A highly efficient thermal catalyst for ammonia synthesis under mild conditions, and a preparation method and application thereof

Abstract

The application relates to the technical field of catalyst material preparation, and discloses a high-efficiency thermal catalyst for synthesizing ammonia under mild conditions and a preparation method and application thereof. The catalyst comprises a foamed metal carrier, an electroplating liquid precursor and an additive; the preparation method comprises the following steps: pretreating the foamed carrier, dissolving the electroplating liquid precursor in deionized water to obtain an electroplating liquid; taking the pretreated foamed carrier as a working electrode, and performing electro-deposition in the electroplating liquid by adopting an electrochemical deposition method to prepare a metal alloy catalyst; and placing the obtained metal alloy catalyst and the additive in the downstream and upstream of a tubular furnace respectively, and performing heating treatment to obtain the high-efficiency thermal catalyst. The catalyst prepared by adopting the method can realize high-efficiency synthesis of ammonia under relatively mild reaction conditions, has the advantages of high catalytic activity, good stability, low cost and the like, and due to the mild reaction conditions, energy consumption and carbon dioxide emission are effectively reduced, and the catalyst has good environmental benefits and industrial application prospects.

Description

Technical Field

[0001] This invention belongs to the field of catalyst material preparation technology, specifically relating to a highly efficient thermal catalyst for ammonia synthesis under mild conditions, its preparation method, and its application. Background Technology

[0002] Ammonia is a crucial chemical raw material with wide applications in various industrial sectors, including fertilizers, pharmaceuticals, plastics, synthetic fibers, and rubber. Due to its high hydrogen content and carbon-free nature, it is also considered a highly promising hydrogen energy carrier. Currently, global industrial-scale ammonia synthesis mainly relies on the traditional Haber-Bosch process. This technology, centered on an iron-based catalyst, requires high-purity nitrogen and hydrogen to react through a catalyst bed under harsh conditions of high temperature (400–525°C) and high pressure (15–32 MPa). Although this process has been developed for over a century, it still suffers from significant drawbacks such as extremely high energy consumption, low single-pass conversion efficiency (typically only 10%–15%), and substantial carbon emissions. Furthermore, the stringent reaction conditions place extremely high demands on equipment materials and manufacturing processes, significantly increasing production costs and equipment maintenance difficulties. This also makes it difficult to integrate with renewable energy-based water electrolysis hydrogen production technologies, limiting the expansion of green ammonia production.

[0003] To overcome the aforementioned technical bottlenecks, researchers have continuously dedicated themselves to the improvement and development of ammonia synthesis catalysts. Early research mainly focused on traditional iron-based catalysts, improving their catalytic performance by introducing promoters or optimizing the support to alleviate problems such as hydrogen poisoning and poor stability. Regarding support materials, carbon materials such as activated carbon and carbon nanotubes have attracted attention due to their high specific surface area. However, under high temperature and high pressure reaction conditions, carbon is prone to methanation with hydrogen, leading to structural damage to the support and catalyst deactivation. Therefore, researchers have gradually shifted towards non-carbon oxide support systems, aiming to achieve ammonia synthesis under milder conditions while avoiding methanation problems, and have made some progress. In recent years, ruthenium (Ru)-based catalysts have gained attention due to their ability to operate at low temperatures and pressures and their long service life; however, the rarity and high cost of ruthenium severely restrict its large-scale industrial application. Furthermore, while some catalysts using transition metals as active components have shown performance improvements, they generally still suffer from insufficient catalytic activity or inadequately mild reaction conditions. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a highly efficient thermal catalyst for ammonia synthesis under mild conditions, its preparation method and application, so as to solve the technical problems of harsh reaction conditions, high cost and low activity of existing ammonia synthesis catalysts, so as to achieve efficient ammonia synthesis under mild conditions, reduce energy consumption and production costs, and reduce environmental pollution.

[0005] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions, comprising the following steps: S1: Pre-treat the foam carrier to obtain the pre-treated foam carrier; S2: Dissolve the electroplating solution precursor in deionized water to obtain the electroplating solution; S3: Using the pretreated foam carrier as the working electrode, a metal alloy catalyst is prepared by electrodeposition in the electroplating solution using an electrochemical deposition method. S4: The obtained metal alloy catalyst and additives are placed downstream and upstream of a tube furnace, respectively, and heated to obtain a highly efficient thermal catalyst for ammonia synthesis under mild conditions.

[0006] A further improvement of the present invention is that, in step S1, the foam carrier is at least one of foamed nickel, foamed copper, foamed aluminum, and foamed titanium, or a foam alloy composed of the same.

[0007] A further improvement of the present invention is that, in step S2, the electroplating solution precursor is at least one of a hydrated chloride or hydrated sulfate of a transition metal, wherein the transition metal is selected from one or two of copper, iron, zinc, manganese, molybdenum, nickel, and cobalt.

[0008] A further improvement of the present invention is that, in step S3, the electrochemical deposition adopts a three-electrode system, with a carbon rod as the counter electrode, a silver chloride electrode as the reference electrode, and a pretreated foam carrier as the working electrode; the deposition conditions are: constant potential -0.1V to -0.5V, deposition time 100 to 500s, and stirring speed 100 to 500rpm.

[0009] A further improvement of the present invention is that, in step S4, the auxiliary agent is at least one of WS2 or Ni2P.

[0010] A further improvement of the present invention is that, in step S4, the heating rate of the heating treatment is 1~5°C / min, the holding temperature is 200~500°C, and the holding time is 1~4h.

[0011] Secondly, the present invention also provides a highly efficient thermal catalyst for ammonia synthesis under mild conditions, the catalyst being prepared by the above-described preparation method; the catalyst comprises a foamed metal carrier, an electroplating solution precursor, and an additive; wherein the electroplating solution precursor is formed into a metal alloy by electrochemical deposition and loaded onto the foamed metal carrier, and the additive is loaded onto the surface of the metal alloy.

[0012] A further improvement of this invention is that the highly efficient thermal catalyst is a copper-based alloy catalyst promoted by an auxiliary agent, and the ammonia synthesis rate is not less than 16 mmol·gcat under the conditions of reaction temperature 280~320°C, pressure 1.5~2.5MPa, and gas flow rate 80~100mL / min. -1 ·h -1 .

[0013] A further improvement of this invention is that the highly efficient thermal catalyst is a zinc-based alloy catalyst promoted by an auxiliary agent, and the ammonia synthesis rate is not less than 15 mmol·gcat under the conditions of reaction temperature 280~320°C, pressure 1.5~2.5MPa, and gas flow rate 80~100mL / min. -1 ·h -1 .

[0014] Thirdly, the present invention also provides an application of a highly efficient thermal catalyst in the synthesis of ammonia under mild conditions, wherein the reaction conditions are: temperature 200~350°C, pressure 0.5~5MPa, and nitrogen-hydrogen mixed gas volume ratio of 1:3.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions. The method first pre-treats a foam support to effectively remove surface oil and oxide layers and enhance surface activity, providing a good foundation for the uniform loading of subsequent active components. Then, using electrochemical deposition, a transition metal is deposited on the support surface under mild conditions to form an alloy structure, avoiding the high energy consumption problem of traditional high-temperature calcination processes, while achieving uniform distribution and strong bonding of the active components. Finally, an additive is introduced via vapor deposition, allowing it to be uniformly loaded on the alloy surface and synergistically interact with the active components, further optimizing the catalyst's electronic structure and surface properties. The entire preparation process is simple, operates under mild conditions, and has controllable parameters. All raw materials used are common materials, requiring no complex equipment and facilitating large-scale industrial production.

[0016] This invention provides a highly efficient thermocatalyst for ammonia synthesis under mild conditions, achieving excellent comprehensive performance through the synergistic combination of a foamed metal support, a metal alloy, and surface additives. The foamed metal support, with its three-dimensional structure of high porosity and large specific surface area, provides ample loading sites for the active components, while its excellent conductivity and electrochemical stability facilitate electron transfer during the catalytic reaction. The metal alloy, formed by electrochemical deposition of an electroplating precursor, is uniformly loaded onto the support surface. The alloy structure endows the catalyst with a unique electronic synergistic effect, optimizing the adsorption and activation capabilities of nitrogen and hydrogen. The additives loaded on the alloy surface, through interaction with the active components, further regulate the electronic structure and surface properties of the catalyst, effectively inhibiting the aggregation and deactivation of the active components, significantly improving catalytic activity and long-term stability. All components of this catalyst are common, widely available, and inexpensive materials, enabling efficient ammonia synthesis under relatively mild temperature and pressure conditions, significantly reducing energy consumption and equipment investment requirements. Simultaneously, the mild reaction conditions effectively reduce carbon dioxide emissions, demonstrating good environmental friendliness. While meeting the needs of industrial production, it aligns with the principles of green chemistry and sustainable development, and has broad industrial application prospects. Attached Figure Description

[0017] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components of the invention.

[0018] Figure 1 This is a schematic diagram of a process for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions. Detailed Implementation

[0019] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0021] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0024] This invention provides a highly efficient thermal catalyst for ammonia synthesis under mild conditions. The catalyst comprises a foamed metal support, an electroplating solution precursor, and an additive. The electroplating solution precursor is formed into a metal alloy by electrochemical deposition and loaded onto the foamed metal support, and the additive is loaded onto the surface of the metal alloy.

[0025] Specifically, the foam metal carrier is selected from at least one of three-dimensional porous foam metals or foam alloy metals with low resistivity and high electrochemical stability, preferably at least one of foam nickel, foam copper, foam aluminum, foam titanium, or foam alloy metals composed of the above.

[0026] The electroplating solution precursor is selected from at least one of transition metal hydrated chlorides or hydrated sulfates with special electronic structures and catalytic activities. The transition metal is selected from one or two of copper, iron, zinc, manganese, molybdenum, nickel, and cobalt. The hydrated chloride is preferably one or two of hydrated copper chloride, hydrated ferric chloride, hydrated zinc chloride, hydrated manganese chloride, hydrated molybdenum chloride, hydrated nickel chloride, and hydrated cobalt chloride. The hydrated sulfate is preferably hydrated copper sulfate or hydrated zinc sulfate.

[0027] The additive is selected from at least one of WS2 or Ni2P. Through interaction with the active component and the support, it modulates the electronic structure and surface properties of the catalyst, thereby further improving the activity, selectivity and stability of the catalyst.

[0028] like Figure 1 As shown, the present invention also provides a method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions, comprising the following steps: S1: Pre-treat the foam carrier to obtain the pre-treated foam carrier; specifically, the foam carrier is first soaked in acetone and ultrasonically treated for 20-30 minutes to remove oil stains from the metal surface; then soaked in ethanol and ultrasonically treated for 20-30 minutes to deeply remove surface oil stains; then soaked in 1M hydrochloric acid and ultrasonically treated for 5-10 minutes to remove the oxide layer and etch the surface, making it easier to electroplate, the metal bonding is stronger, and the bright metal color turns darker; finally, it is rinsed multiple times with deionized water.

[0029] S2: Dissolve the electroplating solution precursor in deionized water at a certain ratio and stir until clear to obtain an electroplating solution; the electroplating solution precursor is at least one of the hydrated chloride or hydrated sulfate of a transition metal, and the transition metal is selected from one or two of copper, iron, zinc, manganese, molybdenum, nickel and cobalt.

[0030] S3: Using the pretreated foam support as the working electrode, a metal alloy catalyst was prepared by electrodeposition in the electroplating solution using electrochemical deposition. Specifically, a three-electrode system was adopted, with a carbon rod as the counter electrode, a silver chloride electrode as the reference electrode, and the pretreated foam support as the working electrode. Electrochemical deposition was performed using a constant voltage it curve in an electrochemical workstation. The deposition conditions were: constant potential -0.1V to -0.5V, deposition time 100 to 500s, and stirring speed 100 to 500rpm. After deposition, the obtained catalyst sample was cleaned and dried.

[0031] S4: The obtained metal alloy catalyst and the additive are placed downstream and upstream of a tube furnace, respectively, and heated to obtain a highly efficient thermal catalyst for ammonia synthesis under mild conditions; specifically: the metal alloy catalyst prepared and dried by electrodeposition is placed in a ceramic boat, and the additive is placed in another ceramic boat, and then placed downstream and upstream of the tube furnace, respectively; the target temperature of 200-500°C is reached at a heating rate of 1-5°C / min, and then held for 1-4 hours, and finally cooled to room temperature to remove the modified alloy catalyst; the additive is at least one of WS2 or Ni2P.

[0032] In step S1, the foam carrier is at least one of foamed nickel, foamed copper, foamed aluminum, and foamed titanium, or a foamed alloy metal composed of them.

[0033] The copper-based alloy catalyst or zinc-based alloy catalyst prepared by the method of this invention, with the high-efficiency thermal catalyst as an auxiliary agent, exhibits an ammonia synthesis rate of not less than 16 mmol·gcat under reaction conditions of 280-320°C, 1.5-2.5 MPa, and 80-100 mL / min. -1 ·h -1The ammonia synthesis rate of the zinc-based alloy catalyst is not less than 15 mmol·gcat. -1 ·h -1 .

[0034] The present invention also provides an application of a highly efficient thermal catalyst in the synthesis of ammonia under mild conditions, wherein the reaction conditions are: temperature 200~350°C, pressure 0.5~5MPa, and nitrogen-hydrogen mixed gas volume ratio of 1:3.

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0036] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents parts by weight, and "ratio" represents weight proportion.

[0037] Example 1 This embodiment provides a method for preparing a copper-based alloy catalyst, including the following steps: (1) Catalyst preparation: 1mm×2cm×2cm nickel foam was selected, first soaked in acetone and sonicated for 30min, then soaked in ethanol and sonicated for 20min, and finally soaked in 1M hydrochloric acid and sonicated for 10min. Afterwards, it was removed, rinsed three times with deionized water, and then clamped onto the working electrode. The electroplating solution precursors used in this invention are copper chloride dihydrate (CuCl2·2H2O) and copper sulfate pentahydrate (CuSO4·5H2O), with a total amount of 8mmol. The molar ratio of copper chloride dihydrate to copper sulfate pentahydrate is 2:1. These precursors were added to 50mL of deionized water and stirred until clear. Electrochemical deposition was then performed using a constant voltage it curve in an electrochemical workstation. The constant voltage potential was -0.3V, the electroplating time was 300s, and the stirring speed was 300rpm. The resulting catalyst sample was then cleaned and dried. Finally, the copper-based metal alloy catalyst prepared and dried by electrodeposition was placed in a ceramic boat, while Ni2P was placed in another ceramic boat. These boats were then placed downstream and upstream of a tube furnace, respectively. After reaching the target temperature of 400°C at a heating rate of 3°C / min, the temperature was held for 2 hours. Finally, the temperature was cooled to room temperature before the phosphated copper-based alloy catalyst A was removed.

[0038] (2) Ammonia synthesis performance test: The catalyst A prepared above was loaded into a fixed-bed reactor. Before the reaction, hydrogen gas was introduced to reduce the catalyst. The reduction conditions were: 450°C, hydrogen flow rate of 100 mL / min, and reduction was completed in 4 hours. After the reduction, a mixture of nitrogen and hydrogen gas (volume ratio of 1:3) was introduced, and the ammonia synthesis reaction was carried out at a reaction temperature of 300°C, a pressure of 2 MPa, and a flow rate of 90 mL / min. The ammonia content in the reaction products was analyzed by gas chromatography, and the ammonia synthesis rate was calculated. The ammonia synthesis rate of catalyst A was tested to be 16.2 mmol·gcat. -1 ·h -1 .

[0039] Example 2 This embodiment provides a method for preparing a zinc-based alloy catalyst, including the following steps: (1) Catalyst preparation: 1mm×2cm×2cm nickel foam was selected, first soaked in acetone and sonicated for 30min, then soaked in ethanol and sonicated for 20min, and finally soaked in 1M hydrochloric acid and sonicated for 10min. Afterwards, it was removed, rinsed three times with deionized water, and then clamped onto the working electrode. The electroplating solution precursors used in this invention are hydrated zinc chloride (ZnCl2·H2O) and zinc sulfate hexahydrate (ZnSO4·6H2O), with a total dosage of 8mmol. The molar ratio of hydrated zinc chloride to zinc sulfate hexahydrate is 3:1. These precursors were added to 50mL of deionized water and stirred until clear. Electrochemical deposition was then performed using a constant voltage it curve in an electrochemical workstation. The constant voltage potential was -0.3V, the electroplating time was 300s, and the stirring speed was 300rpm. The resulting catalyst sample was then cleaned and dried. Finally, the zinc-based metal alloy catalyst prepared and dried by electrodeposition was placed in a ceramic boat, while WS2 was placed in another ceramic boat. These boats were then placed downstream and upstream of a tube furnace, respectively. The target temperature of 400°C was reached at a heating rate of 3°C / min, and the temperature was held for 2 hours. Finally, the temperature was cooled to room temperature before the sulfided zinc-based alloy catalyst B was removed.

[0040] (2) Ammonia synthesis performance test: The catalyst B prepared above was loaded into a fixed-bed reactor. Before the reaction, hydrogen gas was introduced to reduce the catalyst. The reduction conditions were: 450°C, hydrogen flow rate of 100 mL / min, and reduction was completed in 4 hours. After the reduction, a mixture of nitrogen and hydrogen gas (volume ratio of 1:3) was switched to carry out the ammonia synthesis reaction at a reaction temperature of 300°C, a pressure of 2 MPa, and a flow rate of 90 mL / min. The ammonia content in the reaction products was analyzed by gas chromatography, and the ammonia synthesis rate was calculated. The ammonia synthesis rate of catalyst B was tested to be 15.5 mmol·gcat. -1 ·h -1.

[0041] Example 3 This embodiment provides a method for preparing a copper-based alloy catalyst, including the following steps: (1) Catalyst preparation: Aluminum foam with dimensions of 1 mm × 2 cm × 2 cm was selected as the carrier. It was first soaked in acetone and sonicated for 20 min, then soaked in ethanol and sonicated for 30 min, and then soaked in 1 M hydrochloric acid and sonicated for 5 min. After that, it was taken out and washed three times with deionized water before being clamped on the working electrode. The electroplating solution precursors used in this embodiment were copper chloride dihydrate (CuCl2·2H2O) and nickel chloride hexahydrate (NiCl2·6H2O), with a total amount of 8 mmol. The molar ratio of copper chloride dihydrate to nickel chloride hexahydrate was 2:1. It was added to 50 mL of deionized water and stirred until clear. Electrochemical deposition was then performed using the constant voltage it curve in the electrochemical workstation. The constant voltage potential was -0.5 V, the electroplating time was 450 s, and the stirring speed was 450 rpm. The obtained catalyst sample was cleaned and dried. Finally, the copper-nickel based metal alloy catalyst prepared and dried by electrodeposition was placed in a ceramic boat, while Ni2P was placed in another ceramic boat. These boats were then placed downstream and upstream of a tube furnace, respectively. After reaching the target temperature of 450°C at a heating rate of 5°C / min, the temperature was held for 1.5 hours. Finally, the temperature was cooled to room temperature before the phosphated copper-based alloy catalyst C was removed.

[0042] (2) Ammonia synthesis performance test: The catalyst C prepared above was loaded into a fixed-bed reactor. Before the reaction, hydrogen gas was introduced to reduce the catalyst. The reduction conditions were: 450°C, hydrogen flow rate of 100 mL / min, and reduction was completed in 5 hours. After the reduction, a mixture of nitrogen and hydrogen gas (volume ratio of 1:3) was introduced, and the ammonia synthesis reaction was carried out at a reaction temperature of 320°C, a pressure of 1.5 MPa, and a flow rate of 80 mL / min. The ammonia content in the reaction products was analyzed by gas chromatography, and the ammonia synthesis rate was calculated. The ammonia synthesis rate of catalyst C was tested to be 16.3 mmol·gcat. -1 ·h -1 .

[0043] Example 4 This embodiment provides a method for preparing a copper-based alloy catalyst, including the following steps: (1) Catalyst preparation: 1mm×2cm×2cm titanium foam was selected as the carrier. It was first soaked in acetone and sonicated for 25 min, then soaked in ethanol and sonicated for 25 min, and finally soaked in 1M hydrochloric acid and sonicated for 7 min. Afterwards, it was removed, rinsed three times with deionized water, and then clamped onto the working electrode. In this embodiment, the electroplating solution precursors used were copper chloride dihydrate (CuCl2·2H2O) and cobalt chloride hexahydrate (CoCl2·6H2O), with a total amount of 8 mmol. The molar ratio of copper chloride dihydrate to cobalt chloride hexahydrate was 3:1. These were added to 50 mL of deionized water and stirred until clear. Electrochemical deposition was then performed using a constant voltage it curve in an electrochemical workstation. The constant voltage potential was -0.15 V, the electroplating time was 150 s, and the stirring speed was 150 rpm. The obtained catalyst sample was then cleaned and dried. Finally, the copper-cobalt based metal alloy catalyst prepared and dried by electrodeposition was placed in a ceramic boat, while WS2 was placed in another ceramic boat. These boats were then placed downstream and upstream of a tube furnace, respectively. The target temperature of 250°C was reached at a heating rate of 1.5°C / min, and the temperature was held for 3.5 hours. Finally, the temperature was cooled to room temperature before the sulfided copper-based alloy catalyst D was removed.

[0044] (2) Ammonia synthesis performance test: The catalyst D prepared above was loaded into a fixed-bed reactor. Before the reaction, hydrogen gas was introduced to reduce the catalyst. The reduction conditions were: 450°C, hydrogen flow rate of 100 mL / min, and reduction was completed in 6 hours. After the reduction, a mixture of nitrogen and hydrogen gas (volume ratio of 1:3) was introduced, and the ammonia synthesis reaction was carried out at a reaction temperature of 280°C, a pressure of 2.5 MPa, and a flow rate of 100 mL / min. The ammonia content in the reaction products was analyzed by gas chromatography, and the ammonia synthesis rate was calculated. The ammonia synthesis rate of catalyst D was tested to be 16.1 mmol·gcat. -1 ·h -1 .

[0045] Comparative Example 1 Ammonia synthesis was carried out using a conventional molten iron catalyst under industrial production conditions. At a reaction temperature of 450°C, a pressure of 20 MPa, and a flow rate of 90 mL / min, the ammonia synthesis rate was 10.0 mmol·gcat. -1 ·h -1 .

[0046] Comparative Example 2 Ammonia synthesis was carried out using an existing Ru-based catalyst at a reaction temperature of 350°C, a pressure of 5 MPa, and a flow rate of 90 mL / min. The ammonia synthesis rate of this Ru-based catalyst was measured to be 13.0 mmol·gcat. -1 ·h -1.

[0047] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions, characterized in that, Includes the following steps: S1: Pre-treat the foam carrier to obtain the pre-treated foam carrier; S2: Dissolve the electroplating solution precursor in deionized water to obtain the electroplating solution; S3: Using the pretreated foam carrier as the working electrode, a metal alloy catalyst is prepared by electrodeposition in the electroplating solution using an electrochemical deposition method. S4: The obtained metal alloy catalyst and additives are placed downstream and upstream of a tube furnace, respectively, and heated to obtain a highly efficient thermal catalyst for ammonia synthesis under mild conditions.

2. The method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions according to claim 1, characterized in that, In step S1, the foam carrier is at least one of nickel foam, copper foam, aluminum foam, and titanium foam, or a foam alloy composed of the same.

3. The method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions according to claim 1, characterized in that, In step S2, the electroplating solution precursor is at least one of a hydrated chloride or hydrated sulfate of a transition metal, wherein the transition metal is selected from one or two of copper, iron, zinc, manganese, molybdenum, nickel, and cobalt.

4. The method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions according to claim 1, characterized in that, In step S3, the electrochemical deposition adopts a three-electrode system, with a carbon rod as the counter electrode, a silver chloride electrode as the reference electrode, and a pretreated foam carrier as the working electrode; the deposition conditions are: constant potential -0.1V to -0.5V, deposition time 100 to 500s, and stirring speed 100 to 500rpm.

5. The method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions according to claim 1, characterized in that, In step S4, the auxiliary agent is at least one of WS2 or Ni2P.

6. The method for preparing a highly efficient thermal catalyst for ammonia synthesis under mild conditions according to claim 1, characterized in that, In step S4, the heating rate of the heating treatment is 1~5°C / min, the holding temperature is 200~500°C, and the holding time is 1~4h.

7. A highly efficient thermal catalyst for ammonia synthesis under mild conditions, characterized in that, The catalyst is prepared by any one of claims 1 to 6; the catalyst comprises a foamed metal carrier, an electroplating solution precursor and an additive; wherein the electroplating solution precursor is formed into a metal alloy by electrochemical deposition and loaded on the foamed metal carrier, and the additive is loaded on the surface of the metal alloy.

8. The highly efficient thermal catalyst for ammonia synthesis under mild conditions according to claim 7, characterized in that, The highly efficient thermal catalyst is a copper-based alloy catalyst promoted by an auxiliary agent. Under the conditions of reaction temperature 280~320°C, pressure 1.5~2.5MPa, and gas flow rate 80~100mL / min, the ammonia synthesis rate is not less than 16mmol·gcat. -1 ·h -1 .

9. The highly efficient thermal catalyst for ammonia synthesis under mild conditions according to claim 7, characterized in that, The highly efficient thermal catalyst is a zinc-based alloy catalyst promoted by an auxiliary agent. Under the conditions of reaction temperature 280~320°C, pressure 1.5~2.5MPa, and gas flow rate 80~100mL / min, the ammonia synthesis rate is not less than 15mmol·gcat. -1 ·h -1 .

10. The application of a highly efficient thermal catalyst as described in any one of claims 7 to 9 in the synthesis of ammonia under mild conditions, characterized in that, The reaction conditions are: temperature 200~350°C, pressure 0.5~5MPa, and nitrogen-hydrogen mixed gas volume ratio of 1:3.

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