Modification method for improving Raney nickel electrolyzed water performance

Abstract

The invention provides a modification method for improving the performance of Raney nickel electrolyzed water, which comprises the following steps: pre-treating a nickel net, washing the nickel net with alkali, and putting the nickel net into absolute ethyl alcohol for later use; spraying a nickel net, oxidizing the nickel net, carrying out plasma spraying on the nickel net by using powder, roasting at high temperature, and finally activating to obtain the Raney nickel electrode. According to the Raney nickel electrode, the aluminum powder and nickel oxide on the nickel base material can be fully fused through an aluminothermic reaction technology, and the activity of the obtained nickel net after activation is greatly improved compared with that of a traditional Raney nickel electrode; according to the method, nickel powder does not need to be additionally sprayed, the raw material cost in the Raney nickel electrode production process is greatly reduced, operation is easy, and implementation is easy.

Description

Technical Field

[0001] The invention belongs to the technical field of water electrolysis hydrogen production and electrocatalysis, and particularly relates to a modification method for improving the performance of Raney nickel water electrolysis. Background Art

[0002] Raney nickel is a catalyst with excellent catalytic activity, which plays an important role in many fields. The high catalytic activity of Raney nickel is due to its large specific surface area and more active sites. The common method for synthesizing Raney nickel catalyst is to first prepare nickel-aluminum alloy, and then remove the aluminum in the alloy, and finally obtain a Raney nickel catalyst with a large specific surface area and more active sites. However, the Raney nickel catalyst synthesized by this method is mainly powdered Raney nickel, and the hydrogen and oxygen evolution electrodes commonly used in water electrolysis hydrogen production electrolyzers are often nickel-based Raney nickel electrodes. This type of Raney nickel is mostly produced by plasma spraying, spraying the mixed nickel powder and aluminum powder on the nickel mesh, and then activating it with alkaline solution to remove the aluminum powder. However, most of the powder sprayed by this method is actually nickel powder and aluminum powder, and only a part of the nickel-aluminum powder forms an alloy during the spraying process. This part of the alloy can be considered to synthesize a Raney nickel catalyst after being activated with alkaline solution, which has good hydrogen and oxygen evolution catalytic performance. Moreover, since the substrate is a nickel mesh with a certain mesh size, nickel powder and aluminum powder will be wasted during the spraying process. Therefore, how to improve the bonding rate of nickel and aluminum atoms and reduce the waste of nickel and aluminum powder during electrode preparation is the key to improving the performance of hydrogen and oxygen evolution electrodes in water electrolysis and reducing electrode costs.

[0003] In order to further promote the mutual fusion of nickel and aluminum, this patent uses an oxidized nickel mesh for aluminum powder plasma spraying. The resulting sprayed mesh has uniform nickel and aluminum distribution, and then an aluminothermic reaction is carried out at high temperature. The nickel and aluminum components are further fused with each other. The modified electrode mesh has sufficient nickel and aluminum fusion in the early stage. After removing the aluminum oxide component, more reaction active sites will be generated. Only aluminum powder is used in the spraying process, which greatly saves the cost of nickel powder. Summary of the invention

[0004] In view of the problems existing in the prior art, the present application proposes a modification method for improving the performance of Raney nickel electrolysis water, comprising the following steps:

[0005] Pre-treatment of the nickel mesh: washing the nickel mesh with alkali, and then placing the nickel mesh in anhydrous ethanol for standby use;

[0006] The nickel mesh is sprayed, the nickel mesh is oxidized, and the powder is plasma sprayed on the nickel mesh, high-temperature calcined, and finally activated to obtain a Raney nickel electrode.

[0007] Furthermore, the nickel mesh number is 40-80 meshes.

[0008] Furthermore, the nickel mesh number is 50-60 meshes.

[0009] Further, the nickel mesh alkali washing specifically includes:

[0010] Prepare 3L of mixed alkali solution, place the nickel mesh in the mixed alkali solution, and keep it at 60℃ for 30min;

[0011] Rinse the nickel mesh with deionized water.

[0012] Furthermore, after the nickel mesh is alkaline washed, it needs to be weakly corroded in the solution before being placed in anhydrous ethanol.

[0013] Furthermore, the mixed alkali solution is one or more of 5-10 g / L sodium hydroxide, 10-30 g / L sodium silicate, 5-20 g / L sodium carbonate, and 20-60 g / L sodium phosphate.

[0014] Furthermore, in the weak acid corrosion process, one or more of dilute hydrochloric acid, dilute sulfuric acid, phosphoric acid, and acetic acid are used; the acid concentration is 5-40%, the acid treatment temperature is 15-60° C., and the acid treatment time is 0.5-40 min.

[0015] Further, the nickel mesh substrate is oxidized in an oxidizing atmosphere, and aluminum powder is used as a powder material for plasma spraying on the oxidized nickel mesh;

[0016] During the oxidation process, one of air, oxygen and ozone is used; the oxidation temperature is 500-1000°C; and the oxidation time is 0.5h-5h.

[0017] Aluminum powder, particle size 50-250 microns.

[0018] Furthermore, during the high-temperature calcination process, the inert atmosphere is one of argon, nitrogen and helium; the calcination temperature is 500-1000° C.; and the calcination time is 0.5h-4h.

[0019] Furthermore, the activation process is to immerse the calcined nickel mesh in one or more of sodium hydroxide and potassium hydroxide, the concentration of the alkali solution is 4%-20%, and the immersion time is 5-24 hours.

[0020] The modification method for improving the performance of Raney nickel electrolysis water provided by the present invention has the following beneficial effects compared with the prior art:

[0021] The Raney nickel electrode of the present invention can fully fuse aluminum powder and nickel oxide on the nickel substrate through the aluminum thermite reaction technology, and the activity of the obtained nickel mesh after activation is greatly improved compared with the activity of the traditional Raney nickel electrode; the method does not require additional spraying of nickel powder, greatly reduces the raw material cost in the production process of the Raney nickel electrode, is simple to operate, and is relatively easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1This is the LSV hydrogen evolution performance test of the catalysts of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 of the present invention;

[0023] Figure 2 These are the sampling points of the nickel-aluminum ratio distribution on the surface of the nickel mesh of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0025] Example 1

[0026] The modification method for improving the performance of Raney nickel electrolysis water proposed in this application has the following specific process:

[0027] (1) Nickel mesh pretreatment:

[0028] Prepare 3L of mixed alkali solution (5g / L sodium hydroxide, 20g / L sodium silicate, 10g / L sodium carbonate, 40g / L sodium phosphate). Place a 50-mesh 100cm*100cm nickel mesh substrate in the mixed alkali solution and keep it warm at 60℃ for 30min. After alkaline washing and degreasing, rinse the nickel mesh with deionized water. Then, weakly corrode the treated nickel mesh in 20% and 20℃ hydrochloric acid for 20min, and place the pre-treated nickel mesh in anhydrous ethanol and wait for use (to prevent the nickel mesh substrate from being contaminated by dust, grease, etc. in the air).

[0029] (2) Nickel mesh spraying:

[0030] The pre-treated nickel mesh was oxidized in an air atmosphere at 800°C for 3 hours, and aluminum powder with a particle size of 100-150 microns was used as a powder for plasma spraying on the oxidized nickel mesh. After spraying, the sample was calcined at 800°C for 2 hours in an argon atmosphere to obtain a sprayed sample. The sample was activated in a 10% sodium hydroxide solution for 12 hours, and rinsed with deionized water three times to obtain a Raney nickel electrode.

[0031] Example 2

[0032] The specific process of this embodiment is as follows:

[0033] (1) Nickel mesh pretreatment:

[0034] Prepare 3L of mixed alkali solution (5g / L sodium hydroxide, 30g / L sodium silicate, 20g / L sodium carbonate). Place a 50-mesh 100cm*100cm nickel mesh substrate in the mixed alkali solution and keep it warm at 60℃ for 30min. After alkaline washing and degreasing, rinse the nickel mesh with deionized water. Then, weakly corrode the treated nickel mesh in 10% and 20℃ dilute sulfuric acid for 20min, and place the pre-treated nickel mesh in anhydrous ethanol and wait for use (to prevent the nickel mesh substrate from being contaminated by dust, grease, etc. in the air).

[0035] (2) Nickel mesh spraying:

[0036] The pre-treated nickel mesh was oxidized in an oxygen atmosphere at 600°C for 3 hours, and aluminum powder with a particle size of 100-150 microns was used as a powder for plasma spraying on the oxidized nickel mesh. After spraying, the sample was calcined at 800°C for 2 hours in a nitrogen atmosphere to obtain a sprayed sample. The sample was activated in a 10% potassium hydroxide solution for 12 hours, and rinsed with deionized water three times to obtain a Raney nickel electrode.

[0037] Comparative Example 1

[0038] A method for preparing Raney nickel, characterized in that the specific process is as follows:

[0039] A 50-mesh 100cm*100cm nickel mesh substrate was oxidized in an air atmosphere at 800°C for 3 hours, and aluminum powder with a particle size of 100-150 microns was used as a powder for plasma spraying on the oxidized nickel mesh. After spraying, the sample was calcined at 800°C for 2 hours in an argon atmosphere to obtain a sprayed sample. The sample was activated in a 10% sodium hydroxide solution for 12 hours, and rinsed with deionized water three times to obtain a Raney nickel electrode.

[0040] Comparative Example 2

[0041] A method for preparing Raney nickel, characterized in that the specific process is as follows:

[0042] (1) Nickel mesh pretreatment:

[0043] Prepare 3L of mixed alkali solution (5g / L sodium hydroxide, 20g / L sodium silicate, 10g / L sodium carbonate, 40g / L sodium phosphate). Place a 50-mesh 100cm*100cm nickel mesh substrate in the mixed alkali solution and keep it warm at 60℃ for 30min. After alkaline washing and degreasing, rinse the nickel mesh with deionized water. Then, weakly corrode the treated nickel mesh in 20% and 20℃ hydrochloric acid for 20min, and place the pre-treated nickel mesh in anhydrous ethanol and wait for use (to prevent the nickel mesh substrate from being contaminated by dust, grease, etc. in the air).

[0044] (2) Nickel mesh spraying:

[0045] Aluminum powder with a particle size of 100-150 microns and nickel powder were mixed in a mass ratio of 2:8 to prepare a powder and plasma sprayed on a pre-treated nickel mesh to obtain a sprayed sample. The sample was activated in a 10% sodium hydroxide solution for 12 hours and rinsed with deionized water three times to obtain a Raney nickel electrode.

[0046] Table 1. Calculation of oxidation rate of nickel mesh after oxidation in Example 1 and Comparative Example 1

[0047] sample Mass before oxidation Quality after oxidation Oxidation rate Example 1 30.2642 31.7493 9.00％ Comparative Example 1 30.7325 31.8217 6.50％

[0048] Table 2. Surface nickel-aluminum atomic ratio distribution of Example 1 and Comparative Example 2

[0049] sample Position 1 Position 2 Location 3 Position 4 Example 1 1.84：1 1.90：1 1.88：1 1.83：1 Comparative Example 2 1.56：1 1.35：1 2.08：1 1.88：1

[0050] Compared with Example 1, it is used to illustrate that the pretreatment of the nickel mesh is more conducive to the subsequent oxidation of the nickel mesh, and the hydrogen evolution performance of the obtained Raney nickel electrode is more excellent; compared with Example 1, it is used to illustrate that the use of thermite reaction is more conducive to the uniform distribution of nickel and aluminum than the traditional Raney nickel preparation method, and the hydrogen evolution performance of the Raney nickel electrode obtained after activation is more excellent.

[0051] In summary, the above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. All equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification are within the scope covered by the patent of the present invention.

Claims

1. A modification method for improving the performance of Raney nickel electrolysis water, characterized in that: The following steps are involved: Pre-treatment of the nickel mesh: washing the nickel mesh with alkali, and then placing the nickel mesh in anhydrous ethanol for standby use; The nickel mesh is sprayed, the nickel mesh is oxidized, and the powder is plasma sprayed on the nickel mesh, high-temperature calcined, and finally activated to obtain a Raney nickel electrode.

2. The method according to claim 1, characterized in that: The nickel mesh number is 40-80 meshes.

3. The method according to claim 2, characterized in that: The nickel mesh number is 50-60 meshes.

4. The method according to claim 1, characterized in that The nickel screen alkaline washing specifically includes: Prepare 3L of mixed alkali solution, place the nickel mesh in the mixed alkali solution, and keep it at 60℃ for 30min; Rinse the nickel mesh with deionized water.

5. The method according to claim 1, characterized in that: After the nickel mesh is alkaline washed, it needs to be weakly corroded in the solution before being placed in anhydrous ethanol.

6. The method according to claim 5, characterized in that: The mixed alkali solution is one or more of 5-10 g / L sodium hydroxide, 10-30 g / L sodium silicate, 5-20 g / L sodium carbonate, and 20-60 g / L sodium phosphate.

7. The method according to claim 6, characterized in that: During the weak acid corrosion process, one or more of dilute hydrochloric acid, dilute sulfuric acid, phosphoric acid and acetic acid are used; the acid concentration is 5-40%, the acid treatment temperature is 15-60°C, and the acid treatment time is 0.5-40min.

8. The method according to claim 1, characterized in that: The nickel mesh substrate is oxidized in an oxidizing atmosphere, and aluminum powder is used as a powder material for plasma spraying on the oxidized nickel mesh; During the oxidation process, one of air, oxygen and ozone is used; the oxidation temperature is 500-1000°C; and the oxidation time is 0.5h-5h. Aluminum powder, particle size 50-250 microns.

9. The method according to claim 1, characterized in that: During the high-temperature calcination process, the inert atmosphere is one of argon, nitrogen and helium; the calcination temperature is 500-1000°C; and the calcination time is 0.5h-4h.

10. The method according to claim 1, characterized in that: The activation process is to soak the calcined nickel mesh in one or more of sodium hydroxide and potassium hydroxide, the concentration of the alkali solution is 4%-20%, and the soaking time is 5-24 hours.

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