A method for preparing alkaline electrolytic cell diaphragm

Abstract

The invention discloses a method for preparing an alkaline electrolytic cell diaphragm, and the specific steps include: S1. preparing an ultrafiltration diaphragm with finger-shaped pores using an alkali-resistant non-woven fabric as a substrate; S2. filtering a zirconium hydroxide precursor into the ultrafiltration diaphragm by filter pressing; S3. soaking the ultrafiltration diaphragm in a precipitation solution for 24 hours; S4. controlling the formation speed of zirconium hydroxide by adjusting the ratio of alcohol and water or the pH value. The viscosity of the feed liquid during preparation of the invention is lower than 1000cps, while the viscosity range of the high-viscosity nanoparticle slurry of the electrolytic diaphragm is 10000-1000000cps, so the invention is easy to prepare and reduces the cost; in-situ deposition effectively blocks ultrafiltration micropores, greatly improves the bubble point, has good gas barrier properties and is easy to operate, and has high mechanical strength.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen electrolysis, and in particular relates to a method for preparing an alkaline electrolytic cell diaphragm. Background Art

[0002] A hydrogen production electrolyzer is a device that uses electrolysis to produce hydrogen. It usually consists of an electrolyzer and some electrodes. The electrodes are covered with a catalyst to help promote the decomposition of water. According to the classification of water electrolysis hydrogen production technology, hydrogen production electrolyzers can also be divided into four categories: alkaline electrolyzers, proton exchange membrane electrolyzers, high-temperature solid oxide electrolyzers, and solid polymer anion exchange membrane electrolyzers. At present, alkaline electrolyzers have been commercialized, proton exchange membrane electrolyzers have also entered the early stages of commercialization, while high-temperature solid oxide electrolyzers and solid polymer anion exchange membrane electrolyzers are still in the research and development demonstration stage.

[0003] Alkaline electrolyzers are currently the most technologically mature hydrogen production electrolyzers and have been widely used commercially. The hydrogen and oxygen produced in alkaline electrolyzers need to be separated by diaphragms to prevent the explosion of hydrogen and oxygen mixing. Therefore, the diaphragm is a key component for the safe operation of the electrolyzer, and it also affects the purity of the prepared gas and the energy consumption of the electrolyzer. The polyphenylene sulfide (PPS) diaphragm currently used on a large scale in alkaline electrolyzers has the disadvantages of poor hydrophilicity, high resistance, and poor gas barrier properties, resulting in high energy consumption and low safety. Therefore, it is still a challenge to develop high-performance alkaline water electrolysis diaphragms with low surface resistance (for reducing energy consumption), high bubble point pressure (for improving safety), and high stability.

[0004] At present, the third-generation alkaline electrolyzer composite diaphragm is a composite diaphragm with a sandwich structure formed by coating a composite slurry of inorganic and polymer on a PPS mesh. The inorganic substance is mainly zirconium oxide or other nanoparticles with similar properties. The oxygen ions in zirconium oxide form hydrogen bonds with the water in the electrolyte, which is the main substance to improve the hydrophilicity of the composite diaphragm; the polymer can be polysulfone, polyethersulfone, PTFE, PPEK and other materials, and its main function is to bond zirconium oxide nanoparticles to form a film. Since the third-generation composite diaphragm contains a high proportion of nano zirconium oxide particles (>75wt%), the cost of the diaphragm is much higher than that of PPS fabric; in addition, the composite material powder accounts for a high proportion, the mechanical strength is poor (low toughness and hardness), it is not easy to operate, and it is easy to break, resulting in safety hazards.

[0005] Chinese patent CN115928145B discloses an improved organic-inorganic composite diaphragm for hydrogen production by alkaline water electrolysis and its preparation method, wherein zirconium oxychloride is added to a polymer slurry, firstly prepared into an ultrafiltration membrane, and then zirconium hydroxide is deposited in the ultrafiltration membrane by in-situ precipitation. Although zirconium hydroxide particles are introduced in this way, the micropores of the ultrafiltration still exist, the bubble point is not improved, and the gas barrier property is poor. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to solve the deficiencies in the prior art and provide a method for preparing an alkaline electrolytic cell diaphragm.

[0007] A method for preparing an alkaline electrolytic cell diaphragm, comprising the following specific steps:

[0008] S1. An ultrafiltration membrane with finger-like pores prepared using an alkali-resistant non-woven fabric as a substrate;

[0009] S2. filtering the zirconium hydroxide precursor into an ultrafiltration membrane by filter pressing;

[0010] S3. Soak the ultrafiltration membrane in the precipitation solution for 24 hours;

[0011] S4. The rate of zirconium hydroxide formation can be controlled by adjusting the ratio of alcohol to water or the pH value.

[0012] A further improvement of the present invention is that in step S1, the alkali-resistant non-woven fabric material is one or a mixture of polytetrafluoroethylene, polyphenylene sulfide, polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, polypropylene or polyethylene.

[0013] A further improvement of the present invention is that in step S2, the zirconium hydroxide precursor includes an alcohol solution of zirconium tetrabutoxide, zirconium sulfate or an aqueous solution of zirconium oxychloride.

[0014] A further improvement of the present invention is that in step S2, the precursor solution of zirconium hydroxide is filled into the separation skin layer of the ultrafiltration membrane during pressure filtration to effectively block the micropores on the surface of the membrane, and the pore size range of the separation skin layer is 5 to 200 nm.

[0015] A further improvement of the present invention is that in step S2, during the filtration, the precursor solution of zirconium hydroxide is filled into the non-woven fabric layer of the ultrafiltration membrane to effectively block the large pores in the middle of the membrane, and the pore size range of the non-woven fabric layer is 1 to 100 um.

[0016] A further improvement of the present invention is that in step S3, the precipitation solution is a mixed solution of water and ethanol, and the ratio of water to ethanol ranges from 1:9 to 9:1.

[0017] A further improvement of the present invention is that in step S3, the precipitation solution is pure water.

[0018] A further improvement of the present invention is that in step S3, the precipitation solution is an aqueous solution with different pH values, and the pH value of the aqueous solution ranges from 1 to 14.

[0019] A further improvement of the present invention is that in step S2, during the filtration, the precursor solution of zirconium hydroxide is filled into the separation skin layer and the non-woven fabric layer of the ultrafiltration membrane to fill the micropores on the surface of the membrane and the macropores in the middle of the membrane and deposit into zirconium hydroxide.

[0020] Compared with the prior art, the method for preparing an alkaline electrolytic cell diaphragm provided by the present invention achieves at least the following beneficial effects:

[0021] 1. The viscosity of the liquid during preparation of the present invention is lower than 1000 cps, while the viscosity of the high-viscosity nanoparticle slurry of the electrolytic diaphragm is in the range of 10,000 to 1,000,000 cps. Therefore, the present invention is easy to prepare and reduces the cost;

[0022] 2. In-situ deposition effectively blocks the ultrafiltration micropores, greatly improving the bubble point. In the pure water test environment, it can increase the ultrafiltration membrane's 0.1MPa to 0.4MPa;

[0023] 3. The proportion of zirconium hydroxide in the final diaphragm is 30-60%. The surface resistance of the diaphragm is equivalent to that of the composite diaphragm of the third-generation alkaline electrolyzer. It has good gas barrier properties, is easy to operate, and has high mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a cross-sectional SEM image of Example 1 of the present invention;

[0025] Figure 2 This is a cross-sectional SEM image of Example 2 of the present invention. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present invention are now described in detail. It should be noted that unless otherwise specifically stated, the relative arrangement of the components and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of the present invention. The following description of at least one exemplary embodiment is actually only illustrative and is not intended to be any limitation on the present invention and its application or use.

[0027] The techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and devices should be considered as part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0028] See the instruction manual Figure 1-2 , a method for preparing an alkaline electrolytic cell diaphragm, the specific steps comprising:

[0029] S1. An ultrafiltration membrane with finger-like pores prepared using an alkali-resistant non-woven fabric as a substrate;

[0030] S2. filtering the zirconium hydroxide precursor into an ultrafiltration membrane by filter pressing;

[0031] S3. Soak the ultrafiltration membrane in the precipitation solution for 24 hours;

[0032] S4. The rate of zirconium hydroxide formation can be controlled by adjusting the ratio of alcohol to water or the pH value.

[0033] A further improvement of the present invention is that in step S1, the alkali-resistant non-woven fabric material can be one or a mixture of polymers such as polytetrafluoroethylene, polyphenylene sulfide, polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, polypropylene or polyethylene.

[0034] A further improvement of the present invention is that in step S2, the zirconium hydroxide precursor includes an alcohol solution of zirconium tetrabutoxide, an aqueous solution of zirconium sulfate or zirconium oxychloride, etc.

[0035] A further improvement of the present invention is that in step S2, the precursor solution of zirconium hydroxide is filled into the separation skin layer of the ultrafiltration membrane during pressure filtration to effectively block the micropores on the surface of the membrane, and the pore size range of the separation skin layer is 5 to 200 nm.

[0036] A further improvement of the present invention is that in step S2, during the filtration, the precursor solution of zirconium hydroxide is filled into the non-woven fabric layer of the ultrafiltration membrane to effectively block the large pores in the middle of the membrane, and the pore size range of the non-woven fabric layer is 1 to 100 um.

[0037] A further improvement of the present invention is that in step S3, the precipitation solution is a mixed solution of water and ethanol, and the ratio of water to ethanol ranges from 1:9 to 9:1.

[0038] A further improvement of the present invention is that in step S3, the precipitation solution is pure water.

[0039] A further improvement of the present invention is that in step S3, the precipitation solution is an aqueous solution with different pH values, and the pH value of the aqueous solution ranges from 1 to 14.

[0040] A further improvement of the present invention is that in step S2, during the filtration, the precursor solution of zirconium hydroxide is filled into the separation skin layer and the non-woven fabric layer of the ultrafiltration membrane to fill the micropores on the surface of the membrane and the macropores in the middle of the membrane and deposit into zirconium hydroxide.

[0041] In summary, the present invention provides a method for preparing an alkaline electrolytic cell diaphragm. The viscosity of the feed liquid during the preparation of the present invention is lower than 1000cps, while the viscosity range of the high-viscosity nanoparticle slurry of the electrolytic diaphragm is 10000-1000000cps. Therefore, the present invention is easy to prepare and reduces the cost; the in-situ deposition effectively blocks the ultrafiltration micropores, greatly improves the bubble point, and in the environment of pure water testing, can increase the ultrafiltration membrane from 0.1MPa to 0.4MPa; the proportion of zirconium hydroxide in the final diaphragm is 30-60%, the surface resistance of the diaphragm is equivalent to the surface resistance of the third-generation alkaline electrolytic cell composite diaphragm, and the gas barrier is good, easy to operate, and has high mechanical strength.

[0042] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A method for preparing an alkaline electrolytic cell diaphragm, characterized in that: The specific steps include: S1. An ultrafiltration membrane with finger-like pores prepared using an alkali-resistant non-woven fabric as a substrate; S2. filtering the zirconium hydroxide precursor into an ultrafiltration membrane by filter pressing; S3. Soak the ultrafiltration membrane in the precipitation solution for 24 hours; S4. The rate of zirconium hydroxide formation can be controlled by adjusting the ratio of alcohol to water or the pH value.

2. A method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In the step S1, the alkali-resistant non-woven fabric material is one or a mixture of polytetrafluoroethylene, polyphenylene sulfide, polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, polypropylene or polyethylene.

3. A method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In the step S2, the zirconium hydroxide precursor includes an alcohol solution of zirconium tetrabutoxide, zirconium sulfate or an aqueous solution of zirconium oxychloride.

4. A method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In the step S2, the precursor solution of zirconium hydroxide is filled into the separation skin layer of the ultrafiltration membrane during pressure filtration to effectively block the micropores on the surface of the membrane. The pore size range of the separation skin layer is 5 to 200 nm.

5. The method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In the step S2, the precursor solution of zirconium hydroxide is filled into the non-woven fabric layer of the ultrafiltration membrane during pressure filtration to effectively block the large pores in the middle of the membrane. The pore size range of the non-woven fabric layer is 1 to 100 um.

6. A method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In step S3, the precipitation solution is a mixed solution of water and alcohol, and the ratio of water to ethanol is in the range of 1:9 to 9:

1.

7. A method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In step S3, the precipitation solution is pure water.

8. A method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In step S3, the precipitation solution is an aqueous solution with different pH values, and the pH value of the aqueous solution ranges from 1 to 14.

9. A method for preparing an alkaline electrolytic cell diaphragm according to claim 1, characterized in that: In step S2, the precursor solution of zirconium hydroxide is introduced into the separation skin layer and the non-woven fabric layer of the ultrafiltration membrane during pressure filtration to fill the micropores on the surface of the membrane and the macropores in the middle of the membrane and deposit into zirconium hydroxide.

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