Alkaline electrolyzed water hydrogen production diaphragm prepared from PPS core-spun yarn and application of alkaline electrolyzed water hydrogen production diaphragm

Abstract

The invention belongs to the technical field of diaphragms for hydrogen production through electrolysis of water, and particularly relates to an alkaline diaphragm for hydrogen production through electrolysis of water and prepared from PPS covering yarn and application. A core yarn of the diaphragm is a cross-shaped or trefoil PPS filament with the groove depth / fiber equivalent radius larger than 0.05, an outer covering yarn is a short fiber with the sulfonation degree of 10%-12%, the proportion of a core part of the core-spun yarn is 60-70 wt%, the core-spun yarn is woven after being steamed under specific conditions, and then light sulfonation treatment is conducted to obtain the diaphragm. According to the diaphragm, the air tightness can be remarkably improved without a complicated hot rolling shaping process, indexes such as surface resistance and the like can be remarkably improved, the diaphragm has good industrial application value, and subsequent hydrophilic inorganic nanoparticle load modification can be carried out.

Description

Technical Field

[0001] This invention belongs to the field of membrane technology for hydrogen production by water electrolysis, specifically relating to an alkaline membrane for hydrogen production by water electrolysis prepared from PPS core-spun yarn and its applications. Background Technology

[0002] In alkaline water electrolysis hydrogen production equipment, the diaphragm mainly functions as a gas barrier and allows ion passage. The chemical environment of the hydrogen production reaction requires the diaphragm to possess good mechanical strength, alkali resistance, gas barrier properties, and ion passage. Polyphenylene sulfide (PPS) fabric has replaced asbestos as the main material for diaphragms used in alkaline water electrolysis hydrogen production.

[0003] However, due to the inherent poor hydrophilicity of PPS, extensive research has been conducted in this field on PPS composite membranes. This includes methods such as modifying PPS membranes with hydrophilic inorganic particles to improve their hydrophilicity, and chemically modifying PPS fabric surfaces through sulfonation to enhance their hydrophilicity. For example, the hydrogen production membrane disclosed in CN117286538A involves modification with hydrophilic inorganic PPS particles and amino-containing polyphenylene sulfide resin. However, due to the poor adhesion of inorganic hydrophilic particles to PPS, nanoparticles are prone to detachment in practice, leading to decreased product stability. Sun Yapo studied the effects of hot rolling and sulfonation treatment on PPS diaphragms (Sun Yapo. Effects of post-treatment on the performance of PPS fiber diaphragms for hydrogen production in water electrolyzers [J]. Industrial Textiles, 2015, 33(7):4.). The results showed that hot rolling treatment could reduce the thickness of the diaphragm and improve its airtightness and dimensional stability; sulfonation treatment could improve the alkali absorption performance of the diaphragm, but the warp and weft tensile strength of the diaphragm decreased to varying degrees. The effects of PPS filaments and staple fibers on the performance of PPS fiber diaphragms have also been studied (Sun Yapo. Preparation and performance study of polyphenylene sulfide staple fiber diaphragms and filament diaphragms [J]. Journal of Henan University of Engineering: Natural Science Edition, 2022, 34(4):4-9.). The results showed that the overall performance of PPS filament diaphragms (treated with sulfonation modification + hot rolling treatment) is better than that of staple fiber diaphragms, and it has better development prospects.

[0004] It is evident that current improvements to PPS hydrogen production membranes primarily focus on modification techniques, while neglecting research and improvements to PPS yarn and weaving processes. Consequently, the feasibility study and research on improving membrane performance through PPS material processing technology have been overlooked. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a membrane for alkaline water electrolysis to produce hydrogen, prepared from PPS core-spun yarn, and its applications. The inventors have discovered through research that improvements to specific processing techniques for PSS materials can unexpectedly enhance membrane performance. Furthermore, the prepared membrane can be further combined with modification techniques such as inorganic hydrophilic nanoparticles, thereby allowing for further improvements in hydrophilicity. The technical solution of this invention is as follows: A membrane for alkaline water electrolysis to produce hydrogen, prepared from PPS core-spun yarn, wherein the core yarn is a PPS filament with a cross-shaped or trilobal cross-section and a groove depth to fiber equivalent radius ratio greater than 0.05, and the outer sheath yarn is PPS staple fiber with a sulfonation degree of 10-12%; the core portion of the PPS core-spun yarn accounts for 60-70 wt%, and the preparation method of the membrane includes the following steps: S2 Preparation of core-spun yarn: The core-spun yarn is prepared using PPS filament and sulfonated PPS staple fiber; S3 steaming: Steam the yarn at 110℃~160℃ for 30min~120min; S4 woven PPS fabric; S5 PPS fabric sulfonation treatment: Sulfonate the PPS fabric to achieve a sulfonation degree of 5%~15%.

[0006] Preferably, the ratio of the groove depth of the core yarn to the fiber equivalent radius is 0.08 to 0.3.

[0007] Preferably, the PPS filament has a specification of 50~500D and 10~200F.

[0008] Preferably, the PPS staple fiber has a specification of 0.5D to 5D; and the length of the PPS staple fiber is 2mm to 51mm.

[0009] Preferably, the method for preparing the diaphragm further includes the following steps: Preparation of S1 filament and sulfonated staple fiber: The required PPS filament is prepared by melt spinning, and the staple fiber is sulfonated to prepare sulfonated PPS staple fiber.

[0010] Preferably, the relative humidity during the yarn steaming operation is 100%.

[0011] Preferably, the PPS fabric is a reinforced satin weave or a high warp density plain weave.

[0012] Preferably, the PPS fabric has a warp density of 120-200 threads / inch and a weft density of 100-180 threads / inch.

[0013] Preferably, the thickness of the diaphragm is 0.2 mm to 0.6 mm.

[0014] The present invention also provides the use of the aforementioned PPS core-spun yarn-based diaphragm for alkaline water electrolysis hydrogen production in the preparation of diaphragms for alkaline water electrolysis hydrogen production.

[0015] The present invention also provides an alkaline water electrolysis hydrogen production device, wherein the diaphragm used in the alkaline water electrolysis hydrogen production device is a diaphragm for alkaline water electrolysis hydrogen production prepared by the aforementioned PPS core-spun yarn or a composite diaphragm for alkaline water electrolysis hydrogen production prepared by the aforementioned PPS core-spun yarn loaded with inorganic hydrophilic particles.

[0016] Preferably, the inorganic hydrophilic particles are selected from one or more of ZrO2, CeO2, SiO2 and Y2O3 nanoparticles.

[0017] The aforementioned "groove depth" refers to the vertical distance from the outer surface of the profiled filament to the bottom of the groove, which can be measured using the laser confocal testing method commonly used in existing technologies; the fiber equivalent radius is 1 / 2 of the fiber equivalent diameter, which can be measured using the linear density method commonly used in existing technologies.

[0018] The aforementioned determination of "degree of sulfonation" can be achieved using methods commonly used in this field, such as acid-base titration (after thoroughly washing the sulfonated sample to neutral, titrating the -SO3H groups on it with an alkaline solution such as NaOH standard solution, and calculating the degree of sulfonation based on the amount of alkali consumed), or by calculating using nuclear magnetic resonance spectroscopy or elemental analysis.

[0019] The aforementioned "reinforced satin weave" is a common fabric structure. It is a new satin weave structure formed by adding one or more warp (or weft) weave points around the original satin weave points.

[0020] The aforementioned "sulfonation treatment" can employ commonly used sulfonation treatment techniques, such as treating PPS fibers or PPS fabrics with sulfuric acid at a concentration of 30% to 60% at a temperature of 60°C to 90°C for 20 to 40 minutes, followed by rinsing and drying with alkaline solution.

[0021] Beneficial effects

[0022] This invention, through extensive research, reveals that by specifically combining PPS filaments and staple fibers, including the structural characteristics of the shaped filaments and the length of the staple fibers, along with modifications to the steaming process and mild sulfonation, the performance of hydrogen production membranes can be significantly improved without complex hot rolling processes. This optimizes the preparation process and performance of PPS hydrogen production membranes. Ultra-low sheet resistance (≤40 mΩ·cm²) and extremely low oxygen permeability (≤0.05 mL / min·cm²) are simultaneously achieved on the same membrane. These membrane performances far exceed those of existing technologies, resolving the core contradiction between sheet resistance and gas permeability. Furthermore, the long-term stability of the product is significantly improved, with a performance retention rate >95% after 2000 hours of accelerated aging testing.

[0023] The membrane of the present invention can also be further modified with inorganic hydrophilic particles to further improve its performance. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the diaphragm sample from Experiment Example 2; Figure 2 Scanning electron microscope image of the diaphragm sample in Example 5. Detailed Implementation

[0025] The technical concept, solution, and effects of the present invention will be described in detail below through specific embodiments. These embodiments are merely illustrative examples of the present invention and should not be considered as limiting the scope of protection of the present invention. Unless otherwise specified, the preparation techniques for PPS profiled filaments in the following embodiments all employ conventional existing techniques.

[0026] Example 1: Preparation of a core-spun yarn Core yarn: PPS profiled filament with a trilobal cross-section, the ratio of groove depth to fiber equivalent radius is 0.10. The filament specification is 50D / 10F, which is obtained by melt spinning (spinning temperature 310°C) and drawing 3.5 times from PPS resin with a melt index of 60g / 10min.

[0027] Outer yarn: PPS staple fiber with 10% sulfonation. This staple fiber is cut from PPS filaments with a trilobal cross section (specification 100D / 200F; groove depth to fiber equivalent radius ratio of 0.10) and has a fiber length of 5mm (specification 0.5D).

[0028] Short fiber sulfonation method: PPS short fibers are placed in a 50% sulfuric acid solution and treated at 70°C for 30 minutes. Then, they are neutralized with a 5% NaOH solution, rinsed with deionized water until neutral, and dried at 80°C to obtain PPS short fibers with a sulfonation degree of 10%.

[0029] Core-spun yarn preparation: A composite spinning process is adopted to control the feeding speed ratio of the core yarn (shaped PPS filament) and the outer yarn (sulfonated PPS staple fiber) so that the core content of the final core-spun yarn is 60wt%.

[0030] Example 2: Preparation of a core-spun yarn Core yarn: PPS profiled filament with a trilobal cross-section, the ratio of groove depth to fiber equivalent radius is 0.18. The filament specification is 100D / 100F, which is obtained by melt spinning (spinning temperature 310°C) and drawing 3.5 times from PPS resin with a melt index of 60g / 10min.

[0031] Outer yarn: PPS staple fiber with 11% sulfonation. This staple fiber is cut from PPS filaments with a trilobal cross section (specification 100D / 50F; the ratio of groove depth to fiber equivalent radius is 0.18) and has a fiber length of 38mm (specification 2D).

[0032] Short fiber sulfonation method: PPS short fibers are placed in a 55% sulfuric acid solution and treated at 75°C for 30 minutes. Then, they are neutralized with a 5% NaOH solution, rinsed with deionized water until neutral, and dried at 80°C to obtain PPS short fibers with a sulfonation degree of 11%.

[0033] Core-spun yarn preparation: A composite spinning process is adopted to control the feeding speed ratio of the core yarn (shaped PPS filament) and the outer yarn (sulfonated PPS staple fiber) so that the core content of the final core-spun yarn is 65wt%.

[0034] Example 3: Preparation of a core-spun yarn Core yarn: PPS profiled filament with a cross-shaped cross section, the ratio of groove depth to fiber equivalent radius is 0.25. The filament specification is 100D / 100F, which is obtained by melt spinning (spinning temperature 310°C) and drawing 3.5 times from PPS resin with a melt index of 60g / 10min.

[0035] Outer yarn: PPS staple fiber with 12% sulfonation. This staple fiber is made by cutting PPS filaments with a cross-shaped cross section (specification 100D / 100F; the ratio of groove depth to fiber equivalent radius is 0.25) into short lengths of 45mm (specification 1D).

[0036] Short fiber sulfonation method: PPS short fibers are placed in a 60% sulfuric acid solution and treated at 80°C for 30 minutes. Then, they are neutralized with a 5% NaOH solution, rinsed with deionized water until neutral, and dried at 80°C to obtain PPS short fibers with a sulfonation degree of 12%.

[0037] Core-spun yarn preparation: A composite spinning process is adopted to control the feeding speed ratio of the core yarn (shaped PPS filament) and the outer yarn (sulfonated PPS staple fiber) so that the core content of the final core-spun yarn is 70 wt%.

[0038] Example 4: Preparation and performance testing of diaphragms for hydrogen production via alkaline water electrolysis 1. Experimental Example: Preparation of Hydrogen Production Membrane Core-spun yarns from Examples 1-3 were used to prepare diaphragms for alkaline water electrolysis hydrogen production after steaming. These diaphragms served as the diaphragms for alkaline water electrolysis hydrogen production in Examples 1-3. Specific raw materials and process parameters are shown in Table 1, primarily used to verify the influence of yarn structure (trilobal, cross-shaped, different groove depth ratios) on diaphragm performance. PPS fabric sulfonation treatment (uniform method): To control the final sulfonation degree of the PPS fabric within the range of 8±1% (i.e., 7%~9%), the following sulfonation process was adopted: The woven PPS fabric was placed in a 40% sulfuric acid solution and treated at 75°C for 25 minutes. After treatment, it was neutralized with dilute alkali solution (5% NaOH), then thoroughly rinsed with deionized water until neutral, and finally dried at 80°C. Previous verification showed that these process parameters could stably control the fabric sulfonation degree within the target range.

[0039] Table 1. Raw materials and process parameters for hydrogen production membrane in the experimental example.

[0040] 2. Exploratory example of hydrogen production membrane preparation (1) Exploration Example 0 Hydrogen production diaphragm: Compared with the hydrogen production diaphragm of Experiment Example 2, the only difference is that the PPS filament has a conventional circular cross section and the yarn steaming process adopts the conventional yarn steaming process (100°C, 20 min, and the same relative humidity as Experiment Example 2).

[0041] (2) Exploration Example 1 Hydrogen production membrane: Compared with the hydrogen production membrane in Experiment Example 2, the only difference is that the PPS filament has a conventional circular cross section.

[0042] (3) Exploration Example 2 Hydrogen production diaphragm: Compared with the hydrogen production diaphragm in Experiment Example 2, the only difference is that the yarn steaming process is the conventional 100°C, 20min (relative humidity is the same as in Experiment Example 2).

[0043] (4) Exploration Example 3 Hydrogen production diaphragm: Compared with the hydrogen production diaphragm in Experiment Example 2, the only difference is that the yarn steaming process is 200°C for 70 min (relative humidity is the same as in Experiment Example 2).

[0044] (5) Exploration Example 4 Hydrogen Production Membrane: Commercially available PPS short fiber nonwoven fabric (area density 380g / m²) was used. 2 The nano-SiO2 nanoparticles (0.40 mm thick) were impregnated and coated with a hydrophilic coating. The preparation method is as follows: Preparation of hydrophilic nano-SiO2 dispersion: Take 10g of hydrophilic nano-silica powder (average particle size 50nm), add 200mL of a mixed solvent of deionized water and ethanol (water:ethanol volume ratio = 1:1), and add 0.5g of polyethylene glycol (PEG-400) as a dispersant. Ultrasonically disperse at 400W power for 30min to obtain a uniform and stable nano-SiO2 impregnation solution (solid content about 5wt%). Pretreatment of PPS nonwoven fabric: Commercially available PPS short fiber nonwoven fabric is ultrasonically cleaned in acetone and deionized water for 15 minutes each to remove surface grease and impurities, and then dried in an 80°C oven for 2 hours for later use. Impregnation coating process: The pretreated PPS nonwoven fabric is completely immersed in the above nano-SiO2 dispersion, and left to stand at room temperature (25°C) for 30 min. It is then lifted out at a uniform speed of 100 mm / min using the dip-coating method, pre-dried at 80°C for 10 min, and then transferred to a 120°C oven for curing for 1 h. Post-processing and quality inspection: Repeat the above impregnation-lifting-curing process twice to enhance the uniformity and adhesion of the SiO2 coating, and finally obtain a composite membrane with uniformly loaded nano-SiO2 on the surface.

[0045] (6) Exploration Example 5 Hydrogen production diaphragm: Compared with the hydrogen production diaphragm of Experiment Example 2, the difference is that the steaming process is 100°C for 30 min (relative humidity is the same as in Experiment Example 2), and a hot rolling step is added between weaving and PPS fabric sulfonation treatment: hot rolling is carried out at a temperature of 205°C and a pressure of 5 MPa for 20 s.

[0046] 3. Performance testing methods for different hydrogen production membranes The sheet resistance and other properties of different hydrogen production membranes were tested using conventional methods in this field (test temperature 80°C, test alkali solution 30% KOH). The test methods are briefly described below: (1) Sheet resistance: The AC impedance method was used for testing. Before testing, the diaphragm sample was fully immersed in 30% KOH solution at 80°C for 24 hours. Using an electrochemical workstation, the impedance of the electrochemical cell with the diaphragm was measured in the frequency range of 100 kHz to 0.1 Hz. The total resistance (R_total) was obtained by the intercept of the high-frequency region with the real axis. The electrolyte resistance (R_electrolyte) without the diaphragm was measured under the same conditions. The sheet resistance was calculated using the formula: ASR (Ω·cm²) = (R_total - R_electrolyte) × effective electrode area (cm²).

[0047] (2) Air tightness: The pressure difference method is used for testing. Referring to the industry's common method, its comprehensive ability to block gases is expressed in millimeters of water column (mm H2O). The higher the value, the better the barrier performance of the membrane against hydrogen and oxygen.

[0048] (3) Bursting strength: In accordance with GB / T 24218.2-2022 standard, the Mullen Burst Tester was used to test and the maximum pressure (MPa) that the diaphragm could withstand when it ruptured was directly read.

[0049] (4) 2000h performance retention rate (%): The diaphragm sample was continuously immersed in 80°C, 30% KOH solution for 2000h to simulate the accelerated aging process. After aging, its sheet resistance was tested again. The performance retention rate was calculated as: (initial resistance after aging / initial resistance before aging) × 100%.

[0050] All PPS resin raw materials mentioned above are commercially available. The melt index was determined according to ASTM D1238 standard at 316°C and 5.00 kg load. It is expressed as the mass of polymer extruded per 10 min (g). The calculation formula is: MFI (g / 10min) = (mass of extruded material (g) / cutting time interval (s)) × 600.

[0051] 4. Performance test results of different hydrogen production membranes (80°C, 30% KOH) The performance test results of different hydrogen production membranes are shown in Table 2.

[0052] Table 2 Performance test results of different hydrogen production membranes

[0053] Exploratory Example 0 represents a conventional PPS membrane in the prior art (non-shaped PPS long fibers combined with short fibers, and using a conventional steaming process, without the use of inorganic hydrophilic particles or sulfonation modification). As shown in Table 2, among all membrane samples, it has the highest sheet resistance and the poorest airtightness (lower than most exploratory examples and all experimental examples).

[0054] As further compared in Table 2, compared with the diaphragm prepared by non-shaped PPS long fiber combined with short fiber (Exploratory Example 1), the diaphragm prepared by conventional or other steaming processes (Exploratory Examples 2 and 3), the diaphragm made of conventional short PPS fiber loaded with inorganic hydrophilic particles (Exploratory Example 4), and the diaphragm made by conventional steaming combined with hot rolling and sulfonation treatment (Exploratory Example 5), the diaphragms of Experimental Examples 1-3 significantly reduced the sheet resistivity and maintained good performance in terms of air tightness, burst strength, weaving efficiency, and 2000h performance retention. Among them, the sheet resistivity and air tightness of the experimental example samples were better than all the Exploratory Example samples, and the burst strength, weaving efficiency, and 2000h performance retention were not significantly different from or slightly better than the best performance sample in the Exploratory Examples (such as Exploratory Example 1).

[0055] A comparison of the performance of Experimental Examples 1-3 and Exploratory Examples 0-5 shows that this invention, through the combination of irregularly shaped PPS with long and short fiber blending and improved steaming process, significantly and synergistically reduces the sheet resistance of the hydrogen production membrane, improves its airtightness, and maintains good burst strength, weaving efficiency, and 2000-hour performance retention. For example, compared to Exploratory Example 0, the samples of Exploratory Examples 1 and 2 only improved the fiber cross-sectional shape or steaming process, resulting in a reduction in sheet resistance to 10 or 15 mΩ·cm² and an improvement in airtightness of 300 or 500 mmH₂O. In contrast, the sample of Experimental Example 2, compared to Exploratory Example 0, showed a reduction in sheet resistance to 32 mΩ·cm² and an improvement in airtightness of 900 mmH₂O.

[0056] Further field emission scanning electron microscopy (SEM) was used to observe the diaphragm samples of Experimental Example 2 and Exploratory Example 5 at an accelerating voltage of 5.0 kV. The results are as follows: Figure 1 (Sample from Experimental Example 2) and Figure 2 (Example 5 sample) is shown. Figure 1 Within the membrane, the grooved structure of the irregularly shaped PPS filaments is complete and clearly visible, with the fibers arranged in an orderly manner to form a uniform and interconnected porous network. This microstructure provides an ideal channel and barrier for rapid ion conduction (low surface resistivity) and effective gas barrier (high airtightness). Figure 2 In the diaphragm, the groove structure of the irregularly shaped fibers undergoes severe flattening and melt adhesion, with some pores being closed or reduced. This is the direct cause of increased surface resistivity, limited improvement in airtightness, and decreased long-term performance retention. It is evident that the "steaming + weaving + light sulfonation" process route of this invention can excellently preserve the advantageous structure of the irregularly shaped fibers. Introducing a hot rolling post-treatment step would damage this structure, which is detrimental to the optimization of overall performance. This strongly supports the necessity and superiority of avoiding hot rolling in this invention.

Claims

1. A diaphragm for hydrogen production by alkaline electrolysis of water prepared by a PPS core spun yarn, characterized by, The core yarn of the PPS core-spun yarn has a cross section of a cross shape or a trilobal shape, and a ratio of a groove depth to a fiber equivalent radius is greater than 0.05; and the outer covering yarn is PPS staple fiber with a sulfonation degree of 10-12%; the core portion of the PPS core-spun yarn accounts for 60-70wt%; and the preparation method of the separator comprises the following steps: S2: preparing the core-spun yarn by using the PPS filaments and the sulfonated PPS staple fibers; S3: steaming the yarn at 110-160℃ for 30-120min; S4: weaving the PPS fabric; S5: sulfonating the PPS fabric to have a sulfonation degree of 5-15%.

2. A diaphragm for hydrogen production by alkaline electrolysis of water prepared from a PPS core spun yarn according to claim 1, characterized in that, The ratio of the groove depth to the fiber equivalent radius of the core yarn is 0.08-0.

3.

3. The PPS core-spun yarn prepared diaphragm for hydrogen production by alkaline electrolysis water according to claim 1, characterized in that, The PPS filaments have a specification of 50-500D and 10-200F.

4. The PPS core-spun yarn prepared diaphragm for hydrogen production by alkaline electrolysis water according to claim 1, characterized in that, The PPS staple fibers have a specification of 0.5D-5D, and a length of 2-51mm.

5. The PPS core-spun yarn prepared diaphragm for hydrogen production by alkaline electrolysis water according to claim 1, characterized in that, The preparation method of the separator further comprises the following steps: S1: preparing the PPS filaments by melt spinning, and sulfonating the staple fibers to prepare the sulfonated PPS staple fibers.

6. The PPS core-spun yarn prepared diaphragm for hydrogen production by alkaline electrolysis water according to claim 1, characterized in that, The PPS fabric has a reinforcing satin weave or a high-warp-density plain weave.

7. The PPS core-spun yarn prepared diaphragm for hydrogen production by alkaline electrolysis water according to claim 1, characterized in that, The PPS fabric has a warp density of 120-200 threads / inch and a weft density of 100-180 threads / inch.

8. The PPS core-spun yarn prepared diaphragm for hydrogen production from alkaline electrolysis water according to claim 1, characterized by, The separator has a thickness of 0.2-0.6mm.

9. Use of the separator prepared from the PPS core-spun yarn according to any one of claims 1-8 in preparing a separator for an alkaline electrolysis water hydrogen production device.

10. A hydrogen generation apparatus using alkaline electrolysis of water, characterized by comprising: The separator used by the alkaline electrolysis water hydrogen production device is the separator for the alkaline electrolysis water hydrogen production device prepared from the PPS core-spun yarn according to any one of claims 1-8 or a composite separator made by loading inorganic hydrophilic particles on the separator for the alkaline electrolysis water hydrogen production device prepared from the PPS core-spun yarn according to any one of claims 1-8.

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