Recovery process of water electrolysis anode catalyst in waste proton exchange membrane electrode, regenerated water electrolysis anode catalyst obtained by process and application of regenerated water electrolysis anode catalyst

Abstract

The invention relates to the field of recovery and regeneration of PEM electrolyzed water waste membrane electrodes, in particular to a recovery process of a water electrolysis anode catalyst in a waste proton exchange membrane electrode, a regenerated water electrolysis anode catalyst obtained through the process and application of the regenerated water electrolysis anode catalyst. The recovery process of the water electrolysis anode catalyst in the waste proton exchange membrane electrode provided by the invention has the advantages of simple flow and high purity of the recovered product, is suitable for the recovery of a large batch of waste membrane electrodes, and has a good application prospect. The regenerated water electrolysis anode catalyst obtained through the recycling process has good dispersity, shows high activity and stability in the water electrolysis oxygen evolution reaction, and is of great significance in promoting large-scale application and circular economy development of the PEM electrolytic cell technology. Tests show that the regenerated catalyst obtained by the recovery process is applied to proton exchange membrane water electrolysis hydrogen production as an anode catalyst, and the catalytic effect is almost equivalent to that of a catalyst which is not used initially.

Description

Technical Field

[0001] The present invention relates to the field of recycling and regenerating waste PEM water electrolysis membrane electrodes, specifically to a process for recycling water electrolysis anode catalysts in waste proton exchange membrane electrodes, the regenerated water electrolysis anode catalysts obtained by the process and applications thereof. Background Art

[0002] Hydrogen production from water electrolysis (PEMWE) powered by renewable energy is a key path to green hydrogen production. Proton exchange membrane water electrolysis (PEMWE) has attracted considerable attention due to its high current density and rapid response. However, the high energy barrier and slow kinetics of the anodic oxygen evolution reaction (OER) severely restrict the overall efficiency of hydrogen production from water electrolysis. Furthermore, the harsh, highly acidic and oxidizing environment of the OER places high demands on the catalyst. Currently, only iridium oxide (IrO2) can meet the requirements of commercial PEMWE.

[0003] However, as one of the rarest elements, iridium (Ir) has high costs, limited reserves, and low annual production. With the acceleration of global GW-scale green hydrogen production capacity construction, demand for PEM electrolyzers continues to grow rapidly. To meet the huge future demand for iridium in the large-scale PEMWE industry, in addition to significantly reducing the iridium catalyst loading, it is also necessary to achieve the recycling of spent iridium catalysts.

[0004] Currently, research on the recycling and utilization of waste membrane electrodes mainly focuses on the field of PEM fuel cells, while research on the recycling and utilization of PEM electrolyzer membrane electrodes is relatively scarce. In addition, in terms of precious metal recovery, the traditional strategy is usually to directly enter the calcination and smelting or leaching separation process after the catalyst is recovered. The process is complicated and there are toxic gas emissions. Nowadays, there are also a small number of studies that consider the direct reuse of waste catalysts. However, there are problems such as catalyst agglomeration and deactivation in the recycling process, which is not suitable for direct catalytic applications. Therefore, there is an urgent need to improve the strategy to design a simpler and more efficient catalyst recovery route for the reuse of recovered catalysts. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a recovery process for the water electrolysis anode catalyst in the waste proton exchange membrane electrode, the regenerated water electrolysis anode catalyst obtained by the process and its application. The regenerated water electrolysis anode catalyst obtained by the recovery process provided by the present invention has high dispersibility and electrocatalytic performance.

[0006] The present invention provides a process for recovering a water electrolysis anode catalyst in a waste proton exchange membrane electrode, comprising the following steps:

[0007] S1) treating the water electrolysis anode catalyst in the waste proton exchange membrane electrode in an oil bath in a mixed solution of an organic solvent and water; the organic solvent is one or more of cyclohexanol, ethylene glycol, isopropanol, acetone, N-methylpyrrolidone, N, N-dimethylformamide, and dimethyl sulfoxide;

[0008] S2) The material obtained in step S1) is subjected to a hydrothermal reaction in an alcohol solution to obtain a regenerated water electrolysis anode catalyst.

[0009] The waste proton exchange membrane electrode of the present invention is specifically a perfluorosulfonic acid proton exchange membrane electrode. The water electrolysis anode catalyst in the waste proton exchange membrane electrode of the present invention is specifically an iridium-based catalyst, more specifically iridium oxide.

[0010] The inventors of the present application have creatively discovered that by adding the anode catalyst in the waste proton exchange membrane electrode to a mixed solution of an organic solvent and water in an oil bath for dissolution and dispersion treatment, part of the perfluorosulfonic acid ionomers in the anode catalyst obtained from the waste proton exchange membrane electrode can be separated and removed, and then placing it in an alcohol solution for hydrothermal reaction can further remove the perfluorosulfonic acid ionomers. At the same time, the two steps of oil bath and hydrothermal reaction can also achieve activation and regeneration of the catalyst, and finally recover a water electrolysis anode catalyst with high dispersibility and electrocatalytic performance.

[0011] The present invention first subjects the water electrolysis anode catalyst in the waste proton exchange membrane electrode to an oil bath treatment in a mixed solution of an organic solvent and water. This is a dissolution and dispersion step that partially removes perfluorosulfonic acid ionomers. Specifically, the present invention first strips the waste proton exchange membrane electrode to obtain the water electrolysis anode catalyst, and then subjects the resulting water electrolysis anode catalyst to an oil bath treatment in a mixed solution of an organic solvent and water. More specifically, the oil bath treatment also includes centrifugal washing and drying of the resulting material.

[0012] The volume ratio of the organic solvent to water in the mixed solution of the organic solvent and water described herein is (0.1-10):1. The amount of the mixed solution used is 0.1 mL to 10 mL based on 1 mg of the water electrolysis anode catalyst in the waste proton exchange membrane electrode. The oil bath treatment temperature is 50°C to 120°C, and the oil bath treatment time is 5 to 12 hours.

[0013] The present invention treats the water electrolysis anode catalyst in a waste proton exchange membrane electrode in an oil bath in a mixed solution of an organic solvent and water, then subjecting the resulting material to a hydrothermal reaction in an alcohol solution to obtain a regenerated water electrolysis anode catalyst. Specifically, the resulting material is thoroughly ground and ultrasonically dispersed in an alcohol solution, followed by a hydrothermal reaction to obtain the regenerated water electrolysis anode catalyst. More specifically, after the hydrothermal reaction, the resulting product is centrifuged, washed, and then vacuum-dried to obtain the regenerated water electrolysis anode catalyst.

[0014] The alcohol solution of the present invention is selected from one or more of methanol, ethanol, isopropanol, n-butanol, ethylene glycol, and cyclohexanol. The temperature of the hydrothermal reaction of the present invention is 80° C. to 200° C., and the time of the hydrothermal reaction is 5 h to 20 h.

[0015] The present invention provides a regenerated water electrolysis anode catalyst obtained by the recycling process described in any of the above technical solutions. The regenerated water electrolysis anode catalyst obtained by the recycling process of the present invention has high dispersibility and electrocatalytic performance.

[0016] The present invention also provides the use of a regenerated water electrolysis anode catalyst obtained by the recycling process described in any of the above technical solutions as an anode catalyst in proton exchange membrane water electrolysis for hydrogen production. The regenerated water electrolysis anode catalyst obtained by the recycling process described in the present invention can be used as an anode catalyst in proton exchange membrane water electrolysis for hydrogen production, and can achieve a catalytic effect that is almost equivalent to that of the original unused catalyst.

[0017] The present invention provides a process for recovering anode catalysts for water electrolysis in waste proton exchange membrane electrodes, a regenerated anode catalysts for water electrolysis obtained by the process, and applications thereof. The process for recovering anode catalysts for water electrolysis in waste proton exchange membrane electrodes provided by the present invention has a simple flow and high purity of the recovered product, is suitable for the recovery of large quantities of waste membrane electrodes, and has good application prospects. The regenerated anode catalysts for water electrolysis obtained by the recovery process of the present invention have good dispersibility, and show high activity and stability in the electrolysis of water and oxygen evolution reaction, which is of great significance for promoting the large-scale application of PEM electrolyzer technology and the development of a circular economy. Experiments show that the regenerated catalysts obtained by the recovery process of the present invention have good dispersibility and restored activity, and are applied as anode catalysts in proton exchange membrane water electrolysis to produce hydrogen, and the catalytic effect is almost equivalent to that of the initial unused catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a performance diagram of the recovered anode regeneration catalyst after treatment in Example 1 used in a PEM water electrolysis device.

[0019] Figure 2This is a performance diagram of the recovered anode regeneration catalyst after treatment in Comparative Example 1 used in a PEM water electrolysis device.

[0020] Figure 3 This is a performance diagram of the recovered anode regeneration catalyst after treatment in Comparative Example 2 used in a PEM water electrolysis device. DETAILED DESCRIPTION

[0021] The present invention discloses a process for recovering anode catalysts for water electrolysis in waste proton exchange membrane electrodes, a regenerated anode catalyst for water electrolysis obtained by the process, and applications thereof. Those skilled in the art can refer to the contents of this article and appropriately improve the process parameters for implementation. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0022] The waste proton exchange membrane electrodes (waste PEM membrane electrodes) used in the specific embodiment of the present invention are all perfluorosulfonic acid proton exchange membrane electrodes, and the perfluorosulfonic acid proton exchange membrane is specifically Nafion 115 membrane, which has a high conductivity at 2 A / cm 2 After nearly 3000 h of use at this current density.

[0023] The present invention will be further described below with reference to the embodiments:

[0024] Example 1

[0025] 30 mg of anodic iridium oxide catalyst, removed from the waste PEM membrane electrode, was added to a mixture of 30 mL of isopropanol and 10 mL of water. After ultrasonic stirring, the mixture was incubated in an oil bath at 80°C for 6 hours, followed by centrifugal washing and drying. The dried product was thoroughly ground and added to 50 mL of cyclohexanol solution. Ultrasonic dispersion was performed, followed by hydrothermal reaction at 160°C for 12 hours. The product was then centrifuged, washed with deionized water and anhydrous ethanol, and dried in vacuo.

[0026] The treated recycled anode regeneration catalyst was applied to a PEM water electrolysis device and tested with two electrodes. The cathode used a commercial platinum-carbon catalyst for hydrogen evolution reaction, and the anode used the treated recycled anode regeneration catalyst for oxygen evolution reaction. The catalysts of the above cathode and cathode were prepared into membrane electrodes by spray-hot pressing. The anode catalyst loading was 1.0 mg / cm 2 , assembled into a PEM device. The results are as follows Figure 1 As shown, Figure 1 The performance diagram of the treated recycled anode regeneration catalyst used in PEM water electrolysis device. Figure 1It can be seen that at 2 A / cm 2 At the current density, its potential was 1.836 V, demonstrating superior catalytic activity compared to the original, unused membrane electrode. This indicates that the recovered anode catalyst exhibits good dispersion and restored activity after treatment. This recycling process is a method for dispersing and reusing anode catalysts in waste proton exchange membrane electrodes for water electrolysis, and is expected to enable the recycling of large quantities of discarded membrane electrodes.

[0027] Example 2

[0028] 50 mg of anodic iridium oxide catalyst, removed from the waste PEM membrane electrode, was added to a mixture of 82.5 mL of ethylene glycol and 17.5 mL of water. After ultrasonic stirring, the mixture was incubated in an oil bath at 95°C for 6 hours, followed by washing and centrifugation. The dried product was thoroughly ground and added to 60 mL of isopropanol, ultrasonically dispersed, and hydrothermally reacted at 180°C for 10 hours. The product was then centrifuged, washed with deionized water and anhydrous ethanol, and dried in vacuo.

[0029] Comparative Example 1

[0030] 30 mg of the anodic iridium oxide catalyst stripped from the waste PEM membrane electrode was added to a mixed solution of 30 mL of isopropanol and 10 mL of water. After ultrasonic stirring, it was placed in an oil bath at 80°C for 6 h, and then centrifuged and washed and dried.

[0031] The recovered anode regeneration catalyst before and after treatment was tested and characterized. Figure 2 The middle is the performance diagram of the treated recycled anode regeneration catalyst used in PEM water electrolysis device, at 2 A / cm 2 The potential at this current density is 1.956 V.

[0032] Comparative Example 2

[0033] 50 mg of anodic iridium oxide catalyst, removed from the waste PEM membrane electrode, was added to a mixture of 82.5 mL of isopropanol and 17.5 mL of water. After ultrasonic stirring, the mixture was incubated in an oil bath at 80°C for 6 hours, followed by washing and centrifugation. The dried product was thoroughly ground and added to 60 mL of n-butanol solution. Ultrasonic dispersion was performed, followed by hydrothermal reaction at 160°C for 12 hours. The product was centrifuged, washed with deionized water and anhydrous ethanol, and then dried in a vacuum oven.

[0034] The recovered anode regeneration catalyst before and after treatment was tested and characterized. Figure 3 The middle is the performance diagram of the treated recycled anode regeneration catalyst used in PEM water electrolysis device, at 2 A / cm 2 The potential at this current density is 1.989 V.

[0035] In summary, the present invention designs a simpler and more efficient catalyst recovery route. The recovered catalyst has good dispersibility and electrocatalytic performance, which is of great significance for promoting the large-scale application of PEM electrolyzer technology and the development of circular economy.

[0036] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A process for recovering anode catalyst for water electrolysis in waste proton exchange membrane electrodes, characterized in that: The following steps are involved: S1) treating the water electrolysis anode catalyst in the waste proton exchange membrane electrode in an oil bath in a mixed solution of an organic solvent and water; the organic solvent is one or more of cyclohexanol, ethylene glycol, isopropanol, acetone, N-methylpyrrolidone, N, N-dimethylformamide, and dimethyl sulfoxide; S2) The material obtained in step S1) is subjected to a hydrothermal reaction in an alcohol solution to obtain a regenerated water electrolysis anode catalyst.

2. The recycling process according to claim 1, characterized in that In step S1), the volume ratio of the organic solvent to water in the mixed solution of the organic solvent and water is (0.1-10):

1.

3. The recycling process according to claim 1, characterized in that In step S1), the amount of the mixed solution of the organic solvent and water is 0.1 mL to 10 mL based on 1 mg of the water electrolysis anode catalyst in the waste proton exchange membrane electrode.

4. The recycling process according to claim 1, characterized in that In step S1), the temperature of the oil bath treatment is 50° C. to 120° C., and the time of the oil bath treatment is 5 h to 12 h.

5. The recycling process according to claim 1, characterized in that In step S1), the water electrolysis anode catalyst in the waste proton exchange membrane electrode is iridium oxide.

6. The recycling process according to claim 1, characterized in that In step S1), the waste proton exchange membrane electrode is a perfluorosulfonic acid proton exchange membrane electrode.

7. The recycling process according to claim 1, characterized in that In step S2), the alcohol solution is selected from one or more of methanol, ethanol, isopropanol, n-butanol, ethylene glycol, and cyclohexanol.

8. The recycling process according to claim 1, characterized in that In step S2), the temperature of the hydrothermal reaction is 80° C. to 200° C., and the time of the hydrothermal reaction is 5 h to 20 h.

9. A regenerated water electrolysis anode catalyst obtained by the recovery process according to any one of claims 1 to 8.

10. Use of the regenerated water electrolysis anode catalyst obtained by the recovery process according to any one of claims 1 to 8 as an anode catalyst in proton exchange membrane water electrolysis to produce hydrogen.

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