PPS composite fiber diaphragm for alkaline water electrolyser and preparation method of PPS composite fiber diaphragm

Abstract

The invention belongs to the technical field of hydrogen production through water electrolysis, and discloses a PPS composite fiber diaphragm for an alkaline water electrolyser and a preparation method of the PPS composite fiber diaphragm, and the method comprises the following steps: preparing PPS non-woven fabric from PPS resin through a melt-blowing process; the PPS non-woven fabric is placed in a nitric acid solution to be subjected to nitration treatment; carrying out hot pressing treatment on the nitrified PPS non-woven fabric to obtain a PPS fiber membrane; the PPS fiber membrane is placed in a zinc nitrate-dimethylimidazole-methanol mixed solution for in-situ growth, and the PPS composite fiber diaphragm is obtained. According to the present invention, the nitrification, hot pressing and in-situ synthesis combined manner is adopted, such that the hydrophilicity is improved by introducing the hydrophilic group on the hydrophobic PPS fiber membrane, the tensile strength of the PPS fiber membrane is improved through the thermal cross-linking among the fibers, and the gas barrier property of the PPS fiber membrane is improved by using the in-situ synthesis ZIF-8 having the three-dimensional network structure so as to achieve the good gas barrier property; the preparation technology is simple, operation is easy and convenient, and the requirement for hydrogen production through industrial alkaline water electrolysis can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by electrolysis of water, and relates to a PPS composite fiber diaphragm for an alkaline water electrolyzer and a preparation method thereof. Background Art

[0002] With the intensifying global fossil energy crisis and the increasing emissions of pollutants and greenhouse gases from fossil fuel combustion, it is imperative to reduce fossil fuel use and explore clean, sustainable, and green energy sources over the coming decades. For this reason, hydrogen energy has been prioritized in energy development plans at all levels, charting the course for my country's green development and energy transition.

[0003] Currently, alkaline water electrolysis has become a mature industrial hydrogen production technology. As a key component in alkaline water electrolyzers, the diaphragm directly affects electrolysis efficiency and hydrogen production energy consumption. Its main functions are threefold: 1. Separating the cathode and anode, forming independent cathode and anode chambers to prevent short circuits; 2. Isolating the hydrogen and oxygen within the cell to prevent gas crosstalk and explosions; and 3. Providing a channel for ion transport or controlling ion exchange. Therefore, the ideal diaphragm material needs to possess high ionic conductivity, low resistivity, good hydrophilicity and corrosion resistance, high mechanical strength, and good dimensional stability. It also needs to have an appropriate pore size and porosity to meet the requirements for high gas barrier properties.

[0004] Currently, the most suitable diaphragm for alkaline water electrolyzers is a polyphenylene sulfide (PPS) fabric diaphragm. While PPS fabric offers excellent heat and corrosion resistance, its gas barrier properties are mediocre and its hydrophilicity is poor, resulting in increased energy consumption and reduced gas purity for hydrogen production in the electrolyzer. Therefore, industrially used PPS fabric diaphragms are typically sulfonated to further enhance their hydrophilicity. However, the sulfuric acid used in this process is difficult to handle and can pollute the environment. Furthermore, the hydrophilicity of the sulfonated diaphragm decreases in alkaline electrolyte solutions, resulting in poor durability. Therefore, developing and preparing a diaphragm material that can be produced harmlessly and exhibits excellent hydrophilicity, gas barrier properties, dimensional stability, and chemical stability in alkaline solutions is a pressing technical challenge in the field of alkaline water electrolysis for hydrogen production. Summary of the Invention

[0005] The purpose of the present invention is to provide a PPS composite fiber membrane for alkaline water electrolyzers and a preparation method thereof. The hydrophilicity, tensile strength and gas barrier properties of the composite fiber membrane are improved compared with existing products, and the production process will not cause secondary pollution to the environment.

[0006] A technical solution adopted by the present invention is to provide a PPS composite fiber diaphragm for an alkaline water electrolyzer, comprising a PPS fiber membrane, the surface of the PPS fiber membrane is covered with a hydrophilic film layer, and a gas barrier material is adsorbed in the pores of the PPS fiber membrane.

[0007] The invention is also characterized in that the hydrophilic membrane layer is a primary aminophenyl sulfide polymer and the gas barrier material is ZIF-8, i.e., zinc dimethylimidazole.

[0008] Another technical solution adopted by the present invention is to provide a method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer, the method comprising the following steps: Step 1: Using PPS resin material, prepare PPS nonwoven fabric through melt-blowing process; Step 2: Nitration treatment is performed on the PPS nonwoven fabric to form a hydrophilic film layer on the surface of the PPS nonwoven fabric; Step 3: hot pressing the nitrated PPS nonwoven fabric to obtain a PPS fiber membrane; Step 4: placing the PPS fiber membrane in a zinc nitrate-dimethylimidazole-methanol mixed solution for in-situ autogenous treatment to obtain a PPS composite fiber membrane.

[0009] The present invention is also characterized in that: in step 1, the specific steps of preparing the PPS nonwoven fabric from the PPS resin material through the melt-blowing process are: Step 1.1: After vacuum drying, add the PPS resin raw material into the screw extruder; Step 1.2: The screw extruder heats the PPS resin material to melt and plasticize it. The melt is then extruded through a metering pump and melt pipe and ejected from the spinneret. The spinneret is pulled by high-speed hot air on both sides of the spinneret hole to form a fiber web composed of ultra-fine fibers on the receiving mesh curtain. Step 1.3: The fiber web is formed into a meltblown nonwoven fabric by thermal bonding, and finally rolled up to obtain a PPS nonwoven fabric.

[0010] The parameters of the meltblowing process in step 1 are: 1) The metering pump supply is 100-130g / min; 2) Melt pipeline temperature is 280-330℃; 3) The spinneret temperature is 330-380℃; 4) The air volume of high-speed hot air on both sides of the spinneret is 0.7-0.9m 3 / min; 5) The receiving distance of the receiving curtain is 23-32cm; The fiber diameter of the ultrafine fibers in the PPS nonwoven fabric is 5-7 μm; the gram weight of the PPS nonwoven fabric is 50-100 g / m 2 .

[0011] The specific steps of nitrification treatment in step 2 are: Step 2.1: Add concentrated nitric acid to deionized water to prepare a nitric acid solution with a concentration of 40%-50%; Step 2.2: Immerse the PPS nonwoven fabric in a nitric acid solution, heat it in a water bath to 50-70°C, and stir it for 1-2 hours to form a hydrophilic film layer on the surface of the PPS nonwoven fabric through nitration treatment; Step 2.3: Remove the PPS nonwoven fabric from the nitric acid solution and wash it with a cleaning solution until the cleaning solution becomes neutral; Step 2.4: The cleaned PPS nonwoven fabric is vacuum dried at a drying temperature of 40-80°C for a drying time of ≥8 hours until the PPS nonwoven fabric is completely dry.

[0012] The cleaning solution is ethanol or deionized water, and the cleaned PPS nonwoven fabric is dried in a vacuum oven.

[0013] The specific steps of the hot pressing treatment in step 3 are: Step 3.1: Placing the nitrated PPS nonwoven fabric on a hot pressing platform of a flat hot press, adjusting the hot pressing temperature to 70-100°C and the hot pressing pressure to 5-10 MPa, and then hot pressing the PPS nonwoven fabric to obtain a PPS fiber membrane; Step 3.2: The PPS fiber membrane after hot pressing is quickly placed in a coolant at room temperature for rapid cooling to avoid degradation of its mechanical properties.

[0014] Among them, deionized water is selected as the coolant.

[0015] The specific steps of in-situ autogenous treatment in step 4 are: Step 4.1: Dissolve zinc nitrate in methanol solution to prepare a zinc nitrate-methanol solution with a mass fraction of 1-3%; dissolve dimethylimidazole in methanol solution to prepare a dimethylimidazole-methanol solution with a mass fraction of 1-3%; Step 4.2: Mix the zinc nitrate-methanol solution and the dimethylimidazole-methanol solution in a ratio of 1:2, and stir for 5-20 minutes to obtain a zinc nitrate-dimethylimidazole-methanol mixed solution; Step 4.3: Immerse the PPS fiber membrane in the zinc nitrate-dimethylimidazole-methanol mixed solution and let it stand for 4-12 hours to allow ZIF-8 to self-generate on the surface of the PPS fiber membrane to obtain a PPS composite fiber membrane; Step 4.4: Use a cleaning solution to clean the PPS composite fiber membrane, and then vacuum dry the PPS composite fiber membrane at a drying temperature of 50-70° C. for 8-12 hours until the PPS composite fiber membrane is completely dry.

[0016] Deionized water is used as the cleaning fluid. The cleaned PPS composite fiber diaphragm is dried in a vacuum oven. The beneficial effects of the present invention are: (1) The present invention increases the number of in-situ growth points of the hydrophilic group -NH2 and ZIF-8 (full name: Zeolitic Imidazolate Framework-8, Chinese name: dimethylimidazole zinc salt) by nitrating the PPS non-woven fabric, thereby improving the hydrophilicity of the PPS non-woven fabric itself.

[0017] (2) The present invention achieves thermal cross-linking between PPS fibers by hot-pressing the nitrated PPS non-woven fabric, effectively improving the tensile strength of the PPS fiber membrane, and can inhibit the thermal shrinkage of the PPS fiber membrane, thereby improving the dimensional stability of the PPS fiber membrane.

[0018] (3) The present invention introduces ZIF-8 into PPS fibers in situ. As a MOFs (Metalorganic Frameworks, Chinese name: metal organic framework compound) material, ZIF-8 has a unique three-dimensional porous structure that can not only effectively prevent the penetration of gas molecules and improve the gas barrier properties of the PPS composite fiber membrane, but also reduce the resistance to OH- ion transmission in the electrolytic cell and reduce the mass transfer resistance.

[0019] The preparation method of the present invention is simple and easy to implement, and the preparation process does not generate pollutants that are difficult to treat. The problem that sulfuric acid used in the modification process of PPS fabric-type diaphragms in the prior art is difficult to treat and easily pollutes the environment, and the durability of the modified diaphragms is poor, is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the PPS composite fiber diaphragm for alkaline water electrolyzer in the present invention; Figure 2 The present invention is a flow chart of a method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer.

[0021] In the figure: 1. PPS fiber membrane; 2. Hydrophilic membrane layer; 3. Air barrier material. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1: like Figure 1As shown, the PPS composite fiber diaphragm for alkaline water electrolyzer proposed by the present invention includes a PPS fiber membrane 1, the surface of the PPS fiber membrane 1 is covered with a hydrophilic membrane layer 2, and the pores of the PPS fiber membrane 1 are adsorbed with a gas barrier material 3.

[0024] In this embodiment, the hydrophilic film layer 2 is a primary aminophenylene sulfide polymer, which is a product of the combination of polyphenylene sulfide and a hydrophilic group -NH2.

[0025] In this embodiment, the gas barrier material 3 is ZIF-8, namely, dimethylimidazole zinc salt, which is a type of MOFs material.

[0026] In other embodiments of the present invention, the gas barrier material may also be selected from MOFs materials such as ZIF-9 (cobalt benzimidazole framework material) and ZIF-67 (cobalt dimethylimidazole framework material).

[0027] The working principle of this embodiment: The present invention improves the hydrophilicity of the PPS fiber membrane by adding a hydrophilic film layer on the surface of the PPS fiber membrane; and improves the gas barrier property of the PPS fiber membrane by adding an air barrier material in the pores of the PPS fiber membrane, thereby solving the problem of poor gas barrier property and hydrophilicity of the currently used PPS fabric-type membrane.

[0028] Example 2: like Figure 2 As shown, the preparation method of the PPS composite fiber diaphragm for alkaline water electrolyzer proposed by the present invention comprises the following steps: Step 1: Use PPS resin material to prepare PPS nonwoven fabric through melt-blowing process. The specific steps are as follows: Step 1.1: After vacuum drying, add the PPS resin raw material into the screw extruder; Step 1.2: The screw extruder heats the PPS resin material to melt and plasticize it. The melt is then extruded through a metering pump and melt pipe and ejected from the spinneret. The spinneret is pulled by high-speed hot air on both sides of the spinneret hole to form a fiber web composed of ultra-fine fibers on the receiving mesh curtain. Step 1.3: The fiber web is formed into a meltblown nonwoven fabric by thermal bonding, and finally rolled up to obtain a PPS nonwoven fabric.

[0029] In this embodiment, the parameters of the meltblowing process are: 1) The metering pump supply is 120g / min; 2) The melt line temperature is 300°C; 3) The spinneret temperature is 360°C; 4) The air volume of high-speed hot air on both sides of the spinneret is 0.8m 3 / min; 5) The receiving distance of the receiving curtain is 28cm; In this embodiment, the PPS resin raw material is usually a sheet material; the fiber diameter of the ultrafine fibers in the PPS nonwoven fabric is 6 μm; the gram weight of the PPS nonwoven fabric is 80 g / m 2 .

[0030] Step 2: Nitration treatment of PPS nonwoven fabric, the specific steps are: Step 2.1: Add concentrated nitric acid to deionized water to prepare a 50% nitric acid solution and mix well. Step 2.2: Immerse the PPS nonwoven fabric in a nitric acid solution, heat it to 60°C in a water bath, and stir it for 1.5 hours to form a hydrophilic film layer on the surface of the PPS nonwoven fabric through nitration treatment; Step 2.3: Remove the PPS nonwoven fabric from the nitric acid solution and rinse with ethanol or deionized water until the cleaning solution becomes neutral; Step 2.4: The cleaned PPS nonwoven fabric is vacuum dried in a vacuum oven at a drying temperature of 70°C for more than 8 hours until the PPS nonwoven fabric is completely dry.

[0031] Step 3: The nitrated PPS nonwoven fabric is subjected to hot pressing to obtain a PPS fiber membrane. The specific steps are as follows: Step 3.1: Placing the nitrated PPS nonwoven fabric on the hot pressing platform of a flat hot press, adjusting the hot pressing temperature to 80°C and the hot pressing pressure to 8 MPa, and then hot pressing the PPS nonwoven fabric to obtain a PPS fiber membrane; Step 3.2: The PPS fiber membrane after hot pressing is quickly placed in deionized water at room temperature for rapid cooling to avoid degradation of its mechanical properties.

[0032] Step 4: Place the PPS fiber membrane in a zinc nitrate-dimethylimidazole-methanol mixed solution for in-situ autogenous treatment. The specific steps are as follows: Step 4.1: Dissolve zinc nitrate in methanol solution to prepare a 2% by mass zinc nitrate-methanol solution; dissolve dimethylimidazole in methanol solution to prepare a 2% by mass dimethylimidazole-methanol solution; Step 4.2: Mix the zinc nitrate-methanol solution and the dimethylimidazole-methanol solution in a ratio of 1:2, and stir for 10 minutes to obtain a zinc nitrate-dimethylimidazole-methanol mixed solution; Step 4.3: The PPS fiber membrane is immersed in a zinc nitrate-dimethylimidazole-methanol mixed solution and allowed to stand for 8 hours. During the mixing process of the zinc nitrate-methanol solution and the dimethylimidazole-methanol solution, dimethylimidazole zinc salt (ZIF-8) nanoparticles are generated. The surface of the nitrated PPS fiber has a large number of functional groups (-NH2) that easily bind to metal ions. The dimethylimidazole zinc salt (ZIF-8) nanoparticles in the mixed solution are deposited on the surface of the PPS fiber. This process causes ZIF-8 to self-generate on the surface of the PPS fiber membrane, resulting in a PPS composite fiber membrane. Step 4.4: Use deionized water to clean the PPS composite fiber membrane, and then use a vacuum oven to dry the cleaned PPS composite fiber membrane at a drying temperature of 60° C. for 10 hours until the PPS composite fiber membrane is completely dry.

[0033] In step 4.2 of this embodiment, the mixing and stirring is performed using a magnetic stirrer for ultrasonic dispersion and stirring.

[0034] The principle of this embodiment is as follows: a PPS nonwoven fabric is first prepared by meltblowing. A nitration-grafting reaction is then used to increase the number of hydrophilic groups (-NH2) and in-situ growth sites of ZIF-8 on the surface of the PPS nonwoven fabric. The nitrated PPS nonwoven fabric is then hot-pressed to produce a PPS fiber membrane. Finally, the PPS fiber membrane is placed in a zinc nitrate-dimethylimidazole-methanol mixed solution for an in-situ reaction. Zinc dimethylimidazole nanoparticles (ZIF-8) bind to the hydrophilic groups (-NH2) and adsorb on the surface and pores of the PPS fiber membrane, ultimately producing a PPS composite fiber membrane. After cleaning and drying to remove moisture from the membrane, it is ready for use. The present invention introduces hydrophilic -NH2 groups on the PPS fiber surface through the nitration reaction, forming a hydrophilic membrane layer, namely, a primary aminophenyl sulfide polymer, effectively improving the hydrophilicity of the PPS fiber membrane. Furthermore, the in-situ reaction spontaneously introduces ZIF-8 onto the surface of the PPS fiber membrane, effectively preventing the permeation of gas molecules and improving the gas barrier properties of the PPS composite fiber membrane.

[0035] Example 3: The method for preparing the PPS composite fiber diaphragm for alkaline water electrolyzer proposed in the present invention comprises the following steps: Step 1: Using PPS resin material, prepare PPS nonwoven fabric through melt-blown equipment such as screw extruder; Step 2: Add concentrated nitric acid to deionized water to prepare a 50% nitric acid solution; then add the PPS nonwoven fabric to the nitric acid solution, heat it in a water bath to 60°C and stir for 1 hour; then remove the PPS nonwoven fabric and wash it with ethanol or deionized water until the cleaning solution is neutral, and then continue to dry the washed PPS nonwoven fabric in a vacuum environment at 70°C for more than 8 hours until it is completely dry; Step 3: The nitrated PPS nonwoven fabric was cut into 10 cm × 10 cm square pieces of uniform thickness and hot-pressed at a temperature of 80° C. and a pressure of 8 MPa using a flat-plate hot press to obtain a PPS fiber membrane; Step 4: 0.75 g of zinc nitrate and 1.64 g of dimethylimidazole were dissolved in 25 ml of methanol solution respectively, and then the two dissolved solutions were mixed and stirred for 10 minutes to obtain a zinc nitrate-dimethylimidazole-methanol mixed solution. Subsequently, the PPS fiber membrane was quickly immersed in the zinc nitrate-dimethylimidazole-methanol mixed solution and allowed to stand for 8 hours to obtain a PPS composite fiber membrane; The PPS composite fiber membrane was taken out, and the ZIF-8 particles floating on the surface were rinsed with deionized water. The PPS composite fiber membrane was placed in a vacuum oven at 60°C until it was completely dried to obtain the final PPS composite fiber membrane product.

[0036] The working principle of this embodiment is the same as that of embodiment 2 and will not be described in detail.

[0037] Example 4 The method for preparing the PPS composite fiber diaphragm for alkaline water electrolyzer proposed in the present invention comprises the following steps: Step 1: Using PPS resin material, prepare PPS nonwoven fabric through melt-blown equipment such as screw extruder; Step 2: Add concentrated nitric acid to deionized water to prepare a 50% nitric acid solution; then add the PPS nonwoven fabric to the nitric acid solution, heat it in a water bath to 70°C and stir for 1 hour; then remove the PPS nonwoven fabric and wash it with ethanol or deionized water until the washing solution is neutral, and then continue to dry the washed PPS nonwoven fabric in a vacuum environment at 70°C for more than 8 hours until it is completely dry; Step 3: The nitrated PPS nonwoven fabric was cut into 10 cm × 10 cm square pieces of uniform thickness and hot-pressed at 80°C and 8 MPa using a flat-plate hot press to obtain a PPS fiber membrane, which was then quickly placed in deionized water at room temperature for rapid cooling. Step 4: 0.75 g of zinc nitrate and 1.64 g of dimethylimidazole were dissolved in 25 ml of methanol solution respectively, and then the two dissolved solutions were mixed and stirred for 20 minutes to obtain a zinc nitrate-dimethylimidazole-methanol mixed solution. Subsequently, the PPS fiber membrane was quickly immersed in the zinc nitrate-dimethylimidazole-methanol mixed solution and allowed to stand for 8 hours to obtain a PPS composite fiber membrane; The PPS composite fiber membrane was taken out, and the ZIF-8 particles floating on the surface were rinsed with deionized water. The PPS composite fiber membrane was placed in a vacuum oven at 60°C until it was completely dried to obtain the final PPS composite fiber membrane product.

[0038] The working principle of this embodiment is the same as that of embodiment 2 and will not be described in detail.

[0039] Example 5 The method for preparing the PPS composite fiber diaphragm for alkaline water electrolyzer proposed in the present invention comprises the following steps: Step 1: Using PPS resin material, prepare PPS nonwoven fabric through melt-blown equipment such as screw extruder; Step 2: Add concentrated nitric acid to deionized water to prepare a 50% nitric acid solution; then add the PPS nonwoven fabric to the nitric acid solution, heat it in a water bath to 60°C and stir for 2 hours; then remove the PPS nonwoven fabric and wash it with ethanol or deionized water until the washing solution is neutral, and then continue to dry the washed PPS nonwoven fabric in a vacuum environment at 70°C for more than 8 hours until it is completely dry; Step 3: The nitrated PPS nonwoven fabric was cut into 10 cm × 10 cm square pieces of uniform thickness and hot-pressed at 80°C and 8 MPa using a flat-plate hot press to obtain a PPS fiber membrane, which was then quickly placed in deionized water at room temperature for rapid cooling. Step 4: 0.75 g of zinc nitrate and 1.64 g of dimethylimidazole were dissolved in 25 ml of methanol solution respectively, and then the two dissolved solutions were mixed and stirred for 20 minutes to obtain a zinc nitrate-dimethylimidazole-methanol mixed solution. Subsequently, the PPS fiber membrane was quickly immersed in the zinc nitrate-dimethylimidazole-methanol mixed solution and allowed to stand for 8 hours to obtain a PPS composite fiber membrane; The PPS composite fiber membrane was taken out, and the ZIF-8 particles floating on the surface were rinsed with deionized water. The PPS composite fiber membrane was placed in a vacuum oven at 60°C until it was completely dried to obtain the final PPS composite fiber membrane product.

[0040] The working principle of this embodiment is the same as that of embodiment 2 and will not be described in detail.

Claims

1. PPS composite fiber diaphragm for alkaline water electrolyzer, characterized in that: It comprises a PPS fiber membrane (1), the surface of the PPS fiber membrane (1) is covered with a hydrophilic membrane layer (2), and the pores of the PPS fiber membrane (1) are adsorbed with a gas barrier material (3); The hydrophilic membrane layer (2) is a primary aminophenyl sulfide polymer; and the gas barrier material (3) is ZIF-8.

2. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 1, wherein: The steps include: Step 1: Using PPS resin material, prepare PPS nonwoven fabric through melt-blowing process; Step 2: Nitration treatment is performed on the PPS nonwoven fabric to form a hydrophilic film layer on the surface of the PPS nonwoven fabric; Step 3: hot pressing the nitrated PPS nonwoven fabric to obtain a PPS fiber membrane; Step 4: placing the PPS fiber membrane in a zinc nitrate-dimethylimidazole-methanol mixed solution for in-situ autogenous treatment to obtain a PPS composite fiber membrane.

3. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 2, wherein: In step 1, the specific steps of preparing PPS nonwoven fabric from PPS resin material through melt-blowing process are as follows: Step 1.1: After vacuum drying, add the PPS resin raw material into the screw extruder; Step 1.2: The screw extruder heats the PPS resin material to melt and plasticize it. The melt is then extruded through a metering pump and melt pipe and ejected from the spinneret. The spinneret is pulled by high-speed hot air on both sides of the spinneret hole to form a fiber web composed of ultra-fine fibers on the receiving mesh curtain. Step 1.3: The fiber web is formed into a meltblown nonwoven fabric by thermal bonding, and finally rolled up to obtain a PPS nonwoven fabric.

4. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 3, wherein: The parameters of the meltblowing process in step 1 are: 1) The metering pump supply is 100-130g / min; 2) Melt pipeline temperature is 280-330℃; 3) The spinneret temperature is 330-380℃; 4) The air volume of high-speed hot air on both sides of the spinneret is 0.7-0.9m 3 / min; 5) The receiving distance of the receiving curtain is 23-32cm; The fiber diameter of the ultrafine fibers in the PPS nonwoven fabric is 5-7 μm; the gram weight of the PPS nonwoven fabric is 50-100 g / m 2 .

5. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 2, wherein: The specific steps of nitrification treatment in step 2 are: Step 2.1: Add concentrated nitric acid to deionized water to prepare a nitric acid solution with a concentration of 40%-50%; Step 2.2: Immerse the PPS nonwoven fabric in a nitric acid solution, heat it in a water bath to 50-70°C, and stir it for 1-2 hours to form a hydrophilic film layer on the surface of the PPS nonwoven fabric through nitration treatment; Step 2.3: Remove the PPS nonwoven fabric from the nitric acid solution and wash it with a cleaning solution until the cleaning solution becomes neutral; Step 2.4: The cleaned PPS nonwoven fabric is vacuum dried at a drying temperature of 40-80°C for a drying time of ≥8 hours until the PPS nonwoven fabric is completely dry.

6. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 5, characterized in that: In step 2, the cleaning solution is ethanol or deionized water; and the cleaned PPS nonwoven fabric is dried in a vacuum oven.

7. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 2, wherein: The specific steps of the hot pressing treatment in step 3 are: Step 3.1: Placing the nitrated PPS nonwoven fabric on a hot pressing platform of a flat hot press, adjusting the hot pressing temperature to 70-100°C and the hot pressing pressure to 5-10 MPa, and then hot pressing the PPS nonwoven fabric to obtain a PPS fiber membrane; Step 3.2: The PPS fiber membrane after hot pressing is quickly placed in a coolant at room temperature for rapid cooling to avoid degradation of its mechanical properties.

8. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 7, wherein: In step 3, deionized water is used as the coolant.

9. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 2, wherein: The specific steps of in-situ autogenous treatment in step 4 are: Step 4.1: Dissolve zinc nitrate in methanol solution to prepare a zinc nitrate-methanol solution with a mass fraction of 1-3%; dissolve dimethylimidazole in methanol solution to prepare a dimethylimidazole-methanol solution with a mass fraction of 1-3%; Step 4.2: Mix the zinc nitrate-methanol solution and the dimethylimidazole-methanol solution in a ratio of 1:2, and stir for 5-20 minutes to obtain a zinc nitrate-dimethylimidazole-methanol mixed solution; Step 4.3: Immerse the PPS fiber membrane in the zinc nitrate-dimethylimidazole-methanol mixed solution and let it stand for 4-12 hours to allow ZIF-8 to self-generate on the surface of the PPS fiber membrane to obtain a PPS composite fiber membrane; Step 4.4: Use a cleaning solution to clean the PPS composite fiber membrane, and then vacuum dry the PPS composite fiber membrane at a drying temperature of 50-70° C. for 8-12 hours until the PPS composite fiber membrane is completely dry.

10. The method for preparing a PPS composite fiber diaphragm for an alkaline water electrolyzer according to claim 9, characterized in that: In step 4, the cleaning liquid is deionized water; and the cleaned PPS composite fiber membrane is dried in a vacuum oven.

Images