Electrolytic water hydrogen production composite diaphragm material and preparation method thereof

Abstract

The application belongs to the technical field of hydrogen energy conversion by water electrolysis, and particularly relates to a composite diaphragm material for hydrogen production by water electrolysis and a preparation method thereof, which comprises the following steps: adding polysulfone into N-methyl pyrrolidone to prepare a uniformly dispersed PSU solution, adding PVP into the PSU solution, stirring until the PVP is completely dissolved, adding magnesium oxide-carbon nanotube material, stirring until the magnesium oxide-carbon nanotube material is completely uniformly dispersed, and obtaining a casting solution; after degassing treatment of the casting solution, the casting solution is uniformly spread on the surface of a glass film by sliding a scraper at a constant speed to obtain a liquid film; after pre-evaporation of the liquid film, the liquid film is immersed in deionized water to solidify into a film, the film is peeled off from the surface of the glass film, and the magnesium oxide-carbon nanotube modified polysulfone composite diaphragm is obtained after cleaning. The preparation method is simple in steps and mild in conditions, and is easy to realize industrialized continuous production, and can provide a high-performance and low-cost composite diaphragm material for hydrogen production by alkaline water electrolysis.

Description

Technical Field

[0001] This invention belongs to the field of energy conversion technology for hydrogen production through water electrolysis, specifically relating to a composite membrane material for hydrogen production through water electrolysis and its preparation method. Background Technology

[0002] Hydrogen possesses dual attributes as both a raw material and an energy source. It is abundant, clean, low-carbon, and widely applicable, and holds promise for facilitating the large-scale integration of renewable energy. Water electrolysis for hydrogen production utilizes "green electricity" to generate hydrogen, enabling large-scale peak shaving and cross-seasonal regional energy storage for the power grid. Currently, water electrolysis for hydrogen production is gradually advancing towards commercialization and large-scale application. The membrane in water electrolysis equipment is a key component, primarily responsible for conducting hydroxide ions to form an internal pathway and isolating hydrogen and oxygen generated at the electrodes. Currently, membrane materials used in alkaline water electrolysis for hydrogen production include asbestos, polyphenylene sulfide (PPS) woven fabric, and composite membranes. Asbestos, due to its high carcinogenicity, high-temperature instability, and high internal resistance, has been gradually replaced by PPS woven fabric. While the high porosity of PPS woven fabric facilitates hydroxide ion conduction, it leads to severe hydrogen permeation. Furthermore, PPS woven fabric membranes have poor hydrophilicity and high resistance, resulting in high energy consumption and low safety in water electrolysis for hydrogen production equipment. Therefore, developing porous membranes with high hydroxide conductivity, high durability, and low gas permeability is of great significance for alkaline water electrolysis hydrogen production technology. Summary of the Invention

[0003] The purpose of this invention is to provide a composite membrane material for hydrogen production by water electrolysis and its preparation method, so as to solve the technical problem of the lack of porous membranes with high hydroxide conductivity, high durability and low gas permeability in the prior art.

[0004] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, this application discloses a composite membrane material for hydrogen production by water electrolysis, the components of which include 30-70 wt% magnesium oxide-carbon nanotubes, 10-40 wt% polysulfone and 0.5-30 wt% polyvinylpyrrolidone.

[0005] Secondly, this application discloses a method for preparing a composite membrane material for hydrogen production via water electrolysis, comprising: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. PVP was added to the PSU solution and stirred until completely dissolved. Then, magnesium oxide-carbon nanotube material was added and stirred until completely uniformly dispersed to obtain a casting solution. After the casting solution is degassed, it is spread on the front end of the scraper. The scraper is slid at a uniform speed to spread the casting solution evenly on the glass film surface to form a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is immersed in deionized water to solidify into a film. The film is then removed from the glass membrane surface and cleaned to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0006] Preferably, the polysulfone content in the PSU solution is 10-40 wt%.

[0007] Preferably, 0.5-30 wt% PVP is added to the PSU solution.

[0008] Preferably, PVP is added to the PSU solution and stirred at 200-400 r / min at room temperature until completely dissolved.

[0009] Preferably, the content of magnesium oxide-carbon nanotube material in the casting solution is 30-70 wt%.

[0010] Preferably, the casting liquid is stirred at 40-70 r / min for degassing; the distance between the scraper and the glass membrane is 200-500 μm; and the liquid membrane is allowed to stand for pre-evaporation for 10-40 s.

[0011] Preferably, the liquid membrane is rapidly immersed in deionized water at 15-60℃ and solidifies into a film after 5-30 seconds. After being removed from the glass membrane surface, it is immersed in deionized water at room temperature for 3-10 minutes and the process is repeated 3 times to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0012] Preferably, the magnesium oxide-carbon nanotube nanomaterial is prepared by the following steps: Mg(NO3)2 was dissolved in an ethanol / water mixed solvent, and hydroxylated carbon nanotube powder was added and stirred to form a uniformly dispersed precursor solution. Citric acid was added dropwise to the precordial solution until a Mg(OH)2-carbon nanotube composite gel was formed; The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere to form magnesium oxide-carbon nanotube material.

[0013] Preferably, the ethanol / water mixed solvent has an ethanol concentration of 50%~70%; a Mg(NO3)2 content of 0.1~0.5 mol / L; and a hydroxylated carbon nanotube powder content of 0.5~2 wt%. After drying, the Mg(OH)2-carbon nanotube composite gel was calcined in a muffle furnace under a nitrogen atmosphere for 1-3 hours at a calcination temperature of 400-600℃.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The composite membrane material of this invention uses polysulfone (PSU) as a substrate, leveraging its excellent thermal stability, film-forming properties, and alkali resistance to ensure structural stability and long service life of the membrane during water electrolysis for hydrogen production. By introducing a magnesium oxide-carbon nanotube composite into the material, a uniformly distributed conductive network and hydrophilic sites are formed within the polysulfone matrix, significantly improving the poor hydrophilicity and high internal resistance of polysulfone materials. This enhances the conduction efficiency of hydroxide ions and reduces energy consumption during electrolysis. Furthermore, the introduction of polyvinylpyrrolidone (PVP) effectively modulates the pore structure of the membrane, giving it excellent gas barrier capabilities, reducing the risk of hydrogen permeation, and improving the safety and operational stability of the water electrolysis hydrogen production equipment. In summary, this composite membrane material exhibits a synergistic effect in improving conductivity, hydrophilicity, and safety, making it suitable for efficient, low-energy-consumption alkaline water electrolysis hydrogen production processes.

[0015] This preparation method employs a phase inversion process. Polysulfone (PSU) is dissolved in N-methylpyrrolidone (NMP) to form a casting solution, and then polyvinylpyrrolidone (PVP) and magnesium oxide-carbon nanotube materials are sequentially introduced. This achieves uniform dispersion of each component in the matrix, ensuring the structural consistency and performance stability of the composite membrane. PVP, as a pore-forming additive, can effectively control the pore size of the membrane during the phase inversion process. Combined with controlling the membrane thickness at 200–500 μm, composite membranes with target thickness and pore size (50–100 nm) can be precisely fabricated, significantly improving their gas barrier capacity and reducing the risk of hydrogen permeation. Simultaneously, by premixing magnesium oxide-carbon nanotube materials in the casting solution, they are uniformly distributed within the polysulfone matrix during film formation, constructing a continuous conductive network and abundant hydrophilic sites. This allows for simultaneous improvement of the membrane's conductivity and hydrophilicity without adding an additional coating step. The preparation method is simple and mild (stirring at room temperature and solidification with deionized water at room temperature), which makes it easy to achieve continuous industrial production. It does not require complex equipment, has good process operability and cost advantages, and can provide high-performance, low-cost composite membrane materials for alkaline water electrolysis to produce hydrogen. Detailed Implementation

[0016] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0017] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0018] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0019] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0020] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0021] The present invention will now be described in further detail: This application discloses a composite membrane material for hydrogen production via water electrolysis, comprising 30-70 wt% magnesium oxide-carbon nanotubes, 10-40 wt% polysulfone, and 0.5-30 wt% polyvinylpyrrolidone. The material uses polysulfone (PSU) as its substrate, which possesses excellent thermal stability and alkali resistance. Furthermore, modifications have been made to address the poor hydrophilicity and high internal resistance of PSU, effectively reducing the risk of hydrogen permeation by controlling the pore size to 50-100 nm.

[0022] The substrate material chosen is polysulfone (PSU), a thermoplastic with good film-forming properties, easy processing, and a long-term operating temperature of about 160℃. It also has good electrical properties and chemical stability at high temperatures.

[0023] The magnesium oxide-carbon nanotube modified composite membrane material has magnesium oxide-carbon nanotube material uniformly dispersed inside the material to form a conductive network and hydrophilic sites, which improves the hydrophilicity and conductivity of the material. This improves the problem of poor wettability of polysulfone membrane itself, which leads to slow hydroxide ion transport, resulting in high internal resistance and high energy consumption in the water electrolysis hydrogen production electrolyzer.

[0024] Introducing PVP as an additive into magnesium oxide-carbon nanotube modified polysulfone composite membrane materials can control the pore size of polysulfone films. This method can control the pore size to 50-100 nm, effectively reducing the risk of hydrogen permeation.

[0025] Secondly, this application discloses a method for preparing a composite membrane material for hydrogen production via water electrolysis, comprising: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. PVP was added to the PSU solution and stirred until completely dissolved. Then, magnesium oxide-carbon nanotube material was added and stirred until completely uniformly dispersed to obtain a casting solution. After the casting solution is degassed, it is spread on the front end of the scraper. The scraper is slid at a uniform speed to spread the casting solution evenly on the glass film surface to form a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is immersed in deionized water to solidify into a film. The film is then removed from the glass membrane surface and cleaned to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0026] In some embodiments, a method for preparing a composite membrane material for hydrogen production by water electrolysis includes: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. PVP was added to the PSU solution and stirred until completely dissolved. Then, magnesium oxide-carbon nanotube material was added and stirred until completely uniformly dispersed to obtain a casting solution. The polysulfone content in the PSU solution was 10-40 wt%.

[0027] After the casting solution is degassed, it is spread on the front end of the scraper. The distance between the scraper and the glass membrane is 200-500μm. The scraper is slid at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to obtain a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is immersed in deionized water to solidify into a film. The film is then removed from the glass membrane surface and cleaned to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0028] In some embodiments, a method for preparing a composite membrane material for hydrogen production by water electrolysis includes: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. 0.5-30 wt% PVP was added to the PSU solution and stirred until completely dissolved. Magnesium oxide-carbon nanotube material was added and stirred until completely uniformly dispersed to obtain the casting solution. After the casting solution is degassed, it is spread on the front end of the scraper. The distance between the scraper and the glass membrane is 200-500μm. The scraper is slid at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to obtain a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is immersed in deionized water to solidify into a film. The film is then removed from the glass membrane surface and cleaned to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0029] In some embodiments, a method for preparing a composite membrane material for hydrogen production by water electrolysis includes: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. PVP was added to the PSU solution and stirred at 200-400 r / min at room temperature until completely dissolved. Then, magnesium oxide-carbon nanotube material was added and stirred until completely and uniformly dispersed to obtain the casting solution. After the casting solution is degassed, it is spread on the front end of the scraper. The distance between the scraper and the glass membrane is 200-500μm. The scraper is slid at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to obtain a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is immersed in deionized water to solidify into a film. The film is then removed from the glass membrane surface and cleaned to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0030] In some embodiments, a method for preparing a composite membrane material for hydrogen production by water electrolysis includes: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. PVP was added to the PSU solution and stirred until completely dissolved. Then, magnesium oxide-carbon nanotube material was added and stirred until completely uniformly dispersed to obtain a casting solution. The content of magnesium oxide-carbon nanotube material in the casting solution was 30-70 wt%.

[0031] After degassing the casting solution by stirring at 40-70 r / min, it is spread on the front end of the scraper. The distance between the scraper and the glass membrane is 200-500 μm. The scraper is slid at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to obtain a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is immersed in deionized water to solidify into a film. The film is then removed from the glass membrane surface and cleaned to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane. The pre-evaporation time is 10-40 seconds.

[0032] In some embodiments, a method for preparing a composite membrane material for hydrogen production by water electrolysis includes: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. PVP was added to the PSU solution and stirred until completely dissolved. Then, magnesium oxide-carbon nanotube material was added and stirred until completely uniformly dispersed to obtain a casting solution. The content of magnesium oxide-carbon nanotube material in the casting solution was 30-70 wt%.

[0033] After degassing the casting solution by stirring at 40-70 r / min, it is spread on the front end of the scraper. The distance between the scraper and the glass membrane is 200-500 μm. The scraper is slid at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to obtain a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is quickly immersed in deionized water at 15-60℃ and solidified into a film after 5-30 seconds. The membrane is then removed from the glass membrane surface and immersed in deionized water at room temperature for 3-10 minutes. This process is repeated 3 times to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0034] In some embodiments, the magnesium oxide-carbon nanotube nanomaterial is prepared by the following steps: Mg(NO3)2 was dissolved in an ethanol / water mixed solvent, and hydroxylated carbon nanotube powder was added and stirred to form a uniformly dispersed precursor solution. Citric acid was added dropwise to the precordial solution until a Mg(OH)2-carbon nanotube composite gel was formed; The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere to form magnesium oxide-carbon nanotube material.

[0035] More preferably, the ethanol / water mixed solvent has an ethanol concentration of 50%~70%; a Mg(NO3)2 content of 0.1~0.5 mol / L; and a hydroxylated carbon nanotube powder content of 0.5~2 wt%. After drying, the Mg(OH)2-carbon nanotube composite gel was calcined in a muffle furnace under a nitrogen atmosphere for 1-3 hours at a calcination temperature of 400-600℃.

[0036] In some embodiments, a method for preparing a composite membrane material for hydrogen production by water electrolysis includes: Step 1: Prepare the casting solution. Add 10-40 wt% polysulfone (PSU) to N-methylpyrrolidone (NMP) and mechanically stir to obtain a uniformly dispersed PSU solution. Then, add 0.5-30 wt% PVP to the PSU solution and stir at 200-400 r / min at room temperature until completely dissolved. Finally, add 30-70 wt% magnesium oxide-carbon nanotube material to the solution and continue stirring for 24 hours until completely and uniformly dispersed.

[0037] Step 2, Degassing of the casting solution. The casting solution is stirred at 40-70 r / min for 2 hours to degas it.

[0038] Step 3, casting. Set the distance between the doctor blade and the glass membrane to 200-500 μm. Before casting, spread the casting solution on the front end of the doctor blade and slide the doctor blade at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to form a liquid film.

[0039] Step 4, Pre-evaporation. The liquid film obtained by the scraper coating is left to stand in the air for 10-40 seconds for pre-evaporation.

[0040] Step 5: Immersion precipitate phase inversion membrane preparation. The liquid membrane is rapidly immersed in deionized water at 15-60℃ and solidified into a membrane after 5-30 seconds. The membrane is then removed from the glass membrane surface to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0041] Step 6, membrane cleaning. Immerse the magnesium oxide-carbon nanotube modified polysulfone composite membrane in room temperature deionized water for 3-10 minutes, repeating 3 times.

[0042] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0044] Example 1 The preparation steps of magnesium oxide-carbon nanotube nanomaterials are as follows: Step 1, Preparation of precursor solution. Dissolve 0.1 mol / L Mg(NO3)2 in a 50% ethanol / water mixed solvent, add 0.5 wt% hydroxylated carbon nanotube powder, and stir to form a uniformly dispersed solution.

[0045] Step 2, gelation treatment. Citric acid is added dropwise to the precursor solution to form a Mg(OH)2-carbon nanotube composite gel.

[0046] Step 3, drying and calcination. The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere for 2 hours at a calcination temperature of 500℃ to form magnesium oxide-carbon nanotube material.

[0047] The steps of the modified film-forming process are as follows: Step 1: Prepare the casting solution. Add 15 wt% polysulfone (PSU) to N-methylpyrrolidone (NMP) and mechanically stir to obtain a uniformly dispersed PSU solution. Then, add 15 wt% PVP to the PSU solution and stir at 300 r / min at room temperature until completely dissolved. Finally, add 50 wt% magnesium oxide-carbon nanotube material to the solution and continue stirring for 24 hours until completely and uniformly dispersed.

[0048] Step 2, Degassing treatment of the casting solution. The casting solution is stirred at 60 r / min for 2 hours to perform degassing treatment.

[0049] Step 3, casting. Set the distance between the doctor blade and the glass membrane to 300 μm. Before casting, spread the casting solution on the front end of the doctor blade and slide the doctor blade at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to form a liquid film.

[0050] Step 4, Pre-evaporation. The liquid film obtained by the scraper coating is left to stand in the air for 15 seconds for pre-evaporation.

[0051] Step 5: Immersion precipitate phase inversion membrane preparation. The liquid membrane is rapidly immersed in deionized water at 15°C and solidified into a membrane after 15 seconds. The membrane is then removed from the glass membrane surface to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0052] Step 6, membrane cleaning. Immerse the magnesium oxide-carbon nanotube modified polysulfone composite membrane in room temperature deionized water for 5 min, repeat 3 times.

[0053] Example 2 The preparation steps of magnesium oxide-carbon nanotube nanomaterials are as follows: Step 1, Preparation of precursor solution. Dissolve 0.3 mol / L Mg(NO3)2 in a 60% ethanol / water mixed solvent, add 1 wt% hydroxylated carbon nanotube powder, and stir to form a uniformly dispersed solution.

[0054] Step 2, gelation treatment. Citric acid is added dropwise to the precursor solution to form a Mg(OH)2-carbon nanotube composite gel.

[0055] Step 3, drying and calcination. The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere for 2 hours at a calcination temperature of 400℃ to form magnesium oxide-carbon nanotube material.

[0056] The steps of the modified film-forming process are as follows: Step 1: Prepare the casting solution. Add 30 wt% polysulfone (PSU) to N-methylpyrrolidone (NMP) and mechanically stir to obtain a uniformly dispersed PSU solution. Then, add 30 wt% PVP to the PSU solution and stir at 410 r / min at room temperature until completely dissolved. Finally, add 30 wt% magnesium oxide-carbon nanotube material to the solution and continue stirring for 24 hours until completely and uniformly dispersed.

[0057] Step 2, Degassing of the casting solution. The casting solution is stirred at 40 r / min for 2 hours to degas it.

[0058] Step 3, casting. Set the distance between the doctor blade and the glass membrane to 500 μm. Before casting, spread the casting solution on the front end of the doctor blade and slide the doctor blade at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to form a liquid film.

[0059] Step 4, Pre-evaporation. The liquid film obtained by the scraper coating is left to stand in the air for 40 seconds for pre-evaporation.

[0060] Step 5: Immersion precipitate phase inversion membrane preparation. The liquid membrane is rapidly immersed in deionized water at 60°C and solidified into a membrane after 30 seconds. The membrane is then removed from the glass membrane surface to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0061] Step 6, membrane cleaning. Immerse the magnesium oxide-carbon nanotube modified polysulfone composite membrane in room temperature deionized water for 8 min, repeat 3 times.

[0062] Example 3 The preparation steps of magnesium oxide-carbon nanotube nanomaterials are as follows: Step 1, Preparation of precursor solution. Dissolve 0.5 mol / L Mg(NO3)2 in a 70% ethanol / water mixed solvent, add 2 wt% hydroxylated carbon nanotube powder, and stir to form a uniformly dispersed solution.

[0063] Step 2, gelation treatment. Citric acid is added dropwise to the precursor solution to form a Mg(OH)2-carbon nanotube composite gel.

[0064] Step 3, drying and calcination. The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere for 1 hour at a calcination temperature of 600℃ to form magnesium oxide-carbon nanotube material.

[0065] The steps of the modified film-forming process are as follows: Step 1: Prepare the casting solution. Add 40 wt% polysulfone (PSU) to N-methylpyrrolidone (NMP) and mechanically stir to obtain a uniformly dispersed PSU solution. Then, add 0.5 wt% PVP to the PSU solution and stir at 400 r / min at room temperature until completely dissolved. Finally, add 40 wt% magnesium oxide-carbon nanotube material to the solution and continue stirring for 24 hours until completely and uniformly dispersed.

[0066] Step 2, Degassing of the casting solution. The casting solution is stirred at 40 r / min for 2 hours to degas it.

[0067] Step 3, casting. Set the distance between the doctor blade and the glass membrane to 400μm. Before casting, spread the casting solution on the front end of the doctor blade and slide the doctor blade at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to form a liquid film.

[0068] Step 4, Pre-evaporation. The liquid film obtained by the scraper coating is left to stand in the air for 30 seconds for pre-evaporation.

[0069] Step 5: Immersion precipitate phase inversion membrane preparation. The liquid membrane is rapidly immersed in deionized water at 15°C and solidified into a membrane after 5 seconds. The membrane is then removed from the glass membrane surface to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0070] Step 6, membrane cleaning. Immerse the magnesium oxide-carbon nanotube modified polysulfone composite membrane in room temperature deionized water for 3 minutes, repeat 3 times.

[0071] Example 4 The preparation steps of magnesium oxide-carbon nanotube nanomaterials are as follows: Step 1, Preparation of precursor solution. Dissolve 0.25 mol / L Mg(NO3)2 in a 65% ethanol / water mixed solvent, add 1.5 wt% hydroxylated carbon nanotube powder, and stir to form a uniformly dispersed solution.

[0072] Step 2, gelation treatment. Citric acid is added dropwise to the precursor solution to form a Mg(OH)2-carbon nanotube composite gel.

[0073] Step 3, drying and calcination. The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere for 1.5 h at a calcination temperature of 600℃ to form magnesium oxide-carbon nanotube material.

[0074] The steps of the modified film-forming process are as follows: Step 1: Prepare the casting solution. Add 10 wt% polysulfone (PSU) to N-methylpyrrolidone (NMP) and mechanically stir to obtain a uniformly dispersed PSU solution. Then, add 15 wt% PVP to the PSU solution and stir at 200 r / min at room temperature until completely dissolved. Finally, add 70 wt% magnesium oxide-carbon nanotube material to the solution and continue stirring for 24 hours until completely and uniformly dispersed.

[0075] Step 2, Degassing treatment of the casting solution. The casting solution is stirred at 65 r / min for 2 hours to perform degassing treatment.

[0076] Step 3, casting. Set the distance between the doctor blade and the glass membrane to 500 μm. Before casting, spread the casting solution on the front end of the doctor blade and slide the doctor blade at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to form a liquid film.

[0077] Step 4, Pre-evaporation. The liquid film obtained by the scraper coating is left to stand in the air for 35 seconds for pre-evaporation.

[0078] Step 5: Immersion precipitate phase inversion membrane preparation. The liquid membrane is rapidly immersed in deionized water at 20°C and solidified into a membrane after 18 seconds. The membrane is then removed from the glass membrane surface to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0079] Step 6, membrane cleaning. Immerse the magnesium oxide-carbon nanotube modified polysulfone composite membrane in room temperature deionized water for 6 min, repeat 3 times.

[0080] Example 5 The preparation steps of magnesium oxide-carbon nanotube nanomaterials are as follows: Step 1, Preparation of precursor solution. Dissolve 0.35 mol / L Mg(NO3)2 in a 60% ethanol / water mixed solvent, add 1 wt% hydroxylated carbon nanotube powder, and stir to form a uniformly dispersed solution.

[0081] Step 2, gelation treatment. Citric acid is added dropwise to the precursor solution to form a Mg(OH)2-carbon nanotube composite gel.

[0082] Step 3, drying and calcination. The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere for 2 hours at a calcination temperature of 450℃ to form magnesium oxide-carbon nanotube material.

[0083] The steps of the modified film-forming process are as follows: Step 1: Prepare the casting solution. Add 40 wt% polysulfone (PSU) to N-methylpyrrolidone (NMP) and mechanically stir to obtain a uniformly dispersed PSU solution. Then, add 5 wt% PVP to the PSU solution and stir at 500 r / min at room temperature until completely dissolved. Finally, add 30 wt% magnesium oxide-carbon nanotube material to the solution and continue stirring for 24 hours until completely and uniformly dispersed.

[0084] Step 2, Degassing of the casting solution. The casting solution is stirred at 40 r / min for 2 hours to degas it.

[0085] Step 3, casting. Set the distance between the doctor blade and the glass membrane to 350 μm. Before casting, spread the casting solution on the front end of the doctor blade and slide the doctor blade at a uniform speed to spread the casting solution evenly on the surface of the glass membrane to form a liquid film.

[0086] Step 4, Pre-evaporation. The liquid film obtained by the scraper coating is left to stand in the air for 35 seconds for pre-evaporation.

[0087] Step 5: Immersion precipitate phase inversion membrane preparation. The liquid membrane is rapidly immersed in deionized water at 35°C and solidified into a membrane after 30 seconds. The membrane is then removed from the glass membrane surface to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

[0088] Step 6, membrane cleaning. Immerse the magnesium oxide-carbon nanotube modified polysulfone composite membrane in room temperature deionized water for 5 min, repeat 3 times.

[0089] The membrane in a water electrolysis hydrogen production device is a key component, primarily serving to conduct hydroxide ions to form an internal pathway and to isolate hydrogen and oxygen generated at the two electrodes. This invention proposes a magnesium oxide-carbon nanotube modified polysulfone composite membrane material for water electrolysis hydrogen production and its preparation method. The material substrate uses polysulfone (PSU), which possesses excellent thermal stability and alkali resistance. Through material modification, the problems of poor hydrophilicity and high internal resistance of polysulfone (PSU) material are improved, and its pore size can be controlled, effectively reducing the risk of hydrogen permeation.

[0090] To verify the effect of the coating thickness on the structure and performance of the composite membrane, composite membranes were prepared with different coating spacings (200, 300, 400, 500 μm), and the cross-sectional structure and pore size distribution were observed by SEM. The results are shown in Table 1.

[0091] Table 1: Thickness and pore size structure parameters of composite membranes under different doctor blade spacing

[0092] Experimental results show that as the doctor blade spacing increases, the film thickness increases linearly, and the pore size increases slightly, but remains within the range of 50–100 nm. Furthermore, the pore size distribution is concentrated, demonstrating good structural controllability and process repeatability. This indicates that the method of this invention can achieve precise control of the pore size structure over a wide range of film thicknesses, meeting the requirements of low gas permeability and high ion conductivity for membranes in water electrolysis for hydrogen production.

[0093] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite membrane material for hydrogen production via water electrolysis, characterized in that, Its components include 30-70 wt% magnesium oxide-carbon nanotubes, 10-40 wt% polysulfone and 0.5-30 wt% polyvinylpyrrolidone.

2. A method for preparing a composite membrane material for hydrogen production via water electrolysis, characterized in that, include: Polysulfone was added to N-methylpyrrolidone and stirred to obtain a uniformly dispersed PSU solution. PVP was added to the PSU solution and stirred until completely dissolved. Then, magnesium oxide-carbon nanotube material was added and stirred until completely uniformly dispersed to obtain a casting solution. After the casting solution is degassed, it is spread on the front end of the scraper. The scraper is slid at a uniform speed to spread the casting solution evenly on the glass film surface to form a liquid film. After the liquid membrane is allowed to stand for pre-evaporation, it is immersed in deionized water to solidify into a film. The film is then removed from the glass membrane surface and cleaned to obtain a magnesium oxide-carbon nanotube modified polysulfone composite membrane.

3. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 2, characterized in that, The polysulfone content in the PSU solution is 10-40 wt%.

4. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 2, characterized in that, Add 0.5-30 wt% PVP to the PSU solution.

5. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 2, characterized in that, PVP is added to the PSU solution and stirred at 200-400 r / min at room temperature until completely dissolved.

6. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 2, characterized in that, The content of magnesium oxide-carbon nanotube material in the casting solution is 30-70 wt%.

7. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 2, characterized in that, The casting solution was degassed by stirring at 40-70 r / min; the distance between the scraper and the glass membrane was 200-500 μm; and the liquid membrane was allowed to stand for pre-evaporation for 10-40 s.

8. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 2, characterized in that, The liquid membrane is rapidly immersed in deionized water at 15-60℃ and solidifies into a film after 5-30 seconds. After being removed from the glass membrane surface, it is immersed in deionized water at room temperature for 3-10 minutes. This process is repeated 3 times to obtain a polysulfone composite membrane modified with magnesium oxide-carbon nanotubes.

9. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 2, characterized in that, The magnesium oxide-carbon nanotube nanomaterial is prepared by the following steps: Mg(NO3)2 was dissolved in an ethanol / water mixed solvent, and hydroxylated carbon nanotube powder was added and stirred to form a uniformly dispersed precursor solution. Citric acid was added dropwise to the precordial solution until a Mg(OH)2-carbon nanotube composite gel was formed; The Mg(OH)2-carbon nanotube composite gel was dried at 60℃ and then calcined in a muffle furnace under a nitrogen atmosphere to form magnesium oxide-carbon nanotube material.

10. The method for preparing a composite membrane material for hydrogen production by water electrolysis according to claim 9, characterized in that, The ethanol / water mixed solvent has an ethanol concentration of 50%~70%; a Mg(NO3)2 content of 0.1~0.5 mol / L; and a hydroxylated carbon nanotube powder content of 0.5~2 wt%. After drying, the Mg(OH)2-carbon nanotube composite gel was calcined in a muffle furnace under a nitrogen atmosphere for 1-3 hours at a calcination temperature of 400-600℃.

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