Electrically heated catalyst and system for producing hydrogen through electro-thermal catalytic ammonia decomposition

Abstract

The invention belongs to the technical field of hydrogen production, and particularly relates to an electric heating catalyst and an electric heating catalytic ammonia decomposition hydrogen production system. The electrothermal catalyst comprises a catalyst component and a foam alloy electrode, wherein the catalyst component comprises an active metal, a carrier metal oxide and an auxiliary metal oxide; the interior of the foam alloy electrode is of a porous network structure, the catalyst components are uniformly distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure, and the thickness of the catalyst components distributed on the outer surface of the foam alloy electrode and the thickness of the inner wall of the porous network structure are both 5-10 microns. The foam alloy electrode is used as a heating unit and a carrier for catalyst growth, catalyst forming is not needed, good heat transfer and mass transfer efficiency is achieved, meanwhile, the electro-thermal catalytic bed design of multiple sections of bed layers is combined, temperature subsection control of the multiple sections of bed layers is achieved, the optimal reaction conditions can be kept at different reaction stages, and the reaction efficiency is improved. Therefore, the reaction efficiency is obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production, and particularly relates to an electrothermal catalyst and an electrothermal catalytic ammonia decomposition hydrogen production system. Background Art

[0002] Developing clean and carbon-neutral hydrogen energy technologies is crucial for the energy and environmental sustainability of human civilization. However, hydrogen still faces significant challenges in production, transportation, distribution, and storage. Therefore, it is particularly important to seek a low-carbon, environmentally friendly, and economical hydrogen production solution. Ammonia, as a hydrogen carrier, has been recognized as an important carbon-neutral liquid fuel and distributed energy storage material, and has a mature production, storage, and transportation system. Hydrogen in ammonia has a large mass fraction and high energy density, and the decomposition products have high purity. However, current ammonia decomposition technologies still require high power consumption to achieve ammonia cracking.

[0003] For traditional distributed ammonia decomposition hydrogen production reaction systems, the energy for heating reactants and reactions depends on heat transfer from an external heating surface to the internal flow of reactants. Although the use of catalysts can reduce the requirements for reaction temperature and corresponding reaction energy, the low thermal conductivity of reactants (especially gaseous reactants) and internal heat reactions can lead to uneven temperature distribution, showing an obvious temperature gradient throughout the reactor. To achieve higher conversion rates at the reactor outlet with high-throughput gas feeding, many slender reactor tubes with high aspect ratios are required. However, equipping many extended reaction tubes with external combustion furnaces will result in a large volume of the reaction system. The method of directly heating catalyst particles by using Joule heat, thereby greatly reducing the heat diffusion length from the heat source to the catalyst bed and maximizing the use of active sites, has received extensive attention from researchers. Wang et al. achieved efficient formaldehyde removal by electrothermally driving Ag / Co3O4 on mesoporous carbon and reduced the energy consumption by 87% (Wang, et al, Carbon, 2020, 167, 709-717). The electrified reactor device using resistance heating to supply heat shows great potential, and its relatively small reactor volume and high thermal utilization efficiency are beneficial to the modularization and scale-up of the reactor. The electrothermal ammonia decomposition reaction system reported in the current literature (Badakhsh, et al. Chemical Engineering Journal 2021, 426, 130802) achieved the electrification of ammonia decomposition based on Ru-based catalysts, but the regulation of reactor structure and heat transfer is not yet mature. Therefore, an electrothermal ammonia decomposition reaction system with low hydrogen production energy consumption and high hydrogen production rate is needed. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide an electrothermal catalyst and an electrothermal catalytic ammonia decomposition hydrogen production system to solve the problems in the prior art.

[0005] The technical solution of the present invention is as follows:

[0006] On the one hand, the present invention provides an electrothermal catalyst, which includes a catalyst component and a foam alloy electrode. The catalyst component includes an active metal, a support metal oxide, and a promoter metal oxide; the interior of the foam alloy electrode is a porous network structure, and the catalyst component is uniformly distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure. The thickness of the catalyst component distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure is 5-10 microns.

[0007] On the second aspect, the present invention provides a preparation method of an electrothermal catalyst, and the preparation method includes the following steps:

[0008] S1) Mix the salt solution of the active metal, the salt solution of the support metal, and the salt solution of the promoter metal and dissolve them in deionized water to obtain a mixed solution A;

[0009] S2) Add an alkali solution to the mixed solution A obtained in step S1 and stir to obtain a mixed solution B;

[0010] S3) Perform a hydrothermal reaction on the foam alloy electrode and the mixed solution B in step 2) to obtain a layered hydroxide structure with a multi-level hierarchical morphology;

[0011] S4) After washing the layered hydroxide structure obtained in step S3), calcine it in an inert gas atmosphere to obtain an electrothermal catalyst with a porous structure.

[0012] On the third aspect, the present invention provides the application of the electrothermal catalyst as described in the present invention and / or the electrothermal catalyst prepared by the preparation method of the electrothermal catalyst as described in the present invention in an electrothermal catalytic ammonia decomposition hydrogen production system.

[0013] In the fourth aspect of the present invention, an electrothermal catalytic ammonia decomposition hydrogen production system is provided. The system includes an ammonia gas tank, a heat exchanger, an electrothermal catalytic reactor, a power supply, and a purification device. The electrothermal catalytic reactor is provided with an ammonia gas inlet and a decomposed gas outlet. Inside the electrothermal catalytic reactor, there are multiple electrothermal reaction units arranged in series in an array. Each electrothermal reaction unit includes a gas flow channel and an electrothermal catalyst disposed in the gas flow channel. Each electrothermal catalyst is electrically connected to the power supply respectively. The ammonia gas inlet is communicated with the first end of the electrothermal reaction unit, and the decomposed gas outlet is communicated with the last end of the electrothermal reaction unit. The heat exchanger includes an ammonia gas preheating channel and a decomposed gas cooling channel. The ammonia gas tank, the ammonia gas preheating channel, and the ammonia gas inlet are sequentially communicated, and the decomposed gas outlet, the decomposed gas cooling channel, and the purification device are sequentially communicated. Among them, the electrothermal catalyst is the electrothermal catalyst as described above in the present invention and / or the electrothermal catalyst obtained by the preparation method as described above in the present invention.

[0014] By adopting the foregoing technical solutions, the beneficial effects of the present invention are as follows:

[0015] The present invention proposes an electrothermal reaction system suitable for ammonia decomposition hydrogen production, which can obtain hydrogen with low power consumption and large throughput. Compared with traditional heating, using electrothermal energy as the heat source to directly heat the catalyst reduces the distance between the heat conduction interface and the catalyst, can greatly improve the heat supply efficiency, and reduce the overall energy consumption. The present invention can combine the multiple advantages of renewable energy and can be applied on a large scale in various energy fields such as various small-scale distributed hydrogen production.

[0016] The present invention uses a foam alloy electrode as the heating unit and the carrier for catalyst growth, without the need for catalyst forming, has good heat and mass transfer efficiency, and at the same time combines the electrothermal catalytic bed design of multiple bed layers to achieve temperature segmented control of multiple bed layers, so that the best reaction conditions can be maintained in different reaction stages, thereby significantly improving the reaction efficiency.

[0017] The present invention uses the electroheating mode, can combine the diverse advantages of renewable energy, realize completely green hydrogen production, reduce the carbon footprint, and meet the development needs of the low-carbon economy.

[0018] The present invention is applicable to distributed hydrogen production, small energy devices, and other energy networks, and can be extended for use in other chemical reactions that require strict temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of the electrothermal catalytic ammonia decomposition hydrogen production system of the present invention.

[0020] Figure 2 It is a SEM diagram of the cobalt / aluminum oxide-cerium oxide catalyst loaded in Example 1 of the present invention.

[0021] 1 Ammonia tank

[0022] 2 Heat exchanger

[0023] 21 Ammonia preheating channel

[0024] 22 Decomposition gas cooling channel

[0025] 23 Ammonia discharge port

[0026] 3 Electrothermal catalytic reactor

[0027] 31 Ammonia inlet

[0028] 32 Decomposition gas outlet

[0029] 33 Electrothermal reaction unit

[0030] 331 Gas flow channel

[0031] 332 Electrothermal catalyst

[0032] 4 Power supply

[0033] 5 Purification device

[0034] 51 Adsorption module

[0035] 52 Condensation separation module

[0036] 6 Flow control valve Detailed implementation mode

[0037] Hereinafter, an implementation mode of an electrothermal catalyst and an electrothermal catalytic ammonia decomposition hydrogen production system provided by the present invention will be described in detail.

[0038] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include or exclude the end values and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0039] Through a large amount of exploration and research, the inventors of the present invention carried out an electrification transformation on the ammonia decomposition reaction device by utilizing the Joule heat effect. Compared with the traditional thermal catalytic device, the electrothermal reaction device can provide centralized heating for the catalyst layer, achieve uniform temperature distribution of the catalyst layer, reduce the overall heating area, and thus significantly reduce the energy consumption of distributed ammonia decomposition for hydrogen production. By in-situ growing a thin catalyst layer with a micron-level thickness on the foam metal, the heat transfer distance between the catalyst and the heat source is significantly shortened, the utilization rate of the catalyst is improved, and the mass transfer efficiency on the catalyst surface is significantly enhanced at a high reactor space velocity. The design of multiple catalyst beds is realized by connecting foam alloy electrodes in series. Through the segmented temperature control of multiple beds, local overheating can be avoided, the service life of the catalyst can be extended, and appropriate heat can be provided at different reaction stages to ensure the full conversion of reactants under high-throughput conditions. On this basis, this application was completed.

[0040]

Electrothermal Catalyst

[0041] The present invention provides an electrothermal catalyst, which includes a catalyst component and a foam alloy electrode. The catalyst component includes an active metal, a support metal oxide, and a promoter metal oxide. The interior of the foam alloy electrode is a porous network structure, and the catalyst component is uniformly distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure. The thickness of the catalyst component distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure is 5-10 microns.

[0042] In the electrothermal catalyst provided by the present invention, the catalyst component is distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure, and the thickness of the catalyst thin layer can be, for example, 5-8 μm or 8-10 μm. When there is no catalyst on the outer surface of the foam alloy electrode and the inner wall of the porous network structure, it is the contact surface between the foam alloy electrode and the reaction gas.

[0043] In the electrothermal catalyst provided by the present invention, the active metal is selected from one or more of nickel, iron, cobalt, ruthenium, and platinum.

[0044] In the electrothermal catalyst provided by the present invention, the support metal oxide is selected from one or more of alumina, magnesia, ceria, zirconia, and manganese oxide.

[0045] In the electrothermal catalyst provided by the present invention, the promoter metal oxide is selected from one or more of barium oxide, manganese oxide, molybdenum oxide, iron oxide, lanthanum oxide, gallium oxide, indium oxide, zirconia, strontium oxide, or ceria.

[0046] In some embodiments, the catalyst component can be, for example, one of nickel / ceria-alumina, cobalt / zirconia-indium oxide, nickel / manganese oxide-barium oxide, iron / ceria-gallium oxide, cobalt / magnesia-strontium oxide.

[0047] In the electrothermal catalyst provided by the present invention, the foam alloy electrode is selected from one or more of foam iron-chromium-aluminum alloy, foam nickel-chromium-aluminum alloy, foam nickel-chromium alloy, foam iron-nickel-aluminum alloy, foam iron-chromium alloy, and foam iron-nickel-chromium-aluminum.

[0048] In the electrothermal catalyst provided by the present invention, the thermal conductivity of the foam alloy electrode ≥50 W / mK, and the porosity ≥90%. The specific surface area of the porous network structure is 5-20 m 2 / L, and can be selected as 5-10 m 2 / L, 10-15 m 2 / L or 15-20 m 2 / L, etc.

[0049] In the electrothermal catalyst provided by the present invention, based on the catalyst component, the mass fraction of the active metal is 40-70 wt.%, and can be selected as 40-50 wt.%, 50-60 wt.%, 60-70 wt.%, 50-70 wt.%, 48.5%-67.3%, etc. The mass fraction of the support oxide is 12-40 wt.%, 12-35 wt.%, 35-40 wt.%, 12.7%-27.9%, and the mass fraction of the promoter metal oxide is 10-35 wt.%, and can be selected as 10-20 wt.%, 20-35 wt.%, 13.2%-34.3%, etc.

[0050] In the electrothermal catalyst provided by the present invention, the catalyst component grows in-situ on the outer surface of the foam alloy electrode and the inner wall of the porous network structure.

[0051]

Preparation Method of Electrothermal Catalyst

[0052] The present invention also provides a preparation method of an electrothermal catalyst, and the preparation method includes the following steps:

[0053] S1) Mix the salt solution of the active metal, the salt solution of the carrier metal, and the salt solution of the promoter metal and dissolve them in deionized water to obtain a mixed solution A;

[0054] S2) Add an alkali solution to the mixed solution A obtained in step S1 and stir to obtain a mixed solution B;

[0055] S3) Perform a hydrothermal reaction on the foam alloy electrode and the mixed solution B in step 2) to obtain a layered hydroxide structure with a multi-level hierarchical morphology;

[0056] S4) After washing the layered hydroxide structure obtained in step S3), calcine it in an inert gas atmosphere to obtain an electrothermal catalyst with a porous structure.

[0057] In the preparation method of the electrothermal catalyst provided by the present invention, in step S1), the salt solution of the active metal, the salt solution of the carrier metal, and the salt solution of the promoter metal are mixed and dissolved in deionized water to obtain a mixed solution A. Specifically:

[0058] In step S1) of the present invention, the active metal in the salt solution of the active metal is selected from one or more of nickel, iron, cobalt, ruthenium, and platinum.

[0059] In step S1) of the present invention, the carrier metal in the salt solution of the carrier metal is selected from one or more of aluminum, magnesium, cerium, zirconium, and manganese.

[0060] In step S1) of the present invention, the promoter metal in the salt solution of the promoter metal is selected from one or more of metal barium, manganese, molybdenum, iron, lanthanum, gallium, indium, zirconium, strontium, or cerium.

[0061] In step S1) of the present invention, the salt solutions of the active metal, the carrier metal, and the promoter metal are nitrate solutions respectively.

[0062] In step S1) of the present invention, the concentration ratio of the salt solution of the active metal to the salt solution of the carrier metal is 1 to 5. Optionally, the concentration ratio of the salt solution of the active metal to the salt solution of the carrier metal can be, for example, 1 to 3 or 3 to 5, etc.

[0063] In step S1) of the present invention, the concentration ratio of the salt solution of the active metal to the salt solution of the promoter metal is 5 to 20. Optionally, the concentration ratio of the salt solution of the active metal to the salt solution of the promoter metal can be, for example, 5 to 10, 10 to 20, 10 to 15, or 15 to 20, etc.

[0064] In step S1) of the present invention, the molar ratio of the salt solution of the active metal, the salt solution of the support metal, and the salt solution of the promoter metal is 20 to 15:10 to 4:5 to 1. It can be optionally 20 to 18:10 to 6:5 to 3, 18 to 15:6 to 4:3 to 1, etc.

[0065] In the preparation method of the electrothermal catalyst provided by the present invention, in step S2), an alkali solution is added to the mixed solution A obtained in step S1), and stirred to obtain a mixed solution B. Specifically:

[0066] In step S2) of the present invention, the alkali solution is selected from one or more of urea solution, ammonium bicarbonate solution, or ammonia water.

[0067] In step S2) of the present invention, the molar ratio of the metal salt in the mixed solution A to the alkali species of the alkali solution is 3 to 10:1, and it can be optionally 3 to 5:1, 5 to 8:1, 8 to 10:1, etc.

[0068] In step S2) of the present invention, the stirring time is 1 to 3 h, and it can be optionally 1 to 2 h or 2 to 3 h, etc.

[0069] In the preparation method of the electrothermal catalyst provided by the present invention, in step S3), the foam alloy electrode and the mixed solution B in step 2) are subjected to a hydrothermal reaction to obtain a layered hydroxide structure with a multi-level hierarchical morphology. Specifically:

[0070] In step S3) of the present invention, the specific selection and parameters of the foam alloy electrode are the same as those described in the first aspect of the present invention.

[0071] In step S3) of the present invention, the volume ratio of the foam alloy electrode to the mixed solution A is 8 to 4:1. Optionally, it can be 8 to 6:1, 6 to 4:1, etc.

[0072] In step S3) of the present invention, the temperature of the hydrothermal reaction is 120 to 180 °C, and it can be optionally 120 to 140 °C, 140 to 180 °C, 120 to 160 °C, 160 to 180 °C, 140 to 160 °C, etc.

[0073] In step S3 of the present invention, the time of the hydrothermal reaction is 8 to 16 h, and it can be optionally 8 to 12 h, 12 to 16 h, 8 to 10 h, 10 to 16 h, 10 to 12 h, etc.

[0074] In step S3) of the present invention, the inert atmosphere is one or more of nitrogen, argon or helium.

[0075] In the preparation method of the electrothermal catalyst provided by the present invention, in step S4), after washing the layered hydroxide structure obtained in step S3), it is calcined in an inert gas atmosphere to obtain an electrothermal catalyst with a porous structure. Specifically:

[0076] In step S4) of the present invention, the calcination temperature is 400 - 800 °C, and can be 400 - 600 °C or 600 - 800 °C, etc.

[0077] In step S4) of the present invention, the calcination time is 2 - 8 h, and can be 2 - 4 h or 4 - 8 h, etc.

[0078]

Use

[0079] The present invention also provides the application of the electrothermal catalyst as described in the present invention and / or the electrothermal catalyst prepared by the preparation method of the electrothermal catalyst as described in the present invention in an electrothermal catalytic ammonia decomposition hydrogen production system.

[0080]

Electrothermal catalytic ammonia decomposition hydrogen production system

[0081] The present invention also provides an electrothermal catalytic ammonia decomposition hydrogen production system, which includes an ammonia gas tank 1, a heat exchanger 2, an electrothermal catalytic reactor 3, a power supply 4 and a purification device 5.

[0082] In the electrothermal catalytic ammonia decomposition hydrogen production system provided by the present invention, a flow control valve 6 is provided on the connecting pipeline between the ammonia gas tank 1 and the heat exchanger 2 to adjust the ammonia supply through the flow control valve 6.

[0083] In the electrothermal catalytic ammonia decomposition hydrogen production system provided by the present invention, the electrothermal catalytic reactor 3 is provided with an ammonia gas inlet 31 and a decomposition gas outlet 32. Inside the electrothermal catalytic reactor 3, a plurality of electrothermal reaction units 33 in an array are connected in series. Each of the electrothermal reaction units 33 includes a gas flow channel 331 and an electrothermal catalyst 332 provided in the gas flow channel 331. Each of the electrothermal catalysts 332 is electrically connected to the power supply 4.

[0084] Furthermore, the electrothermal reaction unit 33 is a double-layer reaction tube. The outer layer is a stainless steel sleeve, and the inner layer is a quartz tube. The gas flow channel 331 is formed in the quartz tube, and the electrothermal catalyst 332 is filled in the gas flow channel 331.

[0085] Further, the electrothermal reaction unit 33 is arranged along the length direction, and the temperature of each unit can be independently adjusted. The power supply 4 is electrically connected to the electrothermal catalytic reactor 3. Specifically, each electrothermal catalyst 332 is connected to the power supply 4. For example, the electrothermal catalyst 332 is connected to the power supply 4 through a power-on interface. The power supply 4 can provide electric energy supply for segmented independent temperature control of the electrothermal reaction unit 33. Optionally, the power supply 4 is a DC power supply, with the output voltage range extended to 1 - 100V, the output current being 1 - 500A, and the power range being 1 - 50kW.

[0086] In the electrothermal catalytic ammonia decomposition hydrogen production system provided by the present invention, the ammonia inlet 31 is connected to the first end of the electrothermal reaction unit 33 ( Figure 1 the bottom of the gas flow channel 331 of the leftmost electrothermal reaction unit 33 in the figure), and the decomposition gas outlet 32 is connected to the last end of the electrothermal reaction unit 33 ( Figure 1 the top of the gas flow channel 331 of the rightmost electrothermal reaction unit 33 in the figure); the heat exchanger 2 includes an ammonia preheating channel 21 and a decomposition gas cooling channel 22. The ammonia tank 1, the ammonia preheating channel 21, and the ammonia inlet 31 are connected in sequence. Specifically, the ammonia preheating channel 21 is connected to the ammonia tank 1 and the ammonia inlet 31 of the electrothermal catalytic reactor 3 through pipelines. The decomposition gas outlet 32, the decomposition gas cooling channel 22, and the purification device 5 are connected in sequence. Specifically, the decomposition gas cooling channel 22 is connected to the decomposition gas outlet 32 of the electrothermal catalytic reactor 3 and the inlet of the purification device 5 through pipelines.

[0087] Further, the decomposition gas outlet 32 is connected to the heat exchanger 2 through a pipeline. The heat exchanger 2 is used to transfer the heat of the decomposition gas to the ammonia provided by the ammonia tank 1 for preheating.

[0088] In the electrothermal catalytic ammonia decomposition hydrogen production system provided by the present invention, the heat exchanger 2 is provided with an ammonia discharge port 23. The ammonia discharge port 23 is respectively connected to the ammonia preheating channel 21 and the ammonia inlet 31, and is used to supply the preheated ammonia to the electrothermal catalytic reactor 3.

[0089] In the electrothermal catalytic ammonia decomposition hydrogen production system provided by the present invention, the purification device 5 is used to separate and purify hydrogen in the decomposition gas. The purification device 5 includes an adsorption module 51 and a condensation separation module 52. The adsorption module 51 is connected to the outlet of the decomposition gas cooling channel 22 of the heat exchanger 2 and is used to adsorb ammonia and other impurity gases in the decomposition gas. The condensation separation module 52 is connected to the outlet of the adsorption module 51 and is used to further condense and remove residual impurity gases, thereby obtaining high-purity hydrogen.

[0090] Further, the adsorption module 51 is composed of a molecular sieve adsorber and an activated carbon adsorber. The molecular sieve adsorber is used for selectively adsorbing ammonia, and the activated carbon adsorber is used for removing trace carbon-based impurities. The condensation separation module 52 is connected to the system circulating cooling water (not shown) through a cooling unit (not shown), and is used for quickly cooling the decomposition gas and separating impurities.

[0091] After the reaction product of the present invention is subjected to energy recovery through the heat exchanger 2, it enters the adsorption device to separate the impurity gas, thereby obtaining high-purity hydrogen. The system can achieve local heating of the catalyst unit in the reactor and reduce heat loss, effectively reducing the risk of thermal deactivation of the catalyst during the reaction, greatly improving the energy efficiency and thermal management accuracy of the system, and improving the stability and service life of the catalyst.

[0092] The beneficial effects of the present invention are further described below in conjunction with embodiments.

[0093] In order to make the invention purpose, technical solution and beneficial technical effects of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. However, it should be understood that the embodiments of the present invention are only for explaining the present invention and are not for limiting the present invention, and the embodiments of the present invention are not limited to the embodiments given in the specification. The specific experimental conditions or operating conditions not specified in the embodiments are made according to the conventional conditions, or according to the conditions recommended by the material suppliers.

[0094] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps, or the insertion of other method steps between these clearly mentioned steps, unless otherwise specified; it should also be understood that the combined connection relationship between one or more devices / devices mentioned in the present invention does not exclude the existence of other devices / devices before and after the combined devices / devices, or the insertion of other devices / devices between these two clearly mentioned devices / devices, unless otherwise specified. Moreover, unless otherwise specified, the numbers of the method steps are only convenient tools for identifying the method steps, rather than limiting the arrangement order of the method steps or limiting the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0095] In the following embodiments, unless otherwise specified, various raw materials of the present invention can be purchased commercially or prepared according to the conventional methods in the art.

[0096] The electrical conductivity of the foam FeCrAl alloy is 0.2*106S / m, the thermal conductivity is 0.2W(m*K), the porosity is 90%, and the specific surface area is 10m 2 / L;

[0097] The conductivity of the nickel-chromium-aluminum alloy foam is 0.5 * 106 S / m, the thermal conductivity is 1.0 W / (m*K), the porosity is 90%, and the specific surface area is 8 m 2 / L;

[0098] The conductivity of the iron-nickel-chromium-aluminum alloy foam is 0.3 * 106 S / m, the thermal conductivity is 0.5 W / (m*K), the porosity is 90%, and the specific surface area is 12 m 2 / L.

[0099] Preparation Example 1

[0100] Preparation of Electrothermal Catalyst

[0101] Prepare cobalt nitrate solution, aluminum nitrate solution, and cerium nitrate solution with a stoichiometric ratio of 6:2:1, with a total concentration of 0.2 mol / L, and the concentration ratio of cobalt nitrate solution, aluminum nitrate solution, and cerium nitrate solution is 6:2:1; Add an equal volume of 1 mol / L ammonia water solution to the mixed solution and stir continuously for 1 h; Place the iron-chromium-aluminum alloy foam electrode in the mixed solution for full mixing, and then transfer it to a hydrothermal autoclave and react at 160 °C for 10 hours; Calcinate the reacted alloy foam in nitrogen at 600 °C for 4 h to obtain a cobalt-aluminum-cerium mixed oxide with a porous structure, and then form a supported cobalt / aluminum oxide-cerium oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where cobalt contains 48.5%, aluminum oxide contains 27.9%, and cerium oxide contains 23.6%. The thickness of the cobalt / aluminum oxide-cerium oxide distributed on the outer surface of the alloy foam electrode and the inner wall of the porous network structure is 5-10 microns.

[0102] Figure 2 SEM image of the supported cobalt / aluminum oxide-cerium oxide catalyst with a porous structure.

[0103] Preparation Example 2

[0104] Prepare nickel nitrate solution, aluminum nitrate solution, and strontium nitrate solution with a stoichiometric ratio of 9:3:1, with a total concentration of 0.2 mol / L, and the concentration ratio of nickel nitrate solution, aluminum nitrate solution, and strontium nitrate solution is 9:3:1; Add an equal volume of 1.5 mol / L urea solution to the mixed solution and stir continuously for 1 h; Place the nickel-chromium-aluminum alloy foam electrode in the mixed solution for full mixing, and then transfer it to a hydrothermal autoclave and react at 140 °C for 12 hours; Calcinate the reacted alloy foam in nitrogen at 600 °C for 4 h to obtain a nickel-aluminum-strontium mixed oxide with a porous structure, and then form a supported nickel / aluminum oxide-strontium oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where nickel contains 67.3%, aluminum oxide contains 19.5%, and strontium oxide contains 13.2%. The thickness of the nickel / aluminum oxide-strontium oxide distributed on the outer surface of the alloy foam electrode and the inner wall of the porous network structure is 5-10 microns.

[0105] Preparation Example 3

[0106] Prepare a ferric nitrate solution, a magnesium nitrate solution, and a lanthanum nitrate solution with a stoichiometric ratio of 9:3:2, with a total concentration of 0.2 mol / L, and a concentration ratio of the ferric nitrate solution, the magnesium nitrate solution, and the lanthanum nitrate solution of 9:3:2; add an equal volume of 1 mol / L ammonium bicarbonate solution to the mixed solution and continuously stir for 1 h; place the foam iron-nickel-chromium-aluminum electrode in the mixed solution and mix well, and then transfer it to a hydrothermal autoclave and react at 160 °C for 14 hours; calcine the reacted foam alloy in nitrogen at 600 °C for 4 h to obtain a porous iron-magnesium-lanthanum mixed oxide, and then form a supported iron / magnesium oxide-lanthanum oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where iron contains 53.0%, magnesium oxide contains 12.7%, and lanthanum oxide contains 34.3%. The thickness of the iron / magnesium oxide-lanthanum oxide distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure is 5-10 microns.

[0107] Preparation Example 4

[0108] Prepare a nickel nitrate solution, a cerium nitrate solution, and a gallium nitrate solution with a stoichiometric ratio of 9:2:2, with a total concentration of 0.2 mol / L, and a concentration ratio of the nickel nitrate solution, the cerium nitrate solution, and the gallium nitrate solution of 9:2:2; add an equal volume of 1 mol / L ammonia water to the mixed solution and continuously stir for 1 h; place the foam iron-chromium-aluminum electrode in the mixed solution and mix well, and then transfer it to a hydrothermal autoclave and react at 150 °C for 12 hours; calcine the reacted foam alloy in nitrogen at 600 °C for 4 h to obtain a porous nickel-cerium-gallium mixed oxide, and then form a supported nickel / cerium oxide-gallium oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where nickel contains 49.5%, cerium oxide contains 32.7%, and gallium oxide contains 17.8%. The thickness of the nickel / cerium oxide-gallium oxide distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure is 5-10 microns.

[0109] Preparation Example 5

[0110] Prepare cobalt nitrate solution, zirconium nitrate solution, and indium nitrate solution with a stoichiometric ratio of 7:3:1, with a total concentration of 0.2 mol / L, and the concentration ratio of cobalt nitrate solution, zirconium nitrate solution, and indium nitrate solution being 7:3:1; add an equal volume of 1 mol / L ammonium bicarbonate solution to the mixed solution and continuously stir for 1 h; place the foam iron-nickel-chromium-aluminum electrode in the mixed solution for thorough mixing, and then transfer it to a hydrothermal autoclave and react at 160 °C for 14 hours; calcine the reacted foam alloy in nitrogen at 600 °C for 4 h to obtain a cobalt-zirconium-indium mixed oxide with a porous structure, and then form a supported cobalt / zirconia-indium oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where cobalt accounts for 53.2%, zirconia accounts for 34.2%, and indium oxide accounts for 12.5%. The supported cobalt / zirconia-indium oxide is distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure with a thickness of 5-10 microns each.

[0111] Preparation Example 6

[0112] Prepare nickel nitrate solution, manganese nitrate solution, and barium nitrate solution with a stoichiometric ratio of 7:3:1, with a total concentration of 0.2 mol / L, and the concentration ratio of nickel nitrate solution, manganese nitrate solution, and barium nitrate solution being 7:3:1; add an equal volume of 1.5 mol / L urea solution to the mixed solution and continuously stir for 1 h; place the foam nickel-chromium-aluminum electrode in the mixed solution for thorough mixing, and then transfer it to a hydrothermal autoclave and react at 160 °C for 14 hours; calcine the reacted foam alloy in nitrogen at 600 °C for 4 h to obtain a nickel-manganese-barium mixed oxide with a porous structure, and then form a supported nickel / manganese oxide-barium oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where nickel accounts for 59.7%, manganese oxide accounts for 24.6%, and barium oxide accounts for 15.6%. The supported nickel / manganese oxide-barium oxide is distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure with a thickness of 5-10 microns each.

[0113] Preparation Example 7

[0114] Prepare iron nitrate solution, cerium nitrate solution, and gallium nitrate solution with a stoichiometric ratio of 7:2:2, with a total concentration of 0.2 mol / L, and the concentration ratio of iron nitrate solution, cerium nitrate solution, and gallium nitrate solution being 7:2:2; add an equal volume of 1 mol / L urea solution to the mixed solution and continuously stir for 1 h; place the foam iron-nickel-chromium-aluminum electrode in the mixed solution for thorough mixing, and then transfer it to a hydrothermal autoclave and react at 140 °C for 12 hours; calcine the reacted foam alloy in nitrogen at 600 °C for 4 h to obtain a porous iron-cerium-gallium mixed oxide, and then form a supported iron / cerium oxide-gallium oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where iron contains 42.9%, cerium oxide contains 37.2%, and gallium oxide contains 20.3%. The thickness of the supported iron / cerium oxide-gallium oxide distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure is 5 - 10 microns.

[0115] Preparation Example 8

[0116] Prepare cobalt nitrate solution, magnesium nitrate solution, and strontium nitrate solution with a stoichiometric ratio of 5:2:1, with a total concentration of 0.2 mol / L, and the concentration ratio of cobalt nitrate solution, magnesium nitrate solution, and strontium nitrate solution being 5:2:1; add an equal volume of 1 mol / L ammonium bicarbonate solution to the mixed solution and continuously stir for 1 h; place the foam iron-nickel-chromium-aluminum electrode in the mixed solution for thorough mixing, and then transfer it to a hydrothermal autoclave and react at 160 °C for 14 hours; calcine the reacted foam alloy in nitrogen at 600 °C for 4 h to obtain a porous magnesium-strontium mixed oxide, and then form a supported cobalt / magnesium oxide-strontium oxide catalyst by in-situ reduction with ammonia under electrothermal conditions, where cobalt contains 61.6%, magnesium oxide contains 16.8%, and strontium oxide contains 21.7%. The thickness of the cobalt / magnesium oxide-strontium oxide distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure is 5 - 10 microns.

[0117] Example 1

[0118] As Figure 1 shown in the electrothermal ammonia decomposition hydrogen production system, taking the ammonia decomposition hydrogen production reaction as a prototype, the raw material gas is pure ammonia, the active component of the catalyst used is cobalt, and the arrow direction is the gas flow direction.

[0119] The electrothermal catalytic reactor 3 is a reaction chamber with a cylindrical cavity. The main body is made of 316L stainless steel, and five serially-connected electrothermal reaction units 33 are arranged inside, with equal spacing between the electrothermal reaction units 33. To ensure the heat preservation performance, the electrothermal reaction units 33 and the cavity of the electrothermal catalytic reactor 3 are filled with aluminosilicate material. The electrothermal reaction unit 33 is composed of a reaction tube with a double-layer structure. The outer layer is a stainless steel sleeve, and the inner layer is a quartz tube. The foam alloy electrode is a foam iron-chromium-aluminum alloy with a rich pore structure, and the cobalt / aluminum oxide-cerium oxide catalyst (Preparation Example 1) is loaded on the alloy surface by a hydrothermal synthesis method. Both ends of the foam alloy are connected to the wire branch pipe through conductive carbon fibers and are directly electrically connected to the power supply 4 to generate a Joule heat effect for heating up.

[0120] The wire is a silver-plated copper wire with high electrical conductivity, and the outer layer is wrapped with a fluororubber insulation layer, which has high temperature tolerance. The wire branch pipe and the thermocouple branch pipe are sealed with the stainless steel sleeve through a polytetrafluoroethylene gasket. The wire branch pipes of the reaction tubes are connected to the power supply 4 in parallel to facilitate the hierarchical regulation of the temperatures in different reaction tubes. The power supply 4 is a DC power supply, with a rated output range of 1 - 100V, a current of 1 - 500A, and a power of 1 - 50kW. The temperature control module equipped in the system can automatically adjust the voltage and current of each reaction tube according to the temperature data fed back by the thermocouple to ensure the precise control of the temperature in the reaction tube and meet the multi-stage hierarchical temperature control requirements.

[0121] The heat exchanger 2 and the decomposition gas outlet 32 of the electrothermal catalytic reactor 3 are connected by a double-layer corrugated pipe, and the pipe interface is sealed with a metal gasket. The heat exchanger 2 has a double-channel cross-flow structure, including an ammonia preheating channel 21 and a decomposition gas cooling channel 22. The shell of the heat exchanger 2 is made of high-temperature-resistant stainless steel material, and the channel partition is composed of high-thermal-conductivity aluminum alloy and is coated with an anti-corrosion coating to enhance durability. The inlet of the ammonia preheating channel 21 is connected to the outlet of the ammonia tank 1 through a pipe, and the outlet is connected to the ammonia inlet 31 of the electrothermal catalytic reactor 3; the inlet of the decomposition gas cooling channel 22 is connected to the decomposition gas outlet 32 of the electrothermal catalytic reactor 3, and the outlet is connected to the inlet of the purification device 5.

[0122] The ammonia tank 1 and the ammonia inlet 31 of the electrothermal catalytic reactor 3 are connected by a corrosion-resistant steel pipe, and a high-precision flow control valve 6 and a pressure regulating valve are arranged inside the pipe. A flow meter and a pressure sensor are integrated on the pipe to monitor the ammonia supply status in real time. The pure ammonia in the ammonia tank 1 is adjusted to an appropriate flow rate through the flow control valve 6 and enters the electrothermal catalytic reactor 3 after being preheated by the heat exchanger 2. The temperature of the preheated ammonia can be adjusted by adjusting the electric heating power of the electrothermal reaction unit 33 at the last stage in series, and the ammonia preheating temperature can reach 150 - 300°C.

[0123] The purification device 5 consists of an adsorption module 51 and a condensation separation module 52. The adsorption module 51 includes a molecular sieve adsorber, an activated carbon adsorber and an ammonia detector, which respectively achieve the adsorption of residual ammonia and trace carbon-based impurities. The condensation separation module 52 is connected to the system circulating cooling water through a cooling unit, and is used to quickly cool the gas and separate impurities. The decomposed gas enters the adsorption module 51 from the outlet of the heat exchanger 2, removes residual ammonia and carbon-based impurities, and then enters the condensation separation module 52, where it is further cooled and other impurity gases are separated, and finally high-purity hydrogen is obtained.

[0124] During the cold start of the electrothermal catalytic reactor 3, ammonia at a flow rate of 10 Nm 3 / h enters the ammonia preheating channel 21 of the heat exchanger 2 from the ammonia tank 1 via the flow control valve 6, and exchanges heat with the decomposed gas cooling channel 22, so that the temperature of ammonia is quickly increased to the initial reaction temperature (about 150 - 300 °C). Subsequently, the preheated ammonia enters the interior of the electrothermal catalytic reactor 3 and undergoes a decomposition reaction through the action of the multi-bed electrothermal catalyst 332. When the power supply 4 is started, current is input into the electrothermal catalyst 332 composed of foam iron-chromium-aluminum alloy, and the Joule heat effect is used to quickly heat up the catalyst layer, so that the cobalt-aluminum-cerium oxide on the foam iron-chromium-aluminum is in-situ reduced. The heating rate can reach 10 - 50 °C / s, and at the same time, the temperature is ensured to be evenly distributed in the multi-bed catalyst to avoid local overheating. Under the action of the supported cobalt / aluminum oxide-cerium oxide, a mixed gas containing 75% hydrogen and 25% nitrogen can be obtained after passing through the electrothermal catalytic reactor 3, and the decomposition rate can reach 99.9%. After passing through the purification device 5, high-purity hydrogen with a hydrogen content of 99.9% can be obtained. The ammonia detection unit in the system monitors the ammonia concentration at the outlet section in real time and feeds the detection data back to the control program. The control program adjusts the current of the power supply 4 dynamically at the second level through a closed-loop regulation mechanism, so as to accurately adjust the temperature of each layer of electrothermal catalyst 332, ensure complete ammonia decomposition and maintain high energy efficiency operation. In addition, the power supply 4 controls each reaction unit separately according to the actual ammonia flow rate or the downstream hydrogen demand, selectively starts some catalyst layers under low flux conditions, avoids energy waste, and realizes high-efficiency energy saving. The total voltage output by the power supply 4 is 40 V, the total current is 262 A, and the corresponding hydrogen production power consumption is 0.7 kWh / Nm 3 H2, which is significantly lower than the power consumption of traditional thermal catalytic ammonia decomposition furnaces (for example, GESU Group in Suzhou: GSAQ / FC-10 gas production 10 Nm 3 / h, power 12 kW, corresponding power consumption 1.2 kWh / m 3 H2; GSAQ / FC-20 gas production 20 Nm 3 / h, power 24 kW, corresponding power consumption 1.2 kWh / m 3 H2. Suzhou Gaopu Ultra-Pure Gas Co., Ltd.: AF-5C / FC-5 gas production 5 Nm 3 / h, with a power of 6 kW and a corresponding power consumption of 1.2 kWh / m 3 H2; The gas production of AF-10 / FC-10 is 10 Nm 3 / h, with a power of 12 kW and a corresponding power consumption of 1.2 kWh / m 3 H2; The gas production of AF-20 / FC-20 is 20 Nm 3 / h, with a power of 24 kW and a corresponding power consumption of 1.2 kWh / m 3 H2. Guangzhou Qihong Air Equipment Co., Ltd.: The gas production of AG-H2-10 is 10 Nm 3 / h, with a power of 12 kW and a corresponding power consumption of 1.2 kWh / m 3 H2; The gas production of AG-H2-10 is 20 Nm 3 / h, with a power of 22 kW and a corresponding power consumption of 1.1 kWh / m 3 H2). Through rapid heating, precise temperature control and flexible adjustment, the reactor can quickly enter the stable working state during cold start and meet the requirements of various working conditions.

[0125] In the embodiment of the present application, due to the high reaction temperature and strong endothermicity required for ammonia decomposition, there is energy waste caused by the low heat transfer efficiency of traditional electric furnaces or combustion furnaces. The electrothermal catalytic ammonia decomposition system provided by the present invention shortens the distance between the catalyst active sites and the heat source and reduces the process energy consumption during ammonia decomposition. Based on the control of Joule heat, the variable load response rate of the ammonia decomposition hydrogen production system can also be significantly improved, realizing the precise matching of energy consumption and hydrogen production demand.

[0126] Example 2

[0127] Example 2 is basically the same as Example 1, except that: in Example 2, the foam alloy material selects foam nickel-chromium-aluminum as the foam alloy electrode, and the nickel / aluminum oxide-strontium oxide catalyst (Preparation Example 2) is loaded on the alloy surface by hydrothermal synthesis.

[0128] During the cold start of the electrothermal catalytic reactor 3, 10 Nm 3 / h flow rate of ammonia gas enters the ammonia preheating channel 21 of the heat exchanger 2 from the ammonia gas tank 1 through the flow control valve 6 and exchanges heat with the decomposition gas cooling channel 22. After the power supply 4 is started, the current is input into the electrothermal catalyst 332 layer composed of foam nickel-chromium-aluminum alloy, and the Joule heat effect is used to quickly heat up the catalyst, so as to promote the in-situ reduction of nickel-aluminum-strontium oxide on the foam nickel-chromium-aluminum alloy. Under the action of the nickel / aluminum oxide-strontium oxide catalyst, after passing through the electrothermal catalytic reactor 3, a mixed gas containing 75% hydrogen and 25% nitrogen can be obtained, and the decomposition rate can reach 99.8%. The total voltage output by the power supply 4 is 38 V, the total current is 269 A, and the corresponding hydrogen production power consumption is 0.68 kWh / Nm 3 ·H2.

[0129] Example 3

[0130] Example 3 is basically the same as Example 1, except that: the foam alloy material selects foam iron-nickel-chromium-aluminum as the foam alloy electrode, and the iron / magnesium oxide-lanthanum oxide catalyst (Preparation Example 3) is loaded on the alloy surface by hydrothermal synthesis.

[0131] During the cold start of the electrothermal catalytic reactor 3, ammonia at a flow rate of 10 Nm 3 / h enters the ammonia preheating channel 21 of the heat exchanger 2 from the ammonia tank 1 via the flow control valve 6 and exchanges heat with the decomposition gas cooling channel 22. After the power supply 4 is started, current is input into the electrothermal catalyst 332 composed of foam nickel-chromium-aluminum alloy, and the catalyst layer is rapidly heated by the Joule heat effect, causing in-situ reduction of the iron-magnesium-lanthanum oxide on the foam iron-nickel-chromium-aluminum. Under the action of the loaded iron / magnesium oxide-lanthanum oxide, a mixed gas containing 75% hydrogen and 25% nitrogen can be obtained after passing through the electrothermal catalytic reactor 3, and the decomposition rate can reach 99.9%. The total voltage output by the power supply 4 is 45 V, the total current is 249 A, and the corresponding hydrogen production power consumption is 0.75 kWh / Nm 3 H2.

[0132] Examples 4 - 8

[0133] Examples 4 - 8 are basically the same as Example 1, except that different catalysts or different foam alloy electrodes are used, corresponding to Preparation Examples (4 - 8).

[0134] Table 1

[0135]

[0136] In summary, the present invention effectively overcomes various drawbacks in the prior art and has high industrial utilization value.

[0137] The above is only the preferred embodiment of the present invention, and it does not limit the present invention in any form and essence. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. For those skilled in the art, without departing from the spirit and scope of the present invention, any equivalent changes made by using the above-disclosed technical content, such as slight modifications, decorations, and evolutions, are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the substantial technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An electrothermal catalyst, characterized in that, The electrothermal catalyst includes a catalyst component and a foam alloy electrode. The catalyst component includes an active metal, a support metal oxide, and a promoter metal oxide. The interior of the foam alloy electrode is a porous network structure, and the catalyst component is uniformly distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure. The thickness of the catalyst component distributed on the outer surface of the foam alloy electrode and the inner wall of the porous network structure is 5 - 10 micrometers.

2. The electrothermal catalyst according to claim 1, wherein It further includes any one or more of the following features: A1) The active metal is selected from one or more of nickel, iron, cobalt, ruthenium, and platinum; A2) The support metal oxide is selected from one or more of alumina, magnesia, ceria, zirconia, and manganese oxide; A3) The promoter metal oxide is selected from one or more of barium oxide, manganese oxide, molybdenum oxide, iron oxide, lanthanum oxide, gallium oxide, indium oxide, zirconia, strontium oxide, or ceria; A4) By weight of the catalyst component, the mass fraction of the active metal is 40 - 70 wt.%, the mass fraction of the support metal oxide is 12 - 40 wt.%, and the mass fraction of the promoter metal oxide is 10 - 35 wt.%; A5) The thermal conductivity of the foam alloy electrode is ≥50 W / mK, and the porosity is ≥90%; A6) The foam alloy electrode is selected from one or more of foam iron-chromium-aluminum alloy, foam nickel-chromium-aluminum alloy, foam nickel-chromium alloy, foam iron-nickel-aluminum alloy, foam iron-chromium alloy, and foam iron-nickel-chromium-aluminum; A7) The catalyst component grows in-situ on the outer surface of the foam alloy electrode and the inner wall of the porous network structure.

3. The preparation method of the electrothermal catalyst according to any one of claims 1 to 2, characterized in that, The preparation method includes the following steps: S1) Mix and dissolve the salt solution of the active metal, the salt solution of the support metal, and the salt solution of the promoter metal into deionized water to obtain a mixed solution A; S2) Add an alkali solution to the mixed solution A obtained in step S1 and stir to obtain a mixed solution B; S3) Perform a hydrothermal reaction on the foam alloy electrode and the mixed solution B in step 2) to obtain a layered hydroxide structure with a multi-level hierarchical morphology; S4) After washing the layered hydroxide structure obtained in step S3), calcine it in an inert gas atmosphere to obtain a porous electrothermal catalyst.

4. The preparation method of the electrothermal catalyst according to claim 3, characterized in that, It further includes any one or more of the following features: B1) In step S1), the active metal in the salt solution of the active metal is selected from one or more of nickel, iron, cobalt, ruthenium, and platinum; B2) In step S1), the support metal in the salt solution of the support metal is selected from one or more of aluminum, magnesium, cerium, zirconium, and manganese; B3) In step S1), the promoter metal in the salt solution of the promoter metal is selected from one or more of barium, manganese, molybdenum, iron, lanthanum, gallium, indium, zirconium, strontium, or cerium; B4) In step S1), the salt solutions of the active metal, the support metal, and the promoter metal are nitrate solutions respectively; B5) In step S1), the concentration ratio of the salt solution of the active metal to the salt solution of the support metal is 1 - 5; B6) In step S1), the concentration ratio of the salt solution of the active metal to the salt solution of the promoter metal is 5 - 20; B7) In step S1), the molar ratio of the salt solution of the active metal, the salt solution of the support metal, and the salt solution of the promoter metal is 20 - 10:10 - 4:5 - 1; B8) In step S2), the alkali solution is selected from one or more of urea solution, ammonium bicarbonate solution, or ammonia water; B9) In step S2), the molar ratio of the metal salt in the mixed solution A to the alkali species in the alkali solution is 3 - 10:1; B10) In step S2), the volume ratio of the foam alloy electrode to the mixed solution A is 8 - 4:1; B11) In step S3), the temperature of the hydrothermal reaction is 120 - 180 °C; B12) In step S3, the time of the hydrothermal reaction is 8 - 16 h; B13) In step S3), the inert atmosphere is one or more of nitrogen, argon, and helium; B14) In step S4), the calcination temperature is 400 - 800 °C; B15) In step S4), the calcination time is 2 - 8 h.

5. Application of the electrothermal catalyst as described in any one of claims 1 - 2 and / or the electrothermal catalyst prepared by the preparation method of the electrothermal catalyst as described in any one of claims 3 - 4 in an electrothermal catalytic ammonia decomposition hydrogen production system.

6. An electrothermal catalytic ammonia decomposition hydrogen production system, characterized in that, The system includes an ammonia gas tank (1), a heat exchanger (2), an electrothermal catalytic reactor (3), a power supply (4), and a purification device (5); the electrothermal catalytic reactor (3) is provided with an ammonia gas inlet (31) and a decomposed gas outlet (32), and the interior of the electrothermal catalytic reactor (3) is provided with a series of multiple electrothermal reaction units (33) in an array form. Each of the electrothermal reaction units (33) includes a gas flow channel (331) and an electrothermal catalyst (332) provided in the gas flow channel (331). Each of the electrothermal catalysts (332) is electrically connected to the power supply (4) respectively; the ammonia gas inlet (31) is communicated with the first end of the electrothermal reaction unit (33), and the decomposed gas outlet (32) is communicated with the last end of the electrothermal reaction unit (33); the heat exchanger (2) includes an ammonia gas preheating channel (21) and a decomposed gas cooling channel (22). The ammonia gas tank (1), the ammonia gas preheating channel (21), and the ammonia gas inlet (31) are communicated in sequence, and the decomposed gas outlet (32), the decomposed gas cooling channel (22), and the purification device (5) are communicated in sequence; among them, the electrothermal catalyst (332) is the electrothermal catalyst as described in any one of claims 1 - 2 and / or the electrothermal catalyst prepared by the preparation method as described in any one of claims 3 - 4.

7. The electrothermal catalytic ammonia decomposition hydrogen production system according to claim 6, wherein A flow control valve (6) is provided on the connecting pipeline between the ammonia gas tank (1) and the heat exchanger (2).

8. The electrothermal catalytic ammonia decomposition hydrogen production system according to claim 6, wherein The power supply (4) is a DC power supply, with an output voltage of 1 - 100 V, an output current of 1 - 500 A, and a power range of 1 - 50 kW.

9. The electrothermal catalytic ammonia decomposition hydrogen production system according to claim 6, characterized in that, The heat exchanger (2) is provided with an ammonia gas discharge outlet (23), and the ammonia gas discharge outlet (23) is communicated with the ammonia gas preheating channel (21) and the ammonia gas inlet (31) respectively.

10. The electrothermal catalytic ammonia decomposition hydrogen production system according to claim 6, characterized in that, The purification device (5) includes an adsorption module (51) and a condensation separation module (52). The adsorption module (51) is communicated with the outlet of the decomposition gas cooling channel (22) of the heat exchanger (2), and the condensation separation module (52) is communicated with the outlet of the adsorption module (51).

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