Preparation process of rare earth doped multi-element oxide catalyst nickel net electrode

Abstract

The invention belongs to the technical field of catalysts, and discloses a preparation process of a rare earth doped multi-element oxide catalyst nickel net electrode, catalyst powder and an aqueous solvent are mixed to form slurry, the surface of the nickel net electrode is coated with the slurry, and the catalyst and the nickel net electrode are effectively combined through drying, degumming and high-temperature sintering processes, so that the rare earth doped multi-element oxide catalyst nickel net electrode is obtained. The process is simple and effective, high in production efficiency and low in cost; after the process treatment, the catalyst coating generated on the surface of the nickel net electrode is of a porous structure, and the specific surface area and the catalytic activity are higher; performance tests are carried out on the obtained rare earth doped multi-element oxide catalyst nickel net electrode, the catalytic activity of the rare earth doped multi-element oxide catalyst nickel net electrode is superior to that of NiAl alloy, the cell voltage can reach 1.6 V, and in 1000 times of start-stop acceleration simulation experiments, the attenuation speed of the rare earth doped multi-element oxide catalyst nickel net electrode is greatly reduced to about 2% and is obviously lower than that of the NiAl alloy by 20%.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst attachment, and specifically relates to a preparation process of a rare earth-doped multi-component oxide catalyst nickel mesh electrode. Background Art

[0002] Electrolytic water hydrogen production is a technology that decomposes water (H 2 O) into hydrogen (H 2 ) and oxygen (O 2 ) by electric energy. It is one of the main ways of green hydrogen (hydrogen energy produced using renewable energy) production and is also a key link in the clean energy system.

[0003] Its reaction equation is 2H 2 O—electrolysis→2H 2 +O 2 ;

[0004] In an alkaline medium, the reactions at the cathode and anode are as follows.

[0005] An oxidation reaction occurs at the anode: 4OH - ——→O 2 +2H 2 O+4e - , OH - Undergoes multiple-step oxidation on the catalyst surface to generate oxygen intermediates, which eventually combine to form O 2 ;

[0006] A reduction reaction occurs at the cathode: 2H 2 O+2e - ——→H 2 +2OH - , and water molecules dissociate on the catalyst surface, and the adsorbed hydrogen intermediates combine to form H 2 .

[0007] The commonly used catalytically active electrode materials for electrolytic water hydrogen production mainly include precious metals and their alloys, mainly platinum group metals such as Pt, Pd, Ru, etc. These metals are prepared by electroless plating or chemical vapor deposition, with low production efficiency and high costs.

[0008] In addition to platinum group metals, there are also mixed powders of Ni powder and Al powder, as well as NiAl alloys, which are also commonly used catalytic materials in current electrolytic water hydrogen production electrolytic cells. This series of catalytic materials are coated on the surface of nickel mesh electrodes by thermal spraying. The thermal spraying method has high production efficiency, but the bonding strength between the catalyst and the nickel mesh electrode is low and it is easy to fall off, ultimately causing the catalytic performance of the electrode to decay too quickly and reducing the service life of the electrolytic cell.

[0009] Therefore, a preparation process of a nickel mesh electrode with rare earth-doped multi-component oxide catalyst is provided to reduce the cost of hydrogen production by electrolyzing water, improve the bonding strength between the catalyst and the nickel mesh electrode, and thus extend the service life of the electrolytic cell. Summary of the Invention

[0010] Aiming at the problems existing in the prior art that the use of precious metals results in high costs and low production efficiency, and the use of Ni, Al mixed powder or NiAl alloy results in low bonding strength, the purpose of the present invention is to provide a preparation process of a nickel mesh electrode with rare earth-doped multi-component oxide catalyst.

[0011] To achieve the above technical purpose, the technical solution adopted by the present invention is as follows:

[0012] A preparation process of a nickel mesh electrode with rare earth-doped multi-component oxide catalyst includes

[0013] (Ⅰ) Mixing an aqueous solvent with the catalyst powder prepared by high-temperature sintering to form a slurry, and the components of the catalyst powder include La 2 O 3 , NiO, CoO, TiO 2 , MoS 2 ;

[0014] (Ⅱ) Coating the slurry on the surface of the nickel mesh electrode;

[0015] (Ⅲ) Drying;

[0016] (Ⅳ) Degumming;

[0017] (Ⅴ) High-temperature sintering.

[0018] The catalyst powder selected by the present invention contains rare earth element La3+. During high-temperature sintering, rare earth element La3+ diffuses into the crystal lattices of NiO, CoO, and TiO 2 , introducing electron holes, enhancing conductivity, and optimizing the adsorption energy of hydrogen intermediate (H*). In addition, due to the addition of MoS 2 , the sulfur vacancies at the edges of MoS 2 can stabilize hydrogen intermediate (H*), reducing the reaction overpotential. Thus, while reducing costs, the catalyst activity is significantly improved;

[0019] After the catalyst powder is mixed with the aqueous solvent to form a slurry, and the slurry is coated on the surface of the nickel mesh electrode, through the processes of drying, degumming, and high-temperature sintering, the effective combination of the catalyst and the nickel mesh electrode is realized. This process is simple and effective, with high production efficiency and low cost;

[0020] Drying is set because drying can remove moisture, assist the green body of the slurry, and avoid cracking or pore defects of the catalyst caused by the rapid evaporation of moisture during subsequent heating. When drying, the temperature should be slowly raised to the target temperature, and the heating rate is controlled at 2-5 °C / min;

[0021] Degumming is set because the medium in the aqueous solvent needs to be removed after it plays the role of bonding the catalyst and forming the green body to avoid deformation of the catalyst layer during subsequent high-temperature sintering and forming. In the present invention, the degumming process is achieved by heating to promote the decomposition of the medium. It should be noted that the temperature needs to reach the decomposition temperature of the medium in a slow-rising manner to avoid rapid volatilization of the medium, resulting in cracking of the catalyst embryo body, and the heating rate is controlled at 1-3 °C / min;

[0022] High-temperature sintering is set because high temperature can make the catalyst powder particles diffuse and combine with each other, and the material becomes more densified. It should be noted that after high-temperature sintering is completed, do not cool down quickly, but should be cooled slowly or naturally cooled, because rapid cooling will cause cracks in the catalyst layer due to thermal stress;

[0023] After the above process treatment, the catalyst coating formed on the surface of the nickel mesh electrode is a porous structure. The porous structure can significantly increase the specific surface area of the catalyst, expose more active sites to the reactants, and the catalyst per unit mass or unit volume can participate in more chemical reactions, thereby improving the catalytic activity.

[0024] As a preferred technical solution of the present invention, the aqueous solvent includes the following components: water, polyvinyl alcohol, and polyvinyl ether.

[0025] The present invention specifically defines that the components of the aqueous solvent include water, polyvinyl alcohol, and polyvinyl ether because polyvinyl alcohol has good adhesiveness and is relatively stable in aqueous solution. It is a water-based binder with excellent performance, non-toxic, and biodegradable; while polyvinyl ether has good water solubility, adhesiveness, and chemical stability. The two are used in combination because polyvinyl alcohol has the characteristics of high polarity and strong hydrogen bonds, and it can provide high adhesive strength, which is beneficial to ensuring the strength of the green body. Polyvinyl ether can increase the adhesion of the catalyst on the nickel mesh electrode and improve the bonding strength. The hydrophobic side chain of polyvinyl ether can slow down the evaporation of moisture and avoid stress cracks caused by rapid drying. After polyvinyl alcohol and polyvinyl ether assist in bonding and forming the catalyst powder, they can be decomposed and removed through subsequent degumming processes.

[0026] As a preferred technical solution of the present invention, in the slurry, the mass percentage of polyvinyl alcohol is 0.5% - 5%, and in the slurry, the mass percentage of polyvinyl ether is 0.5% - 1.5%.

[0027] The present invention specifically limits the ratio of polyvinyl alcohol and polyvinyl ether because, at this ratio, the two can cooperate with each other and give full play to their respective advantages.

[0028] As a preferred technical solution of the present invention, in step (Ⅱ), the slurry is uniformly coated on the surface of the nickel mesh electrode by an automatic coating method.

[0029] The present invention specifically limits the coating of the slurry on the surface of the nickel mesh electrode by an automatic coating method because the mechanical coating is more reliable than manual coating and has a better coating effect.

[0030] As a preferred technical solution of the present invention, steps (Ⅲ), (Ⅳ) and (Ⅴ) are implemented by a vacuum sintering furnace.

[0031] The present invention specifically limits the use of a vacuum sintering furnace for drying, degumming and high-temperature sintering because the vacuum sintering furnace performs non-oxidizing sintering, which can improve the purity of the catalyst. The vacuum environment is conducive to the decomposition and volatilization of polyvinyl alcohol and polyvinyl ether, avoiding residual pollution. The vacuum sintering furnace heats evenly, can reduce thermal stress, and the temperature rate is controllable, which can effectively avoid the cracking of the catalyst layer caused by rapid heating and cooling.

[0032] As a preferred technical solution of the present invention, in step (Ⅰ), in the components of the catalyst powder, the component percentage of La 2 O 3 does not exceed 2%; in step (Ⅰ), in the components of the catalyst powder, the component percentage of MoS 2 does not exceed 5%.

[0033] Exemplarily, the present invention provides a preparation process of a rare earth-doped multi-component oxide catalyst nickel mesh electrode, including the following steps:

[0034] (1) Mix an aqueous solvent with the catalyst powder prepared by high-temperature sintering to form a slurry. The aqueous solvent includes water, polyvinyl alcohol and polyvinyl ether. In the slurry, the mass percentage of polyvinyl alcohol is 0.5% - 5%, and the mass percentage of polyvinyl ether is 0.5% - 1.5%. The components of the catalyst powder include La 2 O 3 , NiO, CoO, TiO 2 , MoS 2 . In the components of the catalyst powder, the component percentage of La 2 O 3 does not exceed 2%, and in the components of the catalyst powder, the component percentage of MoS 2 does not exceed 5%.

[0035] (2) By an automatic coating method, uniformly coat the slurry on the surface of the nickel mesh electrode;

[0036] (3) The nickel mesh electrode coated with the slurry is dried, degummed, and sintered at high temperature in a vacuum sintering furnace.

[0037] Advantages of the present invention: The catalyst powder is mixed with an aqueous solvent to form a slurry. After the slurry is coated on the surface of the nickel mesh electrode, through the processes of drying, degumming, and high-temperature sintering, an effective combination of the catalyst and the nickel mesh electrode is achieved. This process is simple and effective, has high production efficiency, and low cost; after the above process treatment, the catalyst coating formed on the surface of the nickel mesh electrode is a porous structure, with a higher specific surface area and catalytic activity; the performance of the rare earth-doped multi-component oxide catalyst nickel mesh electrode obtained by the present invention is tested, and its catalytic activity is superior to that of the NiAl alloy. The cell voltage can reach 1.6 V, and in 1000 start-stop acceleration simulation experiments, its attenuation rate drops significantly to about 2%, which is significantly lower than 20% of the NiAl alloy. Description of the Drawings

[0038] The present invention can be further illustrated by the non-limiting embodiments given in the drawings;

[0039] Figure 1 It is the process flow chart of the embodiment of the present invention; Detailed Embodiments

[0040] The technical solution of the present invention will be described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments recorded herein are specific specific implementation manners of the present invention and are used to illustrate the concept of the present invention; these descriptions are all explanatory and exemplary, and should not be construed as limiting the implementation manner of the present invention and the protection scope of the present invention. Except for the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of the present application. These technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments recorded herein.

[0041] Embodiment

[0042] As Figure 1 shown, this embodiment provides a preparation process for a rare earth-doped multi-component oxide catalyst nickel mesh electrode, including the following steps:

[0043] (1) Mix an aqueous solvent with the catalyst powder prepared by high-temperature sintering to form a slurry. The aqueous solvent includes water, polyvinyl alcohol, and polyvinyl ether. In the slurry, the mass percentage of polyvinyl alcohol is 5%, and the mass percentage of polyvinyl ether is 1.5%. The components of the catalyst powder include La 2 O 3 , NiO, CoO, TiO 2 , MoS 2 , in the components of the catalyst powder, La2 O 3 has a mass percentage of 2%, NiO has a mass percentage of 40%, CoO has a mass percentage of 28%, and TiO 2 has a mass percentage of 25%, and MoS 2 has a mass percentage of 5%.

[0044] (2) By means of automatic coating, uniformly coat the slurry on the surface of the nickel mesh electrode;

[0045] (3) Use a vacuum sintering furnace to dry, degum, and perform high-temperature sintering on the nickel mesh electrode coated with the slurry.

[0046] In this embodiment, the selected catalyst powder contains the rare earth element La3+. During high-temperature sintering, the rare earth element La3+ diffuses into the lattices of NiO, CoO, and TiO 2 , introducing electron holes, enhancing conductivity, and optimizing the adsorption energy of hydrogen intermediates (H*). In addition, due to the addition of MoS 2 , the sulfur vacancies at the edges of MoS 2 can stabilize hydrogen intermediates (H*), reducing the reaction overpotential. Thus, while reducing costs, it significantly improves the catalyst activity;

[0047] The catalyst powder is mixed with an aqueous solvent to form a slurry. After the slurry is coated on the surface of the nickel mesh electrode, through the processes of drying, degumming, and high-temperature sintering, an effective combination of the catalyst and the nickel mesh electrode is achieved. This process is simple and effective with high production efficiency;

[0048] After being processed by the above process, the catalyst coating formed on the surface of the nickel mesh electrode is a porous structure. The porous structure can significantly increase the specific surface area of the catalyst, expose more active sites to the reactants, and enable the catalyst per unit mass or unit volume to participate in more chemical reactions, thereby enhancing the catalytic activity;

[0049] Perform performance tests on the rare earth-doped multi-component oxide catalyst nickel mesh electrode obtained in this embodiment. Its catalytic activity is superior to that of the NiAl alloy. The cell voltage can reach 1.6 V, and in 1000 start-stop acceleration simulation experiments, its attenuation rate drops significantly to about 2%, which is significantly lower than 20% of the NiAl alloy.

[0050] The above embodiments only exemplarily illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode, characterized in that: include (I) mixing an aqueous solvent with a catalyst powder prepared by high-temperature sintering to form a slurry, wherein the catalyst powder comprises La2O3, NiO, CoO, TiO2, and MoS2; (II) coating the slurry on the surface of the nickel mesh electrode; (III) drying; (IV) degumming; (V) High temperature sintering.

2. The process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode according to claim 1, characterized in that: The aqueous solvent comprises the following components: water, polyvinyl alcohol and polyvinyl ether.

3. The process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode according to claim 2, characterized in that: In the slurry, the mass percentage of polyvinyl alcohol is 0.5% to 5%.

4. The process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode according to claim 2, characterized in that: In the slurry, the mass percentage of polyethylene ether is 0.5% to 1.5%.

5. The process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode according to claim 1, characterized in that: In step (II), the slurry is evenly coated on the surface of the nickel mesh electrode by automatic coating.

6. The process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode according to claim 1, characterized in that: Step (III), step (IV) and step (V) are carried out by a vacuum sintering furnace.

7. The process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode according to claim 1, characterized in that: In step (I), the percentage of La2O3 in the components of the catalyst powder does not exceed 2%.

8. The process for preparing a rare earth doped multi-element oxide catalyst nickel mesh electrode according to claim 7, characterized in that: In step (I), the percentage of MoS2 in the components of the catalyst powder does not exceed 5%.

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