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CN-122006765-A - High-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition and preparation method and application thereof

CN122006765ACN 122006765 ACN122006765 ACN 122006765ACN-122006765-A

Abstract

The invention discloses a high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition and a preparation method and application thereof, belonging to the technical field of catalysts for producing hydrogen by ammonia decomposition. The method is different from the traditional technical path, the plasma is activated and the high-entropy alloy is catalyzed and combined to form a synergistic reaction system, ce-WO 3 @SiC particles are synchronously added into the high-entropy alloy, the prepared catalyst has synergistic catalysis with active species generated by the plasma, the activation energy barrier of ammonia decomposition is obviously reduced, the Ce-WO 3 @SiC particles synergistically promote the ammonia decomposition reaction while the high-entropy alloy provides a catalytic active site, the catalytic activity of the high-entropy alloy catalyst in the plasma ammonia decomposition hydrogen production technology is improved, the high-efficiency hydrogen production with nearly complete conversion rate is realized at a temperature lower than that of the traditional thermal catalysis, and thermodynamic limitation is broken through.

Inventors

  • XU SHAOJUN
  • WU XUAN
  • LIU YUBING
  • XIANG NIANWEN
  • DING LIJIAN

Assignees

  • 合肥工业大学

Dates

Publication Date
20260512
Application Date
20260416

Claims (10)

  1. 1. The preparation method of the high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition is characterized by comprising the following steps of: s1, weighing at least five metal raw materials of aluminum, magnesium, vanadium, chromium, manganese, iron, cobalt, nickel, niobium and molybdenum, mixing to obtain a metal mixture, and putting the metal mixture into smelting equipment; S2, smelting at a high temperature in an inert atmosphere to form an alloy liquid, and cooling to obtain a high-entropy alloy ingot; s3, crushing the high-entropy alloy ingot, and mechanically ball-milling under inert atmosphere after crushing to obtain alloy powder; s4, adding Ce-WO 3 @SiC particles into the alloy powder, and carrying out mechanical ball milling under an inert atmosphere to obtain the catalyst.
  2. 2. The preparation method of the high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition according to claim 1, wherein the metal mixture is characterized in that the total element mole ratio of three metals of iron, cobalt and nickel is 40-80%, and the total element mole ratio of the other metals is 20-60%.
  3. 3. The method for preparing the high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition according to claim 1, wherein the specific steps of high-temperature smelting are as follows: placing all metal raw materials into a crucible in a smelting furnace, and vacuumizing to be less than or equal to 1 multiplied by 10 2 Pa, introducing inert gas, controlling the pressure to be 0.02-0.06 MPa, smelting to form alloy liquid at 1600-2000 ℃, cooling to room temperature to obtain alloy ingots, turning over the alloy ingots, and repeating smelting for 2-5 times.
  4. 4. The method for preparing the high-entropy alloy catalyst for preparing hydrogen by decomposing ammonia with plasma according to claim 1, wherein the preparation steps of the Ce-WO 3 @SiC particles are as follows: Dissolving ammonium paratungstate in deionized water to obtain an ammonium paratungstate solution, regulating the pH of the ammonium paratungstate solution to 7-9 by ammonia water, preparing a cerium nitrate ethanol solution, dripping the cerium nitrate ethanol solution into the ammonium paratungstate solution, stirring and mixing to obtain colloid, adding SiC powder, uniformly mixing, drying, and calcining to obtain Ce-WO 3 @SiC particles.
  5. 5. The method for preparing the high-entropy alloy catalyst for producing hydrogen by decomposing ammonia with plasma according to claim 4, wherein the concentration of ammonium paratungstate in the ammonium paratungstate solution is 3-5mmol/L; the cerous nitrate ethanol solution is obtained by dissolving cerous nitrate hexahydrate in ethanol according to the concentration of 5-6 mmol/L.
  6. 6. The method for preparing the high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition according to claim 4, wherein the cerium nitrate ethanol solution is dropwise added into the ammonium paratungstate solution according to the element mole ratio of tungsten to cerium of (90-98): (2-10).
  7. 7. The method for preparing the high-entropy alloy catalyst for producing hydrogen by decomposing ammonia with plasma as claimed in claim 4, wherein the mass ratio of the SiC powder to the ammonium paratungstate is 0.1-0.3:1.
  8. 8. The method for preparing the high-entropy alloy catalyst for preparing hydrogen by decomposing ammonia with plasma according to claim 1, wherein the mass ratio of Ce-WO 3 @SiC particles to alloy powder is 1-8:100.
  9. 9. A high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition, which is prepared by the preparation method according to any one of claims 1 to 8.
  10. 10. The application of the high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition is characterized in that a discharge area in a dielectric barrier discharge fixed bed reactor is filled with the catalyst as claimed in claim 9, ammonia gas is introduced, and then discharge is carried out, and ammonia decomposition reaction is carried out, so that nitrogen and hydrogen are obtained.

Description

High-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition and preparation method and application thereof Technical Field The invention belongs to the technical field of catalysts for producing hydrogen by ammonia decomposition, and particularly relates to a high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition, a preparation method and application thereof. Background Ammonia, a promising liquid hydrogen storage medium, is considered as a key carrier for achieving hydrogen energy scale and economic applications. However, the traditional thermal catalytic ammonia decomposition hydrogen production technology has the disadvantages of high energy consumption, severe requirements on reactor materials and high cost, and the high-temperature environment is extremely easy to cause the rapid deactivation of the catalyst, so that the long-term operation stability is challenging. In order to break through the thermodynamic limit, the low-temperature plasma technology is developed, and a new path is provided for ammonia decomposition with low temperature and low energy consumption. While plasma technology successfully circumvents the high temperature requirements, its application alone to ammonia decomposition still faces a series of technical bottlenecks. Firstly, the plasma reaction energy utilization efficiency is low, secondly, if active intermediates (such as NH 2 and H) generated by non-equilibrium plasma cannot be rapidly recombined into nitrogen and hydrogen, side reactions can be possibly caused, the product selectivity is reduced, and most importantly, the plasma environment forms a serious test on the stability of catalytic materials, and the problems of surface reconstruction, component segregation and the like are extremely easy to occur in the traditional single/double metal catalyst under the environment, so that the catalytic activity is low and the ammonia decomposition efficiency is required to be improved. Therefore, the development of a catalyst which has both activity and stability and can perform synergistic catalysis with active species generated by plasma has important significance in overcoming the difficulty of low efficiency in plasma ammonia decomposition. Disclosure of Invention The invention aims to provide a high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition, and a preparation method and application thereof, which can solve the problem of low catalytic activity of the catalyst for producing hydrogen by plasma ammonia decomposition in the prior art. The aim of the invention can be achieved by the following technical scheme: The preparation method of the high-entropy alloy catalyst for producing hydrogen by plasma ammonia decomposition comprises the following steps: s1, weighing at least five metal raw materials of aluminum, magnesium, vanadium, chromium, manganese, iron, cobalt, nickel, niobium and molybdenum, mixing to obtain a metal mixture, and putting the metal mixture into smelting equipment; S2, smelting at a high temperature in an inert atmosphere to form an alloy liquid, and cooling to obtain a high-entropy alloy ingot; s3, crushing the high-entropy alloy ingot, and mechanically ball-milling under inert atmosphere after crushing to obtain alloy powder; s4, adding Ce-WO 3 @SiC particles into the alloy powder, and carrying out mechanical ball milling under an inert atmosphere to obtain the catalyst. Compared with a single/double metal catalyst, the high-entropy alloy can form a unique surface electronic structure under the synergistic effect of various elements in the high-entropy alloy, optimize the adsorption strength of a reaction intermediate, have stable structure at high temperature and high catalytic activity, and have low effective diffusion rate of atoms of each element under the local hot spot generated by plasma discharge due to the slow diffusion effect in dynamics, so that the dynamic stability of the catalyst is improved, and the problem of rapid deactivation of the catalyst is solved. Lattice distortion in high entropy alloys creates a large number of strain sites and defects, which are high active sites for NH 3 dissociation. In the preparation of the catalyst, alloy powder of the high-entropy alloy is formed by high-temperature smelting and mechanical ball milling, and then the high-entropy alloy and Ce-WO 3 @SiC particles are compounded by mechanical ball milling, so that the full combination of metal elements of the high-entropy alloy can be preferentially ensured by two-step mechanical ball milling, and the physical barrier to the combination of elements caused by synchronous addition of the Ce-WO 3 @SiC particles is avoided. On the one hand, the silicon carbide is taken as a high heat conduction material, so that heat generated by plasma discharge and catalytic reaction can be rapidly led out, local overheating is restrained, active sites of high-entropy alloy are protected, the