A modified cerium oxide-based alkaline electrolytic water hydrogen production diaphragm and a preparation method thereof

Abstract

The application discloses a kind of hydrogen separation membrane based on modified cerium oxide of alkaline electrolytic water and preparation method thereof, it is related to alkaline electrolytic water hydrogen separation membrane technical field.The cerium dioxide is modified by acid solution, then it is dispersed in the mixed solution of polysulfone resin, N-methyl pyrrolidone, polyvinyl pyrrolidone) Preparation casting fluid.Polyphenylene sulfide net is immersed in casting fluid, thickness is determined by scraping, then pre-evaporation, phase inversion is carried out in deionized water, cleaning, and the diaphragm is obtained.The application process is simple, the surface of the prepared diaphragm is uniform and smooth, has high chemical inertness, hydrophilic property in strong alkaline electrolytic environment, guarantees the efficient migration channel of hydroxyl ion, and has low surface resistance.

Description

Technical Field

[0001] This invention relates to the field of alkaline water electrolysis for hydrogen production membrane technology, and more specifically to an alkaline water electrolysis for hydrogen production membrane based on modified cerium oxide and its preparation method. Background Technology

[0002] Alkaline water electrolysis is the most commercially mature electrolytic hydrogen production technology. Its core component, the membrane, needs to simultaneously perform three major functions under strongly alkaline and high-temperature environments: gas-tight isolation, ion conduction, and mechanical stability. Existing membrane technologies mainly face the following problems: a trade-off between conductivity and gas-tightness; reducing sheet resistivity requires increasing porosity or pore size, but this leads to a decrease in bubble point pressure, and vice versa; insufficient high-temperature stability; commercial PSF / ZrO2 membranes experience performance degradation rates >12% due to polymer swelling and particle shedding during long-term operation at >100℃; limited ion conduction mechanisms, relying on liquid-phase diffusion to fill pores with electrolyte, with migration rates limited by pore tortuosity; and a contradiction between ultrathinness and strength; when the thickness is <150μm, high-mesh support mesh (>150 mesh) easily leads to coating peeling.

[0003] Cerium oxide, as a rare earth metal oxide, offers new possibilities for overcoming the aforementioned bottlenecks due to its unique properties. It possesses an oxygen vacancy conduction mechanism: Ce... 3+ / Ce 4+ Variable valence states form a dynamic oxygen vacancy network, which may promote OH- - Ions can be transported via vacancy hopping, theoretically overcoming traditional diffusion limitations; redox buffering capacity: reversible Ce 3+ Ce 4+ The conversion process can quench anodic reactive oxygen free radicals and improve the membrane's antioxidant properties; high-temperature stability: melting point up to 2400℃, thermal expansion coefficient (11×10⁻⁶) -6 CeO2 ( / K) is compatible with the polymer matrix and exhibits better alkali corrosion resistance than ZrO2 (mass loss <0.5% over 1000h). Existing research has attempted to apply cerium oxide as a hydrophilic additive in membrane technology. For example, patent CN202411449128 proposes blending cerium oxide with zirconium oxide to reduce the contact angle due to its hydrophilicity; Tongji University's ultrathin membrane research lists CeO2 as one of the optional fillers. However, in existing membrane technologies, cerium oxide particles are prone to detachment, and the unique oxygen ion conduction characteristics and redox protection functions of cerium oxide have not been thoroughly explored in their practical value in alkaline electrolysis environments. Furthermore, there is a lack of effective solutions to the slurry sedimentation problem caused by its high density.

[0004] Therefore, providing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide, which has good stability and can be prepared in high-density slurry, and its preparation method are problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a composite membrane for alkaline water electrolysis hydrogen production based on modified cerium oxide, which has a simple process, a uniform and flat surface, high chemical inertness and hydrophilicity in a strongly alkaline electrolysis environment, ensures efficient migration channels for hydroxide ions, and has low surface resistivity.

[0006] To achieve the above objectives, the present invention first provides a method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide, specifically including the following steps:

[0007] S1, Cerium dioxide powder is placed in an acid solution, stirred and reacted, then washed with ethanol and deionized water respectively, and dried to obtain modified cerium oxide;

[0008] S2, mix and stir the polysulfone resin with N-methylpyrrolidone to uniformly disperse the polysulfone in the N-methylpyrrolidone; then add polyvinylpyrrolidone and continue stirring until it is completely dissolved to obtain a mixed solution;

[0009] S3. Add modified cerium oxide to the mixed solution and stir until the modified cerium oxide is completely and evenly dispersed. Then stir at low speed to degas the solution and obtain the casting solution.

[0010] S4. Immerse the polyphenylene sulfide mesh in the casting solution to ensure that the casting solution fully penetrates the interior of the PPS mesh support. Then, use a scraper to coat the membrane to determine the thickness. Let the coated membrane stand in the air for pre-evaporation. Then, repeatedly soak and wash the supported composite membrane with deionized water until the water is clear and not cloudy to obtain the PPS mesh supported polysulfone-modified cerium oxide composite membrane.

[0011] Preferably, the acid solution in step S1 is a hydrofluoric acid solution or a nitric acid solution; the average particle size of the cerium dioxide is 200 nm; the stirring reaction speed is 400 r / min and the time is 20-30 min; the drying temperature is 60 °C.

[0012] Preferably, the volume fraction of the hydrofluoric acid solution is 0.01%~0.1%, and the ratio of hydrofluoric acid solution to cerium dioxide powder is 10mL:1g.

[0013] Preferably, the concentration of the nitric acid solution is 0.1 mol / L, and the ratio of nitric acid solution to cerium dioxide powder is 2 mL: 1 g.

[0014] Preferably, in step S2, the mass ratio of polysulfone resin, N-methylpyrrolidone, and polyvinylpyrrolidone is 7.5:27.5:5; and the stirring speed is 300 r / min.

[0015] Preferably, the mass ratio of modified cerium oxide to polysulfone resin in step S3 is 7.5:10; the stirring speed after adding modified cerium oxide to the mixed solution is 300 r / min for 24 h; after complete dispersion, the stirring speed for degassing treatment is 100 r / min for 24 h.

[0016] Preferably, the immersion time in step S4 is 10-30 min; the thickness is 400 μm; and the pre-evaporation time is 5-15 min.

[0017] Secondly, the present invention also provides an alkaline water electrolysis hydrogen production membrane prepared by the method described above.

[0018] Finally, the present invention also provides the application of the above-mentioned alkaline water electrolysis hydrogen production diaphragm in alkaline water electrolysis.

[0019] As can be seen from the above technical solution, the present invention discloses an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide and its preparation method. Compared with the prior art, its beneficial effects are as follows:

[0020] 1) Cerium oxide (CeO2) possesses unique Ce... 3+ / Ce 4+ Variable valence properties allow it to undergo reversible redox reactions (Ce) in strongly alkaline environments. 3+ +OH - →Ce 4+ +e - +H2O) effectively consumes reactive oxygen free radicals and corrosive ions (such as OH-) in the electrolyte. - This process blocks the oxidative degradation pathways of polymer chains, such as the sulfonation reaction that easily occurs in PPS membranes. Cerium oxide particles treated with hydrofluoric acid or dilute nitric acid form a micro-nano-scale rough structure on their surface, increasing the specific surface area by 10-40%. The increased density of hydroxyl groups on their surface forms strong hydrogen bonds with the polar groups of the PPS polymer matrix, inhibiting interfacial swelling caused by alkali penetration.

[0021] 2) The cerium oxide surface after hydrofluoric acid etching is rich in oxygen vacancy defects, forming ion transport channels and promoting OH- - Ion migration. Nano-cerium oxide particles (100-500 nm) construct a continuous conductive network within the polymer matrix, reducing the tortuosity of ion transport paths. The composite membrane has a sheet resistance ≤0.20 Ω·cm² (traditional asbestos membranes >0.6 Ω·cm²). The lower the sheet resistance, the smaller the ohmic loss, the less electrical energy consumed per unit of hydrogen produced, and the higher the system's energy efficiency (e.g., hydrogen production power consumption).

[0022] 3) The surface roughness of cerium oxide provides a mechanical interlocking effect, increasing the contact area with the polymer and inhibiting particle shedding under cyclic stress. The bubble point pressure is >0.45 MPa, ensuring structural integrity under high-voltage electrolysis. Using cerium oxide particles treated with hydrofluoric acid or dilute nitric acid as the inorganic filler for the membrane can significantly reduce the membrane's contact angle and increase its hydrophilicity, significantly better than ZrO2 (approximately 15°-45°). This characteristic stems from the abundant hydroxyl (-OH) groups on the CeO2 surface, which can form a strong hydrogen bond network, promoting electrolyte wetting.

[0023] 4) The technical method of this invention has a short reaction time, low cost, and is easy to promote. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 Scanning electron microscope images of commercial cerium oxide and the modified cerium oxide obtained in Example 1.

[0026] Figure 2 Transmission electron microscopy images of commercial cerium oxide and the modified cerium oxide obtained in Example 2.

[0027] Figure 3 Scanning electron microscope (SEM) images of the plane and cross-section of the PPS mesh-supported polysulfone-modified cerium oxide composite film prepared in Example 2.

[0028] Figure 4 Commercial cerium oxide nitrogen adsorption-desorption curves.

[0029] Figure 5 Example 1: Nitrogen adsorption-desorption curve of modified cerium oxide.

[0030] Figure 6 Cell voltage test results of commercial diaphragm ZIRFON-UTP-500 and diaphragms of Examples 1 and 3. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] S1. 20g of commercial cerium dioxide powder with an average particle size of 200nm was placed in 200mL of hydrofluoric acid with a volume fraction of 0.1%, stirred at 400r / min for 25min, then washed with ethanol and deionized water respectively, and dried at 60℃ to obtain modified cerium oxide.

[0034] The microstructures of the modified cerium oxide and commercial cerium oxide were observed by scanning electron microscopy. The results are shown in [Figure number missing]. Figure 1 In the figures, a represents unetched cerium oxide, and b represents cerium oxide etched with 0.1% hydrofluoric acid (by volume). The comparison shows that etching significantly affects the microstructure of cerium oxide. The left image shows the unetched cerium oxide sample, which has a relatively smooth surface, a dense structure, clear particle boundaries, and a relatively limited overall specific surface area. In contrast, the etched cerium oxide in the right image exhibits distinctly different structural characteristics: the surface becomes extremely rough, with numerous nanoscale pores and uneven structures, significantly reduced particle size, and a more dispersed distribution.

[0035] S2, mix 7.5g of polysulfone resin with 27.5g of N-methylpyrrolidone, stir at 300r / min to uniformly disperse the polysulfone in the N-methylpyrrolidone; then add 5g of polyvinylpyrrolidone, continue stirring at 300r / min to completely dissolve it, and obtain a mixed solution.

[0036] S3. Add 10g of modified cerium oxide to the mixed solution, stir at 300r / min for 24h until the modified cerium oxide is completely and evenly dispersed, then stir at 100r / min for 24h for degassing treatment to obtain the casting solution.

[0037] S4. Immerse the polyphenylene sulfide mesh in the casting solution for 10 minutes to ensure that the casting solution fully penetrates the interior of the PPS mesh support. Then, use a doctor blade to coat the membrane to a thickness of 400 μm. Let the coated membrane stand in the air for 5 minutes for pre-evaporation. Then, repeatedly soak and wash the supported composite membrane with deionized water until the water is clear and non-turbid to obtain the PPS mesh supported polysulfone-modified cerium oxide composite membrane.

[0038] Example 2

[0039] S1. 20g of commercial cerium dioxide powder with an average particle size of 200nm was placed in 200mL of 0.01% hydrofluoric acid and stirred at 400r / min for 25min. Then it was washed with ethanol and deionized water respectively and dried at 60℃ to obtain modified cerium oxide.

[0040] The microstructures of the modified cerium oxide and commercial cerium oxide were observed by transmission electron microscopy. The results are shown in [Figure number missing]. Figure 2In the diagram, 'a' represents unetched cerium oxide, and 'b' represents cerium oxide etched with 0.01% hydrofluoric acid (by volume). The comparison shows that the unetched cerium oxide particles on the left have a more regular morphology, a relatively smooth surface, and a more uniform particle size; while the etched cerium oxide particles on the right exhibit significantly more porosity, a rougher structure, and irregular edges, presenting a more complex microstructure. The rough surface and cracks not only significantly increase the specific surface area of ​​the CeO2 nanoparticles, thereby enhancing their contact area with the alkaline electrolyte, but also strengthen their physical interlocking with the film substrate material.

[0041] S2, mix 7.5g of polysulfone resin with 27.5g of N-methylpyrrolidone, stir at 300r / min to uniformly disperse the polysulfone in the N-methylpyrrolidone; then add 5g of polyvinylpyrrolidone, continue stirring at 300r / min to completely dissolve it, and obtain a mixed solution.

[0042] S3. Add 10g of modified cerium oxide to the mixed solution, stir at 300r / min for 24h until the modified cerium oxide is completely and evenly dispersed, then stir at 100r / min for 24h for degassing treatment to obtain the casting solution.

[0043] S4. Immerse the polyphenylene sulfide mesh in the casting solution for 10 minutes to ensure that the casting solution fully penetrates the interior of the PPS mesh support. Then, use a doctor blade to coat the membrane to a thickness of 400 μm. Let the coated membrane stand in the air for 5 minutes for pre-evaporation. Then, repeatedly soak and wash the supported composite membrane with deionized water until the water is clear and non-turbid to obtain the PPS mesh supported polysulfone-modified cerium oxide composite membrane.

[0044] The microstructure of the PPS mesh-supported polysulfone-modified cerium oxide composite film prepared in Example 2 was observed by scanning electron microscopy. The results are shown in [Figure 1]. Figure 3 As can be seen from the images, the composite diaphragm obtained in Example 2 has the characteristics of a smooth surface, uniform structure, good filler dispersion, and tight bonding between the support mesh and the coating. These microstructural features are closely related to the low surface resistivity, high airtightness, good hydrophilicity, and long-term operational stability sought by the diaphragm, providing a structural basis for the efficient and durable application of the diaphragm in alkaline water electrolysis environments.

[0045] Example 3

[0046] S1. 20g of commercial cerium dioxide powder with an average particle size of 200nm was placed in 200ml of 1% dilute nitric acid and stirred at 400r / min for 25min. Then it was washed with ethanol and deionized water respectively and dried at 60℃ to obtain modified cerium oxide.

[0047] S2, mix 7.5g of polysulfone resin with 27.5g of N-methylpyrrolidone, stir at 300r / min to uniformly disperse the polysulfone in the N-methylpyrrolidone; then add 5g of polyvinylpyrrolidone, continue stirring at 300r / min to completely dissolve it, and obtain a mixed solution.

[0048] S3. Add 10g of modified cerium oxide to the mixed solution, stir at 300r / min for 24h until the modified cerium oxide is completely and evenly dispersed, then stir at 100r / min for 24h for degassing treatment to obtain the casting solution.

[0049] S4. Immerse the polyphenylene sulfide mesh in the casting solution for 10 minutes to allow the casting solution to fully penetrate the interior of the PPS mesh support. Then, use a doctor blade to coat the membrane to a thickness of 400 μm. Let the coated membrane stand in the air for 5 minutes for pre-evaporation. Then, repeatedly soak and wash the supported composite membrane with deionized water until the water is clear and not turbid to obtain the PPS mesh supported polysulfone-modified cerium oxide composite membrane.

[0050] Comparative Example 1

[0051] S1. Mix 7.5g of polysulfone resin with 27.5g of N-methylpyrrolidone and stir at 300r / min to uniformly disperse the polysulfone in the N-methylpyrrolidone; then add 5g of polyvinylpyrrolidone and continue stirring at 300r / min to completely dissolve it and obtain a mixed solution.

[0052] S2, add 10g of commercially available nano-cerium oxide powder with an average particle size of 200nm to the mixed solution, stir at 300r / min for 24h until the cerium oxide is completely and uniformly dispersed, then stir at 100r / min for 24h for degassing treatment to obtain the casting solution.

[0053] S3. Immerse the polyphenylene sulfide mesh in the casting solution for 10 minutes to allow the casting solution to fully penetrate the interior of the PPS mesh support. Then, use a doctor blade to coat the membrane to a thickness of 400 μm. Let the coated membrane stand in the air for 5 minutes for pre-evaporation. Then, repeatedly soak and wash the supported composite membrane with deionized water until the water is clear and not turbid to obtain the PPS mesh supported polysulfone-cerium oxide composite membrane.

[0054] Diaphragm surface resistance test

[0055] The surface resistance of the diaphragm in Examples 1, 2, 3 and Comparative Example 1 was tested, and the results are shown in Table 1.

[0056] Table 1. Test results of diaphragm surface resistance

[0057]

[0058] The data comparison in the table shows that the average sheet resistivity of the modified cerium oxide in Examples 1, 2, and 3 are 0.19, 0.13, and 0.12 Ω·cm², respectively, which are relatively low and close. In contrast, the average sheet resistivity of the unmodified cerium oxide in Comparative Example 1 is 0.49 Ω·cm², significantly higher than all other examples. Therefore, the modified cerium oxide exhibits a significantly lower sheet resistivity compared to commercial cerium oxide, directly verifying the effectiveness of surface etching treatment in reducing the sheet resistivity of the composite membrane. This allows the membrane with low sheet resistivity to support higher operating current densities, thereby improving the hydrogen production rate and compactness of the electrolyzer.

[0059] BET test

[0060] BET tests were performed on commercial cerium oxide and the samples from Examples 1 and 3. The results are shown in [Figure 1]. Figure 4 , Figure 5 And Table 2.

[0061] Table 2 BET Test Results

[0062]

[0063] Data shows that acid treatment (especially hydrofluoric acid) significantly increases the specific surface area of ​​cerium oxide by about 10–40%. A higher specific surface area means more surface active sites, stronger hydrophilicity, and better ion conduction interface.

[0064] Small chamber voltage test

[0065] The cell voltages of the commercial diaphragm ZIRFON-UTP-500 and the diaphragms prepared in Examples 1 and 2 were tested, and the results are shown in [Figure number missing]. Figure 6 As shown in the figure, the modified composite membrane maintains stable chamber voltage. Compared to the commercial membrane, Example 3 exhibits a reduction in operating voltage of approximately 0.10V to 0.15V. For an industrial-grade alkaline water electrolysis system, this voltage reduction directly translates to energy savings of approximately 5%-8%, which is of significant practical importance for reducing the cost of green hydrogen production.

[0066] Other tests

[0067] The bubble point pressure, contact angle, alkali absorption rate, heat shrinkage rate, and tensile strength of Examples 1-3 and Comparative Example 1 were analyzed, and the results are shown in the table below:

[0068]

[0069] The data in the table show that modifying cerium oxide with acid solution improves the key properties of the prepared composite membrane, including airtightness, hydrophilicity, and electrolyte retention, while maintaining good dimensional stability and mechanical strength. This synergistic optimization of properties is a crucial foundation for achieving low surface resistivity, high ion conductivity, and long-term operational stability of the membrane in alkaline water electrolysis environments.

[0070] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide, characterized in that, Specifically, the steps include the following: S1, Cerium dioxide powder is placed in an acid solution, stirred and reacted, then washed with ethanol and deionized water respectively, and dried to obtain modified cerium oxide; S2, mix and stir the polysulfone resin with N-methylpyrrolidone to uniformly disperse the polysulfone in the N-methylpyrrolidone; then add polyvinylpyrrolidone and continue stirring until it is completely dissolved to obtain a mixed solution; S3. Add modified cerium oxide to the mixed solution and stir until the modified cerium oxide is completely and evenly dispersed. Then stir at low speed to degas the solution and obtain the casting solution. S4. Immerse the polyphenylene sulfide mesh in the casting solution to ensure that the casting solution fully penetrates the interior of the PPS mesh support. Then, use a scraper to coat the membrane to determine the thickness. Let the coated membrane stand in the air for pre-evaporation. Then, repeatedly soak and wash the supported composite membrane with deionized water until the water is clear and not cloudy to obtain the PPS mesh supported polysulfone-modified cerium oxide composite membrane.

2. The method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide according to claim 1, characterized in that, The acid solution mentioned in step S1 is a hydrofluoric acid solution or a nitric acid solution; The average particle size of the cerium dioxide is 200 nm; the stirring reaction speed is 400 r / min, and the time is 20-30 min; The drying temperature is 60°C.

3. The method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide according to claim 2, characterized in that, The hydrofluoric acid solution has a volume fraction of 0.01% to 0.1%, and the ratio of hydrofluoric acid solution to cerium dioxide powder is 10 mL: 1 g.

4. The method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide according to claim 2, characterized in that, The concentration of the nitric acid solution is 0.1 mol / L, and the ratio of nitric acid solution to cerium dioxide powder is 2 mL: 1 g.

5. The method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide according to claim 1, characterized in that, In step S2, the mass ratio of polysulfone resin, N-methylpyrrolidone, and polyvinylpyrrolidone is 7.5:27.5:5; the stirring speed is 300 r / min.

6. The method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide according to claim 1, characterized in that, In step S3, the mass ratio of modified cerium oxide to polysulfone resin is 7.5:10; after adding modified cerium oxide to the mixed solution, the stirring speed is 300 r / min for 24 h; after complete dispersion, the degassing treatment is carried out by low-speed stirring at 100 r / min for 24 h.

7. The method for preparing an alkaline water electrolysis hydrogen production membrane based on modified cerium oxide according to claim 1, characterized in that, The immersion time in step S4 is 10-30 min; the thickness is 400 μm; and the pre-evaporation time is 5-15 min.

8. An alkaline water electrolysis hydrogen production membrane prepared by the method according to any one of claims 1-7.

9. The application of an alkaline water electrolysis hydrogen production membrane prepared by any one of claims 1-7 or the alkaline water electrolysis hydrogen production membrane as described in claim 8 in alkaline water electrolysis.

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