Plasma ammonia decomposition hydrogen production high-entropy alloy catalyst, preparation method and application thereof

Abstract

The application discloses a kind of high-entropy alloy catalysts for hydrogen production by plasma ammonia decomposition and preparation method and application, belong to ammonia decomposition hydrogen catalyst technical field.The application is different from traditional technical path, and plasma activation is combined with high-entropy alloy catalysis to form a synergistic reaction system, and Ce-WO3@SiC particles are added in high-entropy alloy simultaneously, the catalyst prepared has synergistic catalysis with active species generated by plasma, significantly reduces the activation energy barrier of ammonia decomposition, provides catalytic active sites while high-entropy alloy, Ce-WO3@SiC particles synergistically promote the decomposition reaction of ammonia, improve the catalytic activity of high-entropy alloy catalyst in plasma ammonia decomposition hydrogen production technology, realize near complete conversion rate of efficient hydrogen production at lower temperature than traditional thermal catalysis, break through the limitation of thermodynamics.

Description

Technical Field

[0001] This invention belongs to the field of ammonia decomposition hydrogen production catalyst technology, specifically relating to a high-entropy alloy catalyst for plasma ammonia decomposition hydrogen production, its preparation method, and its application. Background Technology

[0002] Ammonia, as a promising liquid hydrogen storage medium, is considered a key carrier for realizing the large-scale and economical application of hydrogen energy. However, traditional thermocatalytic ammonia decomposition hydrogen production technology is energy-intensive, has stringent requirements for reactor materials, and is costly. Furthermore, the high-temperature environment easily leads to rapid catalyst deactivation, posing challenges to long-term operational stability. To overcome this thermodynamic limitation, low-temperature plasma technology has emerged, providing a new pathway for low-temperature, low-energy ammonia decomposition.

[0003] Although plasma technology successfully circumvents the high-temperature requirement, its application alone in ammonia decomposition still faces a series of technical bottlenecks. First, the energy utilization efficiency of plasma reactions is relatively low. Second, if the active intermediates (such as *NH2 and *H) generated by non-equilibrium plasma cannot be rapidly recombined into nitrogen and hydrogen, side reactions may occur, leading to a decrease in product selectivity. Most importantly, the plasma environment poses a severe challenge to the stability of catalytic materials. Traditional single / bimetallic catalysts are prone to surface reconstruction and component segregation under this environment, resulting in low catalytic activity and requiring improvement in ammonia decomposition efficiency.

[0004] Therefore, developing a catalyst that combines activity and stability and can synergistically catalyze with active species generated by plasma is of great significance for overcoming the challenge of low efficiency in plasma ammonia decomposition. Summary of the Invention

[0005] The purpose of this invention is to provide a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production, its preparation method, and its application, which can solve the problem of low catalytic activity of existing plasma ammonia decomposition to hydrogen production catalysts.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0008] S1. Weigh at least five metal raw materials from aluminum, magnesium, vanadium, chromium, manganese, iron, cobalt, nickel, niobium and molybdenum, mix them to obtain a metal mixture, and put it into a smelting equipment;

[0009] S2. Under an inert atmosphere, high-temperature melting is used to form an alloy liquid, which is then cooled to obtain a high-entropy alloy ingot.

[0010] S3. The high-entropy alloy ingot is crushed, and then mechanically ball-milled under an inert atmosphere to obtain alloy powder.

[0011] S4. Add Ce-WO3@SiC particles to the alloy powder and mechanically ball-mill under an inert atmosphere to obtain the catalyst.

[0012] Compared to single / bimetallic catalysts, high-entropy alloys exhibit a unique surface electronic structure formed through the synergistic effect of multiple elements, optimizing the adsorption strength of reaction intermediates. This results in structural stability at high temperatures and high catalytic activity. Due to the slow diffusion effect in high-entropy alloys, the effective diffusion rate of each element's atom is low under local hot spots generated by plasma discharge, improving the catalyst's dynamic stability and solving the problem of rapid catalyst deactivation. The lattice distortion in high-entropy alloys generates numerous strain sites and defects, which are highly active sites for NH3 dissociation. In catalyst preparation, high-entropy alloy powder is first formed through high-temperature melting and mechanical ball milling. Then, the high-entropy alloy and Ce-WO3@SiC particles are combined through mechanical ball milling. This two-step mechanical ball milling process prioritizes the full bonding between the metal elements in the high-entropy alloy, avoiding the physical barrier to elemental bonding caused by the simultaneous addition of Ce-WO3@SiC particles. The composite addition of Ce-WO3@SiC particles serves two main purposes. First, silicon carbide, as a highly thermally conductive material, can rapidly dissipate the heat generated by plasma discharge and catalytic reactions, suppressing local overheating and protecting the active sites of the high-entropy alloy. The high dielectric constant of SiC can locally enhance the electric field strength, generating stronger micro-discharges and increasing the high-energy electron density, thereby more efficiently exciting and cracking gaseous NH3 molecules and promoting the decomposition reaction of ammonia. Second, under the strong electric field and high-energy electron bombardment generated by plasma, Ce-WO3 readily generates oxygen vacancies, which can act as acceptors for hydrogen overflow, promoting the generation and rapid desorption of H2 molecules and avoiding the decrease in activity caused by hydrogen poisoning.

[0013] Furthermore, the total elemental molar percentage of iron, cobalt, and nickel in the metal mixture is 40-80%, and the total elemental molar percentage of the remaining metals is 20-60%.

[0014] Furthermore, the equipment for high-temperature melting is one of an electric arc melting furnace, an induction melting furnace, and a suspension melting furnace.

[0015] Furthermore, the specific steps of the high-temperature smelting are as follows:

[0016] Place the various metal raw materials into a crucible inside the melting furnace, and evacuate to a vacuum level of ≤1×10⁻⁶. 2 Pa, inert gas is introduced, the pressure is controlled at 0.02~0.06MPa, the melting temperature is 1600-2000℃, an alloy liquid is formed by melting, and the alloy ingot is obtained by cooling to room temperature. The alloy ingot is flipped and the melting is repeated 2-5 times.

[0017] Because of the large differences in the specific gravity of each element in high-entropy alloys, compositional segregation is easily generated in a single melting process, while multiple melting processes with flipping can make the elements tend to be uniform.

[0018] Furthermore, in steps S2, S3, and S4, the inert atmosphere is at least one of argon and helium.

[0019] Furthermore, the equipment used for the mechanical ball mill is a high-energy planetary ball mill.

[0020] Furthermore, the ball-to-material mass ratio of the mechanical ball mill is 1-50:1, the grinding media is grinding balls made of cemented carbide or zirconium oxide, the ball milling speed is 400-1200 rpm, and the ball milling time is 6-30 h.

[0021] Furthermore, the ball-to-material mass ratio in the mechanical ball mill is 5-20:1.

[0022] Furthermore, the grinding media for the mechanical ball mill is zirconia grinding balls with a particle size of Φ5-Φ15cm, wherein the mass ratio of Φ5-Φ8cm zirconia beads to Φ9-Φ15cm zirconia grinding balls is 1-5:1.

[0023] Furthermore, the preparation steps of the Ce-WO3@SiC particles are as follows:

[0024] Ammonium paratungstate was dissolved in deionized water to obtain an ammonium paratungstate solution. The pH of the ammonium paratungstate solution was adjusted to 7-9 with ammonia water. A cerium nitrate ethanol solution was prepared and added dropwise to the ammonium paratungstate solution. The mixture was stirred to obtain a colloid. SiC powder was added, mixed evenly, dried, and calcined to obtain Ce-WO3@SiC particles.

[0025] Ammonium paratungstate solution is weakly acidic. Ammonia is added to adjust the pH and control the hydrolysis of ammonium paratungstate. Cerium nitrate ethanol solution is added dropwise to reduce Ce. 3+ Uniformly dispersed in colloid, after drying and calcination, Ce-doped WO3 is formed and loaded on the SiC surface. Metal oxides have high surface energy and are prone to agglomeration. Using silicon carbide as a carrier can disperse and load it, and it can also make it fully contact the alloy powder during subsequent grinding.

[0026] Furthermore, the concentration of ammonium paratungstate in the ammonium paratungstate solution is 3-5 mmol / L.

[0027] Furthermore, the cerium nitrate ethanol solution is obtained by dissolving cerium nitrate hexahydrate in ethanol at a concentration of 5-6 mmol / L.

[0028] Furthermore, the cerium nitrate ethanol solution is added dropwise to the ammonium paratungstate solution at an elemental molar ratio of tungsten to cerium of (90-98):(2-10).

[0029] Furthermore, the mass ratio of the SiC powder to ammonium paratungstate is 0.1-0.3:1.

[0030] Furthermore, the drying temperature is 70-85℃, and the drying time is 2-4 hours;

[0031] The calcination temperature is 500-550℃, and the calcination time is 1-2 hours.

[0032] Furthermore, the mass ratio of the Ce-WO3@SiC particles to the alloy powder is 1-8:100.

[0033] The present invention also provides a high-entropy alloy catalyst for plasma ammonia decomposition to produce hydrogen, which is prepared by the preparation method described above.

[0034] This invention also provides an application of a high-entropy alloy catalyst for plasma ammonia decomposition to produce hydrogen. The catalyst described above is filled in the discharge region of a dielectric barrier discharge fixed-bed reactor. After ammonia gas is introduced, the reactor is discharged to carry out the ammonia decomposition reaction and obtain nitrogen and hydrogen.

[0035] Furthermore, the plasma power supply for dielectric barrier discharge has a discharge power of 10-200W.

[0036] Furthermore, the flow rate of the ammonia gas is 20-2000 mL / min. -1 .

[0037] The beneficial effects of this invention are:

[0038] (1) This invention differs from traditional technical approaches by combining plasma activation with high-entropy alloy catalysis to form a synergistic reaction system. The synthesized catalyst and the active species generated by plasma have a synergistic catalytic effect, which significantly reduces the activation energy barrier of ammonia decomposition. Thus, it can achieve efficient hydrogen production with near-complete conversion at temperatures lower than those of traditional thermocatalysis, breaking through thermodynamic limitations.

[0039] (2) In this invention, a purely physical path of metal smelting and mechanical ball milling is used to prepare high-entropy alloys. The entire process is carried out under an inert atmosphere, with no harmful emissions. The raw materials are preferably transition metals with high shell abundance, avoiding dependence on precious metals. The process is short and the equipment is highly versatile. This not only significantly reduces production costs and environmental impact, but also lays a solid foundation for subsequent large-scale production.

[0040] (3) The high-entropy alloy powder catalyst provided by the present invention has both high activity and plasma field stability. Its multi-principal component optimizes the adsorption capacity for ammonia and hydrogen, and improves the reaction rate and hydrogen selectivity. At the same time, the inherent high-entropy effect and strong atomic bonding force of the alloy endow it with excellent structural stability in the extreme plasma environment, effectively overcoming the problem of easy deactivation of traditional catalysts and ensuring the reliability of long-term system operation.

[0041] (4) In this invention, Ce-WO3@SiC particles are added to a high-entropy alloy and composited by mechanical ball milling. The Ce-WO3@SiC particles promote the dispersion of the alloy. While the high-entropy alloy provides catalytic active sites, silicon carbide, as a high thermal conductivity material, can quickly dissipate the heat generated by plasma discharge and catalytic reaction, suppress local overheating, and protect the active sites of the high-entropy alloy. The high dielectric constant of SiC can locally enhance the electric field strength, generate stronger micro-discharge, and increase the high-energy electron density, thereby more efficiently exciting and cracking gaseous NH3 molecules and promoting the decomposition reaction of ammonia. Under the strong electric field and high-energy electron bombardment generated by plasma, Ce-WO3 easily generates oxygen vacancies, which can act as acceptors for hydrogen overflow, promote the generation of H2 molecules and rapid desorption, avoid the activity decrease caused by hydrogen poisoning, and improve the catalytic activity of the high-entropy alloy catalyst in plasma ammonia decomposition hydrogen production technology. Attached Figure Description

[0042] The invention will now be further described with reference to the accompanying drawings.

[0043] Figure 1 This is a schematic diagram of the FeCoNiAlNb high-entropy alloy ingot of Embodiment 1 of the present invention;

[0044] Figure 2 These are catalytic stability test graphs for Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0045] 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.

[0046] Example 1

[0047] Preparation of Ce-WO3@SiC particles:

[0048] Ammonium paratungstate was weighed and added to deionized water, and sonicated at 60℃ for 30 min to obtain a 4 mmol / L ammonium paratungstate solution. The pH of the ammonium paratungstate solution was adjusted to 8.0 with 25% ammonia. Cerium nitrate hexahydrate was weighed and added to ethanol, and stirred to obtain a 5 mmol / L cerium nitrate solution. The cerium nitrate solution was added dropwise to the pH-adjusted ammonium paratungstate solution, controlling the molar ratio of tungsten to cerium to be 95:5. The mixture was stirred to obtain a colloid, and SiC powder was added. The mass ratio of SiC powder to ammonium paratungstate was 0.2:1. After mixing evenly, the mixture was dried in an oven at 80℃ for 3 h. After drying, it was transferred to a muffle furnace and calcined at 500℃ for 1.5 h to obtain Ce-WO3@SiC particles.

[0049] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0050] S1. Weigh iron particles, cobalt particles, nickel particles, aluminum particles and niobium particles with a purity of 99.8%, wherein the molar proportions of iron, cobalt, nickel, aluminum and niobium are 15%, 25%, 30%, 18% and 12% respectively. After mixing, a metal mixture is obtained and put into the crucible of the electric arc melting furnace.

[0051] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 Pa, then argon gas is introduced to 0.05 MPa, repeated twice to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to achieve a melting temperature of 1800℃ until all metal raw materials are fully melted and form bright, uniform molten droplets, ensuring complete miscibility and homogenization of the components to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain a FeCoNiAlNb high-entropy alloy ingot. Figure 1 As shown.

[0052] S3. The FeCoNiAlNb high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by using its filling / exhausting valve and then refilling with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 12 hours. After ball milling, FeCoNiAlNb alloy powder was obtained.

[0053] S4. Remove the alloy powder and add Ce-WO3@SiC particles to it. The mass ratio of Ce-WO3@SiC particles to alloy powder is 6:100. After mixing, place the mixture in a stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a mass ratio of 2:1), with a ball-to-powder mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to create an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst with a particle size of 5-50 nm is obtained.

[0054] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0055] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0056] Under high ammonia flow rate: 20g of catalyst was packed into the discharge zone of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced. The ammonia flow rate was set to 2000mL·min. -1 The plasma power supply discharge power was maintained at 200W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0057] Example 2

[0058] The only difference from Example 1 is that the metal raw material formulation of the catalyst is different, and five metal raw materials, namely iron, cobalt, nickel, manganese and vanadium, are used to replace the five metal raw materials, namely iron, cobalt, nickel, aluminum and niobium.

[0059] The conditions and steps for preparing Ce-WO3@SiC particles are the same as in Example 1.

[0060] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0061] S1. Weigh iron granules, cobalt granules, nickel granules, manganese flakes and vanadium granules with a purity of 99.8%, wherein the molar proportions of iron, cobalt, nickel, manganese and vanadium are 15%, 25%, 30%, 13% and 17% respectively. After mixing, a metal mixture is obtained and put into the crucible of the electric arc melting furnace.

[0062] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 The pressure is increased to 0.05 MPa, and then argon gas is introduced to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to maintain the melting temperature at 1800°C until all the metal raw materials are fully melted and form bright, uniform molten droplets, ensuring that the components are fully miscible and homogenized to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain a FeCoNiMnV high-entropy alloy ingot.

[0063] S3. The FeCoNiMnV high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by evacuating the jar through its filling / exhausting valve and then refilling it with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 12 hours. After ball milling, FeCoNiMnV alloy powder was obtained.

[0064] S4. Remove the alloy powder and add Ce-WO3@SiC particles to it. The mass ratio of Ce-WO3@SiC particles to alloy powder is 6:100. After mixing, place the mixture in a stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a mass ratio of 2:1), with a ball-to-powder mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to create an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst with a particle size of 5-50 nm is obtained.

[0065] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0066] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0067] Example 3

[0068] The only difference from Example 1 is that the metal raw material formulation of the catalyst is different, and five metal raw materials, namely iron, cobalt, nickel, aluminum and magnesium, are used to replace the five metal raw materials, namely iron, cobalt, nickel, aluminum and niobium.

[0069] The conditions and steps for preparing Ce-WO3@SiC particles are the same as in Example 1.

[0070] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0071] S1. Weigh iron, cobalt, nickel, aluminum and magnesium particles with a purity of 99.8%, wherein the molar percentages of iron, cobalt, nickel, aluminum and magnesium are 15%, 25%, 30%, 20% and 10% respectively. Mix them to obtain a metal mixture and put it into the crucible of the electric arc melting furnace.

[0072] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 The pressure was increased to 0.05 MPa, and then argon gas was introduced to ensure the furnace was filled with inert gas. The voltage and current of the electric arc melting furnace were adjusted to maintain a melting temperature of 1800°C until all the metal raw materials were fully melted and formed bright, uniform molten droplets, ensuring that the components were fully miscible and homogenized to form an alloy liquid. Heating was then stopped, and the alloy was allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot was flipped using a turning rod, and the above melting process was repeated a total of 3 times to obtain a FeCoNiAlMg high-entropy alloy ingot.

[0073] S3. The FeCoNiAlMg high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by evacuating the jar through its filling / exhausting valve and then refilling it with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 12 hours. After ball milling, FeCoNiAlMg alloy powder was obtained.

[0074] S4. Remove the alloy powder and add Ce-WO3@SiC particles to it. The mass ratio of Ce-WO3@SiC particles to alloy powder is 6:100. After mixing, place the mixture in a stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a mass ratio of 2:1), with a ball-to-powder mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to create an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst with a particle size of 5-50 nm is obtained.

[0075] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0076] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0077] Example 4

[0078] The only difference from Example 1 is that the molar ratio of tungsten to cerium was adjusted to 98:2 when preparing Ce-WO3@SiC particles.

[0079] Preparation of Ce-WO3@SiC particles:

[0080] Ammonium paratungstate was weighed and added to deionized water, and sonicated at 60℃ for 30 min to obtain a 4 mmol / L ammonium paratungstate solution. The pH of the ammonium paratungstate solution was adjusted to 8.0 with 25% ammonia. Cerium nitrate hexahydrate was weighed and added to ethanol, and stirred to obtain a 5 mmol / L cerium nitrate solution. The cerium nitrate solution was added dropwise to the pH-adjusted ammonium paratungstate solution, controlling the molar ratio of tungsten to cerium to be 98:2. The mixture was stirred to obtain a colloid, and SiC powder was added at a mass ratio of SiC powder to ammonium paratungstate of 0.2:1. After mixing evenly, the mixture was dried in an oven at 80℃ for 3 h. After drying, it was transferred to a muffle furnace and calcined at 500℃ for 1.5 h to obtain Ce-WO3@SiC particles.

[0081] The preparation conditions and steps of the plasma ammonia decomposition hydrogen production high-entropy alloy catalyst are the same as in Example 1, except that the Ce-WO3@SiC particles prepared in this example are used to replace the Ce-WO3@SiC particles prepared in Example 1.

[0082] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition: 8g of catalyst was packed into the discharge region of a dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0083] Example 5

[0084] The only difference from Example 1 is that the molar ratio of tungsten to cerium was adjusted to 90:10 when preparing Ce-WO3@SiC particles.

[0085] Preparation of Ce-WO3@SiC particles:

[0086] Ammonium paratungstate was weighed and added to deionized water, and sonicated at 60℃ for 30 min to obtain a 4 mmol / L ammonium paratungstate solution. The pH of the ammonium paratungstate solution was adjusted to 8.0 with 25% ammonia. Cerium nitrate hexahydrate was weighed and added to ethanol, and stirred to obtain a 5 mmol / L cerium nitrate solution. The cerium nitrate solution was added dropwise to the pH-adjusted ammonium paratungstate solution, controlling the molar ratio of tungsten to cerium to be 90:10. The mixture was stirred to obtain a colloid, and SiC powder was added. The mass ratio of SiC powder to ammonium paratungstate was 0.2:1. After mixing evenly, the mixture was dried in an oven at 80℃ for 3 h. After drying, it was transferred to a muffle furnace and calcined at 500℃ for 1.5 h to obtain Ce-WO3@SiC particles.

[0087] The preparation conditions and steps of the plasma ammonia decomposition hydrogen production high-entropy alloy catalyst are the same as in Example 1, except that the Ce-WO3@SiC particles prepared in this example are used to replace the Ce-WO3@SiC particles prepared in Example 1.

[0088] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0089] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0090] Example 6

[0091] The only difference from Example 1 is that the mass ratio of Ce-WO3@SiC particles to alloy powder is adjusted to 1:100.

[0092] The steps and conditions for preparing Ce-WO3@SiC particles are the same as in Example 1.

[0093] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0094] S1. Weigh iron particles, cobalt particles, nickel particles, aluminum particles and niobium particles with a purity of 99.8%, wherein the molar proportions of iron, cobalt, nickel, aluminum and niobium are 15%, 25%, 30%, 18% and 12% respectively. After mixing, a metal mixture is obtained and put into the crucible of the electric arc melting furnace.

[0095] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 Pa, then argon gas is introduced to 0.05 MPa, repeated twice to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to achieve a melting temperature of 1800℃ until all metal raw materials are fully melted and form bright, uniform molten droplets, ensuring complete miscibility and homogenization of the components to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain a FeCoNiAlNb high-entropy alloy ingot. Figure 1 As shown.

[0096] S3. The FeCoNiAlNb high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by using its filling / exhausting valve and then refilling with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 12 hours. After ball milling, FeCoNiAlNb alloy powder was obtained.

[0097] S4. Remove the alloy powder and add Ce-WO3@SiC particles to it. The mass ratio of Ce-WO3@SiC particles to alloy powder is 1:100. After mixing, place the mixture in a stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a mass ratio of 2:1), with a ball-to-powder mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to create an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst with a particle size of 5-50 nm is obtained.

[0098] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0099] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0100] Example 7

[0101] The only difference from Example 1 is that the mass ratio of Ce-WO3@SiC particles to alloy powder is adjusted to 4:100.

[0102] The steps and conditions for preparing Ce-WO3@SiC particles are the same as in Example 1.

[0103] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0104] S1. Weigh iron particles, cobalt particles, nickel particles, aluminum particles and niobium particles with a purity of 99.8%, wherein the molar proportions of iron, cobalt, nickel, aluminum and niobium are 15%, 25%, 30%, 18% and 12% respectively. After mixing, a metal mixture is obtained and put into the crucible of the electric arc melting furnace.

[0105] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2Pa, then argon gas is introduced to 0.05 MPa, repeated twice to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to achieve a melting temperature of 1800℃ until all metal raw materials are fully melted and form bright, uniform molten droplets, ensuring complete miscibility and homogenization of the components to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain a FeCoNiAlNb high-entropy alloy ingot. Figure 1 As shown.

[0106] S3. The FeCoNiAlNb high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by using its filling / exhausting valve and then refilling with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 12 hours. After ball milling, FeCoNiAlNb alloy powder was obtained.

[0107] S4. Remove the alloy powder and add Ce-WO3@SiC particles to it. The mass ratio of Ce-WO3@SiC particles to alloy powder is 4:100. After mixing, place the mixture in a stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a mass ratio of 2:1), with a ball-to-powder mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to create an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst with a particle size of 5-50 nm is obtained.

[0108] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0109] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0110] Example 8

[0111] The only difference from Example 1 is that the mass ratio of Ce-WO3@SiC particles to alloy powder is adjusted to 8:100.

[0112] The steps and conditions for preparing Ce-WO3@SiC particles are the same as in Example 1.

[0113] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0114] S1. Weigh iron particles, cobalt particles, nickel particles, aluminum particles and niobium particles with a purity of 99.8%, wherein the molar proportions of iron, cobalt, nickel, aluminum and niobium are 15%, 25%, 30%, 18% and 12% respectively. After mixing, a metal mixture is obtained and put into the crucible of the electric arc melting furnace.

[0115] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 Pa, then argon gas is introduced to 0.05 MPa, repeated twice to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to achieve a melting temperature of 1800℃ until all metal raw materials are fully melted and form bright, uniform molten droplets, ensuring complete miscibility and homogenization of the components to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain a FeCoNiAlNb high-entropy alloy ingot. Figure 1 As shown.

[0116] S3. The FeCoNiAlNb high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by using its filling / exhausting valve and then refilling with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 12 hours. After ball milling, FeCoNiAlNb alloy powder was obtained.

[0117] S4. Remove the alloy powder and add Ce-WO3@SiC particles to it. The mass ratio of Ce-WO3@SiC particles to alloy powder is 8:100. After mixing, place the mixture in a stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a mass ratio of 2:1), with a ball-to-powder mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to create an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst with a particle size of 5-50 nm is obtained.

[0118] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0119] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0120] Comparative Example 1

[0121] The only difference from Example 1 is that in this comparative example, the catalyst used for ammonia decomposition is not plasma discharge catalysis, but heating catalysis.

[0122] The steps and conditions for preparing Ce-WO3@SiC particles and the high-entropy alloy catalyst for plasma ammonia decomposition to produce hydrogen are the same as in Example 1.

[0123] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0124] At low ammonia flow rates: 8g of catalyst was packed into a fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The reactor was heated to 400°C and held for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0125] Under high ammonia flow rate: 20g of catalyst was packed into the discharge zone of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced. The ammonia flow rate was set to 2000mL·min. -1The reactor was heated to 400°C and held for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0126] Comparative Example 2

[0127] The only difference from Example 2 is that in this comparative example, the catalyst used for ammonia decomposition is not plasma discharge catalysis, but heating catalysis.

[0128] The steps and conditions for preparing Ce-WO3@SiC particles and the high-entropy alloy catalyst for plasma ammonia decomposition to produce hydrogen are the same as in Example 1.

[0129] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0130] At low ammonia flow rates: 8g of catalyst was packed into a fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The reactor was heated to 400°C and held for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0131] Comparative Example 3

[0132] The only difference from Example 3 is that in this comparative example, the catalyst used for ammonia decomposition is not plasma discharge catalysis, but heating catalysis.

[0133] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0134] At low ammonia flow rates: 8g of catalyst was packed into a fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The reactor was heated to 400°C and held for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0135] Comparative Example 4

[0136] The only difference from Example 1 is that in this comparative example, three metal raw materials, iron, nickel, and cobalt, are used to replace five metal raw materials, namely iron, cobalt, nickel, aluminum, and niobium.

[0137] The conditions and steps for preparing Ce-WO3@SiC particles are the same as in Example 1.

[0138] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0139] S1. Weigh iron and cobalt particles with a purity of 99.8%, wherein the molar percentages of iron, nickel and cobalt are 21.5%, 35.5% and 43% respectively. Mix them to obtain a metal mixture and put it into the crucible of the electric arc melting furnace.

[0140] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 The pressure is increased to 0.05 MPa, then argon gas is introduced to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to maintain a melting temperature of 1800°C until all metal raw materials are fully melted and form bright, uniform molten droplets, ensuring complete miscibility and homogenization of the components to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form an alloy ingot. The alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain an FeCoNi alloy ingot.

[0141] S3. The FeCoNi alloy ingot is crushed into small pieces and placed together with zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum is created by evacuating the jar through its filling / exhausting valve and then refilling it with argon gas to form an inert protective atmosphere. The ball mill speed is set to 1000 rpm, and an intermittent operation mode is adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time is 12 hours. After ball milling, FeCoNi alloy powder is obtained.

[0142] S4. Remove the alloy powder and add Ce-WO3@SiC particles to it. The mass ratio of Ce-WO3@SiC particles to alloy powder is 6:100. After mixing, place the mixture in a stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a mass ratio of 2:1), with a ball-to-powder mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to create an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst with a particle size of 5-50 nm is obtained.

[0143] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0144] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0145] Under high ammonia flow rate: 20g of catalyst was packed into the discharge zone of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced. The ammonia flow rate was set to 2000mL·min. -1 The plasma power supply discharge power was maintained at 200W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0146] Comparative Example 5

[0147] The only difference from Example 1 is that SiC powder is used instead of Ce-WO3@SiC particles in this comparative example.

[0148] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0149] S1. Weigh iron particles, cobalt particles, nickel particles, aluminum particles and niobium particles with a purity of 99.8%, wherein the molar proportions of iron, cobalt, nickel, aluminum and niobium are 15%, 25%, 30%, 18% and 12% respectively. After mixing, a metal mixture is obtained and put into the crucible of the electric arc melting furnace.

[0150] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 Pa, then argon gas is introduced to 0.05 MPa, repeated twice to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to achieve a melting temperature of 1800℃ until all metal raw materials are fully melted and form bright, uniform molten droplets, ensuring complete miscibility and homogenization of the components to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain a FeCoNiAlNb high-entropy alloy ingot. Figure 1 As shown.

[0151] S3. The FeCoNiAlNb high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by using its filling / exhausting valve and then refilling with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 12 hours. After ball milling, FeCoNiAlNb alloy powder was obtained.

[0152] S4. Remove the alloy powder and add SiC powder to it. The mass ratio of SiC powder to alloy powder is 6:100. After mixing, place the mixture in the stainless steel grinding jar of a high-energy planetary ball mill. Add zirconia grinding balls (the mass ratio of 5mm diameter zirconia grinding balls to 10mm diameter zirconia grinding balls is 2:1), with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, evacuate it through its charging / evacuation valve and then refill it with argon to form an inert protective atmosphere. Set the ball mill speed to 600 rpm and use an intermittent operation mode (ball milling for 60 minutes, followed by a 30-minute cooling stop) to prevent overheating. The total effective ball milling time is 6 hours. After ball milling, the catalyst is obtained with a particle size of 5-50 nm.

[0153] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0154] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0155] Under high ammonia flow rate: 20g of catalyst was packed into the discharge zone of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced. The ammonia flow rate was set to 2000mL·min. -1 The plasma power supply discharge power was maintained at 200W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0156] Comparative Example 6

[0157] The only difference from Example 1 is that Ce-WO3@SiC particles are not added in this comparative example.

[0158] A method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production includes the following steps:

[0159] S1. Weigh iron particles, cobalt particles, nickel particles, aluminum particles and niobium particles with a purity of 99.8%, wherein the molar proportions of iron, cobalt, nickel, aluminum and niobium are 15%, 25%, 30%, 18% and 12% respectively. After mixing, a metal mixture is obtained and put into the crucible of the electric arc melting furnace.

[0160] S2. The electric arc melting furnace is evacuated to ≤1×10⁻⁶. 2 Pa, then argon gas is introduced to 0.05 MPa, repeated twice to ensure the furnace is filled with inert gas. The voltage and current of the electric arc melting furnace are adjusted to achieve a melting temperature of 1800℃ until all metal raw materials are fully melted and form bright, uniform molten droplets, ensuring complete miscibility and homogenization of the components to form an alloy liquid. Heating is then stopped, and the alloy is allowed to cool naturally to room temperature to form a high-entropy alloy ingot. The high-entropy alloy ingot is flipped using a turning rod, and the above melting process is repeated a total of 3 times to obtain a FeCoNiAlNb high-entropy alloy ingot. Figure 1 As shown.

[0161] S3. The FeCoNiAlNb high-entropy alloy ingot was crushed into small pieces and placed together with zirconia grinding balls (5mm diameter zirconia grinding balls and 10mm diameter zirconia grinding balls in a 2:1 mass ratio) in a stainless steel grinding jar of a high-energy planetary ball mill, with a ball-to-material mass ratio of 15:1. After sealing the grinding jar, a vacuum was created by using its filling / exhausting valve and then refilling with argon gas to form an inert protective atmosphere. The ball mill speed was set to 1000 rpm, and an intermittent operation mode was adopted (ball milling for 30 minutes, followed by a 15-minute cooling stop) to prevent overheating. The total effective ball milling time was 18 hours. After ball milling, the catalyst with a particle size of 10-50 nm was obtained.

[0162] The prepared catalyst was applied to plasma-catalyzed ammonia decomposition:

[0163] At low ammonia flow rate: 8g of catalyst was packed into the discharge region of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced, with the flow rate set to 50mL·min. -1 100 mL·min -1 150 mL·min -1 The plasma power supply discharge power was maintained at 50W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded through a mixing flow meter.

[0164] Under high ammonia flow rate: 20g of catalyst was packed into the discharge zone of the dielectric barrier discharge fixed-bed reactor, and pure ammonia was introduced. The ammonia flow rate was set to 2000mL·min.-1 The plasma power supply discharge power was maintained at 200W for 30 minutes. Unreacted ammonia was absorbed with dilute sulfuric acid solution, and the generated nitrogen and hydrogen were recorded by a mixing flow meter.

[0165] The results of ammonia decomposition for hydrogen production using the catalysts of Examples 1-8 and Comparative Examples 1-6 at low ammonia flow rates are shown in Table 1. The results of ammonia decomposition for hydrogen production using the catalysts of Examples 1, Comparative Examples 1, and Comparative Examples 4-6 at high ammonia flow rates are shown in Table 2. The ammonia decomposition tests for Examples 1 and Comparative Examples 1 were conducted with an ammonia flow rate of 50 mL / min. -1 Long-term continuous monitoring was conducted to obtain catalytic stability test graphs, such as... Figure 2 As shown.

[0166] Table 1

[0167]

[0168] Table 2

[0169]

[0170] As shown in Table 1, the catalyst used in the embodiments of the present invention for plasma-catalyzed ammonia decomposition exhibits high catalytic activity, with high ammonia conversion rates at different ammonia gas flow rates. Combining the results of Example 1 and Comparative Example 6, it can be seen that combining Ce-WO3@SiC particles with a high-entropy alloy can improve the catalytic efficiency of the catalyst under plasma conditions, achieving high efficiency at an ammonia gas flow rate of 50 mL / min. -1 Under these conditions, the conversion rate of Example 1 can reach 99.9%. From the results of Examples 1 and Examples 6-8, it can be seen that excessive addition of Ce-WO3@SiC particles will cover the active sites of the alloy catalyst, thereby reducing the catalytic activity. Appropriate addition can ensure the improvement of catalytic activity.

[0171] As can be seen from Table 2, under the conditions of high space velocity and high flow rate in simulated industrial production, the catalyst described in this invention still exhibits excellent catalytic activity. The conversion rate of Example 1 can reach 67.2%, which fully demonstrates that the catalyst has good application potential in industrial application scenarios.

[0172] Depend on Figure 2 It can be seen that, compared with thermal catalysis, under the synergistic effect of plasma activation and high-entropy alloy catalytic dissociation, the catalyst can achieve the effect of efficient and stable catalytic decomposition of ammonia to produce hydrogen. Compared with Comparative Example 1, the ammonia conversion rate in Example 1 is high, and it can maintain high catalytic activity for a long time and has good catalytic stability.

[0173] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0174] 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 method for preparing a high-entropy alloy catalyst for hydrogen production via plasma ammonia decomposition, characterized in that, Includes the following steps: S1. Weigh at least five metal raw materials from aluminum, magnesium, vanadium, chromium, manganese, iron, cobalt, nickel, niobium and molybdenum, mix them to obtain a metal mixture, and put it into a smelting equipment; S2. Under an inert atmosphere, high-temperature melting is used to form an alloy liquid, which is then cooled to obtain a high-entropy alloy ingot. S3. The high-entropy alloy ingot is crushed, and then mechanically ball-milled under an inert atmosphere to obtain alloy powder. S4. Add Ce-WO3@SiC particles to the alloy powder and mechanically ball mill under an inert atmosphere to obtain the catalyst; The preparation steps of the Ce-WO3@SiC particles are as follows: Ammonium paratungstate was dissolved in deionized water to obtain an ammonium paratungstate solution. The pH of the ammonium paratungstate solution was adjusted to 7-9 with ammonia water. A cerium nitrate ethanol solution was prepared and added dropwise to the ammonium paratungstate solution. The mixture was stirred to obtain a colloid. SiC powder was added, mixed evenly, dried, and calcined to obtain Ce-WO3@SiC particles.

2. The method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production according to claim 1, characterized in that, The total elemental molar percentage of iron, cobalt, and nickel in the metal mixture is 40-80%, while the total elemental molar percentage of the remaining metals is 20-60%.

3. The method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production according to claim 1, characterized in that, The specific steps of the high-temperature smelting are as follows: Place the various metal raw materials into a crucible inside the melting furnace, and evacuate to a vacuum level of ≤1×10⁻⁶. 2 Pa, inert gas is introduced, the pressure is controlled at 0.02~0.06MPa, the melting temperature is 1600-2000℃, an alloy liquid is formed by melting, and the alloy ingot is obtained by cooling to room temperature. The alloy ingot is flipped and the melting is repeated 2-5 times.

4. The method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production according to claim 1, characterized in that, The concentration of ammonium paratungstate in the ammonium paratungstate solution is 3-5 mmol / L; The cerium nitrate ethanol solution was obtained by dissolving cerium nitrate hexahydrate in ethanol at a concentration of 5-6 mmol / L.

5. The method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production according to claim 1, characterized in that, The cerium nitrate ethanol solution was added dropwise to the ammonium paratungstate solution at an elemental molar ratio of tungsten to cerium of (90-98):(2-10).

6. The method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production according to claim 1, characterized in that, The mass ratio of SiC powder to ammonium paratungstate is 0.1-0.3:

1.

7. The method for preparing a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production according to claim 1, characterized in that, The mass ratio of Ce-WO3@SiC particles to alloy powder is 1-8:

100.

8. A high-entropy alloy catalyst for plasma ammonia decomposition to produce hydrogen, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The application of a high-entropy alloy catalyst for plasma ammonia decomposition to hydrogen production, characterized in that, The discharge region of the dielectric barrier discharge fixed-bed reactor is filled with the catalyst as described in claim 8. After ammonia gas is introduced, the reactor is discharged to carry out the ammonia decomposition reaction and obtain nitrogen and hydrogen gas.

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