A platinum-based bimetallic catalyst, its preparation method and use

Abstract

This invention relates to a platinum-based bimetallic catalyst, its preparation method, and its uses. The platinum-based bimetallic catalyst comprises a support and active metal particles supported on the support. The active metal particles comprise a core containing a first metal element and a shell containing a second metal element surrounding the core. The first metal element comprises any one or a combination of at least two of Pd, Rh, Cr, or Ir. The second metal element comprises Pt. This invention also provides a method for preparing the platinum-based bimetallic catalyst, which is obtained through steps such as mixing, sonication, solid-liquid separation, washing, and drying. The platinum-based bimetallic catalyst provided by this invention is used in the SO2 depolarization electrolysis reaction, exhibiting high catalytic activity and stability, and reducing the amount of Pt required. The preparation method provided by this invention is simple to operate, low in cost, and can be widely adopted.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to a platinum-based bimetallic catalyst, its preparation method, and its uses. Background Technology

[0002] Traditional fossil fuels have limited reserves and are non-renewable. Their combustion causes environmental pollution and contributes to the greenhouse effect. Therefore, the development of clean, low-carbon energy sources has received widespread attention from researchers. Hydrogen, as a clean secondary energy source, has advantages such as being renewable, pollution-free, and having a high calorific value. Large-scale utilization of hydrogen energy can reduce the demand for fossil fuels and decrease greenhouse gas emissions. The Hybrid Sulfur Cycle (HyS) is one of the most promising technologies for large-scale hydrogen production. Compared to traditional water electrolysis, the electrochemical step of the Hybrid Sulfur Cycle—the SO2 depolarization electrolysis reaction—requires only one-third of the electrical energy input of traditional water electrolysis, resulting in lower energy consumption. Therefore, the efficiency of hydrogen production using the Hybrid Sulfur Cycle is at least 15% higher than that of conventional water electrolysis. Thus, the development prospects for hydrogen production using the Hybrid Sulfur Cycle are very promising.

[0003] Currently, platinum-carbon catalysts are the main catalysts for SO2 depolarization electrolysis reactions and exhibit excellent performance. However, their high cost and limited heavy metal reserves restrict their large-scale application. In recent years, although promising non-precious metal catalysts have been prepared in existing research, their catalytic performance still lags behind that of platinum-based catalysts.

[0004] CN113403629A discloses a catalyst for a water electrolysis hydrogen production system and its preparation method. The method uses transition metal oxides to reduce the amount of noble metals used, but the preparation method is complex and the electrochemical catalytic effect is relatively poor.

[0005] CN111841600A discloses a platinum-based catalyst, its preparation method, and its application. The catalyst includes a nitrogen-containing carbon support and platinum atoms supported on the nitrogen-containing carbon support. It is a supported catalyst. Although it has a high electrocatalytic effect, it is expensive and not conducive to large-scale promotion.

[0006] Therefore, it is of great significance to develop a catalyst that uses a small amount of precious metal, is inexpensive, and has high catalytic activity for SO2 depolarization electrolysis. Summary of the Invention

[0007] To address the above problems, the present invention aims to provide a platinum-based bimetallic catalyst, its preparation method, and its applications. Compared with the prior art, the platinum-based bimetallic catalyst provided by the present invention has a core-shell structure, which can reduce the amount of heavy metals used, lower costs, and exhibit excellent catalytic performance. The preparation method of the platinum-based bimetallic catalyst provided by the present invention is simple and inexpensive. The platinum-based bimetallic catalyst is used in SO2 depolarization electrolysis reaction and has broad application prospects.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a platinum-based bimetallic catalyst, the platinum-based bimetallic catalyst comprising a support and active metal particles supported on the support; the active metal particles comprising a core containing a first metal element and a spherical shell containing a second metal element surrounding the core; the first metal element comprising any one or a combination of at least two of Pd, Rh, Cr or Ir; the second metal element comprising Pt.

[0010] In this invention, by loading a first metal and Pt, the amount of Pt added in traditional Pt-based catalysts can be reduced, thus lowering production costs. Furthermore, the platinum-based bimetallic catalyst provided by this invention comprises active metal particles with a core-shell structure. These active metal particles include a core containing a first metal and a Pt-containing spherical shell enclosing the core. In this invention, the active metal particles are the main active component of the catalyst. This active component, on the one hand, exhibits electronic and bifunctional effects through the electronic interaction and Pt interaction, significantly enhancing the activity of Pt. On the other hand, the active particles, with their Pt-containing spherical shells enclosing the core, significantly increase the Pt concentration on the particle surface, providing more active sites and further improving catalytic activity. The catalyst of this invention, by loading the active particles onto a support, allows the support to hold more active metal ions. Therefore, the catalyst provided by this invention exhibits excellent catalytic activity and stability, and the amount of noble metal Pt added is significantly reduced.

[0011] The present invention controls the first metal element to include any one or at least two of Pd, Rh, Cr or Ir, wherein typical but non-limiting combinations include the combination of Pd and Rh, the combination of Rh and Cr or the combination of Cr and Ir. The first metal element can generate electronic effects with Pt, which has a certain enhancing effect on SO2 electro-oxidation and makes the catalyst more effective.

[0012] Preferably, the molar ratio of the first metal element to the second metal element is (1-2.5):1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1 or 2.5:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] The present invention preferably controls the molar ratio of the first metal element to the second metal element within a specific range, which can reduce the amount of precious metal Pt and improve the catalytic activity of the catalyst in the SO2 depolarization reaction.

[0014] Preferably, in the platinum-based bimetallic catalyst, the sum of the mass percentages of the first metal element and the second metal element is 20-40%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] The present invention preferably controls the sum of the mass percentages of the first metal element and the second metal element in the platinum-based bimetallic catalyst within a specific range, which can reduce the amount of metal used, thereby saving costs and ensuring high catalytic activity.

[0016] Preferably, the average particle size of the platinum-based bimetallic catalyst is 2.5-3.5 nm, for example, it can be 2.5 nm, 2.6 nm, 2.7 nm, 2.8 nm, 2.9 nm, 3 nm, 3.1 nm, 3.2 nm, 3.3 nm, 3.4 nm or 3.5 nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the carrier comprises carbon black.

[0018] In a second aspect, the present invention provides a method for preparing a platinum-based bimetallic catalyst as described in the first aspect of the present invention, the preparation method comprising the following steps:

[0019] (1) The precursor solution containing the first metal element and the reducing agent are mixed to obtain the first solution;

[0020] (2) The first solution obtained in step (1), the precursor solution containing the second metal element, and the reducing agent are mixed for the second time to obtain the second solution;

[0021] (3) The second solution and the carrier dispersion obtained in step (2) are mixed for the third time, and then subjected to ultrasonication, solid-liquid separation, washing and drying in sequence to obtain the platinum-based bimetallic catalyst.

[0022] In this invention, a reduction reaction first occurs through a first mixing process to generate a core containing a first metal element. Then, a second reduction reaction occurs through a second mixing process to generate a Pt-containing shell. This shell coats the outside of the core, resulting in active metal particles with a core-shell structure. A third mixing process further loads the active metal ions onto a support, yielding the platinum-based bimetallic catalyst of this invention. The platinum-based bimetallic catalyst provided by this invention exhibits excellent catalytic activity and stability, and has a low noble metal content. The preparation method provided by this invention is simple, low-cost, and can be widely applied.

[0023] The present invention does not specifically limit the solid-liquid separation method, and it can be any method known to those skilled in the art that can be used for solid-liquid separation, such as filtration or centrifugation.

[0024] Preferably, in step (1), the molar ratio of the first metal element to the reducing agent in the first solution is 1:(20-30), for example, it can be 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29 or 1:30, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] The present invention preferably controls the molar ratio of the first metal element to the reducing agent in the first solution within a specific range, which can save the amount of reducing agent while ensuring that the first metal element is completely reduced.

[0026] Preferably, the precursor solution containing the first metal element includes any one or a combination of at least two of PdCl2 solution, RhCl3 solution, CrN3O9 solution or H2IrCl6 solution, wherein typical but non-limiting combinations include combinations of PdCl2 solution and RhCl3 solution, combinations of RhCl3 solution and CrN3O9 solution, or combinations of CrN3O9 solution and H2IrCl6 solution, etc.

[0027] In this invention, the precursor solution containing the first metal element is obtained by adding the precursor containing the first element to ethylene glycol and stirring for 1-2 hours.

[0028] Preferably, the reducing agent in step (1) includes a NaBH4 solution.

[0029] In this invention, the NaBH4 solution is prepared by adding NaBH4 to ice water.

[0030] Preferably, the temperature of the first mixture is -5 to 5°C, for example, it can be -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, 1°C, 2°C, 3°C, 4°C or 5°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the first mixing includes stirring.

[0032] Preferably, the first mixing time is 60-120 min, for example, it can be 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min or 120 min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0033] Preferably, in step (2), the molar ratio of the second metal element to the reducing agent in the second solution is 1:(20-30), for example, it can be 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29 or 1:30, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] The present invention preferably controls the molar ratio of the second metal element to the reducing agent in the second solution within a specific range, which can save the amount of reducing agent while ensuring that the second metal element is completely reduced.

[0035] Preferably, the precursor solution containing the second metal element includes an H2PtCl6 solution.

[0036] In this invention, the solvent of the precursor solution containing the second metal element is ethylene glycol.

[0037] Preferably, the reducing agent in step (2) includes a NaBH4 solution.

[0038] Preferably, in the second solution, the molar ratio of the first metal element and the second metal element is (1-2):1, for example, it can be 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the temperature of the second mixture is -5 to 5°C, for example, it can be -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, 1°C, 2°C, 3°C, 4°C or 5°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the second mixing includes stirring.

[0041] Preferably, the second mixing time is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, in step (2), the first solution is first mixed with a precursor solution containing a second metal element, and then mixed with a reducing agent for the second time.

[0043] Preferably, in step (3), the metal element in the second solution accounts for 25-67% of the mass of the carrier in the carrier dispersion. For example, it can be 25%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, or 67%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, the carrier in the carrier dispersion comprises carbon black.

[0045] In this invention, the solvent of the carrier dispersion is ethylene glycol.

[0046] Preferably, the third mixing includes stirring.

[0047] Preferably, the third mixing time is 12-15 hours, for example, it can be 12 hours, 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours or 15 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] Preferably, the ultrasound duration is 30-90 minutes, for example, it can be 30 minutes, 32 minutes, 35 minutes, 38 minutes, 40 minutes, 42 minutes, 45 minutes, 48 ​​minutes, 50 minutes, 52 minutes, 55 minutes, 58 minutes, 60 minutes, 62 minutes, 65 minutes, 68 minutes, 70 minutes, 72 minutes, 75 minutes, 78 minutes, 80 minutes, 82 minutes, 85 minutes, 88 minutes or 90 minutes, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0049] Preferably, acid is added after ultrasound to adjust the pH value.

[0050] Preferably, the acid solution includes a nitric acid solution.

[0051] Preferably, the concentration of the acid solution is 0.4-0.6 mol / L, for example, it can be 0.4 mol / L, 0.42 mol / L, 0.44 mol / L, 0.46 mol / L, 0.48 mol / L, 0.5 mol / L, 0.52 mol / L, 0.54 mol / L, 0.56 mol / L, 0.58 mol / L or 0.6 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] Preferably, the pH value is adjusted to <3 after the acid is added. For example, it can be 3, 2.8, 2.6, 2.4, 2.2 or 2, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0053] In this invention, the purpose of adding acid is to make the catalyst surface acidic, which is beneficial for its application in SO2 depolarization electrolysis reaction.

[0054] As a preferred embodiment of the second aspect of the present invention, the preparation method includes the following steps:

[0055] (1) Stir the precursor solution containing the first metal element and the NaBH4 solution at -5-5℃ for 60-120 min to obtain the first solution; the molar ratio of the first metal element to the NaBH4 solution in the first solution is 1:(20-30); the precursor solution containing the first metal element includes any one or a combination of at least two of PdCl2 solution, RhCl3 solution, CrN3O9 solution or H2IrCl6 solution;

[0056] (2) Mix the first solution obtained in step (1) with the precursor solution containing the second metal element, and then add NaBH4 solution. Stir at -5-5℃ for 1-3 hours to obtain the second solution. The molar ratio of the second metal element to the NaBH4 solution in the second solution is 1:(20-30). The precursor solution containing the second metal element includes H2PtCl6 solution. The molar ratio of the first metal element to the second metal element in the second solution is (1-2):1.

[0057] (3) Stir the second solution obtained in step (2) with the carbon black dispersion for 12-15 h. The metal element in the second solution accounts for 25-67% of the mass of carbon black in the carbon black dispersion. Then sonicate for 30-90 min. Then add 0.4-0.6 mol / L nitric acid solution to adjust the pH value to <3. Then perform solid-liquid separation, washing and drying in sequence to obtain the platinum-based bimetallic catalyst.

[0058] Thirdly, the present invention provides a use of the platinum-based bimetallic catalyst as described in the first aspect of the present invention, characterized in that the platinum-based bimetallic catalyst is used in the SO2 depolarization electrolysis reaction.

[0059] The platinum-based bimetallic catalyst provided by this invention has active metal particles with a core-shell structure, exhibiting excellent catalytic activity and stability for SO2 depolarization electrolysis. Pt is concentrated on the surface of the spherical shell, and Pt has a high utilization rate. The platinum-based bimetallic catalyst of this invention can effectively improve electrolysis efficiency and has great development prospects in SO2 oxidation reaction.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) The platinum-based bimetallic catalyst provided by this invention has a core-shell structure, which reduces the amount of Pt used, improves the utilization rate of Pt, and has good stability. When performing electrochemical tests on SO2 depolarization reactions, the maximum current density can reach 200 mA / cm² under a voltage not exceeding 1.2 V. 2 Under optimal conditions, the above can reach 350 mA / cm. 2 The above exhibits high catalytic activity.

[0062] (2) The preparation method of the platinum-based bimetallic catalyst provided by the present invention is simple, requires less precious metal, has low production cost, and can be promoted on a large scale.

[0063] (3) The platinum-based bimetallic catalyst provided by the present invention has high catalytic activity and stability for SO2 depolarization electrolysis reaction, which can effectively improve electrolysis efficiency and has broad development prospects. Attached Figure Description

[0064] Figure 1 This is a TEM image of the platinum-based bimetallic catalyst described in Example 1 of this invention.

[0065] Figure 2 This is a TEM image of the platinum-based bimetallic catalyst described in Example 4 of this invention.

[0066] Figure 3 This is an XPS image of the Cr element in the platinum-based bimetallic catalyst described in Example 1 of this invention.

[0067] Figure 4 This is the XPS image of the Pt element in the platinum-based bimetallic catalyst described in Example 1 of this invention.

[0068] Figure 5 This is the XPS image of the Cr element in the platinum-based bimetallic catalyst described in Example 2 of this invention.

[0069] Figure 6This is the XPS image of the Pt element in the platinum-based bimetallic catalyst described in Example 2 of this invention.

[0070] Figure 7 These are polarization curves of the platinum-based bimetallic catalysts described in Examples 1 and 2 of this invention.

[0071] Figure 8 These are polarization curves of the platinum-based bimetallic catalysts described in Examples 3 and 4 of this invention.

[0072] Figure 9 These are polarization curves of the platinum-based bimetallic catalysts described in Examples 5 and 6 of this invention.

[0073] Figure 10 These are polarization curves of the platinum-based bimetallic catalysts described in Comparative Examples 1 and 2 of this invention. Detailed Implementation

[0074] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0075] Example 1

[0076] This embodiment provides a method for preparing a platinum-based bimetallic catalyst, the method comprising the following steps:

[0077] (1) Dissolve 1.296g CrN3O9·9H2O in 30mL ethylene glycol to obtain a CrN3O9 solution; dissolve 3.0740g NaBH4 in 39mL ice water to obtain a NaBH4 solution; stir the CrN3O9 solution and the NaBH4 solution at 0℃ for 90min to obtain the first solution; the molar ratio of Cr to NaBH4 solution in the first solution is 1:25;

[0078] (2) Dissolve 1.678g H2PtCl6·6H2O in 30mL ethylene glycol to obtain H2PtCl6 solution; dissolve 3.0740g NaBH4 in 39mL ice water to obtain NaBH4 solution; mix the first solution obtained in step (1) with the H2PtCl6 solution, and then add the NaBH4 solution from step (2), and stir at 0℃ for 2h to obtain the second solution; the molar ratio of Pt to NaBH4 solution in the second solution is 1:25; the molar ratio of Cr to Pt in the second solution is 1:1;

[0079] (3) Dissolve 1.2g of carbon black in 80mL of ethylene glycol to obtain a carbon black dispersion; stir the second solution obtained in step (2) with the carbon black dispersion for 12h. The metal element in the second solution accounts for 67% of the mass of carbon black in the carbon black dispersion. Then sonicate for 60min, and then add 0.5mol / L nitric acid solution to adjust the pH value to 2.8. Then filter, wash and dry in sequence to obtain the platinum-based bimetallic catalyst.

[0080] This embodiment also provides a platinum-based bimetallic catalyst obtained by the above preparation method. The platinum-based bimetallic catalyst includes a carbon black support and active metal particles supported on the support. The active metal particles include a core containing Cr and a shell containing Pt. The molar ratio of Cr to Pt is 1:1. In the platinum-based bimetallic catalyst, the sum of the mass percentages of Cr and Pt is 40%, and the average particle size is 3.05 nm.

[0081] TEM analysis of the platinum-based bimetallic catalyst yielded the following results: Figure 1 As shown, the active metal particles are spherical and uniformly distributed on the carbon black support. They have a large specific surface area and more exposed active sites, which is beneficial to improving catalytic activity.

[0082] XPS analysis of the platinum-based bimetallic catalyst yielded the following results: Figure 3 and Figure 4 As shown, XPS mainly tests the surface, indicating that Pt elements are more present in the surface layer, suggesting that the catalyst surface has more active sites, which is beneficial to improving its catalytic activity in the electrolysis reaction.

[0083] The platinum-based bimetallic catalyst was ground and then sprayed onto a Nafion 117 film, with a metal loading of 0.5 mg / cm² on both sides. 2 The sample was assembled into an SO2 depolarization electrolytic cell, and electrochemical tests were conducted under the conditions of a sulfuric acid mass concentration of 30%, an anolyte circulation rate of 240 mL / min, and a temperature of 80 °C. The obtained polarization curves are shown below. Figure 7 As shown, the results indicate that the current density can reach up to 350 mA / cm² when the potential voltage does not exceed 1.2 V. 2 .

[0084] Example 2

[0085] This embodiment provides a method for preparing a platinum-based bimetallic catalyst, the method comprising the following steps:

[0086] (1) Dissolve 2.1405g of CrN3O9·9H2O in 50mL of ethylene glycol to obtain a CrN3O9 solution; dissolve 6.0910g of NaBH4 in 77mL of ice water to obtain a NaBH4 solution; stir the CrN3O9 solution and the NaBH4 solution at 0℃ for 90min to obtain the first solution; the molar ratio of Cr to NaBH4 solution in the first solution is 1:30;

[0087] (2) Dissolve 1.3854g of H2PtCl6·6H2O in 30mL of ethylene glycol to obtain an H2PtCl6 solution; dissolve 2.4967g of NaBH4 in 30mL of ice water to obtain a NaBH4 solution; mix the first solution obtained in step (1) with the H2PtCl6 solution, and then add the NaBH4 solution from step (2), and stir at 0℃ for 2h to obtain a second solution; the molar ratio of Pt to NaBH4 solution in the second solution is 1:25; the molar ratio of Cr to Pt in the second solution is 2:1;

[0088] (3) Dissolve 1.2g of carbon black in 60mL of ethylene glycol to obtain a carbon black dispersion; stir the second solution obtained in step (2) with the carbon black dispersion for 12h. The metal element in the second solution accounts for 67% of the mass of carbon black in the carbon black dispersion. Then sonicate for 60min, and then add 0.5mol / L nitric acid solution to adjust the pH value to 2.8. Then filter, wash and dry in sequence to obtain the platinum-based bimetallic catalyst.

[0089] This embodiment also provides a platinum-based bimetallic catalyst obtained by the above preparation method. The platinum-based bimetallic catalyst includes a carbon black support and active metal particles supported on the support. The active metal particles include a core containing Cr and a shell containing Pt. The molar ratio of Cr to Pt is 2:1. The total mass percentage of Cr and Pt in the platinum-based bimetallic catalyst is 40%, and the average particle size is 2.79 nm.

[0090] XPS analysis of the platinum-based bimetallic catalyst yielded the following results: Figure 5 and Figure 6 As shown, XPS mainly tests the surface, indicating that Pt elements are more present in the surface layer, suggesting that the catalyst surface has more active sites, which is beneficial to improving its catalytic activity in the electrolysis reaction.

[0091] The platinum-based bimetallic catalyst described in this embodiment was subjected to electrochemical testing under the same conditions as in Example 1. The obtained polarization curves are shown below. Figure 7 As shown, the results indicate that the current density can reach up to 350 mA / cm² when the potential voltage does not exceed 1.2 V. 2 .

[0092] Example 3

[0093] This embodiment provides a method for preparing a platinum-based bimetallic catalyst, the method comprising the following steps:

[0094] (1) Dissolve 0.5320g H2IrCl6·6H2O in 30mL of ethylene glycol to obtain H2IrCl6 solution; dissolve 0.9801g NaBH4 in 13mL of ice water to obtain NaBH4 solution; stir the H2IrCl6 solution and NaBH4 solution at 0℃ for 90min to obtain the first solution; the molar ratio of Ir to NaBH4 solution in the first solution is 1:25;

[0095] (2) Dissolve 0.5349g H2PtCl6·6H2O in 30mL ethylene glycol to obtain H2PtCl6 solution; dissolve 0.9801g NaBH4 in 30mL ice water to obtain NaBH4 solution; mix the first solution obtained in step (1) with the H2PtCl6 solution, and then add the NaBH4 solution from step (2), stir at 0℃ for 2h to obtain the second solution; the molar ratio of Pt to NaBH4 solution in the second solution is 1:25; the molar ratio of Ir to Pt in the second solution is 1:1;

[0096] (3) Dissolve 1.6g of carbon black in 80mL of ethylene glycol to obtain a carbon black dispersion; stir the second solution obtained in step (2) with the carbon black dispersion for 12h, the metal element in the second solution accounts for 25% of the mass of carbon black in the carbon black dispersion, then sonicate for 60min, then add 0.5mol / L nitric acid solution to adjust the pH value to 2.8, and then filter, wash and dry in sequence to obtain the platinum-based bimetallic catalyst.

[0097] This embodiment also provides a platinum-based bimetallic catalyst obtained by the above preparation method. The platinum-based bimetallic catalyst includes a carbon black support and active metal particles supported on the support. The active metal particles include a core containing Ir and a shell containing Pt. The molar ratio of Ir to Pt is 1:1. In the platinum-based bimetallic catalyst, the sum of the mass percentages of Ir and Pt is 20%, and the average particle size is 2.68 nm.

[0098] The platinum-based bimetallic catalyst described in this embodiment was subjected to electrochemical testing under the same conditions as in Example 1. The obtained polarization curves are shown below. Figure 8 As shown, the results indicate that the current density can reach up to 210 mA / cm² when the potential voltage does not exceed 1.2 V. 2 .

[0099] Example 4

[0100] This embodiment provides a method for preparing a platinum-based bimetallic catalyst, the method comprising the following steps:

[0101] (1) Dissolve 1.0640g H2IrCl6·6H2O in 30mL of ethylene glycol to obtain H2IrCl6 solution; dissolve 1.9601g NaBH4 in 25mL of ice water to obtain NaBH4 solution; stir the H2IrCl6 solution and NaBH4 solution at 0℃ for 90min to obtain the first solution; the molar ratio of Ir to NaBH4 solution in the first solution is 1:25;

[0102] (2) Dissolve 1.0698g H2PtCl6·6H2O in 30mL ethylene glycol to obtain H2PtCl6 solution; dissolve 1.9601g NaBH4 in 30mL ice water to obtain NaBH4 solution; mix the first solution obtained in step (1) with the H2PtCl6 solution, and then add the NaBH4 solution from step (2), and stir at 0℃ for 2h to obtain the second solution; the molar ratio of Pt to NaBH4 solution in the second solution is 1:25; the molar ratio of Ir to Pt in the second solution is 1:1;

[0103] (3) Dissolve 1.2g of carbon black in 80mL of ethylene glycol to obtain a carbon black dispersion; stir the second solution obtained in step (2) with the carbon black dispersion for 12h. The metal element in the second solution accounts for 67% of the mass of carbon black in the carbon black dispersion. Then sonicate for 60min, and then add 0.5mol / L nitric acid solution to adjust the pH value to 2.8. Then filter, wash and dry in sequence to obtain the platinum-based bimetallic catalyst.

[0104] This embodiment also provides a platinum-based bimetallic catalyst obtained by the above preparation method. The platinum-based bimetallic catalyst includes a carbon black support and active metal particles supported on the support. The active metal particles include a core containing Ir and a shell containing Pt. The molar ratio of Ir to Pt is 1:1. In the platinum-based bimetallic catalyst, the sum of the mass percentages of Ir and Pt is 40%, and the average particle size is 2.91 nm.

[0105] TEM analysis of the platinum-based bimetallic catalyst yielded the following results: Figure 2 As shown, the active metal particles are spherical and uniformly distributed on the carbon black support. They have a large specific surface area and more exposed active sites, which is beneficial to improving catalytic activity.

[0106] The platinum-based bimetallic catalyst described in this embodiment was subjected to electrochemical testing under the same conditions as in Example 1. The obtained polarization curves are shown below. Figure 8As shown, the results indicate that the current density can reach up to 300 mA / cm² when the potential voltage does not exceed 1.2 V. 2 .

[0107] Example 5

[0108] This embodiment provides a method for preparing a platinum-based bimetallic catalyst, the method comprising the following steps:

[0109] (1) Dissolve 1.296g CrN3O9·9H2O in 30mL ethylene glycol to obtain a CrN3O9 solution; dissolve 3.0740g NaBH4 in 39mL ice water to obtain a NaBH4 solution; stir the CrN3O9 solution and the NaBH4 solution at -5℃ for 120min to obtain the first solution; the molar ratio of Cr to NaBH4 solution in the first solution is 1:25;

[0110] (2) Dissolve 1.678g H2PtCl6·6H2O in 30mL ethylene glycol to obtain H2PtCl6 solution; dissolve 3.6758g NaBH4 in 39mL ice water to obtain NaBH4 solution; mix the first solution obtained in step (1) with the H2PtCl6 solution, and then add the NaBH4 solution from step (2), stir at 5℃ for 3h to obtain the second solution; the molar ratio of Pt to NaBH4 solution in the second solution is 1:30; the molar ratio of Cr to Pt in the second solution is 1:1;

[0111] (3) Dissolve 1.2g of carbon black in 80mL of ethylene glycol to obtain a carbon black dispersion; stir the second solution obtained in step (2) with the carbon black dispersion for 12h. The metal element in the second solution accounts for 67% of the mass of carbon black in the carbon black dispersion. Then sonicate for 30min, and then add 0.6mol / L nitric acid solution to adjust the pH value to 2.6. Then filter, wash and dry in sequence to obtain the platinum-based bimetallic catalyst.

[0112] This embodiment also provides a platinum-based bimetallic catalyst obtained by the above preparation method. The platinum-based bimetallic catalyst includes a carbon black support and active metal particles supported on the support. The active metal particles include a core containing Cr and a shell containing Pt. The molar ratio of Cr to Pt is 1:1. The total mass percentage of Cr and Pt in the platinum-based bimetallic catalyst is 40%, and the average particle size is 2.99 nm.

[0113] The platinum-based bimetallic catalyst described in this embodiment was subjected to electrochemical testing under the same conditions as in Example 1, and the results are as follows: Figure 9 As shown.

[0114] Example 6

[0115] This embodiment provides a method for preparing a platinum-based bimetallic catalyst, the method comprising the following steps:

[0116] (1) Dissolve 1.296g CrN3O9·9H2O in 30mL ethylene glycol to obtain a CrN3O9 solution; dissolve 3.0740g NaBH4 in 39mL ice water to obtain a NaBH4 solution; stir the CrN3O9 solution and the NaBH4 solution at 5℃ for 60min to obtain the first solution; the molar ratio of Cr to NaBH4 solution in the first solution is 1:25;

[0117] (2) Dissolve 1.678g H2PtCl6·6H2O in 30mL of ethylene glycol to obtain H2PtCl6 solution; dissolve 3.6758g NaBH4 in 39mL of ice water to obtain NaBH4 solution; mix the first solution obtained in step (1) with the H2PtCl6 solution, and then add the NaBH4 solution from step (2), and stir at -5℃ for 1h to obtain the second solution; the molar ratio of Pt to NaBH4 solution in the second solution is 1:30; the molar ratio of Cr to Pt in the second solution is 1:1;

[0118] (3) Dissolve 1.2g of carbon black in 80mL of ethylene glycol to obtain a carbon black dispersion; stir the second solution obtained in step (2) with the carbon black dispersion for 15h. The metal element in the second solution accounts for 67% of the mass of carbon black in the carbon black dispersion. Then sonicate for 90min, and then add 0.4mol / L nitric acid solution to adjust the pH value to 2.6. Then filter, wash and dry in sequence to obtain the platinum-based bimetallic catalyst.

[0119] This embodiment also provides a platinum-based bimetallic catalyst obtained by the above preparation method. The platinum-based bimetallic catalyst includes a carbon black support and active metal particles supported on the support. The active metal particles include a core containing Cr and a shell containing Pt. The molar ratio of Cr to Pt is 1:1. The total mass percentage of Cr and Pt in the platinum-based bimetallic catalyst is 40%, and the average particle size is 3.08 nm.

[0120] The platinum-based bimetallic catalyst described in this embodiment was subjected to electrochemical testing under the same conditions as in Example 1, and the results are as follows: Figure 9 As shown.

[0121] Comparative Example 1

[0122] This comparative example provides a method for preparing a platinum-based bimetallic catalyst. Compared with Example 1, the only difference is that in step (1), the CrN3O9 solution, NaBH4 solution, and carbon black dispersion are mixed, and then step (2) is performed. The product obtained in step (2) is filtered, washed, and dried to obtain the platinum-based bimetallic catalyst. The specific operation is as follows:

[0123] (1) Dissolve 1.296g CrN3O9·9H2O in 30mL ethylene glycol to obtain a CrN3O9 solution; dissolve 3.0740g NaBH4 in 39mL ice water to obtain a NaBH4 solution; dissolve 1.2g carbon black in 80mL ethylene glycol to obtain a carbon black dispersion; stir the CrN3O9 solution, NaBH4 solution and carbon black dispersion at 0℃ for 90min to obtain the first solution;

[0124] (2) Dissolve 1.678g H2PtCl6·6H2O in 30mL ethylene glycol to obtain H2PtCl6 solution; dissolve 3.0740g NaBH4 in 39mL ice water to obtain NaBH4 solution; mix the first solution obtained in step (1) and the H2PtCl6 solution, and then add the NaBH4 solution from step (2), stir at 0℃ for 2h, then sonicate for 60min, then add 0.5mol / L nitric acid solution to adjust the pH value to 2.8, and then filter, wash and dry in sequence to obtain the platinum-based bimetallic catalyst.

[0125] This comparative example also provides a platinum-based bimetallic catalyst, which has a core-shell structure, with the carbon black support as the core and the spherical shell containing Pt and Cr.

[0126] Electrochemical tests were performed on the platinum-based bimetallic catalyst described in this comparative example under the same conditions as in Example 1. The results are as follows: Figure 10 As shown.

[0127] Comparative Example 2

[0128] This comparative example provides a method for preparing a platinum-based bimetallic catalyst. Compared with Example 1, the only difference is that CrN3O9 solution, NaBH4 solution, H2PtCl6 solution, and carbon black dispersion are added simultaneously to prepare the catalyst. The specific operation is as follows:

[0129] 1.296 g of CrN3O9·9H2O was dissolved in 30 mL of ethylene glycol to obtain a CrN3O9 solution; 6.148 g of NaBH4 was dissolved in 78 mL of ice water to obtain a NaBH4 solution; 1.2 g of carbon black was dissolved in 80 mL of ethylene glycol to obtain a carbon black dispersion; 1.678 g of H2PtCl6·6H2O was dissolved in 30 mL of ethylene glycol to obtain an H2PtCl6 solution; the CrN3O9 solution, H2PtCl6 solution, carbon black dispersion, and NaBH4 solution were stirred at 0 °C for 2 h, then sonicated for 60 min, and the pH was adjusted to 2.8 by adding 0.5 mol / L nitric acid solution. Then, the mixture was filtered, washed, and dried sequentially to obtain the platinum-based bimetallic catalyst.

[0130] Electrochemical tests were performed on the platinum-based bimetallic catalyst described in this comparative example under the same conditions as in Example 1. The results are as follows: Figure 10 As shown.

[0131] The electrochemical performance test results of the platinum-based bimetallic catalysts described in Examples 1-6 for SO2 depolarization reaction are as follows: Figure 7-9 As shown, when the potential voltage does not exceed 1.2V, the maximum current density of the platinum-based bimetallic catalysts provided in Examples 1-6 of this invention can reach 200mA / cm². 2 Under optimal conditions, the above can reach 350 mA / cm. 2 Therefore, it is evident that the platinum-based bimetallic catalyst provided by this invention possesses excellent electrochemical catalytic performance.

[0132] Comparing Examples 1 and 2, only the mass ratio of the Cr and Pt precursors was changed in Examples 1 and 2, and the amounts of NaBH4, ice water, and ethylene glycol were adjusted accordingly to ensure that the sum of the mass percentages of Cr and Pt in the final platinum-based bimetallic catalyst was 40%. Only the molar ratio of Cr to Pt was changed; in Example 1, the molar ratio of Cr to Pt was 1:1, and in Example 2, the molar ratio of Cr to Pt was 2:1. Figure 3-6 It can be seen that as the Cr content increases, the relative content of metallic Pt on the catalyst surface increases; from Figure 7 It can be seen that, at the same level of 350 mA / cm 2 When the potential voltage of Example 2 is lower than that of Example 1, it indicates that the present invention preferably controls the molar ratio of the first metal element and the second metal element within a specific range ((1-2):1), which can increase the content of metallic Pt on the catalyst surface and improve the catalytic performance of the catalyst.

[0133] Comparing Examples 3-4, only the total amount of metal elements was changed in Examples 3-4, while maintaining the same ratio of Ir precursor mass to Pt precursor mass. The amounts of NaBH4, ice water, and ethylene glycol were adjusted accordingly to ensure that the final molar ratio of Ir to Pt in the platinum-based bimetallic catalyst was 1:1. In contrast, the sum of the mass percentages of Ir and Pt in Example 3 was 20%, and in Example 4 it was 40%. Figure 8 It can be seen that the potential voltage in Example 3 increases rapidly with the increase of current density, and the maximum current density in Example 4 is greater than that in Example 3. This indicates that the present invention preferably controls the mass percentage of metal elements in the platinum-based bimetallic catalyst within a specific range (20-40%), which can improve the catalytic activity of the catalyst.

[0134] Comparing Example 1 and Comparative Examples 1-2, the only difference between Comparative Example 1 and Example 1 is that in step (1), CrN3O9 solution, NaBH4 solution, and carbon black dispersion are mixed, and then step (2) is performed, where the product obtained in step (2) is filtered, washed, and dried. The only difference between Comparative Example 2 and Example 1 is that CrN3O9 solution, NaBH4 solution, H2PtCl6 solution, and carbon black dispersion are added simultaneously to prepare the catalyst. Figure 7 and Figure 10 It can be seen that, under a voltage not exceeding 1.2V, the maximum current density of the platinum-based bimetallic catalyst in Example 1 reaches 350 mA / cm². 2 In contrast, the maximum current density in Comparative Example 1 only reached 300 mA / cm². 2 The maximum current density in Comparative Example 2 only reached 250 mA / cm². 2 This indicates that by first performing the reduction of Pt in step (1), then the reduction of Cr in step (2), and then loading the carbon black support, the present invention can concentrate Pt in the shell of the active metal ions of the catalyst, thereby making the catalytic activity higher.

[0135] In summary, the platinum-based bimetallic catalyst provided by this invention has a simple preparation method, requires less precious metal, and has low production costs. The platinum-based bimetallic catalyst provided by this invention has a core-shell structure, which reduces the amount of Pt used and improves Pt utilization. During electrochemical testing of the SO2 depolarization reaction, the maximum current density can reach 200 mA / cm² under a voltage not exceeding 1.2 V. 2 Under optimal conditions, the above can reach 350 mA / cm. 2 The above-mentioned catalysts exhibit excellent catalytic activity and good stability.

[0136] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A platinum-based bimetallic catalyst for SO2 depolarization electrolysis, characterized in that, The platinum-based bimetallic catalyst comprises a support and active metal particles supported on the support; The active metal particle comprises a core containing a first metal element and a spherical shell containing a second metal element surrounding the core; The first metallic element includes any one or a combination of at least two of Rh, Cr, or Ir; The second metallic element includes Pt; The average particle size of the platinum-based bimetallic catalyst is 2.5-3.5 nm; The platinum-based bimetallic catalyst was prepared using the following method: (1) The precursor solution containing the first metal element and the reducing agent are mixed for the first time to obtain the first solution; (2) The first solution obtained in step (1), the precursor solution containing the second metal element, and the reducing agent are mixed for the second time to obtain the second solution; (3) The second solution and the carrier dispersion obtained in step (2) are mixed for the third time, and then subjected to ultrasonication, solid-liquid separation, washing and drying in sequence to obtain the platinum-based bimetallic catalyst.

2. The platinum-based bimetallic catalyst according to claim 1, characterized in that, The molar ratio of the first metal element to the second metal element is (1-2):

1.

3. The platinum-based bimetallic catalyst according to claim 1 or 2, characterized in that, In the platinum-based bimetallic catalyst, the sum of the mass percentages of the first metal element and the second metal element is 20-40%.

4. The platinum-based bimetallic catalyst according to claim 1, characterized in that, The carrier includes carbon black.

5. A method for preparing a platinum-based bimetallic catalyst as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: (1) The precursor solution containing the first metal element and the reducing agent are mixed for the first time to obtain the first solution; (2) The first solution obtained in step (1), the precursor solution containing the second metal element, and the reducing agent are mixed for the second time to obtain the second solution; (3) The second solution and the carrier dispersion obtained in step (2) are mixed for the third time, and then subjected to ultrasonication, solid-liquid separation, washing and drying in sequence to obtain the platinum-based bimetallic catalyst.

6. The preparation method according to claim 5, characterized in that, Step (1) The molar ratio of the first metal element to the reducing agent in the first solution is 1:(20-30).

7. The preparation method according to claim 5, characterized in that, The precursor solution containing the first metal element includes any one or a combination of at least two of the following: RhCl3 solution, CrN3O9 solution, or H2IrCl6 solution.

8. The preparation method according to claim 5, characterized in that, The reducing agent in step (1) includes a NaBH4 solution.

9. The preparation method according to claim 5, characterized in that, The temperature of the first mixture is -5 to 5°C.

10. The preparation method according to claim 5, characterized in that, The first mixing includes stirring, and the first mixing time is 60-120 min.

11. The preparation method according to claim 5, characterized in that, Step (2) The molar ratio of the second metal element to the reducing agent in the second solution is 1:(20-30).

12. The preparation method according to claim 5, characterized in that, The precursor solution containing the second metal element includes an H2PtCl6 solution.

13. The preparation method according to claim 5, characterized in that, The reducing agent in step (2) includes a NaBH4 solution.

14. The preparation method according to claim 5, characterized in that, In the second solution, the molar ratio of the first metal element to the second metal element is (1-2):

1.

15. The preparation method according to claim 5, characterized in that, The temperature of the second mixture is -5 to 5°C.

16. The preparation method according to claim 5, characterized in that, The second mixing includes stirring, and the second mixing time is 1-3 hours.

17. The preparation method according to claim 5, characterized in that, Step (2) The first solution is first mixed with the precursor solution containing the second metal element, and then mixed with the reducing agent in the second mixing.

18. The preparation method according to claim 5, characterized in that, In step (3), the metal element in the second solution accounts for 25-67% of the mass of the carrier in the carrier dispersion.

19. The preparation method according to claim 5, characterized in that, The carrier in the carrier dispersion includes carbon black.

20. The preparation method according to claim 5, characterized in that, The third mixing includes stirring, and the third mixing time is 12-15 hours.

21. The preparation method according to claim 5, characterized in that, The ultrasound duration is 30-90 minutes.

22. The preparation method according to claim 5, characterized in that, After ultrasound, acid is added to adjust the pH value.

23. The preparation method according to claim 22, characterized in that, The acid solution includes a nitric acid solution.

24. The preparation method according to claim 22, characterized in that, The concentration of the acid solution is 0.4-0.6 mol / L.

25. The preparation method according to claim 22, characterized in that, After the acid solution is added, the pH value is adjusted to <3.

26. The preparation method according to claim 5, characterized in that, The preparation method includes the following steps: (1) Stir the precursor solution containing the first metal element and the NaBH4 solution at -5-5℃ for 60-120 min to obtain the first solution; the molar ratio of the first metal element to the NaBH4 solution in the first solution is 1:(20-30); the precursor solution containing the first metal element includes any one or a combination of at least two of RhCl3 solution, CrN3O9 solution or H2IrCl6 solution; (2) Mix the first solution obtained in step (1) with the precursor solution containing the second metal element, and then add NaBH4 solution. Stir at -5-5℃ for 1-3h to obtain the second solution; the molar ratio of the second metal element to the NaBH4 solution in the second solution is 1:(20-30); the precursor solution containing the second metal element includes H2PtCl6 solution; the molar ratio of the first metal element to the second metal element in the second solution is (1-2):1; (3) Stir the second solution obtained in step (2) with the carbon black dispersion for 12-15 h. The metal element in the second solution accounts for 25-67% of the mass of carbon black in the carbon black dispersion. Then sonicate for 30-90 min. Then add 0.4-0.6 mol / L nitric acid solution to adjust the pH value to <3. Then perform solid-liquid separation, washing and drying in sequence to obtain the platinum-based bimetallic catalyst.

27. Use of a platinum-based bimetallic catalyst as described in any one of claims 1-4, characterized in that, The platinum-based bimetallic catalyst is used for SO2 depolarization electrolysis.

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