Preparation method of polyphenylene sulfide filament fiber diaphragm for hydrogen production of alkaline water electrolytic tank

Abstract

The invention relates to the field of preparation of diaphragms for hydrogen production through alkaline water electrolysis, and discloses a preparation method of a polyphenylene sulfide filament fiber diaphragm for hydrogen production through an alkaline water electrolysis tank. The preparation method comprises the following steps: melting polyphenylene sulfide resin to prepare filament fibers, carrying out yarn steaming, plying and plied yarn steaming on the filament fibers, weaving the filament fibers into plain weave diaphragm base cloth, and carrying out sulfonation, hot rolling shaping and other processes to prepare the polyphenylene sulfide filament fiber diaphragm. The polyphenylene sulfide filament fiber used in the invention can provide high mechanical strength for the diaphragm, and can optimize the pore structure and aperture of the diaphragm; the hydrophilic performance of the diaphragm can be remarkably improved through sulfonation treatment, so that the surface resistance and the electrolysis energy consumption of the diaphragm are reduced; the hot rolling shaping treatment can improve the air tightness of the diaphragm and reduce the thickness of the diaphragm. Therefore, the prepared diaphragm is high in mechanical strength, free of hairiness, high in porosity, uniform in pore diameter, good in hydrophilicity, low in surface resistance, high in air tightness and good in hot alkali durability, and the preparation method is simple and good in economical efficiency.

Description

Technical Field

[0001] The invention belongs to the field of diaphragm preparation, and in particular relates to a method for preparing a diaphragm for hydrogen production in an alkaline water electrolyzer. Background Art

[0002] With the continuous development and progress of the world economy, the increasing demand for energy, along with the climate deterioration caused by the excessive use of fossil energy and the increasing scarcity of fossil energy, the development and utilization of renewable and pollution-free energy is particularly important and urgent. Hydrogen energy, as a secondary renewable green energy, has the advantages of high efficiency and cleanliness. The development and utilization of green hydrogen energy is the most effective way to solve the current energy crisis and achieve the "dual carbon" goal. At present, alkaline water electrolysis is a relatively mature technology, simple operation, low cost and widely used large-scale method for preparing green hydrogen. How to reduce the power consumption in the alkaline water electrolysis process is the focus and hot spot of current research. As an important part of the alkaline water electrolyzer, the diaphragm mainly plays the role of conducting hydroxide ions to form an internal path and isolating the H2 and O2 produced by the two electrodes. The size and airtightness of the diaphragm resistance will directly affect the energy consumption, efficiency, gas purity and safety of water electrolysis. Therefore, the diaphragm has a large research space and a good development prospect.

[0003] At present, the commercial diaphragms for hydrogen production by alkaline water electrolysis are mainly divided into three categories: asbestos cloth diaphragms, fabric-type short-fiber polyphenylene sulfide (PPS) diaphragms and Zirfon PERL composite diaphragms. Asbestos cloth diaphragms have disadvantages such as high carcinogenicity, high temperature instability, thick membrane and high resistance. They have been banned from use in various countries around the world and gradually replaced by fabric-type polyphenylene sulfide (PPS) diaphragms. The Belgian Zirfon PERL composite diaphragm is composed of nano ZrO2 (85% (w)) and polysulfone, with an average pore size of 150nm and a dense polysulfone thin layer on the surface (the skin thickness is about 1μm). This surface layer is not conducive to the transfer of hydroxide. The ZrO2 / polysulfone composite diaphragm prepared by Lee et al. has a uniform porous structure. In a 30% (w) KOH electrolytic solution at 80°C, the current density is 1000mA / cm when the cell voltage is 1.83V. 2. Although 25%-30% (w) KOH electrolytic solution is conducive to the conduction of hydroxide in the porous diaphragm, the alkali resistance of polysulfone is poor. The Zirfon PERL composite diaphragm cannot withstand high temperature and concentrated alkali in high-concentration alkali, which can easily cause the coating to crack and fall off, and the isolation effect fails (causing explosion). The stability of the ZrO2 / polysulfone composite diaphragm is much lower than that of the fabric-type polyphenylene sulfide (PPS) diaphragm, and it is difficult to use stably for a long time (10-20 years). In the production of hydrogen by alkaline water electrolysis, polytetrafluoroethylene (PTFE) is also a diaphragm material that has attracted much attention. Wang Baoguo's research group has studied and prepared a composite ion-conducting diaphragm of PTFE / layered hydroxide (LDH) with strong alkali resistance. The PTFE / LDH composite ion-conducting diaphragm has a dense membrane cross-section, which can effectively prevent H2 penetration, and can obtain 1000mA / cm at a small chamber voltage of 1.8V. 2 The current density is 500 mA / cm in KOH electrolytic solution at 60 °C. 2 The current density can be stably operated for 180 hours. Although some achievements have been made in the research on the use of porous membranes for hydrogen production by alkaline water electrolysis, the disadvantages of high surface resistance and low gas barrier properties have hindered the further development of membranes in the field of hydrogen production by alkaline aqueous solution electrolysis.

[0004] Polyphenylene sulfide (PPS) is a new type of membrane material with many excellent properties such as acid and alkali resistance, solvent resistance, dimensional stability and high temperature resistance. It can maintain excellent performance in harsh environments. The fabric-type polyphenylene sulfide (PPS) diaphragms widely used in alkaline water electrolysis hydrogen production at home and abroad are basically short-fiber woven or non-woven diaphragms. U.S. Patent US4895634 uses pure polyphenylene sulfide fiber to make woven fabric or non-woven felt, and uses different means (sulfonation, carbonization, phosphophthalization) for hydrophilic modification. According to the patent, its diaphragm has excellent performance, heat resistance and corrosion resistance, water absorption rate of 300%, and gas purity can reach 99.99%; but its diaphragm thickness is large (about 2mm), resulting in high surface resistance. At the same time, its hydrophilic post-treatment process is complicated and takes a long time (about 2h), and its processing technology is complicated. The third-generation polyphenylene sulfide (PPS) short fiber diaphragm of Toray Company of Japan is resistant to high and low temperature changes, has certain corrosion resistance and tensile properties, has a thickness of 0.85mm, an air tightness of 500mm water column, and a surface resistance of about 0.25Ω·cm 2, the maximum operating temperature can reach 110°C, but its diaphragm is thick and has low strength, the gas purity is not high, and the polyphenylene sulfide (PPS) staple fiber will swell and shed hairiness during the electrolysis process, affecting the electrolysis efficiency. Tianjin University of Technology and Tianjin Kairui New Materials Technology Co., Ltd. have developed various types of polyphenylene sulfide (PPS) diaphragms that can be used for alkaline water electrolysis to produce hydrogen. The SC-L series diaphragms are 0.7-0.8mm thick and have an airtightness of 350mm water column; the SC-H series diaphragms are 0.8-0.95mm thick and have an airtightness of 400mm water column. The surface resistance of the two series of diaphragms is 0.2-0.35Ω·cm 2 Due to its low air tightness and imperfect process, it has not been commercialized for large-scale use. The polyphenylene sulfide (PPS) short fiber diaphragm for alkaline water electrolysis hydrogen production equipment developed by Suzhou Yuemo has a maximum thickness of (0.85±0.1) mm, an air tightness of 500 mm water column, a maximum operating temperature of 110°C, and a surface resistance of less than 0.25Ω·cm 2 Although it has been used commercially in China, polyphenylene sulfide (PPS) staple fibers will lose hairiness in high-temperature hot alkali and have poor hydrophilicity, so long-term operation will affect their electrolysis efficiency and durability.

[0005] At present, except for the asbestos cloth diaphragm which has been banned from use, the composite diaphragm has certain safety issues and high cost because its composite layer is prone to cracking and falling off in high temperature and concentrated alkali, and the isolation function fails (causing explosion). There is still a lot of room for research. Fabric-type polyphenylene sulfide (PPS) diaphragms, whether woven or non-woven, use polyphenylene sulfide (PPS) short fibers as raw materials, and the hydrophilic modification process is still under research and improvement, resulting in the prepared diaphragms having problems such as low mechanical strength, complex process, large and uneven pore size, low porosity, high surface resistance, low air tightness, poor hydrophilicity, and hairiness shedding in high temperature and concentrated alkali. At present, it is urgent to develop polyphenylene sulfide (PPS) diaphragms with balanced performance to replace the original fabric-type polyphenylene sulfide (PPS) short fiber diaphragms. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in an alkaline water electrolysis cell in view of the shortcomings of the existing diaphragm technology and performance for hydrogen production by alkaline water electrolysis. The polyphenylene sulfide (PPS) filament fiber is used as a raw material (to replace the PPS staple fiber used in the existing diaphragm), the polyphenylene sulfide (PPS) resin is melted to prepare the filament fiber, and the filament fiber is woven into a plain weave diaphragm base fabric after steaming, plying, and steaming the ply yarn, and then the sulfonation hydrophilic modification treatment is carried out with concentrated sulfuric acid (H2SO4) and then hot rolling and shaping treatment is carried out to obtain the polyphenylene sulfide (PPS) filament fiber diaphragm. The polyphenylene sulfide filament fiber used in the present invention can provide a high mechanical strength for the diaphragm, can prevent the generation and shedding of hairiness during electrolysis, and can optimize the pore structure and pore size of the diaphragm; the sulfonation hydrophilic modification treatment can significantly improve the hydrophilicity of the polyphenylene sulfide (PPS) fiber, thereby reducing the surface resistance of the diaphragm, improving the electrolysis efficiency and reducing energy consumption; the high-temperature hot rolling shaping treatment can improve the air tightness of the diaphragm and reduce the thickness of the diaphragm, and indirectly reduce the resistance of the diaphragm while improving the purity of hydrogen and oxygen gas. Therefore, the diaphragm prepared by the present invention has high mechanical strength, no hairiness, uniform pores and pore sizes, good hydrophilicity, low surface resistance, high air tightness, good hot alkali durability, and the preparation method and equipment are simple and economical.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention is a method for preparing a polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in an alkaline water electrolyzer, which is characterized by: selecting polyphenylene sulfide (PPS) filament fibers with excellent physical and chemical properties, and subjecting them to melt spinning, yarn steaming, plying, ply yarn steaming, weaving, sulfonation, cleaning and drying, and hot rolling and shaping, wherein:

[0009] 1. Raw material selection: Polyphenylene sulfide fiber (PPS) resin is selected as the raw material, and then melted to prepare filament fibers. The filament specifications are 200D / 50F or 200D / 100F, and the cross-section of the single fiber can be conventional round or other non-round shapes. Filament fibers of different specifications cannot be mixed or used in combination.

[0010] 2. Steaming of filament raw materials: The steaming process can eliminate the static electricity and internal stress of the fiber generated during the spinning process. The temperature of filament fiber steaming is generally 80-90℃, the steaming time is 10-15min, and the steaming cycle number is 1.

[0011] 3. Filament plying: Generally, 2 or 4 filaments are used for plying, and the twist is 6-10 twists / 10cm, using Z twist.

[0012] 4. Steaming yarn for ply yarn: Steaming yarn for ply yarn can stabilize the twist and improve the weaving production efficiency. The steaming temperature is generally 90-100℃, the steaming time is 15-20min, and the steaming cycle number is 1-2 times.

[0013] 5. Weaving: Through the processes of warping, drawing-in, reeding, etc., appropriate weaving process parameters such as pre-tension, beating force, warp density, weft density, etc. are selected to weave the plain weave filament diaphragm base fabric.

[0014] 6. Sulfonation hydrophilic modification treatment: The diaphragm base fabric is subjected to sulfonation treatment at 60-90°C and 30-50% H2SO4 for 20-40 minutes, and then washed with 30% KOH solution and dried.

[0015] 7. Hot rolling shaping treatment: The hydrophilic modified diaphragm is treated on a calender, the pressure is generally 1-3MPa, the temperature is 160-180℃, and the time is 20-60s.

[0016] The invention adopts raw material selection, plying, yarn steaming, weaving, sulfonation hydrophilic modification treatment and hot rolling shaping process design and parameter optimization, so that the diaphragm product has good performance, simple process equipment and low cost. The diaphragm prepared by the preparation method of the invention has high strength and no hairiness, high temperature resistance, electrolyte corrosion resistance, good hydrophilicity, small surface resistance, high porosity, uniform pore size, high air tightness and the like. In addition, the preparation process is easy to operate and control, the raw materials are easily available, the equipment is simple, the product quality is stable and the cost is relatively low. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with embodiments.

[0018] The preparation method of the present invention involves melt spinning, which is to melt polyphenylene sulfide (PPS) resin and use spinnerets of different specifications and shapes to prepare filament fibers of different specifications. The specifications, cross-sectional shape and performance of the filament fibers directly affect the subsequent weaving process and the performance of the diaphragm.

[0019] The yarn steaming process can eliminate static electricity and internal stress of the fiber generated during the spinning process, while stabilizing the twist of the strands and improving the weaving production efficiency. In the present invention, different temperatures and times are selected for the filament fibers and the strands to be steamed, while eliminating the internal stress and fixing the twist of the strands, so as to facilitate weaving.

[0020] Plying is twisting, which is to twist two or four single yarns together to form a strand. The properties of the strand mainly depend on the distribution state of stress on the fibers in the strand and the structural relationship, so appropriate process parameters should be selected. It should be noted that the appropriate twist is selected according to the different specifications and cross-sectional shapes of the filaments.

[0021] The warping process is to wind a certain number of bobbins in parallel on the weaving beam with appropriate and uniform tension according to the length, width and arrangement order specified in the process design for use in warping. It should be noted that the appropriate tension is selected according to the specifications of the strands, the cross-sectional shape of the monofilaments and the warp and weft density.

[0022] The warp drawing process is to pass the warp yarn on the weaving beam into the drop wire, heald eyelet and reed in a certain pattern according to the fabric process design requirements, so as to form a shed during weaving, introduce the weft yarn, and weave the desired fabric.

[0023] The weaving process is the key link in the entire manufacturing process and is the process of forming the diaphragm base fabric. It is the process of interweaving the warp and weft yarns on the loom according to the fabric structure rules to form the fabric. It should be noted that the fabric structure is a plain weave, and different warp and weft densities and beating force values ​​are selected according to different strand specifications.

[0024] Sulfonation hydrophilic modification treatment, due to the simple molecular chain structure of polyphenylene sulfide (PPS), without polar groups, resulting in poor hydrophilic performance, the membrane made directly affects the ion passing efficiency and resistance, energy consumption, often need to be hydrophilic modification treatment of the membrane. The present invention has shown through multiple experimental studies that the membrane base fabric is sulfonated at 60-90 ° C, 30-50% H2SO4 for 20-40 minutes, and then washed with 30% KOH solution and dried, can obtain a more ideal hydrophilic performance.

[0025] The purpose of hot rolling shaping treatment is to improve the air tightness of the diaphragm while reducing the thickness of the diaphragm and thus reducing the resistance. It can also prevent the size of the manufactured diaphragm from deforming during use. The heat setting involved in this patent requires the use of appropriate temperature and time. If the temperature is too low, the shaping effect cannot be achieved. If the temperature is too high, the fabric surface will turn yellow, and energy will be wasted and costs will increase. The present invention has shown through multiple experimental studies that a heat setting treatment of 20-60s at a pressure of 1-3MPa and a temperature of 160-180°C can achieve a more ideal air tightness and shaping effect.

[0026] It should be noted that a certain amount of oil should be evenly applied before weaving in order to prevent static electricity from being generated, increase moisture content and reduce friction, and facilitate weaving. The oil used in the present invention is an antistatic agent. If too little oil is added, it will not have the corresponding effect; if too much is added, it will make it difficult to clean the diaphragm. Therefore, a suitable oil should be applied during weaving.

[0027] The matters not described in the preparation method of the present invention are applicable to the prior art.

[0028] The preparation method of the present invention can be used to prepare the polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in an alkaline water electrolyzer of the present invention, and its main technical indicators are shown in Table 1.

[0029] Table 1 Performance of the diaphragm base fabric of the present invention

[0030]

[0031]

[0032] Embodiment 1:

[0033] (1) Raw material: polyphenylene sulfide (PPS) filament fiber, specification: 200D / 50F, conventional round cross-section fiber.

[0034] (2) Yarn steaming: The yarn steaming process parameters are shown in Table 2.

[0035] Table 2 Yarn steaming process parameters

[0036] Yarn Yarn steaming temperature / ℃ Steaming time / min Steaming cycle number / times Single yarn 90 15 1 Strands 100 20 2

[0037] (3) Plying: The strands are made of 4 strands with a twist of 6 twists / 10cm.

[0038] (4) Weaving: The fabric structure is plain weave, with a warp density of 100 threads / 10cm and a weft density of 90 threads / 10cm.

[0039] (5) Sulfonation: Sulfonation treatment was performed using 50% H2SO4 at 80°C for 40 minutes, followed by washing with 30% KOH solution and drying.

[0040] (6) Hot rolling: heat setting treatment at a temperature of 175°C and a pressure of 3 MPa for 30 seconds.

[0041] Embodiment 2:

[0042] (1) Raw materials: polyphenylene sulfide (PPS) filament fiber, specification: 200D / 100F, special-shaped cross-section fiber.

[0043] (2) Yarn steaming: The yarn steaming process parameters are shown in Table 3.

[0044] Table 3 Yarn steaming process parameters

[0045] Yarn Yarn steaming temperature / ℃ Steaming time / min Steaming cycle number / times Single yarn 80 10 1 Strands 90 15 2

[0046] (3) Plying: Plying uses 2 strands with a twist of 8 twists / 10cm.

[0047] (4) Weaving: The fabric structure is plain weave, with a warp density of 190 threads / 10cm and a weft density of 175 threads / 10cm.

[0048] (5) Sulfonation: Sulfonation treatment was performed using 40% H2SO4 at 80°C for 30 minutes, followed by washing with 30% KOH solution and drying.

[0049] (6) Hot rolling: heat setting treatment at a temperature of 160°C and a pressure of 2 MPa for 20 seconds.

[0050] Although the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention.

Claims

1. A method for preparing a polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in an alkaline water electrolyzer, It is characterized in that include: (1) melt spinning polyphenylene sulfide (PPS) resin to prepare filament fibers of different specifications and cross-sectional shapes; (2) steaming the filament fibers obtained in step (1) to eliminate static electricity and internal stress during the manufacturing process of the filament fibers; (3) Plying and twisting the filament fibers obtained in step (2) to improve weavability; (4) steaming the combined and twisted yarns obtained in step (3) again to stabilize their twist for easier weaving; (5) warping, drawing in, and reeding the strands obtained in step (4), and then weaving them into a diaphragm base fabric on a machine; (6) performing a sulfonation hydrophilic modification treatment on the diaphragm base fabric prepared in step (5) to improve the hydrophilicity of the diaphragm; (7) The modified diaphragm in step (6) is subjected to high-temperature hot rolling and shaping treatment using a calender to obtain the filament fiber diaphragm.

2. The method for preparing the polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in alkaline water electrolyzer according to claim 1, It is characterized in that The polyphenylene sulfide (PPS) resin is melt-spun to obtain filament fibers with specifications of 200D / 50F or 200D / 100F and a single-filament cross-section shape of a circle, an ellipse or a polygon.

3. The method for preparing the polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in alkaline water electrolyzer according to claim 1, Features: In step (2), the temperature of the steamed yarn is generally 80-90°C, the time is 10-15 minutes, and the number of cycles is 1; In step (4), the steaming temperature of the strands is generally 90-100° C., the time is 15-20 minutes, and the number of cycles is 1-2 times.

4. The method for preparing the polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in alkaline water electrolyzer according to claim 1, Features: In step (3), 2 or 4 strands are generally used for plying, the twist is 6-10 twists / 10cm, and Z twist is used.

5. The method for preparing the polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in alkaline water electrolyzer according to claim 1, Features: In step (5), the fabric structure is plain weave, the twist of 4 strands is 6 twists / 10cm, the warp density is 100 strands / 10cm, and the weft density is 90 strands / 10cm; the twist of 2 strands is 8 twists / 10cm, the warp density is 190 strands / 10cm, and the weft density is 175 strands / 10cm.

6. The method for preparing the polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in alkaline water electrolyzer according to claim 1, Features: In step (6), the temperature is 60-90°C, and the sulfonating agent H 2 SO 4 The concentration is 30-50%, the treatment time is 20-40min, and after sulfonation treatment, it is washed with 30% KOH solution and dried.

7. The method for preparing a polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in an alkaline water electrolyzer according to claim 1, Features: In step (7), the heat setting pressure is 1-3 MPa, the temperature is 160-180° C., and the time is 20-60 s.

8. A polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in an alkaline water electrolyzer, It is characterized in that The diaphragm is prepared by the preparation method according to any one of claims 1 to 7.

9. An application of the polyphenylene sulfide (PPS) filament fiber diaphragm for hydrogen production in an alkaline water electrolyzer as claimed in claim 8, wherein the diaphragm is used for hydrogen production by alkaline water electrolysis.

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