Regeneration of catalyst, method for regeneration of spent catalyst of a spray process and use thereof

Abstract

This invention relates to catalyst waste recycling technology, specifically to a regenerated catalyst, a method for regenerating spent catalyst from the spraying process, and their applications. The regenerated catalyst includes an active component and fluorine. The active component is iridium oxide or an iridium-platinum alloy, and the fluorine content is 0.1-1% by mass, with an average particle size of 30-260 nm. The regeneration method involves adding the anode waste generated during the spraying of the membrane electrode to a first cleaning solvent, performing ultrasonic cleaning, then heating and pressurizing to 120-200°C and 0.2-1.5 MPa for dissociation treatment, followed by calcination at 250-450°C to obtain the catalyst. The regeneration method provided by this invention not only efficiently recovers the catalytic active component but also regenerates a catalyst with specific chemical composition and surface state and excellent electrochemical catalytic performance, achieving direct high-value reuse of spent catalysts at the production end.

Description

Technical Field

[0001] This invention relates to the recycling and regeneration technology of catalyst waste, specifically to a method for regenerating catalysts, waste catalysts from the spraying process, and their applications. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Membrane electrode assemblies (MEAs) are core components of electrochemical energy conversion devices. Their industrial production typically involves spraying or coating processes to uniformly load catalyst slurries onto proton exchange membranes or gas diffusion layers. These catalyst slurries generally contain high-value precious metal catalysts and key materials; for example, the anode side of a proton exchange membrane electrolysis (PEM) cell electrode contains iridium-based catalysts and perfluorosulfonic acid resins. During the large-scale production of MEAs, various process wastes are inevitably generated. These include unused catalyst slurries after preparation, dry or wet catalysts scraped from spraying equipment and carriers, and membrane electrode coating materials discarded due to substandard coating uniformity, thickness, or other performance characteristics. These process wastes are rich in precious metals such as iridium and perfluorosulfonic acid resins. Direct disposal as waste not only results in significant resource waste but also significantly increases production costs and environmental burden.

[0004] Currently, the treatment methods for such process waste mainly fall into two categories. One category involves using the waste as a low-grade raw material to recover precious metals such as iridium through pyrometallurgical or hydrometallurgical processes. However, this type of recovery method is typically energy-intensive and has a complex process flow. Furthermore, because the deactivation mechanism of the catalyst in the spraying process waste differs from that of conventional waste membrane electrodes, its surface is often coated with ionomers or undergoes physical morphological changes. Using traditional dissolution recovery methods would result in a significant loss of the value of precious metals such as iridium, leading to poor economic benefits. The other category of treatment uses simple physical cleaning methods, such as ball milling, to attempt to directly reuse the recovered catalyst. However, preliminary practice of this invention has shown that catalysts after such simple regeneration treatment often have residual fluorides (derived from perfluorosulfonic acid resin) that are difficult to remove on their surface. Moreover, catalyst nanoparticles are prone to uncontrolled agglomeration during drying and other processes, leading to a decrease in the active specific surface area and the covering of active sites. The activity and stability of the catalyst are far lower than those of freshly prepared catalysts, making it difficult to meet the stringent requirements of high-performance devices. For example, during the recovery and drying process of iridium anode catalysts, nanoparticles may agglomerate, and residual fluorides on the surface may cover the active sites, severely limiting their electrochemical catalytic performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a regenerated catalyst, a method for regenerating waste catalysts from the spraying process, and their applications. The regenerated catalyst provided by the present invention can not only efficiently recover the catalytically active components therein, but also has specific chemical composition and surface state, exhibiting excellent electrochemical catalytic performance, thereby realizing the direct high-value reuse of waste catalysts at the production end.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, a regenerating catalyst includes an active component and fluorine, wherein the active component is iridium oxide or an iridium-platinum alloy, and the fluorine content is 0.1-1% by mass; the average particle size of the regenerating catalyst is 30-260 nm.

[0007] The regenerated catalyst of this invention is obtained by regenerating waste catalyst from the spraying process. Studies have shown that the fluorine content of the regenerated catalyst obtained by this invention is strictly controlled between 0.1% and 1%. When the fluorine content is too high, the residual ionomer in the regenerated catalyst is severe, thus poisoning the active sites and hindering the recovery of catalyst activity. Furthermore, because this invention employs heating and high pressure for dissociation treatment, this method enables the decomposition of some perfluorosulfonic acid resin to produce F... - Furthermore, under the current dissociation treatment conditions, F is easily made - When fluorine enters the crystal lattice of active components such as iridium oxide, a low fluorine content may cause the F in the lattice to... - Removal not only disrupts the surface state of the original catalyst but also causes irreversible damage to the catalyst's bulk structure. Furthermore, further low-temperature calcination can form a specific particle size range (30-260 nm) with good dispersibility and a suitable specific surface area. Larger particle sizes reduce the specific surface area, failing to provide sufficient reactive sites, leading to a significant performance decrease. Excessively small particle sizes result in reduced hierarchical pores and excessive hydrophilicity after spraying, thus deteriorating water transport capacity, increasing mass transfer resistance, and ultimately impairing catalytic performance at high current densities. Therefore, the regenerated catalyst provided by this invention ensures both a highly clean catalyst surface and maintains its structural stability, thereby guaranteeing the catalytic activity of the regenerated catalyst.

[0008] Secondly, a method for regenerating spent catalyst from a spraying process includes the following steps: The anode waste generated during the coating process of the membrane electrode is added to the first cleaning solvent and ultrasonically cleaned. After solid-liquid separation, the cleaned solid is obtained. The cleaning solid is added to a second cleaning solvent, and under sealed conditions, it is heated and pressurized to 120-200℃ and 0.2-1.5 MPa for dissociation treatment to obtain the precursor. The precursor is calcined at 250-450°C in an air or inert atmosphere to obtain the product.

[0009] This invention first uses ultrasonic cleaning to clean the anode waste generated during the coating process of the membrane electrode, aiming to initially disperse agglomerated particles and dissolve some soluble organic impurities. Then, it employs heating and high pressure for dissociation treatment, which powerfully breaks down and dissolves residual ionomers coated on the surface of the anode waste catalyst particles, thus ensuring the recovery of the iridium catalyst activity. Simultaneously, low-temperature calcination at 250-450℃ further removes residual trace organic matter, modulates the electronic structure of the catalyst, and exposes a pure catalytic surface, improving the utilization rate of active sites and achieving the "awakening" and stabilization of catalytic activity. This avoids excessive sintering caused by high-temperature calcination, thereby improving the catalytic activity of the regenerated catalyst. Studies have shown that this regeneration method can prepare regenerated catalysts with a fluorine content of 0.1-1% and an average particle size of 30-260 nm.

[0010] Thirdly, the application of the regenerated catalyst described in the first aspect of the present invention in the catalytic oxygen evolution reaction.

[0011] Fourthly, a membrane electrode comprising the regenerating catalyst described in the first aspect of the present invention.

[0012] Fifthly, a proton exchange membrane electrolyzer includes the membrane electrode described in the fourth aspect of the present invention.

[0013] The beneficial effects of this invention are as follows: 1. This invention addresses the problem of severe ionomer encapsulation in the anode waste generated during the spray coating process of membrane electrodes. By using a heating and pressurizing solvent dissociation step, the stubborn perfluorosulfonic acid resin can be efficiently stripped off. Then, by low-temperature calcination, the particles are redispersed while being cleaned, thereby restoring their electrocatalytic activity. This also ensures efficient catalyst recovery and has a significant regeneration effect.

[0014] 2. The regenerated catalyst obtained through the regeneration method of this invention exhibits excellent performance and can directly replace fresh catalyst. This invention, through precise control of key impurity elements (fluorine), particle size, and surface state, enables the electrocatalytic activity (oxygen evolution reaction (OER) overpotential) and electrochemical active area (ECSA) of the regenerated catalyst to be restored to 95%-100% of the level of fresh commercial catalysts of equivalent specifications. This fully meets the application requirements of high-performance PEM electrolyzers, achieving a fundamental leap from "waste" to "equivalent replacement." It pioneers a new path for the targeted regeneration of production waste, providing a solution for catalyst regeneration of spraying waste from the PEM electrolyzer membrane electrode production process, greatly improving the efficiency and value of resource recycling.

[0015] 3. The regenerated catalyst obtained by the regeneration method of this invention has stable and uniform quality. The regeneration method provided by this invention has clear process steps, clearly defines the impact of fluorine content on the regenerated catalyst, and can ensure the consistency of composition and performance of catalyst products obtained from different batches of waste through the establishment of standardized regeneration process flow. At the same time, it provides objective and quantifiable inspection standards for product quality, ensuring its reliability in the application of end products.

[0016] 4. The present invention has significant cost advantages. Compared with expensive fresh iridium, platinum and other precious metal catalysts, the regenerated catalyst of the present invention can reduce raw material costs by 30%-60%, and the raw materials are derived from the production process itself, ensuring a stable supply and being unaffected by drastic fluctuations in precious metal market prices, thus significantly improving the economic efficiency of PEM electrolyzer production.

[0017] 5. The regeneration method of this invention is simple and easy to integrate. The regeneration process provided by this invention does not require complex steps of dissolving, separating, and resynthesizing precious metals. The process is relatively simple, with low energy and chemical reagent consumption. It is easy to integrate within the production base, realizing the immediate recycling and reuse of waste materials and forming a rapid internal material closed loop.

[0018] 6. This invention offers significant economic and environmental benefits. Direct recycling avoids the value loss associated with downgrading high-value catalyst waste into crude metals, significantly reducing the procurement cost of precious metals. Simultaneously, it greatly reduces energy consumption and environmental impact from primary mineral mining, while avoiding the emissions of waste gas, wastewater, and solid waste from traditional metallurgical recycling processes, aligning with the core concepts of green manufacturing and a circular economy. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a graph showing the particle size distribution and cumulative curve of the original, untreated blocky iridium oxide-based recovery catalyst of the present invention.

[0021] Figure 2 This is a graph showing the particle size distribution and cumulative curve of the original, untreated powdered iridium-platinum alloy recovered catalyst of the present invention.

[0022] Figure 3 The figure shows a particle size comparison curve between the original untreated blocky iridium oxide-based recovery catalyst of the present invention and the catalysts prepared in Examples 1, 2, 1, 2, and 3; the blocky iridium oxide-based recovery catalyst in the figure is the original untreated blocky iridium oxide-based recovery catalyst.

[0023] Figure 4 This is a comparison of the OER curves of the catalysts prepared in Examples 1, 3, 1, 2, and 3 of this invention. Preparation method of the rotating disk electrode: The catalyst powder was dispersed in a mixed solvent composed of isopropanol and deionized water (volume ratio 4:1), and 5 wt% Nafion® solution was added as a binder and proton conductor. The catalyst concentration in the mixed system was 5.0 mg / mL. -1 The Nafion® content is 2.0% of the total slurry volume (based on solids). Uniformly dispersed catalyst ink is obtained through ultrasonic treatment in an ice-water bath (60 minutes). The catalyst loading is precisely controlled at 0.10 mg / cm³ by adjusting the slurry concentration and drop volume. -2 . Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] The alcohol-water solution described in this invention refers to a mixed solution of alcohol and water.

[0027] The inert atmosphere conditions described in this invention refer to nitrogen atmosphere conditions or inert atmosphere conditions such as helium, argon, and xenon, which are mainly used to avoid the oxidation of active ingredients by oxidizing atmospheres.

[0028] Given that it is difficult to balance the recovery efficiency and catalytic performance of catalysts in the anode waste during the industrial preparation of membrane electrodes, this invention proposes a method for regenerating catalysts, a method for regenerating waste catalysts from the spraying process, and their applications in order to solve the above-mentioned technical problems.

[0029] In a typical embodiment of the present invention, a regenerating catalyst is provided, comprising an active component and fluorine, wherein the active component is iridium oxide or an iridium-platinum alloy, and the mass content of fluorine is 0.1-1%; the average particle size of the regenerating catalyst is 30-260 nm.

[0030] In some embodiments, the average particle size is 50-100 nm.

[0031] Another embodiment of the present invention provides a method for regenerating waste catalysts from a spraying process, comprising the following steps: The anode waste generated during the coating process of the membrane electrode is added to the first cleaning solvent and ultrasonically cleaned. After solid-liquid separation, the cleaned solid is obtained. The cleaning solid is added to a second cleaning solvent, and under sealed conditions, it is heated and pressurized to 120-200℃ and 0.2-1.5 MPa for dissociation treatment to obtain the precursor. The precursor is calcined at 250-450°C in an air or inert atmosphere to obtain the product.

[0032] In some embodiments, the catalytically active component in the anode waste is iridium oxide or an iridium-platinum alloy. This invention demonstrates that the regeneration method is suitable for catalyst regeneration from anode waste containing this catalytically active component (especially iridium oxide). When the active component is iridium oxide, the calcination atmosphere is air or an inert atmosphere; when the active component is iridium oxide, the calcination atmosphere is an inert atmosphere.

[0033] In some embodiments, the first cleaning solvent is an aqueous alcohol solution. The aqueous alcohol solution described in this invention refers to a mixed solution of C1-C3 alcohols and water. The C1-C3 alcohols refer to alcohols with 1-3 carbon atoms, such as methanol, ethanol, and isopropanol. The C1-C3 alcohols and water can be mixed in any proportion, preferably at a volume ratio of 1:0.8-1.2.

[0034] In some embodiments, the solid-liquid ratio during ultrasonic cleaning is 1:4.5-5.5 (g:mL). Studies have shown that ultrasonic cleaning under these conditions yields better results.

[0035] In some embodiments, during ultrasonic cleaning, the ultrasonic power is 500-2000W, the temperature is 20-60℃, and the cleaning time is 0.5-3 hours. Studies have shown that ultrasonic cleaning under these conditions yields better results.

[0036] In some embodiments, the solid-liquid ratio during the dissociation treatment is 1:2.5-3.5, g:mL. Studies have shown that the dissociation effect is better under these conditions.

[0037] In some embodiments, during the dissociation process, the second cleaning solvent is a mixed solution of a polar solvent and water, wherein the polar solvent is dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF). The polar solvent and water can be mixed in any proportion, and the volume ratio of the polar solvent to water is preferably 1:0.5~2.

[0038] In some embodiments, the dissociation process takes 1-6 hours. Studies have shown that dissociation is more effective under these conditions.

[0039] In some embodiments, the calcination time is 1-4 hours.

[0040] A third embodiment of the present invention provides an application of the above-mentioned regenerated catalyst in the catalytic oxygen evolution reaction.

[0041] In some embodiments, the catalytic oxygen evolution reaction is used for proton exchange membrane electrolysis.

[0042] A fourth embodiment of the present invention provides a membrane electrode comprising the regenerating catalyst described in the second aspect of the present invention.

[0043] A fifth embodiment of the present invention provides a proton exchange membrane electrolyzer, including the membrane electrode described in the fourth aspect of the present invention.

[0044] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0045] Example 1 A method for regenerating waste catalyst from a spraying process, comprising the following steps: 1. Collect 10g of iridium oxide-based waste catalyst lumps (containing ionomer residue and approximately 8g of catalyst) cleaned from the anode side spraying equipment of the proton exchange membrane electrolyzer.

[0046] 2. Add 50 mL of ethanol-water (1:1) solution to the waste catalyst collected in step 1, treat it under ultrasonic treatment at 40℃ and 1000W for 1.5 hours, and centrifuge to obtain solid.

[0047] 3. Transfer the solid obtained in step 2 to an autoclave, add 20 mL of DMSO and 10 mL of H2O, and react at 160 °C and 0.3 MPa for 3 hours. After cooling, filter and wash thoroughly with ethanol and water.

[0048] 4. After washing and drying in step 3, the solid was calcined in air at 350°C for 2 hours to obtain 7.71g of regenerated iridium oxide powder.

[0049] XPS analysis showed that the surface fluorine content (from the ionomer) decreased from 4.7 wt% before regeneration to 0.1 wt%, and laser particle size analyzer results showed that the particle size decreased from 19.51 μm before regeneration to 30 nm. Figure 1 and Figure 3 As shown.

[0050] Electrochemical test results show that the performance of the regenerated catalyst has been fully recovered: Catalytic activity: Regenerated anode catalyst at 10 mA cm⁻¹ -2 The overpotential of the oxygen evolution reaction (OER) at current density is η.10 = 282 mV, OER curve as shown Figure 4 As shown, compared with fresh commercial IrO2 catalyst (η) under the same testing conditions, 10 = 278 mV) is equivalent.

[0051] Example 2 A method for regenerating waste catalyst from a spraying process, comprising the following steps: 1. Collect 10g of iridium oxide-based waste catalyst powder (containing ionomer residue and approximately 8g of catalyst) cleaned from the anode side spraying equipment of the proton exchange membrane electrolyzer.

[0052] 2. Add 50 mL of ethanol-water (1:1) solution to the waste catalyst collected in step 1, treat it under ultrasonic treatment at 40℃ and 1000W for 1.5 hours, and centrifuge to obtain solid.

[0053] 3. Transfer the solid obtained in step 2 to an autoclave, add 15 mL of DMSO and 15 mL of H2O, and react at 180 °C and 1.2 MPa for 4 hours. After cooling, filter and wash thoroughly with ethanol and water.

[0054] 4. After washing and drying in step 3, the solid was calcined in air at 350°C for 2 hours to obtain 7.82g of regenerated iridium oxide powder.

[0055] XPS analysis showed that the surface fluorine content (from the ionomer) decreased from 9.2 wt% before regeneration to 1 wt%, and laser particle size analyzer results showed that the particle size decreased from 13.24 μm before regeneration to 260 nm. Figure 3 As shown.

[0056] Electrochemical test results show that the performance of the regenerated catalyst has been fully recovered: Catalytic activity: Regenerated anode catalyst at 10 mA cm⁻¹ -2 The overpotential of the oxygen evolution reaction (OER) at current density is η. 10 = 285 mV, compared with fresh commercial IrO2 catalyst (η) under the same testing conditions. 10 = 278 mV) is equivalent.

[0057] Example 3 A method for regenerating waste catalyst from a spraying process, comprising the following steps: 1. Collect 10g of iridium-platinum alloy-based waste catalyst powder (containing ionomer residue and approximately 8g of catalyst) cleaned from the anode side spraying equipment of the proton exchange membrane electrolyzer.

[0058] 2. Add 50 mL of ethanol-water (1:1) solution to the waste catalyst collected in step 1, treat it under ultrasonic treatment at 60℃ and 800W for 1.5 hours, and centrifuge to obtain solid.

[0059] 3. Transfer the solid obtained in step 2 to an autoclave, add 15 mL of N,N-dimethylformamide (DMF) and 15 mL of H2O, and react at 160 °C and 1.0 MPa for 3 hours. After cooling, filter and wash thoroughly with ethanol and water.

[0060] 4. The solid washed and dried in step 3 was calcined at 350°C for 2 hours under a nitrogen atmosphere to obtain 7.89g of regenerated iridium-platinum powder.

[0061] XPS analysis showed that the surface fluorine content (from the ionomer) decreased from 6.2 wt% before regeneration to 0.3 wt%. Laser particle size analyzer results showed that the particle size before regeneration was 11.67 μm. Figure 2 As shown, the regenerated size drops to 50nm.

[0062] Electrochemical test results show that the performance of the regenerated catalyst has been fully recovered: Catalytic activity: Regenerated anode catalyst at 10 mA cm⁻¹ -2 The overpotential of the oxygen evolution reaction (OER) at current density is η. 10 = 279 mV, OER curve as shown Figure 4 As shown, compared with fresh commercial IrO2 catalyst (η) under the same testing conditions, 10 = 278 mV) is equivalent.

[0063] Example 4 A method for regenerating waste catalyst from a spraying process, comprising the following steps: 1. Collect 10g of iridium oxide-based waste catalyst lumps (containing ionomer residue and approximately 8g of catalyst) cleaned from the anode side spraying equipment of the proton exchange membrane electrolyzer.

[0064] 2. Add 50 mL of isopropanol-water (1:1) solution to the waste catalyst collected in step 1, treat it under ultrasonic treatment at 60℃ and 800W for 2 hours, and centrifuge to obtain solid.

[0065] 3. Transfer the solid obtained in step 2 to an autoclave, add 10 mL of DMF and 20 mL of H2O, and react at 185 °C and 1.5 MPa for 3 hours. After cooling, filter and wash thoroughly with ethanol and water.

[0066] 4. After washing and drying in step 3, the solid was calcined in air at 350°C for 2 hours to obtain 7.65g of regenerated iridium oxide powder.

[0067] XPS analysis showed that the surface fluorine content (from the ionomer) decreased from 6.2 wt% before regeneration to 0.6 wt%, and laser particle size analyzer results showed that the particle size decreased from 19.51 μm before regeneration to 100 nm.

[0068] Electrochemical test results show that the performance of the regenerated catalyst has been fully recovered: Catalytic activity: Regenerated anode catalyst at 10 mA cm⁻¹ -2 The overpotential of the oxygen evolution reaction (OER) at current density is η. 10 = 283 mV, compared with fresh commercial IrO2 catalyst (η) under the same testing conditions. 10 = 278 mV) is equivalent.

[0069] Comparative Example 1 A method for regenerating waste catalyst from a spraying process, comprising the following steps: 1. Collect 10g of iridium oxide-based waste catalyst lumps (containing ionomer residue and approximately 8g of catalyst) cleaned from the anode side spraying equipment of the proton exchange membrane electrolyzer.

[0070] 2. Add 50 mL of ethanol-water (1:1) solution to the waste catalyst collected in step 1, treat it under ultrasonic treatment at 40℃ and 1000W for 1.5 hours, and centrifuge to obtain solid.

[0071] 3. The solid obtained in step 2 was calcined in air at 350°C for 2 hours to obtain 8.28g of regenerated iridium oxide powder.

[0072] XPS analysis showed that the surface fluorine content (from ionomers) decreased from 9.4 wt% before regeneration to 2.5 wt%, and laser particle size analyzer results showed that the particle size decreased from 19.51 μm before regeneration to 11.7 μm.

[0073] Electrochemical test results show that the performance recovery of the regenerated catalyst is poor: Catalytic activity: Regenerated anode catalyst at 10 mA cm⁻¹ -2 The overpotential of the oxygen evolution reaction (OER) at current density is η. 10 = 345 mV, OER curve as shown Figure 4 As shown, performance degradation is severe.

[0074] Comparative Example 2 A method for regenerating waste catalyst from a spraying process, comprising the following steps: 1. Collect 10g of iridium oxide-based waste catalyst lumps (containing ionomer residue and approximately 8g of catalyst) cleaned from the anode side spraying equipment of the proton exchange membrane electrolyzer.

[0075] 2. Transfer the waste catalyst collected in step 1 to an autoclave, add 15 mL of DMF and 15 mL of H2O, and react at 180 °C and 1.5 MPa for 3 hours. After cooling, filter and wash thoroughly with ethanol and water. Collect 8.66 g of the weighed powder.

[0076] XPS analysis showed that the surface fluorine content (from the ionomer) decreased from 9.5 wt% before regeneration to 5.5 wt%, and laser particle size analyzer results showed that the particle size decreased from 19.51 μm before regeneration to 1.8 μm.

[0077] Electrochemical test results show that the performance recovery of the regenerated catalyst is poor: Catalytic activity: Regenerated anode catalyst at 10 mA cm⁻¹ -2 The overpotential of the oxygen evolution reaction (OER) at current density is η. 10 = 328 mV, OER curve as shown Figure 4 As shown, performance degradation is severe.

[0078] Comparative Example 3 A method for regenerating waste catalyst from a spraying process, comprising the following steps: 1. Collect 10g of iridium oxide-based waste catalyst lumps (containing ionomer residue and approximately 8g of catalyst) cleaned from the anode side spraying equipment of the proton exchange membrane electrolyzer.

[0079] 2. Add 50 mL of ethanol-water (1:1) solution to the waste catalyst collected in step 1, treat it under ultrasonic treatment at 40℃ and 1000W for 6 hours, and centrifuge to obtain the solid.

[0080] 3. Transfer the solid obtained in step 2 to an autoclave, add 15 mL of DMSO and 15 mL of H2O, and react at 220 °C and 1.6 MPa for 8 hours. After cooling, filter and wash thoroughly with ethanol and water.

[0081] 4. After washing and drying in step 3, the solid was calcined in air at 500°C for 2 hours to obtain 7.16g of regenerated iridium oxide powder.

[0082] XPS analysis showed that the surface fluorine content (from the ionomer) decreased from 8.6 wt% before regeneration to 0.05 wt%, and laser particle size analyzer results showed that the particle size decreased from 19.51 μm before regeneration to 16 nm.

[0083] Electrochemical test results show that the performance recovery of the regenerated catalyst is poor: Catalytic activity: Regenerated anode catalyst at 10 mA cm⁻¹ -2 The overpotential of the oxygen evolution reaction (OER) at current density is η. 10 = 361mV, performance degradation is severe.

[0084] The parameters of the regenerated catalysts prepared in each embodiment and comparative example are shown in Table 1.

[0085] Table 1. Parameters of the regenerated catalysts prepared in each example and comparative example.

[0086] The above results indicate that the regenerated catalysts prepared in Examples 1-4 have a fluorine content of 0.1-1% by mass and an average particle size of 30-260 nm, exhibiting catalytic activity comparable to that of fresh iridium oxide. Comparative Example 1, which only involves ultrasonic cleaning and low-temperature calcination, and Comparative Example 2, which only employs high-pressure heating and dissociation, cannot simultaneously break up agglomerates, reduce particle size, and completely remove fluorine, thus affecting the activity of the regenerated catalyst. While Comparative Example 3, using a high-intensity cleaning process, can further reduce the fluorine content to below 0.1% by mass and the particle size to below 30 nm, it actually negatively impacts catalytic performance. This demonstrates that excessive cleaning can cause irreversible damage to the catalyst's bulk structure, thereby reducing its catalytic performance.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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 regenerated catalyst characterized by, It includes an active ingredient and fluorine, wherein the active ingredient is iridium oxide or an iridium-platinum alloy, and the fluorine content is 0.1-1% by mass; the average particle size of the regenerated catalyst is 30-260 nm; The method for preparing the regenerated catalyst includes the following steps: The anodic waste generated during the coating process of the film electrode is added to the first cleaning solvent and ultrasonically cleaned. After solid-liquid separation, the cleaned solid is obtained. The first cleaning solvent is an alcohol-water solution, which is a mixed solution of C1-C3 alcohols and water. The C1-C3 alcohols are alcohols with 1-3 carbon atoms. The volume ratio of the C1-C3 alcohols to water is 1:0.8~1.

2. The cleaned solid is added to a second cleaning solvent, and under sealed conditions, it is heated and pressurized to 120-200℃ and 0.2-1.5 MPa for dissociation treatment to obtain the precursor; the second cleaning solvent is a mixed solution of dimethyl sulfoxide and water or a mixed solution of N,N-dimethylformamide and water, wherein the volume ratio of dimethyl sulfoxide to water or the volume ratio of N,N-dimethylformamide to water is 1:0.5~2; The precursor is calcined at 250-450°C in an air or inert atmosphere to obtain the product.

2. The regenerated catalyst according to claim 1, characterized by In ultrasonic cleaning, the solid-liquid ratio is 1:4.5-5.5 (g:mL), the ultrasonic power is 500-2000W, the temperature is 20-60℃, and the cleaning time is 0.5-3 hours.

3. The regenerated catalyst as described in claim 1, characterized in that, During the dissociation process, the solid-liquid ratio was 1:2.5-3.5, g:mL.

4. The regenerated catalyst as described in claim 1, characterized in that, The average particle size is 50-100 nm.

5. A method for preparing the regenerated catalyst as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The anodic waste generated during the coating process of the film electrode is added to the first cleaning solvent and ultrasonically cleaned. After solid-liquid separation, the cleaned solid is obtained. The first cleaning solvent is an alcohol-water solution, which is a mixed solution of C1-C3 alcohols and water. The C1-C3 alcohols are alcohols with 1-3 carbon atoms. The volume ratio of the C1-C3 alcohols to water is 1:0.8~1.

2. The cleaned solid is added to a second cleaning solvent, and under sealed conditions, it is heated and pressurized to 120-200℃ and 0.2-1.5 MPa for dissociation treatment to obtain the precursor; the second cleaning solvent is a mixed solution of a polar solvent and water, wherein the polar solvent is dimethyl sulfoxide or N,N-dimethylformamide, and the volume ratio of the polar solvent to water is 1:0.5~2; The precursor is calcined at 250-450°C in an air or inert atmosphere to obtain the product.

6. The preparation method according to claim 5, characterized in that, The catalytically active components in the anode waste are iridium oxide or iridium-platinum alloy.

7. The preparation method according to claim 5, characterized in that, In ultrasonic cleaning, the solid-liquid ratio is 1:4.5-5.5 (g:mL), the ultrasonic power is 500-2000W, the temperature is 20-60℃, and the cleaning time is 0.5-3 hours.

8. The preparation method according to claim 5, characterized in that, During the dissociation process, the solid-liquid ratio was 1:2.5-3.5, g: mL.

9. The use of the regenerated catalyst according to any one of claims 1 to 4 in the catalytic oxygen evolution reaction.

10. The application as described in claim 9, characterized in that, The catalytic oxygen evolution reaction is used for proton exchange membrane electrolysis.

11. A membrane electrode, characterized in that, Includes the regenerated catalyst as described in any one of claims 1 to 4.

12. A proton exchange membrane electrolyzer, characterized in that, Includes the membrane electrode as described in claim 11.

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