Preparation method for noble metal alloy / carbon material composite catalyst

Abstract

The present invention relates to the technical field of nanomaterial synthesis and electrochemical catalysis. Disclosed is a preparation method for a noble metal alloy / carbon material composite catalyst, comprising the following steps: step 1, loading precursors of platinum and palladium on a three-dimensional porous nitrogen-doped carbon support by means of an impregnation method, the precursors being chloroplatinic acid and chloropalladic acid; and step 2, reducing chloroplatinic acid and chloropalladic acid into alloy particles of platinum and palladium by means of reduction. In the step 1, the impregnation process is carried out under a vacuum condition, and lasts for 12 h; and an inert atmosphere is one or more atmospheres selected from gas, nitrogen or argon. The precursors of platinum and palladium are loaded on the nitrogen-doped carbon support, and are converted into the alloy particles of platinum and palladium by means of reduction. Vacuum impregnation and the introduction of nitrogen-rich functional groups in the preparation process further optimize the structure and performance of the catalyst, thereby improving reaction efficiency, enhancing stability, and reducing costs.

Description

A method for preparing a noble metal alloy / carbon material composite catalyst Technical Field

[0001] This invention relates to the fields of nanomaterial synthesis and electrochemical catalysis, specifically to a method for preparing a noble metal alloy / carbon material composite catalyst. Background Technology

[0002] Noble metal alloy nanocatalysts possess suitable adsorption / desorption capabilities for reactants and products, playing a crucial role in multiphase catalytic reactions such as environmental catalysis, fuel cells, and fine chemicals. For example, the active component of three-way catalysts for purifying automobile exhaust is platinum group elements, and platinum-based nanostructured electrodes exhibit excellent performance in fuel cell electrocatalytic reactions. Due to the scarcity and high cost of precious metals, reducing their usage while maintaining or even improving their catalytic performance and recycling rate has become a research focus. Preparing nanocatalysts with smaller and thinner noble metal alloy particles can increase their specific surface area, thereby improving the mass activity and utilization efficiency of the noble metals.

[0003] Currently, there are numerous methods for preparing noble metal alloy supported catalysts, including low-temperature organic liquid-phase reduction, microemulsion method, vapor deposition, electrochemical deposition, and immersion-high-temperature reduction method. Among these, the high-temperature reduction method for preparing noble metal alloy catalysts has unique advantages. Because it allows for high-temperature annealing, the desired crystal structure of the alloy can be easily controlled. The required equipment and raw materials are relatively common, and the process is simple and easy to control, making it promising for large-scale production to reduce costs. However, the particle size and uniformity, as well as the controllability of the crystal structure, of noble metal alloy catalysts prepared by the high-temperature reduction method remain significant problems, greatly affecting their catalytic performance.

[0004] Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a noble metal alloy / carbon material composite catalyst. This method solves the problem that the particle size and uniformity, as well as the controllability of crystal structure, of noble metal alloy catalysts prepared by high-temperature reduction methods are still prominent issues, which greatly affect the catalytic performance of noble metal alloy catalysts.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a noble metal alloy / carbon material composite catalyst, comprising the following components:

[0007] (a) Platinum and palladium precursors were loaded onto a three-dimensional porous nitrogen-doped carbon support by impregnation. The precursors were chloroplatinic acid and chloropalladic acid.

[0008] (b) Reduction of chloroplatinic acid and chloropalladic acid to platinum and palladium alloy particles.

[0009] A method for preparing a noble metal alloy / carbon material composite catalyst includes the following steps:

[0010] Step 1: Load platinum and palladium precursors onto a three-dimensional porous nitrogen-doped carbon support by impregnation. The precursors are chloroplatinic acid and chloropalladic acid.

[0011] Step 2: Reduce chloroplatinic acid and chloropalladiumic acid to platinum and palladium alloy particles through reduction.

[0012] Preferably, in step one, the impregnation process is carried out under vacuum conditions, and the impregnation time is 12 hours.

[0013] Preferably, the inert atmosphere is one or more atmospheres selected from gases, nitrogen or argon.

[0014] Preferably, in step two, the average diameter of the noble metal alloy particles is between 2 and 5 nm.

[0015] Preferably, in step one, the specific surface area of ​​the three-dimensional porous nitrogen-doped carbon support is 1000 m². 2 / g, with a loading of 5% for precious metal alloy particles.

[0016] Preferably, the surface of the three-dimensional porous nitrogen-doped carbon support has nitrogen-rich functional groups.

[0017] Preferably, the introduction of the nitrogen-rich functional groups is achieved by nitrogen doping on a carbon material support followed by high-temperature treatment.

[0018] Preferably, the high-temperature treatment step involves heat-treating the precursor mixture at a temperature range of 500–900°C.

[0019] This invention provides a method for preparing a noble metal alloy / carbon material composite catalyst. It has the following beneficial effects:

[0020] This invention achieves highly efficient catalytic performance by loading platinum and palladium precursors onto a three-dimensional porous nitrogen-doped carbon support and then reducing them to platinum and palladium alloy particles. This catalyst provides higher activity and selectivity in catalytic reactions, thereby improving reaction efficiency and product purity. Secondly, the impregnation process is carried out under vacuum conditions, which can effectively control the loading and distribution of precursors, further optimizing the structure and performance of the catalyst. In addition, by introducing nitrogen-rich functional groups, the surface active sites of the carbon material support can be increased, improving the stability and anti-poisoning performance of the catalyst. Finally, the catalyst preparation process is simple and feasible, suitable for industrial production, and has low preparation cost, offering advantages such as improved catalytic efficiency, enhanced catalyst stability, and reduced preparation cost. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1:

[0023] This invention provides a method for preparing a noble metal alloy / carbon material composite catalyst, comprising the following components: a precursor of platinum and palladium loaded on a three-dimensional porous nitrogen-doped carbon support by impregnation, wherein the precursor is chloroplatinic acid and chloropalladic acid; and chloroplatinic acid and chloropalladic acid are reduced to platinum and palladium alloy particles by reduction. The carbon material has a high specific surface area and abundant pore structure, which can provide good catalytic activity and loading capacity.

[0024] The catalyst is prepared as follows: First, platinum and palladium precursors are loaded onto a three-dimensional porous nitrogen-doped carbon support by impregnation. The precursors are chloroplatinic acid and chloropalladic acid. The impregnation process is carried out under vacuum conditions to ensure that the precursors are uniformly dispersed on the surface of the carbon support. The impregnation time is 12 hours to fully realize the adsorption and diffusion of the precursors. Next, chloroplatinic acid and chloropalladic acid are reduced to platinum and palladium alloy particles by reduction. The reduction process can be carried out in nitrogen to provide an inert environment and prevent oxidation reaction. The reduction process gradually reduces the metal ions in the precursors to metal particles, which interact with the carbon support to form a noble metal alloy / carbon material composite catalyst.

[0025] During the fabrication process, the specific surface area of ​​the three-dimensional porous nitrogen-doped carbon support was 1000 m². 2 / g, the loading of precious metal alloy particles is 5%, and the content of precious metal can be adjusted to meet specific application requirements. In addition, the surface of the three-dimensional porous nitrogen-doped carbon support has nitrogen-rich functional groups. These nitrogen-rich functional groups can be achieved by nitrogen doping on the carbon material support and high temperature treatment. The introduction of nitrogen-rich functional groups is achieved by nitrogen doping on the carbon material support and high temperature treatment. The high temperature treatment step is carried out in the temperature range of 800°C to treat the precursor mixture and promote the bonding of nitrogen atoms with carbon materials.

[0026] The alloy particles of the prepared noble metal alloy / carbon material composite catalyst have an average diameter between 2 and 5 nm. These nanoscale particles help to increase the reaction surface area and improve catalytic efficiency.

[0027] The finished product is manufactured according to the above steps, and its performance is tested in various aspects. The data is recorded in Table 1.

[0028] Comparative Example 1:

[0029] This invention provides a method for preparing a noble metal alloy / carbon composite catalyst, comprising the following steps to prepare a three-dimensional porous nitrogen-doped carbon support: A suitable amount of polyaniline and sulfuric acid are mixed and added to a reaction vessel, and the reaction is carried out at 0°C for 2 hours with stirring. Then, the resulting precipitate is washed to a neutral pH value and dried in a vacuum drying oven. Finally, the sample is heat-treated at 800°C for 2 hours to obtain the three-dimensional porous nitrogen-doped carbon support.

[0030] Impregnation method for loading precursors: Dissolve chloroplatinic acid and chloropalladic acid in an appropriate amount of deionized water according to the required molar ratio, and then place the three-dimensional porous nitrogen-doped carbon support into the solution and impregnate it under vacuum for 12 hours.

[0031] Reduction process: The impregnated sample is transferred to a furnace tube and reduced under a nitrogen atmosphere. First, it is preheated at 200℃ for 30 minutes, then the temperature is raised to 500℃ and held for 1 hour, and finally cooled to room temperature to obtain the noble metal alloy / carbon material composite catalyst: After reduction treatment, the noble metal alloy / carbon material composite catalyst is obtained.

[0032] This comparative example uses a commercially available precious metal catalyst as a control.

[0033] Next, we will compare the differences in catalytic activity between the two catalysts. We selected a common catalytic reaction as the test reaction, such as the oxidation of methanol, and used the same experimental conditions and reactant concentrations. We also added the noble metal alloy / carbon composite catalyst prepared in the examples and the control catalyst. By monitoring the conversion rate of reactants, product selectivity and catalyst stability during the reaction process, we can evaluate the differences in catalytic activity between the two catalysts and record the data in Table 1.

[0034] Table 1

[0035] Comparative Example 2:

[0036] This invention provides a method for preparing a noble metal alloy / carbon material composite catalyst, comprising the following steps:

[0037] Preparation of three-dimensional porous nitrogen-doped carbon support: Mix an appropriate amount of glucose and sulfuric acid and add it to the reaction vessel. Maintain the reaction temperature at 80℃ for 4 hours with stirring. Then, wash the obtained precipitate to a neutral pH value and dry it in a vacuum drying oven. Finally, heat treat the sample at 900℃ for 2 hours to obtain a three-dimensional porous nitrogen-doped carbon support.

[0038] Impregnation method for loading precursors: Dissolve chloroplatinic acid and chloropalladic acid in an appropriate amount of deionized water according to the required molar ratio, and then place the three-dimensional porous nitrogen-doped carbon support into the solution and impregnate it under vacuum for 24 hours.

[0039] Reduction process: The impregnated sample is transferred to a furnace tube and reduced under a hydrogen atmosphere. First, it is preheated at 200℃ for 30 minutes, then the temperature is raised to 500℃ and held for 2 hours, and finally cooled to room temperature to obtain the noble metal alloy / carbon material composite catalyst.

[0040] This comparative example uses a single-metal noble metal catalyst as a control.

[0041] Next, we will compare the differences in catalytic activity between the two catalysts. We selected a common catalytic reaction as the test reaction, such as the hydrogenation of ethylene, using the same experimental conditions and reactant concentrations, and added both the noble metal alloy / carbon composite catalyst prepared in the examples and the control group catalyst.

[0042] The finished product is manufactured according to the above steps, and its performance is tested in various aspects. The data is recorded in Table 2.

[0043] Table 2

[0044] In summary, the noble metal alloy / carbon composite catalyst of Example 1 exhibits superior performance in terms of reaction conversion, product selectivity, and stability. Compared with the noble metal catalysts of Comparative Examples 1 and 2, it demonstrates higher catalytic activity and selectivity while maintaining better stability. These results indicate that the preparation method of Example 1 can effectively improve the performance of noble metal catalysts and has potential application prospects.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A noble metal alloy / carbon material composite catalyst, characterized in that, Includes the following components: (a) Platinum and palladium precursors were loaded onto a three-dimensional porous nitrogen-doped carbon support by impregnation. The precursors were chloroplatinic acid and chloropalladic acid. (b) Reduction of chloroplatinic acid and chloropalladic acid to platinum and palladium alloy particles.

2. A method for preparing a noble metal alloy / carbon material composite catalyst, according to the noble metal alloy / carbon material composite catalyst of claim 1, characterized in that, Includes the following steps: Step 1: Load platinum and palladium precursors onto a three-dimensional porous nitrogen-doped carbon support by impregnation. The precursors are chloroplatinic acid and chloropalladic acid. Step 2: Reduce chloroplatinic acid and chloropalladiumic acid to platinum and palladium alloy particles through reduction.

3. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 2, characterized in that, In step one, the impregnation process is carried out under vacuum conditions for 12 hours.

4. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 2, characterized in that, The inert atmosphere is one or more atmospheres selected from gases, nitrogen or argon.

5. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 2, characterized in that, In step one, the impregnation process is carried out under vacuum conditions for 12 hours.

6. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 2, characterized in that, In step two, the average diameter of the precious metal alloy particles is between 2 and 5 nm.

7. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 2, characterized in that, In step one, the specific surface area of ​​the three-dimensional porous nitrogen-doped carbon support is 1000 m². 2 / g, with a loading of 5% for precious metal alloy particles.

8. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 2, characterized in that, The surface of the three-dimensional porous nitrogen-doped carbon support has nitrogen-rich functional groups.

9. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 8, characterized in that, The introduction of the nitrogen-rich functional groups is achieved by nitrogen doping on a carbon material support followed by high-temperature treatment.

10. The method for preparing a noble metal alloy / carbon material composite catalyst according to claim 9, characterized in that, The high-temperature treatment step involves heat-treating the precursor mixture at a temperature range of 500–900°C.

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