Iron-based catalyst, preparation method of iron-based catalyst, electrothermal catalytic synthesis ammonia method and electrothermal catalytic synthesis ammonia system

Abstract

The invention discloses an iron-based catalyst, a preparation method of the iron-based catalyst, and an electrothermal catalytic synthesis ammonia method and system, and belongs to the field of synthesis ammonia catalysts, the iron-based catalyst comprises the following components by mass: 30-90% of a catalyst main component FeO1-x, 5-40% of a catalytic promoter and 10-80% of a conductive additive; the value range of x in the FeO < 1-x > is 0.01 to 0.1; the catalytic promoter comprises potassium oxide, aluminum oxide and alkaline earth metal oxide; the conductive auxiliary agent comprises at least one of a carbon-containing material and a conductive metal compound. The catalytic activity of the iron-based catalyst is effectively improved mainly through catalyst component design and dosage optimization. When the device is applied to an ammonia synthesis process, low-temperature, low-pressure and efficient electro-thermal catalytic ammonia synthesis is realized under the condition of no external heating, the ammonia production rate is remarkably increased, meanwhile, the ammonia production energy consumption is reduced, and the industrial application prospect is excellent.

Description

Technical Field

[0001] This application belongs to the field of ammonia synthesis catalysts, specifically relating to an iron-based catalyst and its preparation method, as well as an electrothermal catalytic ammonia synthesis method and system. Background Technology

[0002] Ammonia is not only widely used in the production of fertilizers and various chemical intermediates, but it can also be used as a carbon-free energy carrier in power generation, transportation and industrial fuel, significantly expanding the application scope of hydrogen energy.

[0003] Currently, the industrial ammonia synthesis process mainly adopts the Haber-Bosch process, which catalytically converts nitrogen and hydrogen into ammonia (N2 + 3H2) over an iron-based catalyst. 2NH3). This reaction is exothermic and entropy-decreasing; thermodynamically, low temperature and high pressure favor the formation of ammonia. However, due to the high dissociation energy of the N≡N bond in nitrogen molecules (941 kJ·mol⁻¹), the reaction is difficult to complete. -1 The reaction kinetics are very resistant, and in actual production, it still relies on high temperature (400℃~500℃) and high pressure (15MPa~30MPa) conditions to achieve a high reaction rate and ammonia yield, resulting in extremely high energy consumption and carbon dioxide emissions. In addition, according to statistics, the energy consumed by the ammonia synthesis process accounts for 1%-2% of the world's total energy supply annually, and carbon emissions account for 1.5% of global emissions.

[0004] Therefore, developing efficient ammonia synthesis technology under mild conditions is of great significance for promoting the green and low-carbon transformation of the ammonia synthesis industry. Summary of the Invention

[0005] This application aims to at least partially address one of the technical problems in related technologies. Therefore, the purpose of this application is to propose an iron-based catalyst and its preparation method, as well as an electrothermal catalytic ammonia synthesis method and system. This application primarily improves the catalytic activity of the iron-based catalyst through catalyst component design and dosage optimization. When applied to the ammonia synthesis process, it achieves low-temperature, low-pressure, and high-efficiency electrothermal catalytic ammonia synthesis without external heating, significantly increasing the ammonia production rate while reducing energy consumption, demonstrating excellent industrial application prospects.

[0006] The first aspect of this application discloses an iron-based catalyst. According to embodiments of this application, the iron-based catalyst comprises the following components by mass percentage: Catalyst main component FeO 1-x 30%~90%, catalyst 5%~40%, and conductive agent 10%~80%; The catalyst's main component is FeO 1-x The value of x in the equation ranges from 0.01 to 0.1. The catalyst aids include potassium oxide, aluminum oxide, and alkaline earth metal oxides; The conductive additive includes at least one of carbon-containing materials and conductive metal compounds.

[0007] The iron-based catalysts described in the above embodiments of this application effectively enhance their catalytic activity primarily through catalyst component design and dosage optimization. When applied to ammonia synthesis processes, they achieve low-temperature, low-pressure, high-efficiency electrothermal catalytic ammonia synthesis without external heating, significantly improving the ammonia production rate while reducing energy consumption, demonstrating excellent industrial application prospects. Specifically: This application, through catalyst component design and dosage optimization, enables the directional migration of electrons under current-driven conditions. First, electrons are transferred from the conductive promoter to the catalytic promoter, and then further enriched in the main catalyst component FeO. 1-x The electrons are transferred to the surface and ultimately fed back to the antibonding orbitals of nitrogen molecules. This directional electron migration process enhances the adsorption and dissociation of nitrogen on the catalyst surface, lowers the nitrogen activation energy barrier, and effectively promotes the dissociation and activation of nitrogen, thereby significantly improving the catalytic activity of iron-based catalysts.

[0008] In addition, the iron-based catalyst according to the above embodiments of this application may also have the following additional technical features: In some embodiments of this application, the catalyst main component is FeO 1-x The mass percentage is 30%~60%; And / or, the mass percentage of the catalyst promoter is 5% to 15%; And / or, the conductive additive has a mass percentage of 30% to 60%.

[0009] In some embodiments of this application, the catalyst main component is FeO 1-x The value of x in the equation ranges from 0.02 to 0.05. And / or, the potassium oxide accounts for 5% to 40% of the mass percentage of the catalyst promoter; And / or, the alumina accounts for 20% to 60% of the mass percentage of the catalyst promoter; And / or, the alkaline earth metal oxide accounts for 5% to 40% of the mass percentage of the catalyst.

[0010] In some embodiments of this application, the alkaline earth metal oxide includes at least one of magnesium oxide, calcium oxide, strontium oxide, and barium oxide; And / or, the carbon-containing material includes at least one of graphene, carbon nanotubes, activated carbon, conductive carbon black, nitrogen-doped carbon material, silicon carbide, and titanium carbide, and the conductive metal compound includes at least one of indium tin oxide and antimony tin oxide.

[0011] The second aspect of this application provides a method for preparing the iron-based catalyst as described in any one of the first aspects above. According to embodiments of this application, the method for preparing the iron-based catalyst includes the following steps: Raw materials, excluding conductive additives, are mixed and melted in a certain proportion, then cooled and pulverized to obtain a catalyst precursor. The catalyst precursor and conductive additive are mixed and ground, and then reduced and activated to obtain the iron-based catalyst.

[0012] The preparation method of the iron-based catalyst in the above embodiments of this application is simple to operate, requires no additional specific equipment, and is suitable for industrial mass production.

[0013] In addition, the preparation method of the iron-based catalyst according to the above embodiments of this application may also have the following additional technical features: In some embodiments of this application, the catalyst main component is FeO 1-x The raw materials include magnetite powder and iron powder, and the mass ratio of the magnetite powder to the iron powder is (2~4):1; And / or, the raw materials for the catalyst promoter include at least one of metal oxides, metal nitrates and metal carbonates; And / or, the mass ratio of the catalyst precursor to the conductive agent is (1~20):(1~20). And / or, the working conditions parameters for the mixed grinding include: grinding speed of 50 rpm to 300 rpm and grinding time of 0.5 h to 5 h; And / or, the working conditions parameters for the reduction activation include: reduction temperature of 300℃~600℃, reduction time of 10h~30h, and hydrogen volume percentage content in the reducing atmosphere ≥30%.

[0014] A third aspect of this application discloses a method for electrothermal catalytic ammonia synthesis. According to embodiments of this application, the catalyst used in the electrothermal catalytic ammonia synthesis method includes the iron-based catalyst described in the first aspect or an iron-based catalyst prepared using the method described in the second aspect. This significantly improves the ammonia production rate of electrothermal catalytic ammonia synthesis and reduces the energy consumption for ammonia production in this process.

[0015] In addition, the electrothermal catalytic ammonia synthesis method according to the above embodiments of this application may also have the following additional technical features: In some embodiments of this application, the operating conditions for the electrothermal catalytic ammonia synthesis include: pressure of 0.1 MPa to 5 MPa, power supply output current of 1 A to 20 A, power supply output voltage of 1 V to 20 V, and power supply output power of 5 W to 100 W.

[0016] A fourth aspect of this application discloses an electrothermal catalytic ammonia synthesis system. According to embodiments of this application, the system is used to implement the electrothermal catalytic ammonia synthesis method described in the third aspect; It includes a reaction device and a power source. The reaction device contains electrodes, and the electrodes are connected to the power source to form a closed circuit.

[0017] The electrothermal catalytic ammonia synthesis system described in the above embodiments of this application has a simple structure and can be successfully constructed by adding an external power source to a reaction device such as a fixed bed. Therefore, low-temperature, low-pressure, and highly efficient electrothermal catalytic ammonia synthesis is achieved without external heating, demonstrating excellent prospects for industrial application.

[0018] In addition, the electrothermal catalytic ammonia synthesis system according to the above embodiments of this application may also have the following additional technical features: In some embodiments of this application, the reaction apparatus is provided with a gas inlet and a gas outlet, and the gas outlet is connected to a conductivity meter; And / or, the reaction apparatus is provided with a conductive filter element, the conductive filter element comprising a first conductive filter element layer and a second conductive filter element layer, and the catalyst is placed between the first conductive filter element layer and the second conductive filter element layer; And / or, the conductive filter element is connected to a thermocouple and the electrode.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the electrothermal catalytic ammonia synthesis system provided in an embodiment of this application.

[0021] Figure 2 This figure shows a comparison of the ammonia production rates of the iron-based catalyst under electrothermal catalysis and conventional thermocatalysis conditions in the test examples of this application.

[0022] Figure 3 FeO in the test examples of this application 0.974 Comparison of energy consumption for electrothermal and thermothermal ammonia production using the Al2O3-K2O-MgO-G catalyst.

[0023] Explanation of reference numerals in the attached figures: Figure 1In the diagram: 1 is the reaction apparatus, 2 is the conductive filter element, 3 is the catalyst, 4 is the electrode, 5 is the thermocouple, 6 is the power supply, 7-1 is the gas inlet, 7-2 is the gas outlet, and 8 is the conductivity meter. Detailed Implementation

[0024] The embodiments of this application are described in detail below, and the embodiments described below with reference to the accompanying drawings are merely exemplary and intended to explain this application, and should not be construed as limiting this application.

[0025] Compared to traditional thermocatalysis, electrothermal catalysis can effectively regulate the electronic structure, adsorption behavior, and bonding strength of reactants and intermediates by applying an external electric field, thereby achieving precise control of the reaction pathway and enabling efficient catalytic reactions under mild conditions. In recent years, electrothermal catalytic ammonia synthesis has attracted widespread attention from researchers. However, current technology mainly uses metal oxides such as cerium oxide or zirconium oxide as catalysts. While this reduces the temperature of ammonia synthesis to some extent, their inherent low thermal and electrical conductivity also brings two limitations: firstly, external heating is still required to bring the catalyst bed to the reaction temperature, failing to completely eliminate dependence on the thermocatalytic process; secondly, the poor conductivity easily induces localized plasma discharge phenomena. These problems result in relatively high overall energy consumption and limited energy-saving effects.

[0026] To solve the above problems, the technical solution provided in this application is as follows: The first aspect of this application discloses an iron-based catalyst. According to embodiments of this application, the iron-based catalyst comprises the following components by mass percentage: Catalyst main component FeO 1-x 30%~90%, catalyst 5%~40%, and conductive agent 10%~80%; The catalyst's main component is FeO 1-x The value of x in the equation ranges from 0.01 to 0.1. The catalyst aids include potassium oxide, aluminum oxide, and alkaline earth metal oxides; The conductive additive includes at least one of carbon-containing materials and conductive metal compounds.

[0027] The iron-based catalyst described in the above embodiments of this application (specifically, an iron-based catalyst that can be used for electrothermal catalytic synthesis of ammonia, hereinafter referred to as FeO) 1-x / MO-C), mainly through catalyst component design and dosage optimization, effectively improved the catalytic activity of iron-based catalysts. When applied to the ammonia synthesis process, it achieved low-temperature, low-pressure, high-efficiency electrothermal catalytic ammonia synthesis without external heating, significantly increasing the ammonia production rate while reducing energy consumption, demonstrating excellent industrial application prospects. Specifically: This application, through catalyst component design and dosage optimization, enables directional electron migration under current-driven conditions. First, electrons are transferred from the conductive promoter (hereinafter referred to as C) to the catalytic promoter (hereinafter referred to as MO), and then further enriched in the main catalyst component FeO. 1-x The electrons are transferred to the surface and ultimately fed back to the antibonding orbitals of nitrogen molecules. This directional electron migration process enhances the adsorption and dissociation of nitrogen on the catalyst surface, lowers the nitrogen activation energy barrier, and effectively promotes the dissociation and activation of nitrogen, thereby significantly improving the catalytic activity of iron-based catalysts.

[0028] The main component of the catalyst mentioned above in this application is FeO. 1-x The mass percentage can be 30%, 35%, 38%, 40%, 45%, 50%, 53%, 58%, 60%, 70%, 80%, 90%, or any range between the above values, preferably 30% to 60%; Meanwhile, this FeO 1-x The value of x can be 0.01, 0.03, 0.05, 0.08, 0.1 or any of the above values, preferably 0.02 to 0.05.

[0029] The mass percentage of the catalyst aid mentioned above in this application may be 5%, 8%, 10%, 15%, 20%, 22%, 25%, 28%, 30%, 35%, 37%, 40%, or any range between the above values, preferably 5% to 15%.

[0030] The mass percentage of the conductive additive mentioned above in this application may be 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 70%, 80%, or any of the above values, preferably 30% to 60%.

[0031] According to some specific embodiments of this application, the potassium oxide accounts for 5% to 40% of the mass percentage of the catalyst promoter (e.g., 5%, 8%, 10%, 15%, 20%, 22%, 25%, 28%, 30%, 35%, 37%, 40%, or any range between the above values); and / or, the alumina accounts for 20% to 60% of the mass percentage of the catalyst promoter (e.g., 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, or any range between the above values); and / or, the alkaline earth metal oxide accounts for 5% to 40% of the mass percentage of the catalyst promoter (e.g., 5%, 8%, 10%, 15%, 20%, 22%, 25%, 28%, 30%, 35%, 37%, 40%, or any range between the above values). This application, by using the above-mentioned suitable proportions of potassium oxide, alumina, and alkaline earth metal oxides as catalyst promoters, is beneficial for improving the catalytic activity of iron-based catalysts.

[0032] According to some specific embodiments of this application, the alkaline earth metal oxide includes at least one selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide; and / or, the carbon-containing material includes at least one selected from graphene, carbon nanotubes, activated carbon, conductive carbon black, nitrogen-doped carbon materials, silicon carbide, and titanium carbide; and the conductive metal compound includes at least one selected from indium tin oxide and antimony tin oxide. The raw materials described above are inexpensive and readily available, avoiding the use of precious metals and reducing production costs.

[0033] The second aspect of this application provides a method for preparing the iron-based catalyst as described in any one of the first aspects above. According to embodiments of this application, the method for preparing the iron-based catalyst includes the following steps: Raw materials, excluding conductive additives, are mixed and melted in a certain proportion, then cooled and pulverized to obtain a catalyst precursor. The catalyst precursor and conductive additive are mixed and ground, and then reduced and activated to obtain the iron-based catalyst.

[0034] The preparation method of the iron-based catalyst in the above embodiments of this application is simple to operate, requires no additional specific equipment, and is suitable for industrial mass production.

[0035] In this application, the raw materials, excluding the conductive additive, are mixed and melted in a specific ratio. This can be achieved by methods such as electric heating melting, until the raw materials reach a molten state. In practical operation, this may include the following process: mixing and melting the raw materials, excluding the conductive additive (such as FeO, the main component of the catalyst) in a specific ratio... 1-xAfter the magnetite powder, reduced iron powder, and catalyst additive are mixed evenly in the required amounts, they are loaded into an electric melting furnace for electrofusion. The power supply for the electric melting furnace can be provided by a 50kV·A salt bath furnace transformer. The maximum melting current generally does not exceed 2700A (e.g., 500A, 800A, 1000A, etc.). The furnace is heated to a high temperature and maintained for a period of time (e.g., melting for 0.5h~3h), allowing the raw materials in the electric melting furnace to gradually melt into a molten slurry. At the same time, the molten slurry is cooled to a final temperature generally below 100℃ (e.g., 50℃, 25℃, etc.), so that the molten slurry can be cooled into a solid melt. The resulting solid melt is then crushed and sieved (150~200 mesh sieve) to obtain the catalyst precursor.

[0036] In addition, the preparation method of the iron-based catalyst according to the above embodiments of this application may also have the following additional technical features: According to some specific embodiments of the present application, the catalyst main component FeO 1-x The raw materials include magnetite powder and iron powder, with a mass ratio of magnetite powder to iron powder of (2~4):1. This results in the catalyst's main component, FeO. 1-x The value of x in the equation is between 0.01 and 0.1.

[0037] According to some specific embodiments of this application, the raw materials for the catalyst promoter include at least one selected from metal oxides, metal nitrates, and metal carbonates. Specifically, the raw materials for the catalyst promoters described above in this application are their respective metal oxides, metal nitrates, or metal carbonates, which may be alumina, potassium nitrate, magnesium oxide, calcium carbonate, barium carbonate, etc.

[0038] According to some specific embodiments of this application, the mass ratio of the catalyst precursor to the conductive agent is (1~20):(1~20), for example, it can be 1:2, 1:5, 1:10, 1:20, 3:5, 10:7, 20:1, etc. Thus, an iron-based catalyst satisfying the above-mentioned dosage composition is obtained.

[0039] According to some specific embodiments of this application, the working conditions parameters for the mixed grinding include: a grinding speed of 50 rpm to 300 rpm (e.g., 50 rpm, 65 rpm, 80 rpm, 100 rpm, 120 rpm, 150 rpm, 200 rpm, 300 rpm, or any range between the above values), and a grinding time of 0.5 h to 5 h (e.g., 0.5 h, 1.0 h, 2.5 h, 3.5 h, 5 h, or any range between the above values); and / or, The working conditions parameters for the reduction and activation include: a reduction temperature of 300℃~600℃ (e.g., 300℃, 350℃, 400℃, 450℃, 500℃, 600℃ or any range between the above values), a reduction time of 10h~30h (e.g., 10h, 12h, 15h, 20h, 30h or any range between the above values), and a hydrogen volume percentage content ≥30% in the reducing atmosphere (e.g., pure hydrogen, a mixture of hydrogen and argon, or a mixture of hydrogen and nitrogen).

[0040] A third aspect of this application discloses a method for electrothermal catalytic ammonia synthesis. According to embodiments of this application, the catalyst used in the electrothermal catalytic ammonia synthesis method includes the iron-based catalyst described in the first aspect or an iron-based catalyst prepared using the method described in the second aspect. This significantly improves the ammonia production rate of electrothermal catalytic ammonia synthesis and reduces the energy consumption for ammonia production in this process.

[0041] In addition, the electrothermal catalytic ammonia synthesis method according to the above embodiments of this application may also have the following additional technical features: According to some specific embodiments of this application, the operating conditions parameters for the electrothermal catalytic ammonia synthesis include: pressure of 0.1MPa to 5MPa (e.g., 0.1MPa, 0.5MPa, 1MPa, 1.5MPa, 2.0MPa, 2.5MPa, 4MPa, 5MPa, or any range between the above values), power supply output current of 1A to 20A (e.g., 1A, 3A, 5A, 7A, 9A, 15A, 17A, 20A, or any range between the above values), power supply output voltage of 1V to 20V (e.g., 1V, 3V, 5V, 7V, 9V, 15V, 17V, 20V, or any range between the above values), and power supply output power of 5W to 100W (e.g., 5W, 10W, 15W, 25W, 30W, 40W, 70W, 100W, or any range between the above values). Preferably, the operating parameters for the electrothermal catalytic ammonia synthesis include: pressure of 0.1 MPa-3 MPa, power supply output current of 5 A-20 A, power supply output voltage of 2 V-10 V, and power supply output power of 10 W-60 W. Thus, this application achieves self-heating by utilizing the Joule heating effect generated when current passes through the catalyst, realizing the electrothermal catalytic ammonia synthesis process and improving energy utilization efficiency. Specifically, using the iron-based catalyst described above, an ammonia production rate achieved at 300°C (i.e., the temperature of the reaction system after conversion to thermal energy under suitable current parameters) and 1 MPa is superior to the performance of conventional thermocatalytic iron-based catalysts reported in the prior art at 400°C and 1 MPa. This method achieves highly efficient ammonia synthesis under mild conditions.

[0042] A fourth aspect of this application discloses an electrothermal catalytic ammonia synthesis system. According to embodiments of this application, the system is used to implement the electrothermal catalytic ammonia synthesis method described in the third aspect; like Figure 1 As shown ( Figure 1 The small yellow ball represents element N. Figure 1 The small green sphere represents hydrogen element. The device includes a reaction apparatus 1 and a power supply 6. The reaction apparatus contains an electrode 4, which is connected to the power supply 6 to form a closed circuit.

[0043] The electrothermal catalytic ammonia synthesis system described in the above embodiments of this application has a simple structure. It can be successfully constructed by adding an external power source (such as a programmable external power source) to a reaction apparatus such as a fixed bed. Therefore, low-temperature, low-pressure, and high-efficiency electrothermal catalytic ammonia synthesis is achieved without external heating, demonstrating excellent prospects for industrial application.

[0044] In addition, the electrothermal catalytic ammonia synthesis system according to the above embodiments of this application may also have the following additional technical features: According to some specific implementations of the embodiments of this application, such as Figure 1 As shown, the reaction apparatus 1 is equipped with a gas inlet 7-1 and a gas outlet 7-2. The gas outlet 7-2 is connected to a conductivity meter 8, enabling real-time online monitoring of the ammonia generation rate. Alternatively, the reaction apparatus 1 is equipped with a conductive filter element 2, which includes a first conductive filter layer and a second conductive filter layer. A catalyst 3 is placed between the first and second conductive filter layers to form a catalyst bed. Or, the conductive filter element 2 is connected to a thermocouple 5 and the electrode 4. The thermocouple is used to measure the temperature at the contact point of the conductive filter element, monitoring the ambient temperature of the reaction. Simultaneously, by adjusting the input current, voltage, and other parameters of the external power supply, the influence of different electric field parameters on the ammonia synthesis performance can be systematically investigated without additional heating, allowing for the selection of the optimal electric field operating conditions and improvement of ammonia synthesis efficiency.

[0045] It should be noted that in the electrothermal catalytic ammonia synthesis system of the above embodiments of this application, the electrodes can be copper electrodes, aluminum electrodes, or stainless steel electrodes, etc., the conductive filter element can be a copper filter element, aluminum filter element, or stainless steel filter element, etc., the power supply can be a DC power supply, etc., the voltage output range of the DC power supply is 0V~1500V (e.g., 5V, 10V, 150V, 500V, 1000V, etc.), the current output range is 0A~30A (e.g., 5A, 10A, 15A, 20A, etc.), and the catalyst bed resistance can be 0.1Ω~500Ω (e.g., 0.5Ω, 1Ω, 5Ω, 10Ω, 20Ω, 50Ω, 100Ω, etc.). Meanwhile, when this electrothermal catalytic ammonia synthesis system is used, the reaction conditions can be as follows: the amount of catalyst loaded into the reactor is 30mg~150mg (e.g., 30mg, 40mg, 50mg, 70mg, 100mg, 130mg, etc.); the volume ratio of the inlet nitrogen-hydrogen reaction gas N2:H2 is 1:9~9:1 (e.g., 1:1, 1:3, 1:5, 3:1, 6:1, 7:2, etc.); the total pressure is 0.1MPa~5MPa (e.g., 0.1MPa, 0.5MPa, 1MPa, 2MPa, 5MPa, etc.); the reaction temperature is 200℃~350℃ (e.g., 200℃, 240℃, 270℃, 300℃, 350℃, etc.); and the gas hourly space velocity is 1000mL·g·cat. -1 ·h -1 ~1,000,000 mL·g·cat -1 ·h -1 (For example, it can be 1000 mL·g·cat) -1 ·h -1 1200mL·g·cat -1 ·h -1 1500mL·g·cat -1·h -1 2000mL·g·cat -1 ·h -1 4000mL·g·cat -1 ·h -1 5000mL·g·cat -1 ·h -1 wait).

[0046] The embodiments of this application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known methods. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0047] Example 1 This embodiment provides an iron-based catalyst, which, by mass percentage, comprises the following components: Catalyst main component FeO 1-x 44%, catalyst accelerator 6%, and conductive accelerator 50%; The catalyst's main component is FeO 1-x The value of x is 0.026; The catalyst promoter includes potassium oxide, aluminum oxide, and alkaline earth metal oxide (specifically magnesium oxide), wherein potassium oxide accounts for 26% of the mass percentage of the catalyst promoter, aluminum oxide accounts for 48% of the mass percentage of the catalyst promoter, and alkaline earth metal oxide accounts for 26% of the mass percentage of the catalyst promoter.

[0048] The preparation method of the iron-based catalyst includes the following steps: Accurately weigh 72.80g of magnetite, 23.41g of pure iron powder, 1.82g of alumina, 2.17g of potassium nitrate, and 1.00g of magnesium oxide, and place them in an electric melting furnace. Melt for 2 hours using a 50kV·A salt bath furnace transformer. The melting current is 2000A, yielding a molten slurry. Quickly cool the slurry to below 100°C in a water-jacketed cooling tank. The resulting molten block is then pulverized and passed through a 200-mesh sieve to obtain a catalyst precursor. Weigh 0.06g of this catalyst precursor and 0.06g of graphene (G), and ball-mill at 200rpm for 1 hour. The resulting mixture is then reduced at 450°C for 20 hours in a nitrogen-hydrogen mixture (hydrogen volume percentage 67%) to obtain an iron-based catalyst (denoted as FeO). 0.974 / Al2O3-K2O-MgO-G).

[0049] Example 2 This embodiment provides an iron-based catalyst, which, by mass percentage, comprises the following components: Catalyst main component FeO 1-x 44%, catalyst accelerator 6%, and conductive accelerator 50%; The catalyst main component, FeO 1-x The value of x is 0.026; The catalyst promoter includes potassium oxide, aluminum oxide, and alkaline earth metal oxide (specifically calcium oxide), wherein potassium oxide accounts for 26% of the mass percentage of the catalyst promoter, aluminum oxide accounts for 48% of the mass percentage of the catalyst promoter, and alkaline earth metal oxide accounts for 26% of the mass percentage of the catalyst promoter.

[0050] The preparation method of the iron-based catalyst includes the following steps: Accurately weigh 72.80g of magnetite, 23.41g of pure iron powder, 1.82g of alumina, 2.17g of potassium nitrate, and 1.78g of calcium carbonate and charge them into an electric melting furnace. Melt for 2 hours using a 50kV·A salt bath furnace transformer. The melting current is 2000A, yielding a molten slurry. Quickly cool the slurry to below 100°C in a water-jacketed cooling tank. The resulting molten block is then pulverized and passed through a 200-mesh sieve to obtain a catalyst precursor. Weigh 0.06g of this catalyst precursor and 0.06g of carbon nanotubes (CNTs) and ball-mill at 200rpm for 1 hour. Reduce the resulting mixture in a nitrogen-hydrogen mixture (hydrogen volume percentage 67%) at 450°C for 20 hours to obtain an iron-based catalyst (denoted as FeO). 0.974 / Al2O3-K2O-CaO-CNTs).

[0051] Example 3 This embodiment provides an iron-based catalyst, which, by mass percentage, comprises the following components: Catalyst main component FeO 1-x 44%, catalyst accelerator 6%, and conductive accelerator 50%; The catalyst's main component is FeO 1-x The value of x is 0.026; The catalyst promoter includes potassium oxide, aluminum oxide, and alkaline earth metal oxide (specifically strontium oxide), wherein potassium oxide accounts for 26% of the mass percentage of the catalyst promoter, aluminum oxide accounts for 48% of the mass percentage of the catalyst promoter, and alkaline earth metal oxide accounts for 26% of the mass percentage of the catalyst promoter.

[0052] The preparation method of the iron-based catalyst includes the following steps: Accurately weigh 72.80g of magnetite, 23.41g of pure iron powder, 1.82g of alumina, 2.17g of potassium nitrate, and 1.42g of strontium carbonate and charge them into an electric melting furnace. Melt for 2 hours using an electric furnace powered by a 50kV·A salt bath furnace transformer. The melting current is 2000A, yielding a molten slurry. The molten slurry is rapidly discharged into a cooling tank with a water jacket and cooled to below 100°C. The resulting molten block is then pulverized and passed through a 200-mesh sieve to obtain a catalyst precursor. 0.06g of this catalyst precursor and 0.06g of activated carbon (AC) are ball-milled at 200rpm for 1 hour. The resulting mixture is then reduced at 450°C for 20 hours in a nitrogen-hydrogen mixture (hydrogen volume percentage 67%) to obtain an iron-based catalyst (denoted as FeO). 0.974 / Al2O3-K2O-SrO-AC).

[0053] Example 4 This embodiment provides an iron-based catalyst, which, by mass percentage, comprises the following components: Catalyst main component FeO 1-x 44%, additives 6%, and conductive components 50%; The catalyst's main component is FeO 1-x The value of x is 0.026; The catalyst promoter includes potassium oxide, aluminum oxide, and alkaline earth metal oxide (specifically barium oxide), wherein potassium oxide accounts for 26% of the mass percentage of the catalyst promoter, aluminum oxide accounts for 48% of the mass percentage of the catalyst promoter, and alkaline earth metal oxide accounts for 26% of the mass percentage of the catalyst promoter.

[0054] The preparation method of the iron-based catalyst includes the following steps: Accurately weigh 72.80g of magnetite, 23.41g of pure iron powder, 1.82g of alumina, 2.17g of potassium nitrate, and 1.29g of barium carbonate and charge them into an electric melting furnace. Melt for 2 hours using a 50kV·A salt bath furnace transformer. The melting current is 2000A, yielding a molten slurry. Quickly discharge the molten slurry into a cooling tank with a water jacket to cool to below 100°C. The resulting molten block is then pulverized and passed through a 200-mesh sieve to obtain a catalyst precursor. Weigh 0.06g of this catalyst precursor and 0.06g of antimony tin oxide (ATO) and ball-mill at 200rpm for 1 hour. The resulting mixture is then reduced at 450°C for 20 hours in a nitrogen-hydrogen mixture (hydrogen volume percentage 67%) to obtain an iron-based catalyst (denoted as FeO). 0.974 / Al2O3-K2O-BaO-ATO).

[0055] Example 5 This embodiment provides an iron-based catalyst and its preparation method, which differs from Example 1 only in that: (1) Catalyst main component FeO 1-x The value of x is 0.01.

[0056] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.99 / Al2O3-K2O-MgO-G.

[0057] Example 6 This embodiment provides an iron-based catalyst and its preparation method, which differs from Example 1 only in that: (1) Catalyst main component FeO 1-x The value of x is 0.02.

[0058] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.98 / Al2O3-K2O-MgO-G.

[0059] Example 7 This embodiment provides an iron-based catalyst and its preparation method, which differs from Example 1 only in that: (1) Catalyst main component FeO 1-x The value of x is 0.05.

[0060] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.95 / Al2O3-K2O-MgO-G.

[0061] Example 8 This embodiment provides an iron-based catalyst and its preparation method, which differs from Example 1 only in that: (1) By mass percentage, the iron-based catalyst comprises the following components: catalyst main component FeO 1-x 30%, catalyst 5% and conductive auxiliaries 65%.

[0062] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / Al2O3-K2O-MgO-G-1.

[0063] Example 9 This embodiment provides an iron-based catalyst and its preparation method, which differs from Example 1 only in that: (1) By mass percentage, the iron-based catalyst comprises the following components: catalyst main component FeO 1-x 50%, catalyst 10%, and conductive auxiliaries 40%.

[0064] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / Al2O3-K2O-MgO-G-2.

[0065] Example 10 This embodiment provides an iron-based catalyst and its preparation method, which differs from Example 1 only in that: (1) By mass percentage, the iron-based catalyst comprises the following components: catalyst main component FeO 1-x 85%, catalyst 5% and conductive auxiliaries 10%.

[0066] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / Al2O3-K2O-MgO-G-3.

[0067] Example 11 This embodiment provides an electrothermal catalytic ammonia synthesis system, such as... Figure 1 As shown, the apparatus includes a reaction device 1 and a power supply 6. The reaction device contains an electrode 4, which is connected to the power supply 6 to form a closed circuit. The reaction device 1 is provided with a gas inlet 7-1 and a gas outlet 7-2, and the gas outlet 7-2 is connected to a conductivity meter 8. The reaction device 1 is provided with a conductive filter element 2, which includes a first conductive filter element layer and a second conductive filter element layer. A catalyst 3 is placed between the first conductive filter element layer and the second conductive filter element layer to form a catalyst bed. The conductive filter element 2 is connected to a thermocouple 5 and the electrode 4.

[0068] Comparative Example 1 This comparative example provides an iron-based catalyst and its preparation method, which differs from Example 10 only in that: (1) By mass percentage, the iron-based catalyst comprises the following components: catalyst main component FeO 1-x 85%, catalyst 10%, and conductive agent 5% (i.e., the content of conductive component in the iron-based catalyst provided in this comparative example is too low).

[0069] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / Al2O3-K2O-MgO-G-3-1.

[0070] Comparative Example 2 This comparative example provides an iron-based catalyst and its preparation method, which differs from Example 10 only in that: (1) By mass percentage, the iron-based catalyst comprises the following components: catalyst main component FeO 1-x 20%, catalyst promoter 50%, and conductive promoter 30% (i.e., FeO in the iron-based catalyst provided in this comparative example) 1-x (The content is too low and the content of catalyst aid is too high).

[0071] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / Al2O3-K2O-MgO-G-3-2.

[0072] Comparative Example 3 This comparative example provides an iron-based catalyst and its preparation method, which differs from Example 10 only in that: (1) The potassium oxide accounts for 0% of the mass of the catalyst promoter, the aluminum oxide accounts for 60% of the mass of the catalyst promoter, and the alkaline earth metal oxide accounts for 40% of the mass of the catalyst promoter (i.e., the catalyst promoter composition of the iron-based catalyst provided in this comparative example does not contain potassium oxide).

[0073] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / Al2O3-MgO-G-3.

[0074] Comparative Example 4 This comparative example provides an iron-based catalyst and its preparation method, which differs from Example 10 only in that: (1) The potassium oxide accounts for 50% of the mass of the catalyst promoter, the aluminum oxide accounts for 0% of the mass of the catalyst promoter, and the alkaline earth metal oxide accounts for 50% of the mass of the catalyst promoter (i.e., the catalyst promoter composition of the iron-based catalyst provided in this comparative example does not contain aluminum oxide).

[0075] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / K2O-MgO-G-3.

[0076] Comparative Example 5 This comparative example provides an iron-based catalyst and its preparation method, which differs from Example 10 only in that: (1) The potassium oxide accounts for 40% of the mass of the catalyst promoter, the aluminum oxide accounts for 60% of the mass of the catalyst promoter, and the alkaline earth metal oxide accounts for 0% of the mass of the catalyst promoter (i.e., the catalyst promoter composition of the iron-based catalyst provided in this comparative example does not contain alkaline earth metal oxide).

[0077] The iron-based catalyst obtained in this embodiment is denoted as FeO. 0.974 / Al2O3-K2O-G-3.

[0078] Test Example 1 This test example applies the iron-based catalysts obtained in the above examples and comparative examples to the electrothermal catalytic ammonia synthesis system provided in the above examples to investigate its catalytic performance. In the electrothermal catalytic ammonia synthesis system, the power supply output current is 10A, the output voltage is 3.5-3.9V, the output power is 35-39W, no additional heating device is used, and the catalyst bed temperature is stabilized at 300-320°C. The N2:H2 ratio is 1:3, the reaction pressure is 1.0MPa, and the gas hourly space velocity (GHSV) is 72000 mL·g·cat. -1 ·h -1 .

[0079] When the iron-based catalysts obtained in the above embodiments and comparative examples are applied to the electrothermal catalytic ammonia synthesis system provided in the above embodiments for electrothermal catalytic ammonia synthesis process, the ammonia production rate measured by the conductivity meter is shown in Table 1.

[0080] Table 1

[0081] As shown in Table 1: When the content of conductive promoter in the catalyst is too low, its Joule heating effect and electronic conduction effect will be weakened, resulting in a significant decrease in catalytic activity (see Example 10 and Comparative Example 1).

[0082] When the content of the main component of the catalyst is too low, the number of effective active sites required for the reaction decreases accordingly, which will also lead to a decrease in activity (Example 10 and Comparative Example 2).

[0083] Furthermore, when any component of the catalyst is missing, the structural stability of the catalyst is affected, which in turn leads to a decrease in activity (Example 10 and Comparative Examples 3-5).

[0084] Therefore, this application demonstrates that, through reasonable catalyst component design and dosage optimization, the electrothermal catalytic ammonia synthesis performance of iron-based catalysts can be significantly improved (Examples 1-10). Moreover, the ammonia production rate achieved at 300-320°C (i.e., the temperature of the reaction system after conversion to heat energy under suitable current parameters) and 1 MPa is superior to the performance of conventional thermocatalytic iron-based catalysts reported in the prior art at 400°C and 1 MPa.

[0085] Test Example 2 Based on Test Example 1, this test example further applies the iron-based catalysts provided in Examples 1-4 to a conventional thermocatalytic ammonia synthesis process to examine their catalytic performance. The reaction conditions for the thermocatalytic ammonia synthesis process include: heating in a furnace at a rate of 5°C / min to 300-320°C (the temperature is consistent with that of the electrothermal catalysis), a gas composition of N2:H2 = 1:3, a reaction pressure of 1.0 MPa, and a gas hourly space velocity of 72000 mL·g·cat. -1 ·h -1 .

[0086] The iron-based catalysts obtained in the above embodiments and comparative examples were applied to the electrothermal catalytic ammonia synthesis system provided in the above embodiments for electrothermal catalytic ammonia synthesis processes, and to conventional thermocatalytic ammonia synthesis processes, respectively. The ammonia production rates measured by the conductivity meter are summarized in Table 2 and below. Figure 2 As shown.

[0087] Table 2

[0088] From Table 2 and Figure 2 It can be seen that, under electrothermal catalysis conditions, the ammonia production rate achieved by the iron-based catalyst provided in this application at a lower reaction temperature (300~320℃) is nearly an order of magnitude higher than that of traditional thermocatalysis under the same temperature conditions, which fully demonstrates the significant advantages of the iron-based catalyst provided in this application in electrothermal catalytic ammonia synthesis.

[0089] Test Example 3 Based on Test Example 2, this test example examines the energy consumption of ammonia synthesis when the iron-based catalyst provided in Example 1 is applied to the electrothermal catalytic ammonia synthesis system provided in the above examples for electrothermal catalytic ammonia synthesis, and when applied to the traditional thermocatalytic ammonia synthesis process. The electrical energy consumed to generate a unit mass of ammonia is used as the energy consumption standard. The test results are as follows: Figure 3 As shown, the electrothermal catalytic ammonia synthesis method of this application consumes only 452 kWh of electricity to produce 1 kg of ammonia, while the conventional thermocatalytic ammonia synthesis process requires 3681 kWh of electricity to produce 1 kg of ammonia. This indicates that the electrothermal catalytic ammonia synthesis method provided by this application can significantly reduce energy consumption.

[0090] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0091] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An iron-based catalyst characterized in that, The iron-based catalyst comprises the following components in percentage by mass: Catalyst main component FeO 1-x 30%~90%, catalytic assistant 5%~40% and conductive assistant 10~80%; the FeO 1-x x is in the range of 0.01 to 0.1; The catalytic assistant comprises potassium oxide, aluminum oxide and alkaline earth metal oxide; The conductive assistant comprises at least one of carbon-containing material and conductive metal compound.

2. The iron-based catalyst according to claim 1, characterized in that The catalyst main component FeO 1-x 30%~60% And / or, the mass percentage of the catalytic assistant is 5% to 15%; And / or, the mass percentage of the conductive assistant is 30% to 60%.

3. The iron-based catalyst of claim 1, wherein The catalyst main component FeO 1-x x is in the range of 0.02 to 0.05; And / or, the mass percentage of the potassium oxide in the catalytic assistant is 5% to 40%; And / or, the mass percentage of the aluminum oxide in the catalytic assistant is 20% to 60%; And / or, the mass percentage of the alkaline earth metal oxide in the catalytic assistant is 5% to 40%.

4. The iron-based catalyst of claim 1, wherein The alkaline earth metal oxide comprises at least one of magnesium oxide, calcium oxide, strontium oxide and barium oxide; And / or, the carbon-containing material comprises at least one of graphene, carbon nanotube, activated carbon, conductive carbon black, nitrogen-doped carbon material, silicon carbide and titanium carbide, and the conductive metal compound comprises at least one of indium tin oxide and antimony tin oxide.

5. A process for the preparation of the iron-based catalyst according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: Mixing and melting raw materials except for the conductive assistant in proportion, and then cooling and crushing to obtain a catalyst precursor; Mixing and grinding the catalyst precursor and the conductive assistant, and then reducing and activating to obtain the iron-based catalyst.

6. The process for the preparation of an iron-based catalyst according to claim 5, characterized in that, The catalyst main component FeO 1-x The raw material includes magnetite powder and iron powder, and the mass ratio of the magnetite powder and the iron powder is (2-4):

1. And / or, the raw materials of the catalytic assistant comprise at least one of metal oxide, metal nitrate and metal carbonate; And / or, the mass ratio of the catalyst precursor to the conductive assistant is (1-20):(1-20); And / or, the working condition parameters of the mixing and grinding comprise a grinding rotation speed of 50 rpm to 300 rpm and a grinding time of 0.5 h to 5 h; And / or, the working condition parameters of the reducing and activating comprise a reducing temperature of 300°C to 600°C, a reducing time of 10 h to 30 h, and a volume percentage content of hydrogen in the reducing atmosphere of ≥30%.

7. A method for the electrothermo catalytic synthesis of ammonia, characterized in that, The catalyst used in the method for electrothermal catalytic synthesis of ammonia comprises the iron-based catalyst of any one of claims 1 to 4 or the iron-based catalyst prepared by the preparation method of any one of claims 5 to 6.

8. The electrothermal catalytic ammonia synthesis method according to claim 7, characterized in that, The working condition parameters of the electrothermal catalytic synthesis of ammonia comprise a pressure of 0.1 MPa to 5 MPa, an output current of the power supply of 1 A to 20 A, an output voltage of the power supply of 1 V to 20 V, and an output power of the power supply of 5 W to 100 W.

9. An electrothermo catalytic system for synthesis of ammonia, characterized in that, The method for electrothermal catalytic synthesis of ammonia of any one of claims 7 to 8 is realized; The reaction device comprises an electrode, and the electrode is connected with the power supply to form a closed loop.

10. The system for the electro thermo catalytic synthesis of ammonia according to claim 9, wherein, The reaction device is provided with a gas inlet and a gas outlet, and the gas outlet is connected with an electric conductivity meter; And / or, the reaction device is provided with a conductive filter element, the conductive filter element comprises a first conductive filter element layer and a second conductive filter element layer, and the catalyst is placed between the first conductive filter element layer and the second conductive filter element layer; And / or, the conductive filter element is connected with a thermocouple and the electrode.

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