A high-entropy metal olefin catalyst for ammonia oxidation, its preparation method and application

Abstract

This invention belongs to the field of catalytic materials technology, specifically relating to a high-entropy metal olefin catalyst for ammonia oxidation, its preparation method, and its application. The high-entropy metal olefin catalyst is a PdCoNiPtZn high-entropy alloy, which has a two-dimensional olefinic structure. The preparation method of the high-entropy metal olefin catalyst includes the following steps: S1, mixing palladium acetylacetone, nickel acetylacetone, platinum acetylacetone, cobalt acetylacetone, zinc acetylacetone, ascorbic acid, and tungsten hexacarbonyl uniformly to obtain mixture one; S2, adding mixture one obtained in step S1 to a mixed solution of N,N-dimethylformamide and glacial acetic acid to obtain a mixed liquid; S3, subjecting the above mixed liquid to ultrasonic vibration to obtain a uniform solution, and then placing the uniform solution in a sealed container to react to obtain mixture two; S4, adding an ethanol solution to mixture two, and then centrifuging, washing, and drying to obtain the high-entropy metal olefin catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a high-entropy metal olefin catalyst for ammonia oxidation, its preparation method, and its application. Background Technology

[0002] In recent years, ammonia has been proposed as a promising candidate fuel for anion exchange membrane fuel cell technology. Direct ammonia is a carbon-free technology that combines the high energy density of ammonia with the high efficiency of fuel cells. However, this technology faces two main challenges: ammonia cross-linking (due to the high solubility of ammonia in water) and the slow ammonia oxidation reaction.

[0003] Platinum is considered the most effective catalyst for ammonia oxidation due to its moderate binding strength with nitrogen-adsorbed substances. However, its performance in practical ammonia oxidation reactions is far from satisfactory. Platinum metal readily aggregates, resulting in low atom utilization. Metal olefins, on the other hand, consist primarily of thin atomic layers composed of undercoordinated metal atoms. This structure provides an ultra-high specific surface area, improving atom utilization and exposing highly active surface metal atoms. Therefore, it can significantly enhance catalyst activity. Furthermore, pure platinum catalysts are prone to catalyst poisoning, leading to a sharp decline in catalytic performance, while PdCoNiPtZn high-entropy metal olefin catalysts exhibit extremely strong resistance to poisoning, allowing the catalyst to maintain its activity. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a high-entropy metal olefin catalyst for ammonia oxidation, its preparation method, and its application.

[0005] The objective of this invention can be achieved through the following technical solutions: A high-entropy metal olefin catalyst for ammonia oxidation, wherein the high-entropy metal olefin catalyst is a PdCoNiPtZn high-entropy alloy, which has a two-dimensional olefinic structure.

[0006] Furthermore, the two-dimensional olefinic structure is a curved sheet-like structure.

[0007] Furthermore, the monolayer thickness of the high-entropy metal olefin catalyst is 0.1-0.3 nm.

[0008] Furthermore, the atomic percentage of a single metal element in the high-entropy metal olefin catalyst is 5-50%.

[0009] A method for preparing a high-entropy metal olefin catalyst for ammonia oxidation, the method comprising the following steps: S1. Mix palladium acetylacetone, nickel acetylacetone, platinum acetylacetone, cobalt acetylacetone, zinc acetylacetone, ascorbic acid, and tungsten hexacarbonyl uniformly to obtain mixture one; S2. Add the mixture obtained in step S1 to a mixed solution of N,N-dimethylformamide and glacial acetic acid to obtain a mixed solution; S3. The above mixture is subjected to ultrasonic oscillation to obtain a homogeneous solution, and then the homogeneous solution is placed in a sealed container to react and obtain mixture two. S4. Add ethanol solution to mixture two, and then obtain high-entropy metal olefin catalyst after centrifugation, washing and drying.

[0010] Further, the mass ratio of palladium acetylacetone, nickel acetylacetone, platinum acetylacetone, cobalt acetylacetone, zinc acetylacetone, ascorbic acid, and tungsten hexacarbonyl is (0.1-1.5): (0.1-1.5): (0.1-1.5): (0.1-1.5): (4-8): (3-6).

[0011] Furthermore, when preparing the mixed solution, the volume ratio of N,N-dimethylformamide to glacial acetic acid is 4:1.

[0012] Furthermore, in step S3, the temperature during ultrasonic oscillation is 20–35°C, and the oscillation time is 1–4 hours; the reaction temperature inside the sealed container is 60–90°C, and the reaction time is 6–18 hours.

[0013] Furthermore, in step S4, the centrifugation speed is 6000-10000 rpm, the centrifugation time is 1-2 hours, the cleaning solution used is an ethanol solution, and the drying temperature is 50-80℃.

[0014] The high-entropy metal olefin catalyst described above is used in the ammonia oxidation reaction.

[0015] The beneficial effects of this invention are: 1. Compared with conventional commercial platinum-iridium-carbon catalysts, the high-entropy metal olefin catalyst for ammonia oxidation provided in this application has significantly improved ammonia oxidation activity, can prevent catalyst poisoning, and has good stability.

[0016] 2. The preparation method of the high-entropy metal olefin catalyst provided in this application requires raw materials that are all commercially available products and have low cost.

[0017] 3. The preparation method of the high-entropy metal olefin catalyst for ammonia oxidation provided in this application has the advantages of simple and safe preparation process, and is easy to achieve large-scale preparation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0019] Figure 1 The image shows a scanning electron microscope image of the PdCoNiPtZn catalyst in Example 1.

[0020] Figure 2 The X-ray diffraction patterns are for Example 1 and Comparative Examples 1-4.

[0021] Figure 3 The graph shows a performance comparison between Example 1 and Comparative Examples 1-4.

[0022] Figure 4 This is a comparison chart of the stability of Example 1 and Comparative Examples 1-4. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] As previously stated, this application relates to a method for preparing high-entropy metal olefin catalysts for ammonia oxidation. The metal olefin catalyst described in this application is prepared via a wet chemical method. Compared with existing commercial platinum-iridium-carbon catalysts, the high-entropy metal olefin catalyst prepared in this application exhibits higher activity and shows promising application prospects.

[0025] Unless otherwise specified, all figures appearing in this application specification and claims, such as temperature and time, should not be construed as absolutely precise values, as the measured values ​​inevitably contain a certain degree of experimental error due to the standard deviation of measurement techniques.

[0026] The present application is described in detail below with reference to embodiments, but is not limited to these embodiments.

[0027] Unless otherwise specified, the raw materials and reagents used in the embodiments of this application are all commercially available. The invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Preparation of high-entropy metal olefin catalyst: Palladium acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, platinum acetylacetonate, zinc acetylacetonate, ascorbic acid and tungsten hexacarbonyl were added to a mixed solution of N,N-dimethylformamide and glacial acetic acid, and sonicated for 1-4 hours. Then the reaction was carried out at 80°C for 1 hour. After cooling to room temperature, the catalyst was collected by centrifugation and washed to obtain the high-entropy metal olefin catalyst.

[0029] Example 1 This embodiment provides a method for preparing a high-entropy metal olefin catalyst for ammonia oxidation, specifically as follows: S1. Mix 10 mg palladium acetylacetone, 10 mg cobalt acetylacetone, 8 mg nickel acetylacetone, 10 mg platinum acetylacetone, 6 mg zinc acetylacetone, 80 mg ascorbic acid and 60 mg tungsten hexacarbonyl uniformly to obtain mixture one; S2. Add the mixture obtained in step S1 to a mixed solution of 16 mL N,N-dimethylformamide and 4 mL glacial acetic acid to obtain a mixed solution; S3. The above mixture is subjected to ultrasonic oscillation treatment to obtain a homogeneous solution. The ultrasonic treatment temperature is 25℃ and the ultrasonic oscillation time is 1h. Then, the homogeneous solution is placed in a sealed container to react and obtain mixture two. The reaction temperature is 80℃ and the reaction time is 12h. S4. Cool the second mixture to room temperature, then add an ethanol solution to the second mixture, wash with ethanol 6 times, and then obtain the high-entropy metal olefin catalyst after centrifugation, washing and drying.

[0030] Comparative Example 1 Compared with Example 1, Comparative Example 1 lacked cobalt acetylacetone in its preparation materials, while other preparation materials were the same as in Example 1, thus obtaining a high-entropy metal olefin catalyst.

[0031] Comparative Example 2 Compared with Example 1, Comparative Example 2 lacked nickel acetylacetone in its preparation materials, while other preparation materials were the same as in Example 1, thus obtaining a high-entropy metal olefin catalyst.

[0032] Comparative Example 3 Compared with Example 1, Comparative Example 3 lacked platinum acetylacetone in its preparation materials, while other preparation materials were the same as in Example 1, thus obtaining a high-entropy metal olefin catalyst.

[0033] Comparative Example 4 Compared with Example 1, Comparative Example 4 lacked zinc acetylacetone in its preparation materials, while other preparation materials were the same as in Example 1, thus obtaining a high-entropy metal olefin catalyst.

[0034] Performance testing: The specific steps for testing the catalysts for ammonia oxidation prepared in Example 1 and Comparative Examples 1-4 are as follows: (1) Typically, 2 mg of catalyst, 0.5 mg of acetylene black, and 10 μL of Nafion solution (5 wt%) are dispersed in 190 μL of ethanol and sonicated for at least 1 hour to form a uniform ink. 15 μL of the catalyst ink is loaded onto a substrate with an area of ​​0.196 cm². -2 On the electrodes, dry at room temperature for 30 minutes; (2) In a 1M potassium hydroxide solution (argon atmosphere), the voltammetry was performed at 50 mV / s. -1 The scan rate was adjusted to activate the device within a voltage range of 0.22-1.12V (vs. RHE) until the CV curves completely overlapped. (3) The activated catalyst was placed in a 1M potassium hydroxide + 0.1M ammonia solution (argon atmosphere), and voltammetry was used to measure the catalytic activity at 5mV s. -1 The catalyst performance is obtained by scanning the rate and taking the overlapping curves.

[0035] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0036] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation, characterized in that, The high-entropy metal olefin catalyst is a PdCoNiPtZn high-entropy alloy, which has a two-dimensional olefinic structure. The preparation method of the high-entropy metal olefin catalyst includes the following steps: S1. Mix palladium acetylacetone, nickel acetylacetone, platinum acetylacetone, cobalt acetylacetone, zinc acetylacetone, ascorbic acid, and tungsten hexacarbonyl uniformly to obtain mixture one; S2. Add the mixture obtained in step S1 to a mixed solution of N,N-dimethylformamide and glacial acetic acid to obtain a mixed solution; S3. The above mixture is subjected to ultrasonic oscillation to obtain a homogeneous solution, and then the homogeneous solution is placed in a sealed container to react and obtain mixture two. S4. Add ethanol solution to mixture two, and then obtain high-entropy metal olefin catalyst after centrifugation, washing and drying.

2. The high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation according to claim 1, characterized in that, The two-dimensional olefinic structure is a curved sheet-like structure.

3. The high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation according to claim 1, characterized in that, The monolayer thickness of the high-entropy metal olefin catalyst is 0.1-0.3 nm.

4. The high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation according to claim 1, characterized in that, The atomic percentage of a single metal element in the high-entropy metal olefin catalyst is 5-50%.

5. The high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation according to claim 1, characterized in that, The mass ratio of palladium acetylacetone, nickel acetylacetone, platinum acetylacetone, cobalt acetylacetone, zinc acetylacetone, ascorbic acid, and tungsten hexacarbonyl is (0.1-1.5): (0.1-1.5): (0.1-1.5): (0.1-1.5): (4-8): (3-6).

6. The high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation according to claim 1, characterized in that, When preparing the mixed solution, the volume ratio of N,N-dimethylformamide to glacial acetic acid is 4:

1.

7. The high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation according to claim 1, characterized in that, In step S3, the temperature during ultrasonic oscillation is 20–35°C, and the oscillation time is 1–4 hours; the reaction temperature inside the sealed container is 60–90°C, and the reaction time is 6–18 hours.

8. The high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation according to claim 1, characterized in that, In step S4, the centrifugation speed is 6000-10000 rpm and the centrifugation time is 1-2 hours; the cleaning solution used for cleaning is ethanol solution; and the drying temperature is 50-80℃.

9. A high-entropy metal olefin catalyst for electrocatalytic ammonia oxidation as described in any one of claims 1 to 4, used for the electrocatalytic ammonia oxidation reaction.

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