A method for recovering waste platinum-carbon catalyst from fuel cell to prepare platinum-carbon catalyst

Abstract

The present invention provides a method for recovering and preparing a platinum-carbon catalyst from waste platinum-carbon catalysts of fuel cells, and belongs to the technical field of resource recycling and utilization. The present invention performs solid-liquid separation, solid drying and calcination on waste platinum-carbon catalyst slurry of fuel cells, and then performs acid treatment and oxidation treatment on the obtained material, and adjusts the pH value of the obtained oxidation treatment solution to 5-7 and then mixes it with acidic powder for gelation reaction, and obtains platinum complex colloid and rich sulfite solution after solid-liquid separation; the carbon carrier is modified by the rich sulfite solution to obtain a modified carbon carrier, and the platinum complex colloid is mixed with a dispersant to obtain a platinum complex colloid dispersion, and then mixed with the modified carbon carrier and a second oxidizing solution for oxidation and decomposition reaction, and then subjected to reduction treatment to obtain a platinum-carbon catalyst. The method of the present invention can achieve high-selective recovery of Pt in waste platinum-carbon catalysts and prepare green recovered Pt into a highly active platinum-carbon catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of resource recycling and utilization, and in particular to a method for recycling waste platinum-carbon catalysts of fuel cells to prepare platinum-carbon catalysts. Background Art

[0002] In the field of fuel cells, platinum-carbon catalysts are favored for their excellent catalytic performance and wide range of applications. However, this high-efficiency platinum-carbon catalyst gradually loses its activity during use due to various factors such as carbon deposition, sintering, poisoning and wear, and becomes waste. This not only causes a waste of resources, but also increases processing costs. Therefore, it is particularly important to develop an effective method for recycling and reusing waste platinum-carbon catalysts.

[0003] Existing methods for recycling and reusing waste platinum-carbon catalysts mainly focus on physical and chemical methods. Although they can restore the activity of the catalyst to a certain extent, they are often accompanied by environmental pollution problems, making it difficult to achieve green recycling and reuse of waste platinum-carbon catalysts. Summary of the invention

[0004] The purpose of the present invention is to provide a method for recovering waste platinum-carbon catalysts from fuel cells and preparing platinum-carbon catalysts. The method provided by the present invention can achieve green recovery and reuse of waste platinum-carbon catalysts.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for recovering waste platinum-carbon catalyst of a fuel cell and preparing a platinum-carbon catalyst, comprising the following steps:

[0007] The waste platinum-carbon catalyst slurry of the fuel cell is sequentially subjected to solid-liquid separation, solid drying and calcination to obtain a mixture of sponge platinum and platinum oxide;

[0008] The sponge platinum and platinum oxide mixture is mixed with an acidic solution and subjected to acid treatment to obtain an acid-treated solution;

[0009] The acid treatment solution is mixed with a first oxidizing solution to perform oxidation treatment to obtain an oxidation treatment solution;

[0010] The pH value of the oxidation treatment solution is adjusted to 5-7, and then mixed with an acidic powder to perform a colloid reaction, and then solid-liquid separation is performed to obtain a platinum complex colloid and a sulfite-rich solution, respectively; the acidic powder is a hyposulfite and / or a sulfite;

[0011] The carbon carrier is mixed with the sulfite-rich solution, subjected to modification treatment, and then subjected to solid-liquid separation to obtain a modified carbon carrier;

[0012] mixing the platinum complex colloid with a dispersant to obtain a platinum complex colloid dispersion;

[0013] The modified carbon support, the colloidal dispersion containing the platinum complex and the second oxidizing solution are mixed to carry out an oxidative decomposition reaction, and then a reduction treatment is carried out in the presence of a reducing gas, and a platinum-carbon catalyst is obtained through solid-liquid separation.

[0014] Preferably, the calcination temperature is 500-700° C., and the holding time is 1-4 hours.

[0015] Preferably, the acidic solution is hydrochloric acid, and the concentration of the acidic solution is 1-6 mol / L; the mass ratio of the acidic solution to the sponge platinum and platinum oxide mixture is 1-50:1; the temperature of the acid treatment is 60-100°C, and the time is 0.5-3h.

[0016] Preferably, the first oxidizing solution is a hydrogen peroxide solution, and the concentration of the first oxidizing solution is 3~10wt%; the mass ratio of the first oxidizing solution to the sponge platinum and platinum oxide mixture is 1~20:1; the temperature of the oxidation treatment is 60~100°C, and the time is 0.5~3h.

[0017] Preferably, the pH adjuster used to adjust the pH value of the oxidation treatment solution includes one or more of sodium carbonate solution, sodium bicarbonate solution and sodium hydroxide solution; the concentration of the pH adjuster is 0.3~3mol / L.

[0018] Preferably, the mass ratio of the oxidation treatment solution to the acidic powder is 0.5-1.5:1; the temperature of the gelling reaction is 25-50° C., and the time is 0.5-2 h.

[0019] Preferably, the temperature of the modification treatment is 80-100° C. and the time is 1-2 hours.

[0020] Preferably, the dispersant includes hydrochloric acid, sulfuric acid or nitric acid, and the concentration of the dispersant is 0.1-3 mol / L; the mass ratio of the platinum complex colloid to the dispersant is 1:0.5-1.5.

[0021] Preferably, the second oxidizing solution comprises potassium permanganate solution, sodium hypochlorite solution or hydrogen peroxide solution, and the concentration of the second oxidizing solution is 1~2 mol / L; the mass ratio of the modified carbon support, the platinum complex colloidal dispersion and the second oxidizing solution is 1:1~3:1~3; the temperature of the oxidative decomposition reaction is 25~85°C, and the time is 1~3h.

[0022] Preferably, the reducing gas is hydrogen; the temperature of the reduction treatment is 25-85° C., and the time is 1-3 hours.

[0023] Beneficial effects: The present invention sequentially performs solid-liquid separation, solid drying and calcination on waste platinum-carbon catalyst slurry of fuel cells to obtain a mixed material of sponge platinum and platinum oxide; the mixed material of sponge platinum and platinum oxide is mixed with an acidic solution, subjected to acid treatment, and obtained an acid-treated solution; the acid-treated solution is mixed with a first oxidizing solution, subjected to oxidation treatment, and obtained an oxidation-treated solution; the pH value of the oxidation-treated solution is adjusted to 5-7 and then mixed with an acidic powder to perform a gelling reaction, and then subjected to solid-liquid separation to obtain a platinum-containing complex colloid and a sulfite-rich solution, respectively; the acidic powder is hyposulfite and / or sulfite; the carbon carrier is mixed with the sulfite-rich solution, subjected to modification treatment, and then subjected to solid-liquid separation to obtain a modified carbon carrier; the platinum-containing complex colloid is mixed with a dispersant to obtain a platinum-containing complex colloid dispersion; the modified carbon carrier and the platinum-containing complex colloid dispersion are mixed with a second oxidizing solution, subjected to an oxidation decomposition reaction, and then subjected to a reduction treatment in the presence of a reducing gas, and subjected to solid-liquid separation to obtain a platinum-carbon catalyst. The present invention uses waste platinum-carbon catalysts from fuel cells as raw materials to prepare platinum-carbon catalysts, which can achieve the recycling and reuse of waste platinum-carbon catalysts from fuel cells, greatly reducing the production cost of platinum-carbon catalysts; and the method of the present invention fully utilizes the waste liquid generated during the treatment process, i.e., a sulfite-rich solution, to modify the carbon carrier, thereby achieving zero pollution emissions and having better green economy. At the same time, the present invention has a high recovery rate of active metal platinum, and the prepared platinum-carbon catalyst has good catalytic performance, which is comparable to the performance of the platinum-carbon catalyst prepared using commercial chloroplatinic acid.

[0024] Furthermore, the method provided by the present invention has low energy consumption, which is beneficial to further reduce production costs and is convenient for large-scale promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for recovering waste platinum-carbon catalysts for fuel cells and preparing platinum-carbon catalysts according to an embodiment of the present invention;

[0026] Figure 2 TEM comparison diagram of the 60% Pt / C catalyst in Example 3 and the 60% Pt / C catalyst in Comparative Example 1;

[0027] Figure 3 3 is a comparison diagram of polarization curves of the 60% Pt / C catalyst in Example 3 and the 60% Pt / C catalyst in Comparative Example 1;

[0028] Figure 4 This is a comparison chart of the IV curve test results of the 60% Pt / C catalyst in Example 3 and the 60% Pt / C catalyst in Comparative Example 1. DETAILED DESCRIPTION

[0029] The present invention provides a method for recovering waste platinum-carbon catalyst of a fuel cell and preparing a platinum-carbon catalyst, comprising the following steps:

[0030] The waste platinum-carbon catalyst slurry of the fuel cell is sequentially subjected to solid-liquid separation, solid drying and calcination to obtain a mixture of sponge platinum and platinum oxide;

[0031] The sponge platinum and platinum oxide mixture is mixed with an acidic solution and subjected to acid treatment to obtain an acid-treated solution;

[0032] The acid treatment solution is mixed with a first oxidizing solution to perform oxidation treatment to obtain an oxidation treatment solution;

[0033] The pH value of the oxidation treatment solution is adjusted to 5-7, and then mixed with an acidic powder to perform a colloid reaction, and then solid-liquid separation is performed to obtain a platinum complex colloid and a sulfite-rich solution, respectively; the acidic powder is a hyposulfite and / or a sulfite;

[0034] The carbon carrier is mixed with the sulfite-rich solution, subjected to modification treatment, and then subjected to solid-liquid separation to obtain a modified carbon carrier;

[0035] mixing the platinum complex colloid with a dispersant to obtain a platinum complex colloid dispersion;

[0036] The modified carbon support, the colloidal dispersion containing the platinum complex and the second oxidizing solution are mixed to carry out an oxidative decomposition reaction, and then a reduction treatment is carried out in the presence of a reducing gas, and a platinum-carbon catalyst is obtained through solid-liquid separation.

[0037] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art or are prepared by methods well known to those skilled in the art.

[0038] The present invention sequentially performs solid-liquid separation, solid drying and calcination on the waste platinum-carbon catalyst slurry of the fuel cell to obtain a mixture of sponge platinum and platinum oxide. As one embodiment of the present invention, the waste platinum-carbon catalyst in the waste platinum-carbon catalyst slurry of the fuel cell comes from the coating on the surface of the waste fuel cell membrane electrode (the coating is dispersed in an alcohol-containing solution), and the alcohol-containing solution is removed by solid-liquid separation, and the composition of the obtained solid material mainly includes platinum nanoparticles (the mass fraction is generally between 20 and 70%, for example, specifically 20%, 40%, 50% or 60%) and carbon carriers. As one embodiment of the present invention, the solid-liquid separation can be filtration; the temperature of the solid drying can be 75 to 85°C, specifically 80°C, and the time can be 5 to 7h, specifically 6h. As an embodiment of the present invention, the calcination temperature can be 500-700°C, specifically 500°C, 550°C, 600°C, 650°C or 700°C; the holding time can be 1-4h, specifically 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h; the calcination can be carried out in an oxygen-containing atmosphere, and the oxygen-containing atmosphere can be air. In the embodiment of the present invention, the calcination treatment under the above conditions can effectively realize the physical separation of platinum nanoparticles and carbon carriers in waste platinum-carbon catalysts, thereby effectively removing the carbon carriers in waste platinum-carbon catalysts. As an embodiment of the present invention, the content of sponge platinum in the sponge platinum and platinum oxide mixture can be 50-70wt%, further 52.5-67.2wt%; the content of platinum oxide can be 30-50wt%, further 32.7-46.6wt%; the content of carbon <1wt%, further ≤0.9wt%, and further ≤0.1wt%. As an embodiment of the present invention, the calcination may further include sequential crushing and screening, and the particle size of the material after screening may be 200-400 mesh, and further may be 200-300 mesh; in the embodiment of the present invention, the particle size of the sponge platinum and platinum oxide mixture is controlled within the above range, which is beneficial to the full dissolution of the sponge platinum and platinum oxide in the acidic solution.

[0039] After obtaining the sponge platinum and platinum oxide mixed material, the present invention mixes the sponge platinum and platinum oxide mixed material with an acidic solution, performs acid treatment, and obtains an acid-treated solution. As an embodiment of the present invention, the acidic solution can be hydrochloric acid, and the concentration of the acidic solution can be 1-6 mol / L, specifically 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L or 6 mol / L; the mass ratio of the acidic solution to the sponge platinum and platinum oxide mixed material can be 1-50:1, further 5-30:1, further 8-20:1, specifically 8:1, 10:1, 13:1, 15:1, 17:1 or 20:1. As an embodiment of the present invention, the temperature of the acid treatment can be 60-100°C, specifically 60°C, 70°C, 80°C, 90°C or 100°C; the heating rate to the temperature required for the acid treatment can be 5-25°C / min, further 5-10°C / min; the time of the acid treatment can be 0.5-3h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h or 3h; the acid treatment can be carried out under stirring conditions, and the stirring rate can be 20-600rpm, further 400-600rpm. In the acid treatment process of the present invention, the acidic solution can promote the detachment of platinum nanoparticles from the residual carbon carrier to form platinum ions (such as Pt 2+ ) enters the solution, and this process may be accompanied by surface oxidation of the carbon support to form carbon surface oxides, which may further react with the acidic solution to cause corrosion and decomposition of the carbon support. In the embodiment of the present invention, the acid treatment is carried out under the above conditions, and the leaching rate of platinum is 70-80%.

[0040] After obtaining the acid treatment solution, the present invention mixes the acid treatment solution with the first oxidizing solution, performs oxidation treatment, and obtains an oxidized solution. As an embodiment of the present invention, the first oxidizing solution can be a hydrogen peroxide solution, and the concentration of the first oxidizing solution can be 3-10wt%, specifically 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%; the mass ratio of the first oxidizing solution to the sponge platinum and platinum oxide mixture can be 1-20:1, further can be 1-12:1, specifically can be 1:1, 3:1, 5:1, 7:1, 10:1 or 12:1. As an embodiment of the present invention, the temperature of the oxidation treatment can be 60-100°C, specifically 60°C, 70°C, 80°C, 90°C or 100°C; the heating rate to the temperature required for the oxidation treatment can be 5-25°C / min, and further can be 5-10°C / min; the time of the oxidation treatment can be 0.5-3h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h or 3h; the oxidation treatment can be carried out under stirring conditions, and the stirring rate can be 20-600rpm, and further can be 400-600rpm. In the oxidation treatment process of the present invention, in the first oxidizing solution, a strong oxidant (such as hydrogen peroxide) reacts with the residual carbon carrier, oxidizing the carbon carrier into carbon dioxide or other oxygen-containing compounds, thereby destroying the structure of the waste platinum carbon catalyst and further releasing residual platinum nanoparticles. In the embodiment of the present invention, the oxidation treatment is carried out under the above conditions, and the leaching rate of platinum is 95-99%.

[0041] After obtaining the oxidation treatment solution, the present invention adjusts the pH value of the oxidation treatment solution to 5-7 and then mixes it with the acidic powder to perform a gelling reaction, and then separates the solid and liquid to obtain a platinum complex colloid and a sulfite-rich solution. As an embodiment of the present invention, the pH value regulator used to adjust the pH value of the oxidation treatment solution is specifically an alkaline reagent, and the alkaline reagent can include one or more of sodium carbonate solution, sodium bicarbonate solution and sodium hydroxide solution, and can specifically be sodium carbonate solution, sodium bicarbonate solution or sodium hydroxide solution; the concentration of the pH value regulator can be 0.3-3 mol / L, and can further be 0.5-1.5 mol / L. As an embodiment of the present invention, specifically, a pH value regulator is added to the oxidation treatment solution so that the pH value of the obtained system is 5-7, and can specifically be 5, 5.5, 6, 6.5 or 7. In the present invention, the acidic powder is hyposulfite and / or sulfite, and can specifically be hyposulfite or sulfite; the hyposulfite can be sodium hyposulfite, and the sulfite can be sodium sulfite. As an embodiment of the present invention, the mass ratio of the oxidation treatment solution to the acidic powder can be 0.5~1.5:1, specifically 0.5:1, 0.8:1, 1:11.2:1 or 1.5:1; the temperature of the gelling reaction can be 25~50°C, specifically 25°C, 30°C, 35°C, 40°C, 45°C or 50°C; the time can be 0.5~2h, specifically 0.5h, 1h, 1.5h or 2h; the gelling reaction can be carried out under stirring conditions, and the stirring rate can be 20~600rpm, and further can be 400~600rpm. In the gelling reaction process of the present invention, sulfite ions will react with platinum ions to form a precipitated colloid; in the embodiment of the present invention, the gelling reaction is carried out under the above conditions, so that the coordination reaction can be fully carried out, which is conducive to the recovery of platinum ions leached into the solution. As an embodiment of the present invention, the solid-liquid separation may be filtration; the solid-liquid separation may also include solid drying. The present invention has no special limitation on the conditions for the solid drying, and conditions familiar to those skilled in the art may be used.

[0042] After obtaining the sulfite-rich solution, the present invention mixes the carbon carrier with the sulfite-rich solution, performs a modification treatment, and then performs solid-liquid separation to obtain a modified carbon carrier. As an embodiment of the present invention, the carbon carrier may include one or more of ECP600, XC-72 and BP2000, specifically ECP600; the mass ratio of the carbon carrier to the sulfite-rich solution may be 1:20-500, specifically 1:20, 1:50, 1:100, 1:150, 1:200, 1:300, 1:400 or 1:500. As an embodiment of the present invention, the temperature of the modification treatment can be 80-100°C, specifically 80°C, 85°C, 90°C, 95°C or 100°C; the heating rate to the temperature required for the modification treatment can be 5-25°C / min, further 5-10°C / min; the time of the modification treatment can be 1-2h, specifically 1.5-2h; the modification treatment can be carried out under stirring conditions, and the stirring rate can be 20-600rpm, further 400-600rpm. The present invention can increase the oxygen-containing functional groups (such as carbonyl functional groups, phenolic hydroxyl functional groups, carboxyl functional groups, lactone functional groups) on the surface of the carbon carrier by using a sulfite-rich solution to modify the carbon carrier, thereby improving the surface activity of the carbon carrier. As an embodiment of the present invention, the solid-liquid separation can be filtration; the solid-liquid separation can also include solid drying. The present invention does not specifically limit the conditions for the solid drying, and the conditions familiar to those skilled in the art can be used. As an embodiment of the present invention, liquid material is obtained after the solid-liquid separation. The main component of the liquid material is water and does not contain other polluting components, so it can be discharged as waste liquid.

[0043] After obtaining the platinum-containing complex colloid, the present invention mixes the platinum-containing complex colloid with a dispersant to obtain a platinum-containing complex colloid dispersion. As one embodiment of the present invention, the dispersant may include hydrochloric acid, sulfuric acid or nitric acid, and the concentration of the dispersant may be 0.1-3 mol / L, specifically 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L; the mass ratio of the platinum-containing complex colloid to the dispersant may be 1:0.5-1.5, specifically 1:0.5, 1:0.8, 1:1, 1:1.2 or 1:1.5. As one embodiment of the present invention, the mixing temperature may be 15-30°C, further 20-25°C, specifically room temperature; the time may be 5-15 min, specifically 10 min; the mixing may be carried out under stirring conditions, and the stirring rate may be 20-600 rpm, further 400-600 rpm. In the mixing process of the present invention, the platinum complex colloid is dispersed and dissolved in the dispersant and the sulfite ions are removed; in the embodiment of the present invention, mixing is carried out under the above conditions, which can fully disperse and dissolve the platinum complex colloid and effectively remove the sulfite ions, which is beneficial to the extraction of pure platinum element.

[0044] After obtaining the modified carbon support and the colloidal dispersion containing the platinum complex, the present invention mixes the modified carbon support, the colloidal dispersion containing the platinum complex and the second oxidizing solution, performs an oxidative decomposition reaction, and then performs a reduction treatment in the presence of a reducing gas, and obtains a platinum-carbon catalyst through solid-liquid separation. As an embodiment of the present invention, the second oxidizing solution may include a potassium permanganate solution, a sodium hypochlorite solution or a hydrogen peroxide solution, and the concentration of the second oxidizing solution may be 1 to 2 mol / L, specifically 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L or 2 mol / L; the mass ratio of the modified carbon support, the colloidal dispersion containing the platinum complex and the second oxidizing solution may be 1:1 to 3:1 to 3, further may be 1:1.5 to 2.5:1.5 to 2.5, specifically may be 1:2:2. As an embodiment of the present invention, the temperature of the oxidative decomposition reaction can be 25-85°C, specifically 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C or 85°C; the time can be 1-3h, specifically 1h, 1.5h, 2h, 2.5h or 3h; the oxidative decomposition reaction can be carried out under stirring conditions, and the stirring rate can be 20-600rpm, and further can be 400-600rpm. In the oxidative decomposition reaction process of the present invention, platinum ions are oxidized to a higher valence state to obtain platinum oxide loaded on the modified carbon carrier, and the remaining sulfite ions in the system are removed; in the embodiment of the present invention, the oxidative decomposition reaction is carried out under the above conditions, which can fully oxidize the platinum ions to a higher valence state to realize the loading of platinum oxide, which is conducive to obtaining a pure platinum oxide supported catalyst (i.e., modified carbon carrier loaded platinum oxide).

[0045] As an embodiment of the present invention, after the oxidative decomposition reaction is completed, no post-treatment is required, and a reducing gas is directly introduced into the obtained feed liquid for reduction treatment, and then solid-liquid separation is performed to obtain a platinum-carbon catalyst. As an embodiment of the present invention, the reducing gas can be hydrogen, specifically dry hydrogen; the flow rate of the reducing gas can be 100-800mL / min, specifically 100mL / min, 150mL / min, 200mL / min, 250mL / min, 300mL / min, 350mL / min, 400mL / min, 500mL / min, 600mL / min, 700mL / min or 800mL / min. As an embodiment of the present invention, the temperature of the reduction treatment can be 25~85℃, specifically 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃ or 85℃; the time can be 1~3h, specifically 1h, 1.5h, 2h, 2.5h or 3h; the reduction treatment can be carried out under stirring conditions, and the stirring rate can be 20~600rpm, and further can be 400~600rpm. In the reduction treatment process of the present invention, hydrogen reduces platinum oxide to platinum and generates water, and as the reduction treatment proceeds, the generated platinum itself can be used as a catalyst to further accelerate the reduction treatment; in the embodiment of the present invention, the reduction treatment is carried out under the above conditions, which can achieve rapid reduction of platinum oxide under load, which is conducive to obtaining a high-purity platinum-carbon catalyst. As an embodiment of the present invention, the solid-liquid separation may be filtration; after the solid-liquid separation, solid drying may be included, and the solid drying may be vacuum drying. The vacuum drying temperature may be 60°C, and the vacuum drying time is not particularly limited, as long as sufficient drying can be ensured. As an embodiment of the present invention, a liquid material is obtained after the solid-liquid separation. The liquid material mainly contains water and does not contain other pollutants, so it can be discharged as waste liquid.

[0046] The platinum-carbon catalyst prepared by the above method of the present invention includes a carbon carrier and an active metal platinum supported on the carbon carrier. The content of the carbon carrier in the platinum-carbon catalyst can be 40-70wt%, specifically 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt% or 70wt%; the content of active metal platinum can be 30-60wt%, specifically 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt% or 60wt%. The platinum-carbon catalyst prepared by the above method of the present invention can be used in a fuel cell. The present invention does not specifically limit its specific use method, and a method familiar to those skilled in the art can be used; after the platinum-carbon catalyst is used to deactivate, the waste platinum-carbon catalyst can be treated by the above technical solution of the present invention, so as to recover Pt in the waste platinum-carbon catalyst with high selectivity and prepare the green recovered Pt into a highly active platinum-carbon catalyst for use.

[0047] Figure 1 The flowchart of the method for recovering and preparing platinum-carbon catalyst from waste platinum-carbon catalyst of fuel cell in the embodiment of the present invention is shown below. The technical scheme of the present invention will be described clearly and completely in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] The waste platinum-carbon catalyst in the fuel cell waste platinum-carbon catalyst slurry used in the following examples comes from the coating on the surface of the waste fuel cell membrane electrode (the coating is dispersed in an alcohol-containing solution), and the solid material obtained after solid-liquid separation mainly comprises platinum nanoparticles (mass fraction of 60%) and carbon carriers.

[0049] Example 1

[0050] (1) 200 mL of fuel cell waste platinum-carbon catalyst slurry was filtered at room temperature, the filter cake was collected, dried at 80° C. for 6 h, and then placed in a muffle furnace and calcined at 600° C. in an air atmosphere for 1.5 h to obtain a sponge platinum and platinum oxide mixed material, wherein the sponge platinum content was 52.5wt%, the platinum oxide content was 46.6wt%, and the carbon content was ≤0.9wt%. The sponge platinum and platinum oxide mixed material was crushed and sieved to obtain a mixed powder with a particle size of 300 mesh;

[0051] (2) 10 g of the mixed powder was mixed with 100 g of hydrochloric acid having a concentration of 1 mol / L, and the mixture was heated to 70° C. at a heating rate of 10° C. / min under a stirring rate of 400 rpm, and the mixture was treated with acid at a constant temperature for 1 hour to obtain an acid-treated solution (based on the mixed powder, the leaching rate of platinum was 74%);

[0052] (3) adding 100 g of a 3 wt % hydrogen peroxide solution to the acid treatment solution, and performing oxidation treatment at a constant temperature of 70° C. for 1 h with a stirring rate of 400 rpm to obtain an oxidation treatment solution (based on the mixed powder, the total leaching rate of platinum is 97.8%);

[0053] (4) adding the oxidation treatment solution to the reactor, controlling the stirring rate to 400 rpm, adding a sodium carbonate solution with a concentration of 0.5 mol / L to adjust the pH value of the system to 6, then adding sodium bisulfite powder to the reactor (the mass ratio of the sodium bisulfite powder to the oxidation treatment solution is 1:1), controlling the stirring rate to 400 rpm, and conducting a gelling reaction at a constant temperature of 70° C. for 1 hour, then cooling to room temperature, filtering, and obtaining a sulfite-rich solution and a platinum complex-containing colloidal filter cake, respectively, and drying the platinum complex-containing colloidal filter cake for later use;

[0054] (5) The carbon carrier ECP600 and the rich sulfite solution were mixed in a mass ratio of 1:100, the stirring rate was controlled to 400 rpm, the temperature was increased to 90°C at a heating rate of 10°C / min, and the modification treatment was carried out at a constant temperature for 1.5 hours, then the temperature was lowered to room temperature, filtered, and liquid material and solid material were obtained respectively, the liquid material was discharged as waste liquid, and the solid material was dried to obtain a modified carbon carrier;

[0055] (6) mixing the platinum complex colloidal filter cake with 1 mol / L sulfuric acid at a mass ratio of 1:1, controlling the stirring rate to 400 rpm, and stirring at room temperature for 10 min to obtain a platinum complex colloidal dispersion;

[0056] (7) The modified carbon support and the colloidal dispersion containing the platinum complex are added to a reactor, and then a hydrogen peroxide solution with a concentration of 1 mol / L is added to the reactor, wherein the mass ratio of the modified carbon support, the colloidal dispersion containing the platinum complex and the hydrogen peroxide solution is 1:2:2, and the stirring rate is controlled to be 400 rpm. The oxidation decomposition reaction is carried out at 80°C for 2 hours. Thereafter, hydrogen is introduced into the reactor at a flow rate of 200 mL / min, and a reduction treatment is carried out at 80°C for 1 hour (at this time, no precipitation is generated in the system), and the reaction mixture is filtered to obtain a liquid material and a solid material, respectively. The liquid material is discharged as a waste liquid, and the solid material is vacuum dried at 60°C to obtain a platinum-carbon catalyst.

[0057] Example 2

[0058] The method of Example 1 is used for operation, except that the calcination time in this example is 2 hours, as follows:

[0059] (1) 200 mL of fuel cell waste platinum-carbon catalyst slurry was filtered at room temperature, the filter cake was collected, dried at 80° C. for 6 h, and then placed in a muffle furnace and calcined at 600° C. in an air atmosphere for 2 h to obtain a sponge platinum and platinum oxide mixed material, wherein the sponge platinum content was 67.2 wt %, the platinum oxide content was 32.7 wt %, and the carbon content was ≤0.1 wt %. The sponge platinum and platinum oxide mixed material was crushed and sieved to obtain a mixed powder with a particle size of 300 mesh;

[0060] (2) mixing 10 g of the mixed powder with 100 g of 1 mol / L hydrochloric acid, heating the mixture to 70° C. at a heating rate of 10° C. / min under a stirring rate of 400 rpm, and performing acid treatment at a constant temperature for 1 h to obtain an acid-treated solution (based on the mixed powder, the leaching rate of platinum is 77%);

[0061] (3) adding 100 g of a 3 wt % hydrogen peroxide solution to the acid treatment solution, and performing oxidation treatment at a constant temperature of 70° C. for 1 h with a stirring rate of 400 rpm to obtain an oxidation treatment solution (based on the mixed powder, the total leaching rate of platinum is 98.2%);

[0062] (4) adding the oxidation treatment solution to the reactor, controlling the stirring rate to 400 rpm, adding a sodium carbonate solution with a concentration of 0.5 mol / L to adjust the pH value of the system to 6, then adding sodium bisulfite powder to the reactor (the mass ratio of the sodium bisulfite powder to the oxidation treatment solution is 1:1), controlling the stirring rate to 400 rpm, and conducting a gelling reaction at a constant temperature of 70° C. for 1 hour, then cooling to room temperature, filtering, and obtaining a sulfite-rich solution and a platinum complex-containing colloidal filter cake, respectively, and drying the platinum complex-containing colloidal filter cake for later use;

[0063] (5) The carbon carrier ECP600 and the rich sulfite solution were mixed in a mass ratio of 1:100, the stirring rate was controlled to 400 rpm, the temperature was increased to 90°C at a heating rate of 10°C / min, and the modification treatment was carried out at a constant temperature for 1.5 hours, then the temperature was lowered to room temperature, filtered, and liquid material and solid material were obtained respectively, the liquid material was discharged as waste liquid, and the solid material was dried to obtain a modified carbon carrier;

[0064] (6) mixing the platinum complex colloidal filter cake with 1 mol / L sulfuric acid at a mass ratio of 1:1, controlling the stirring rate to 400 rpm, and stirring at room temperature for 10 min to obtain a platinum complex colloidal dispersion;

[0065] (7) The modified carbon support and the colloidal dispersion containing the platinum complex are added to a reactor, and then a hydrogen peroxide solution with a concentration of 1 mol / L is added to the reactor, wherein the mass ratio of the modified carbon support, the colloidal dispersion containing the platinum complex and the hydrogen peroxide solution is 1:2:2, and the stirring rate is controlled to be 400 rpm. The oxidation decomposition reaction is carried out at 80°C for 2 hours. Thereafter, hydrogen is introduced into the reactor at a flow rate of 200 mL / min, and a reduction treatment is carried out at 80°C for 1 hour (at this time, no precipitation is generated in the system), and the reaction mixture is filtered to obtain a liquid material and a solid material, respectively. The liquid material is discharged as a waste liquid, and the solid material is vacuum dried at 60°C to obtain a platinum-carbon catalyst.

[0066] Example 3

[0067] The method of Example 1 is used for operation, except that the calcination time in this example is 2 h and the concentration of hydrochloric acid used for acid treatment is 2 mol / L, as follows:

[0068] (1) 200 mL of fuel cell waste platinum-carbon catalyst slurry was filtered at room temperature, the filter cake was collected, dried at 80° C. for 6 h, and then placed in a muffle furnace and calcined at 600° C. in an air atmosphere for 2 h to obtain a sponge platinum and platinum oxide mixed material, wherein the sponge platinum content was 67.2 wt %, the platinum oxide content was 32.7 wt %, and the carbon content was ≤0.1 wt %. The sponge platinum and platinum oxide mixed material was crushed and sieved to obtain a mixed powder with a particle size of 300 mesh;

[0069] (2) mixing 10 g of the mixed powder with 100 g of 2 mol / L hydrochloric acid, heating the mixture to 70° C. at a heating rate of 10° C. / min under a stirring rate of 400 rpm, and performing acid treatment at a constant temperature for 1 h to obtain an acid-treated solution (based on the mixed powder, the leaching rate of platinum is 86%);

[0070] (3) adding 100 g of a 3 wt % hydrogen peroxide solution to the acid treatment solution, and performing oxidation treatment at a constant temperature of 70° C. for 1 h with a stirring rate of 400 rpm to obtain an oxidation treatment solution (based on the mixed powder, the total leaching rate of platinum is 99.1%);

[0071] (4) adding the oxidation treatment solution to the reactor, controlling the stirring rate to 400 rpm, adding a sodium carbonate solution with a concentration of 0.5 mol / L to adjust the pH value of the system to 6, then adding sodium bisulfite powder to the reactor (the mass ratio of the sodium bisulfite powder to the oxidation treatment solution is 1:1), controlling the stirring rate to 400 rpm, and conducting a gelling reaction at a constant temperature of 70° C. for 1 hour, then cooling to room temperature, filtering, and obtaining a sulfite-rich solution and a platinum complex-containing colloidal filter cake, respectively, and drying the platinum complex-containing colloidal filter cake for later use;

[0072] (5) The carbon carrier ECP600 and the rich sulfite solution were mixed in a mass ratio of 1:100, the stirring rate was controlled to 400 rpm, the temperature was increased to 90°C at a heating rate of 10°C / min, and the modification treatment was carried out at a constant temperature for 1.5 hours, then the temperature was lowered to room temperature, filtered, and liquid material and solid material were obtained respectively, the liquid material was discharged as waste liquid, and the solid material was dried to obtain a modified carbon carrier;

[0073] (6) mixing the platinum complex colloidal filter cake with 1 mol / L sulfuric acid at a mass ratio of 1:1, controlling the stirring rate to 400 rpm, and stirring at room temperature for 10 min to obtain a platinum complex colloidal dispersion;

[0074] (7) The modified carbon support and the colloidal dispersion containing the platinum complex are added to a reactor, and then a hydrogen peroxide solution with a concentration of 1 mol / L is added to the reactor, wherein the mass ratio of the modified carbon support, the colloidal dispersion containing the platinum complex and the hydrogen peroxide solution is 1:2:2, and the stirring rate is controlled to be 400 rpm. The oxidation decomposition reaction is carried out at 80°C for 2 hours. Thereafter, hydrogen is introduced into the reactor at a flow rate of 200 mL / min, and a reduction treatment is carried out at 80°C for 1 hour (at this time, no precipitation is generated in the system), and the reaction mixture is filtered to obtain a liquid material and a solid material, respectively. The liquid material is discharged as a waste liquid, and the solid material is vacuum dried at 60°C to obtain a platinum-carbon catalyst.

[0075] The platinum-carbon catalyst prepared in this example is recorded as a 60% Pt / C catalyst, that is, the content of Pt in the platinum-carbon catalyst is 60 wt %.

[0076] Comparative Example 1

[0077] Commercial chloroplatinic acid was used as a precursor to prepare a 60% Pt / C catalyst using a polyol synthesis method. Specifically, ECP600 was used as a carbon carrier, ECP600, chloroplatinic acid and ethylene glycol were mixed, and a reduction reaction was carried out at 180°C for 4 hours to obtain a 60% Pt / C catalyst.

[0078] Test Example 1

[0079] Figure 2 TEM comparison diagram of the 60% Pt / C catalyst in Example 3 and the 60% Pt / C catalyst in Comparative Example 1, wherein (a) is the 60% Pt / C catalyst in Example 3, and (b) is the 60% Pt / C catalyst in Comparative Example 1; the results show that the sizes of the 60% Pt / C catalyst in Example 3 and the 60% Pt / C catalyst in Comparative Example 1 are relatively uniform.

[0080] Figure 3 It is a comparison diagram of polarization curves of the 60% Pt / C catalyst in Example 3 and the 60% Pt / C catalyst in Comparative Example 1, wherein the test conditions include: using an acidic electrolyte, the experimental temperature is room temperature, and the scanning rate is 5 mV / s; the results show that the polarization discharge performance of the 60% Pt / C catalyst in Example 3 can reach the level of the 60% Pt / C catalyst in Comparative Example 1.

[0081] Figure 4 This is a comparison chart of IV curve test results of the 60% Pt / C catalyst in Example 3 and the 60% Pt / C catalyst in Comparative Example 1, wherein the test conditions include: performing cyclic voltammetry tests in a 0.1 mol / L HClO4 solution in a nitrogen-saturated environment with a scan rate of 20 mV / s; the results show that the electrochemically active area of ​​the 60% Pt / C catalyst in Example 3 is equivalent to that of Comparative Example 1, indicating that the catalytic activity and electrochemical stability of the two are equivalent.

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recovering waste platinum-carbon catalysts from fuel cells to prepare platinum-carbon catalysts, characterized in that: The following steps are involved: The waste platinum-carbon catalyst slurry of the fuel cell is sequentially subjected to solid-liquid separation, solid drying and calcination to obtain a mixture of sponge platinum and platinum oxide; the calcination temperature is 500-700° C., and the insulation time is 1-4 hours; The sponge platinum and platinum oxide mixture is mixed with an acidic solution and subjected to acid treatment to obtain an acid-treated solution; The acidic solution is hydrochloric acid, and the concentration of the acidic solution is 1-2 mol / L; the mass ratio of the acidic solution to the mixed material of sponge platinum and platinum oxide is 1-10:1; the temperature of the acid treatment is 60-100° C., and the time is 0.5-3 h; The acid treatment solution is mixed with a first oxidizing solution to perform oxidation treatment to obtain an oxidized solution; the first oxidizing solution is a hydrogen peroxide solution; The pH value of the oxidation treatment solution is adjusted to 5-7, and then mixed with an acidic powder to perform a colloid reaction, and then solid-liquid separation is performed to obtain a platinum complex colloid and a sulfite-rich solution, respectively; the acidic powder is a hyposulfite and / or a sulfite; The carbon carrier is mixed with the sulfite-rich solution, subjected to modification treatment, and then subjected to solid-liquid separation to obtain a modified carbon carrier; The platinum complex colloid is mixed with a dispersant to obtain a platinum complex colloid dispersion; the dispersant is hydrochloric acid, sulfuric acid or nitric acid; The modified carbon support, the colloidal dispersion containing the platinum complex and the second oxidizing solution are mixed to carry out an oxidative decomposition reaction, and then a reduction treatment is carried out in the presence of a reducing gas, and a platinum-carbon catalyst is obtained through solid-liquid separation; the second oxidizing solution is a potassium permanganate solution, a sodium hypochlorite solution or a hydrogen peroxide solution, and the concentration of the second oxidizing solution is 1-2 mol / L; the temperature of the oxidative decomposition reaction is 25-85°C, and the time is 1-3h.

2. The method according to claim 1, characterized in that The concentration of the first oxidizing solution is 3-10wt%; the mass ratio of the first oxidizing solution to the sponge platinum and platinum oxide mixture is 1-20:1; the temperature of the oxidation treatment is 60-100°C, and the time is 0.5-3h.

3. The method according to claim 1, characterized in that The pH regulator used to adjust the pH value of the oxidation treatment solution includes one or more of sodium carbonate solution, sodium bicarbonate solution and sodium hydroxide solution; the concentration of the pH regulator is 0.3-3 mol / L.

4. The method according to claim 1 or 3, characterized in that: The mass ratio of the oxidation treatment solution to the acidic powder is 0.5-1.5:1; the temperature of the gelling reaction is 25-50° C., and the time is 0.5-2 hours.

5. The method according to claim 1, characterized in that The temperature of the modification treatment is 80-100° C. and the time is 1-2 hours.

6. The method according to claim 1, characterized in that The concentration of the dispersant is 0.1-3 mol / L; the mass ratio of the platinum complex colloid to the dispersant is 1:0.5-1.

5.

7. The method according to claim 1 or 6, characterized in that: The mass ratio of the modified carbon support, the platinum complex-containing colloidal dispersion and the second oxidizing solution is 1:1-3:1-3.

8. The method according to claim 1, characterized in that The reducing gas is hydrogen; the temperature of the reduction treatment is 25-85° C., and the time is 1-3 hours.

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