed repeatedly, and dried in vacuo to obtain polybenzimidazole.
[0051] 1 mol of polybenzimidazole was weighed and added to a reactor, N-methylpyrrolidone was added, 0.5 mol of sodium hydroxide and 1.2 mol of 1-(6-bromodecane)-1-methylpiperidine were added, the temperature was raised to 120 °C for reaction for 6 h, and it was precipitated in ether, washed, and dried in vacuo to obtain ammonium polybenzimidazole;
[0052] 1 mol of ammonium polybenzimidazole was weighed and dissolved in dimethyl sulfoxide, 0.3 mol of 1,6-dibromodecane ((e) in the crosslinking agent given in the section of the invention content) was added to the solution, stirred and cast into a film, and dried at 60 °C to obtain a crosslinked polybenzimidazole anion exchange membrane.
Claims
1. A method for preparing a cross-linked polybenzimidazole resin, characterized in that: The method comprises the following steps: copolymerizing aromatic tetraamine and dicarboxylic acid to obtain polybenzimidazole resin; reacting the polybenzimidazole resin with a crosslinking agent to obtain a crosslinked polybenzimidazole resin; and The invention relates to the following steps: weighing an aromatic tetraamine and a dicarboxylic acid in equal molar ratios, dissolving them in polyphosphoric acid, heating the temperature to 120-210° C. under the protection of an inert gas to react until a viscous polybenzimidazole solution is obtained; cooling the reaction solution, precipitating it in deionized water, washing it with water, and drying it to obtain a polybenzimidazole resin; preparing a 0.5-20wt% solution of polybenzimidazole with a solvent, adding 0.5-5wt% of an initiator or not adding an initiator, and then adding a crosslinking agent to react at 20-120° C. for 0.5-30h, precipitating it, filtering it, and drying it to obtain a crosslinked polybenzimidazole resin.
2. The method for preparing a cross-linked polybenzimidazole resin according to claim 1, characterized in that: The aromatic tetraamine in the step is one or a mixture of two or more of the following compounds:
3. The method for preparing a cross-linked polybenzimidazole resin according to claim 1, characterized in that: The dicarboxylic acid is one or a mixture of two or more of the following compounds: Here, p is a positive integer ranging from 2 to 18.
4. The method for preparing a cross-linked polybenzimidazole resin according to claim 1, characterized in that: The cross-linking agent is one or a mixture of two or more of the following compounds: Wherein, R1 and R2 are Cl or Br, R1 and R2 are the same or different; j is a positive integer of 2 to 10; h is a positive integer of 1 to 8; k is a positive integer of 1 to 10.
5. The method for preparing a cross-linked polybenzimidazole resin according to claim 1, characterized in that: The solvent is one of dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone and NN-dimethylacetamide or a mixture of two or more thereof; the initiator is peroxide, azo compound or photosensitive initiator.
6. A method for preparing a cross-linked polybenzimidazole anion exchange membrane, comprising preparing the cross-linked polybenzimidazole resin by the method according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: dissolving the cross-linked polybenzimidazole resin in a solvent, using NaOH as a catalyst, adding bromoalkane-1-methylpiperidinium salt, reacting at 50-120° C. for 5-70 hours, precipitating, washing, and drying to obtain ammonium polybenzimidazole; Step 2: Prepare a 0.5-20wt% solution of ammonium polybenzimidazole with a solvent, then add a crosslinking agent, the mass fraction of the crosslinking agent in the ammonium polybenzimidazole solution is 2-50wt%, react at 20-120°C for 0.5-30h to obtain a casting solution, then cast it on a clean substrate, after the membrane is dried, transfer it to 1-2M KOH for exchange to obtain a cross-linked polybenzimidazole anion exchange membrane.
7. The method for preparing a cross-linked polybenzimidazole anion exchange membrane according to claim 6, characterized in that: The solvent is one of dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone and NN-dimethylacetamide or a mixture of two or more thereof.
8. The method for preparing a cross-linked polybenzimidazole anion exchange membrane according to claim 6, characterized in that: The cross-linking agent is one or a mixture of two or more of the following compounds: Wherein, R1 and R2 are Cl or Br, R1 and R2 are the same or different; j is a positive integer of 2 to 10; h is a positive integer of 1 to 8; k is a positive integer of 1 to 10.
9. Application of the cross-linked polybenzimidazole resin prepared by the method for preparing a cross-linked polybenzimidazole resin according to any one of claims 1 to 5 in aerospace, automobile, ship, transportation and other industries.
10. The cross-linked polybenzimidazole anion exchange membrane prepared by the method for preparing a cross-linked polybenzimidazole anion exchange membrane according to any one of claims 6 to 8 is used for ion exchange membrane water electrolysis, fuel cells or membrane separation.