System, process and catalyst for driving rapid cold start of ammonia decomposition by magnetic induction heating

Abstract

The invention discloses a system, a process and a catalyst for driving rapid cold start of ammonia decomposition through magnetic induction heating, and belongs to the technical field of hydrogen energy preparation. The system comprises a gas path unit, a catalyst bed filled with a magnetic cobalt-based catalyst, a detection unit, a magnetic induction heating device and a hydrogen fuel cell integration unit. The catalyst takes Al2O3 as a carrier, metal cobalt nanoparticles are loaded, and the catalyst has high saturation magnetization. When the system works, the magnetic induction heating device generates an alternating magnetic field, so that the catalyst quickly generates heat, the ammonia decomposition reaction temperature can be reached within 10 seconds, and second-level cold start is realized. Meanwhile, the catalyst has high activity on ammonia decomposition, and the ammonia conversion rate is close to 100%. The problems that a traditional ammonia decomposition system is slow in starting and high in energy consumption are solved, and the system is particularly suitable for mobile scenes such as ammonia power vehicles and portable fuel cells needing rapid and instant hydrogen production.

Description

Technical Field

[0001] The technical field of this invention is the intersection of hydrogen energy production and catalysis technology and magnetic induction heating technology. Specifically, it relates to a system, process and catalyst for rapid cold start of ammonia decomposition driven by magnetic induction heating, which is particularly suitable for on-site hydrogen production scenarios of mobile devices such as ammonia-powered vehicles and portable hydrogen fuel cells. Background Technology

[0002] Hydrogen energy, with its advantages of zero carbon emissions and high energy density, has become one of the core clean energy sources to replace fossil fuels. However, the large-scale application of hydrogen energy has long been limited by storage and transportation challenges, as gaseous hydrogen has a low volumetric energy density (only 0.09 kg / m³ at 1 atm). 3 Liquid hydrogen requires ultra-low temperature storage at -253℃, which is costly and has poor safety. Against this backdrop, the potential of ammonia (NH3) as a hydrogen carrier has attracted widespread attention: its hydrogen mass fraction is as high as 17.6%, far exceeding that of liquid hydrogen (11.1%); it is liquid at room temperature and pressure, and can be transported at low cost using existing fertilizer storage and transportation systems; moreover, the combustion or decomposition products of ammonia are only H2 and N2, with zero carbon emissions throughout the process. It is regarded by the industry as a "bridge connecting renewable energy and hydrogen energy applications," and shows strong application competitiveness, especially in on-site hydrogen production scenarios such as ammonia-powered vehicles and distributed hydrogen power plants.

[0003] On-site hydrogen production from ammonia relies on the ammonia decomposition reaction (2NH3→3H2+N2), but this reaction is strongly endothermic and requires high temperatures of 600-800℃ to proceed efficiently. Furthermore, the reaction rate is highly dependent on catalyst activity and heating efficiency. For mobile applications such as ammonia-powered vehicles and portable hydrogen fuel cells, rapid cold start is a core technological bottleneck. Traditional ammonia decomposition systems often employ resistance furnace heating, gas heating, or electric heating wire heating. These methods suffer from heat conduction lag: heat must be gradually transferred from the outer wall of the equipment to the inside of the catalyst bed, resulting in a system startup time of 40-60 minutes to reach the reaction temperature, far from meeting the actual demand for second-level vehicle startup. Simultaneously, traditional heating methods have low thermal efficiency (energy loss exceeds 60% during startup), and uneven local temperature distribution can easily lead to catalyst sintering and deactivation, further limiting the practical application of ammonia decomposition technology.

[0004] To address the high-temperature requirements of ammonia decomposition, existing technologies primarily focus on developing highly efficient catalysts, such as iron-based, nickel-based, and ruthenium-based catalysts. Iron-based catalysts are low-cost but lack sufficient activity, requiring temperatures above 800℃ to achieve ammonia conversion rates above 90%. Ruthenium-based catalysts exhibit the highest activity (efficient decomposition at 500℃), but are expensive (ruthenium costs over 1000 RMB / g), hindering large-scale application. Nickel-based catalysts balance cost and activity, but still require temperatures above 650℃, and traditional nickel-based catalysts lack specific thermal response properties, making them unsuitable for rapid heating scenarios. More critically, current catalyst designs only focus on catalytic activity, failing to synergistically integrate heating performance with catalytic performance. The catalysts rely on external heating equipment for temperature rise, failing to overcome the bottleneck of heating lag, thus the cold-start problem of ammonia decomposition systems remains fundamentally unresolved.

[0005] Magnetic induction heating technology, as a localized rapid heating technique, has achieved breakthroughs in metallurgy, materials synthesis, and medical thermotherapy in recent years. Its principle is that magnetic materials (such as iron, cobalt, and nickel nanoparticles) in an alternating magnetic field convert electromagnetic energy into heat energy through hysteresis loss, eddy current loss, or Nell relaxation effect, achieving rapid heating of the material itself. The heating rate can be precisely controlled by the magnetic field strength and frequency (heating rates can reach over 100℃ / s), far exceeding traditional heat conduction heating (≤10℃ / min). Currently, magnetic induction heating has been attempted for catalytic reactions such as methane steam reforming and CO2 methanation. By combining magnetic materials with catalysts, an integrated "heating-catalysis" process is achieved, significantly improving reaction start-up efficiency. However, in existing research, magnetic induction heating technology has not yet been applied to ammonia decomposition reactions, and a complete "magnetic catalyst-heating system-product application" design tailored to the characteristics of ammonia decomposition is lacking. In particular, key issues such as how to design magnetic catalysts to adapt to ammonia decomposition activity and how to integrate the heating system with hydrogen fuel cells to achieve second-level cold start-ups remain unresolved. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a system, process, and catalyst for rapid cold start-up of ammonia decomposition driven by magnetic induction heating.

[0007] To achieve the above objectives, the following technical solution is provided: In a first aspect, the present invention proposes a rapid cold start system for ammonia decomposition driven by magnetic induction heating, comprising a gas path unit, a catalyst bed, a detection unit, a magnetic induction heating device, and a hydrogen fuel cell integrated unit. The gas path unit includes an ammonia cylinder for supplying reaction raw materials and an inert gas cylinder for system purging; The catalyst bed includes a quartz reaction tube and a magnetic cobalt-based catalyst filled inside the quartz reaction tube. The detection unit includes an infrared thermometer for monitoring the catalyst bed temperature and a gas chromatograph for detecting ammonia conversion rate and analyzing product composition. The magnetic induction heating device generates an alternating magnetic field that acts on the magnetic cobalt-based catalyst in the catalyst bed. The outlet of the gas path unit is sequentially connected to a buffer tank, an ammonia absorption bottle, and a drying bottle, and the purified product gas path branch is connected to the gas chromatograph and the hydrogen fuel cell integrated unit.

[0008] The system has a cold start time of ≤10s for ammonia decomposition and an ammonia conversion rate of nearly 100%.

[0009] Furthermore, the magnetic induction heating device comprises three parts: an induction heating power supply, a magnetic field generating coil, and a magnetic field parameter control unit; the induction heating power supply is a high-frequency power supply with a power of 2.0-3.0kW; the magnetic field generating coil is a solenoid coil wound with copper wire; the magnetic field parameter control unit controls the magnetic field strength by adjusting the coil current; the magnetic induction heating device outputs an alternating magnetic field with a frequency of 203kHz, and the magnetic field strength can reach 36.4-66.8mT.

[0010] Furthermore, the inlet end of the ammonia cylinder and the quartz reaction tube are connected, and a first shut-off valve and a first flow meter are installed on the connecting pipeline; the outlet end of the inert gas cylinder is connected to the quartz reaction tube, and a second shut-off valve and a second flow meter are installed on the connecting pipeline; the quartz reaction tube passes through the magnetic field generating coil.

[0011] Furthermore, the highest surface temperature (T) of the catalyst bed IR,m The magnetic field strength can be adjusted. The magnetic field parameter control unit of the magnetic induction heating device controls the magnetic field strength by adjusting the coil current, thereby regulating the maximum surface temperature of the catalyst bed. At a magnetic field strength of 66.8 mT, T... IR,m ≥600℃; Built-in magnetic cobalt-based catalyst.

[0012] Furthermore, a buffer tank, an ammonia absorption bottle, and a drying bottle are sequentially connected to the outlet pipe of the quartz reaction tube. The outlet of the drying bottle is the product gas outlet, and the outlet gas path of the drying bottle is connected to the gas chromatograph and the hydrogen fuel cell integrated unit. The product gas passes through the buffer tank, ammonia absorption bottle, and drying bottle before finally reaching the gas chromatograph and the hydrogen fuel cell integrated unit. The product gas is used in the hydrogen fuel cell integrated unit to receive the H2 / N2 mixture generated by ammonia decomposition and drive the load operation.

[0013] Furthermore, the buffer tank is equipped with a porous ceramic filter membrane; the ammonia absorption bottle contains dilute sulfuric acid; the drying bottle is filled with 4A molecular sieve; and the inert gas bottle is an argon gas bottle.

[0014] Secondly, the present invention also proposes a magnetic cobalt-based catalyst for the system described above, wherein the catalyst is a cobalt-based catalyst with synergistic magnetic induction heating and ammonia decomposition catalytic performance; the magnetic cobalt-based catalyst uses γ-Al2O3 as a support (specific surface area of ​​approximately 180 m² / g, pore size of approximately 8 nm), and the active component is metallic Co. 0 The cobalt mass fraction is 20%-30%, preferably 25%, and the active component, metallic cobalt, exists in the form of nanoparticles with an average size of 30-35 nm. The exposed crystal planes are mainly (0001) crystal planes, and the saturation magnetization of the catalyst is not less than 136 A•m. 2 •kg Co -1 .

[0015] Furthermore, the preparation method of the magnetic cobalt-based catalyst includes the following steps: S1. A cobalt salt solution is impregnated onto an Al2O3 support using a wet impregnation method; the cobalt salt is cobalt nitrate or cobalt chloride. S2. Dry the impregnated support at 80-120℃ for 4-8 hours, and then calcine it at 500-600℃ for 3-5 hours to obtain the catalyst precursor; S3. The catalyst precursor is pre-reduced at 500-700°C for 2-4 hours under a hydrogen atmosphere to obtain the active component as metallic Co. 0 Magnetic cobalt-based catalysts.

[0016] Thirdly, the present invention also proposes a rapid cold start method for ammonia decomposition driven by magnetic induction heating, employing the system described above, including the following steps: a) System purging: Open the inert gas cylinder to purge the system gas path, then close it; b) Magnetic induction heating start-up: Start the magnetic induction heating device to raise the temperature of the magnetic cobalt-based catalyst in the quartz reaction tube (10) to above 500°C within 10 seconds; c) Feed reaction: Open the ammonia cylinder to allow ammonia to enter the inlet of the quartz reaction tube (10) and undergo a decomposition reaction through the heated magnetic cobalt-based catalyst; d) Product purification and application: The gas produced by the reaction is sent to the hydrogen fuel cell integrated unit after passing through a buffer tank, an ammonia absorption bottle and a drying bottle in sequence.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1) Second-level temperature rise start-up: This invention relies on the high hysteresis heating performance of cobalt-based catalysts (the saturation magnetization of the pre-reduced catalyst at 700℃ reaches 161 A•m). 2 •kg Co -1The highest specific absorption rate of 370 W•g was observed under a magnetic field of 203 kHz. -1 This enables rapid and direct heating of the catalyst itself, with a heating rate exceeding 100℃ / s, allowing the system to complete a cold start within 8-10 seconds, and the catalyst bed heating rate exceeding 100℃ / s; simultaneously, metallic Co... 0 The synergistic effect of the (0001) crystal facet and magnetic induction heating makes the ammonia decomposition reaction temperature more than 100°C lower than that of traditional heating, and can achieve a near 100% ammonia conversion rate at a relatively low temperature. The magnetic induction heating energy acts directly on the catalyst, with high thermal efficiency. The energy efficiency during the start-up phase is more than 30% higher than that of traditional resistance furnace heating, further reducing the overall energy consumption. It is perfectly suited to the needs of "instant start-up and low energy consumption" in mobile scenarios such as ammonia-powered vehicles and portable fuel cells, and solves the core efficiency problem of ammonia hydrogen energy implementation.

[0018] 2) The system of this invention possesses excellent long-term stability and reliability, providing crucial support for industrial applications. In 100 heating-cooling cycle tests (20 minutes heating / 10 minutes cooling), the size of the cobalt nanoparticles in the cobalt-based catalyst only slightly increased from 32.2 nm to 33.1 nm, with a saturation magnetization decrease of less than 2%. This catalyst exhibits high activity for ammonia decomposition, with the ammonia conversion rate consistently maintained above 97%, demonstrating that the catalyst structure and catalytic activity show no significant deactivation. In terms of safety design, the triple protection system of "argon purging + buffer tank + purification unit" can control the ammonia leakage concentration below 25 ppm, preventing acidic absorbent from backflowing and contaminating the catalyst bed. At the same time, the particle filtration function of the buffer tank ensures that downstream components are not affected by impurities, meeting the industrial requirements for long-term cyclic operation. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of the magnetic induction heating driven ammonia decomposition rapid cold start system of the present invention.

[0020] In the diagram: 1. Ammonia cylinder; 2. First shut-off valve; 3. First flow meter; 4. Infrared thermometer; 5. Gas chromatograph; 6. Buffer tank; 7. Ammonia absorption bottle; 8. Drying bottle; 9. Magnetic induction heating device; 10. Quartz reaction tube; 11. Magnetic cobalt-based catalyst; 12. Second flow meter; 13. Second shut-off valve; 14. Argon cylinder. Detailed Implementation

[0021] The structural and working principles of the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] Example 1 like Figure 1 As shown, a magnetic induction heating-driven ammonia decomposition rapid cold start system includes a gas path unit, a catalyst bed, a detection unit, a magnetic induction heating device, and a hydrogen fuel cell integrated unit. The gas path unit includes an ammonia cylinder for supplying reaction raw materials and an argon cylinder for system purging; the catalyst bed includes a quartz reaction tube and a magnetic cobalt-based catalyst filled inside the quartz reaction tube. The detection unit includes an infrared thermometer for monitoring the catalyst bed temperature and a gas chromatograph for detecting ammonia conversion rate and analyzing product composition; the infrared thermometer 4 is installed 5 mm directly above the catalyst bed.

[0024] The outlet of the gas path unit is sequentially connected to a buffer tank, an ammonia absorption bottle, and a drying bottle, and the purified product gas path branch is connected to the gas chromatograph and the hydrogen fuel cell integrated unit.

[0025] The magnetic induction heating device generates an alternating magnetic field that acts on the magnetic cobalt-based catalyst within the catalyst bed. The magnetic induction heating device comprises three parts: an induction heating power supply, a magnetic field generating coil, and a magnetic field parameter control unit. The induction heating power supply is a high-frequency power supply with a power of 2.0-3.0 kW. The magnetic field generating coil is a solenoid coil wound with copper wire. The magnetic field parameter control unit controls the magnetic field strength by adjusting the coil current. The magnetic induction heating device outputs an alternating magnetic field with a frequency of 203 kHz and a magnetic field strength of 36.4-66.8 mT.

[0026] The ammonia cylinder and the inlet end of the quartz reaction tube are connected, and a first shut-off valve and a first flow meter are installed on the connecting pipeline; the argon cylinder and the outlet end of the quartz reaction tube are connected, and a second shut-off valve and a second flow meter are installed on the connecting pipeline; the quartz reaction tube passes through the magnetic field generating coil.

[0027] The maximum surface temperature of the catalyst bed can be controlled by the magnetic field strength. At a magnetic field strength of 66.8 mT, T IR,m≥600℃; Built-in magnetic cobalt-based catalyst with a cobalt loading of 80mg.

[0028] A buffer tank, an ammonia absorption bottle, and a drying bottle are sequentially connected to the outlet pipe of the quartz reaction tube. The outlet of the drying bottle is the product gas outlet, and the outlet gas path of the drying bottle is connected to the gas chromatograph and the hydrogen fuel cell integrated unit. The buffer tank is equipped with a porous ceramic filter membrane; the ammonia absorption bottle contains dilute sulfuric acid; and the drying unit is filled with 4A molecular sieve.

[0029] The gas path module of this invention adopts a three-stage design of "supply-purification-transportation" to ensure a stable supply of ammonia and product cleanliness. The ammonia supply unit includes an ammonia cylinder and an argon cylinder. The ammonia flow rate is controlled at 50 mL / min by a first flow meter, and the reaction pressure is maintained at 1 atm. Argon (purity ≥99.99%) is used for pre-experimental gas path purging (flow rate 20-30 mL / min) and as a carrier gas assist at low ammonia flow rates (flow rate 5-10 mL / min), avoiding residual air and airflow fluctuations in the gas path. The purification unit includes an ammonia absorption bottle and a drying unit: the ammonia absorption bottle contains 10% dilute sulfuric acid to adsorb unreacted ammonia, ensuring ammonia residue in the product is ≤5 ppm; the drying unit is filled with 4A molecular sieves (moisture removal rate ≥99.9%) to reduce the moisture content of the product gas to below 5 ppm. Furthermore, the gas path unit is equipped with a buffer tank containing a 0.1-1 μm porous ceramic filter membrane, which serves to filter out catalyst particles and prevent backflow of dilute sulfuric acid from the ammonia absorption bottle.

[0030] Example 2 A magnetic cobalt-based catalyst for the system described above. γ-Al₂O₃ with a specific surface area of ​​180 m² / g and a pore size of 8 nm was selected as the support. Cobalt nitrate (Co(NO₃)₂•6H₂O, purity 99.5%) was used as the cobalt source. Based on a cobalt mass fraction of 25%, 12.5 g of cobalt nitrate was dissolved in 50 mL of deionized water (resistivity 18.2 MΩ•cm) to prepare a 0.8 mol / L cobalt salt solution. 10 g of the Al₂O₃ support was placed in a beaker, and the cobalt salt solution was slowly added dropwise while stirring until the support was completely wetted. After standing at room temperature for 2 h, the sample was dried in a 100℃ forced-air drying oven for 6 h to remove moisture. The dried sample was then transferred to a muffle furnace and calcined at a heating rate of 5℃ / min to 550℃ for 4 h to obtain the Co₃O₄ / Al₂O₃ precursor. The precursor was loaded into a quartz boat and placed in a tube furnace. Hydrogen gas with a purity of 99.999% (flow rate 30 mL / min) was introduced and heated to 700℃ at a heating rate of 10℃ / min. The temperature was maintained at this rate for 3 hours and then naturally cooled to room temperature to obtain the 25Co / Al2O3 catalyst.

[0031] Characterization revealed that the cobalt-based catalyst of this invention exhibits excellent magnetic properties and catalytic activity: after pre-reduction at 700℃, the average size of the cobalt nanoparticles is 22.6 nm, with the exposed crystal plane being the (0001) crystal plane (which exhibits high selectivity for NH bond breaking in the ammonia decomposition reaction); the saturation magnetization (Ms) can reach 161 A•m. 2 •kg Co -1 Under an alternating magnetic field of 203 kHz, the specific absorptivity (SAR) can reach up to 370 W•g. -1 It can achieve a heating rate of over 100℃ / s, providing a hysteresis heating basis for "second-level cold start"; at the same time, metallic Co 0 The presence of this catalyst enables efficient ammonia decomposition at temperatures below 500°C, reducing the reaction temperature by more than 100°C compared to traditional nickel-based catalysts, thus significantly reducing energy loss. It also meets the requirements for magnetic induction heating and catalysis.

[0032] Example 3 To meet the hysteresis heating requirements of cobalt-based catalysts, this invention designs a dedicated magnetic induction heating device, which comprises three parts: an induction heating power supply, a magnetic field generating coil, and a magnetic field parameter control unit. The induction heating power supply uses a high-frequency power supply with a power of 2.0-3.0kW and a fixed output frequency of 203kHz to ensure maximum hysteresis loss of the cobalt nanoparticles. The magnetic field generating coil is a solenoid coil wound with copper wire, with 30 turns, an inner diameter of 50mm, and a length of 80mm. The uniformity of the magnetic field strength in the central region (30mm length) of the coil fluctuates by ≤5%, completely covering the catalyst bed (20mm length). The magnetic field parameter control unit controls the magnetic field strength by adjusting the coil current (180-330A). The current and magnetic field strength are linearly positively correlated, corresponding to a magnetic field strength range of 36.4-66.8mT at the coil center. This allows for precise control of the catalyst bed temperature (T) according to the ammonia decomposition requirements. IR,m ).

[0033] In this embodiment, the magnetic induction heating device uses a Kejing KJ-2.5kW medium-frequency induction furnace (output frequency 203kHz), equipped with a self-made magnetic field generating coil (copper wire, cross-sectional area 2.5mm², 30 turns, inner diameter 50mm, length 80mm). The central axis of the coil is coaxial with the quartz reaction tube (outer diameter 40mm, inner diameter 30mm, effective length 200mm). The 25Co / Al2O3 catalyst (cobalt loading 80mg) prepared in Example 1 is loaded into the middle of the quartz reaction tube, forming a catalyst bed 20mm high. A Raytek MX2 infrared thermometer (accuracy ±2℃) is installed 5mm directly above the catalyst bed to monitor T. IR,m In the gas path module, the gas path outlet of the reaction device is sequentially connected to a buffer tank, an ammonia absorption bottle, and a drying bottle.

[0034] Example 4 A system for rapid cold start-up of ammonia decomposition driven by magnetic induction heating has a simple and efficient operation process. The rapid cold start-up process specifically includes the following steps: Step 1, system preparation: Load 80mg of magnetic cobalt-based catalyst into the catalyst bed made of quartz reaction tube, place it in the center of the magnetic induction coil, and then turn on the argon cylinder 14, the second flow meter 12, and the second shut-off valve 13 to purge the gas path for 5 minutes to remove air, and then turn off the argon cylinder. The second step is heating start-up: Activate the magnetic induction heating device, set the frequency to 203kHz, and adjust the coil current to the target value (e.g., 300A corresponds to a magnetic field strength of 66.8mT), so that the catalyst bed heats up to 500-700℃ (T) within 8-10 seconds. IR,m ).

[0035] The third step is the ammonia decomposition reaction: The ammonia cylinder is opened, and the ammonia flow rate is adjusted to 50 mL / min using the MFC. The ammonia gas passes through the drying unit and enters the catalyst bed, where it reacts with Co... 0 It decomposes into a H2-N2 mixture at the active site.

[0036] The fourth step is product purification and application: the product gas is purified sequentially through a buffer tank, an ammonia absorption bottle, and a drying bottle before being introduced into the hydrogen fuel cell to drive the load. When the system ends, the ammonia bottle and heating device are turned off first, and then the argon purging gas path is turned on for 10-15 minutes to remove residual gas.

[0037] This invention achieves synergistic optimization of the catalyst's "magnetic properties-catalytic performance" by controlling the pre-reduction temperature: when the pre-reduction temperature is below 500℃, cobalt mainly exists in the oxidized state (Co). 2+ / Co 3+ It exists, but the saturation magnetization is low (Ms≤114A•m). 2 •kg Co -1 The heating rate is slow and the catalytic activity is insufficient; when the pre-reduction temperature reaches 700℃, cobalt is completely converted into metallic Co. 0 Ms increased to 161 A•m 2 •kg Co -1 The hysteresis loop has the largest area and the best heating efficiency, while Co 0 The (0001) crystal plane is fully exposed, resulting in the highest ammonia decomposition activity—at a magnetic field of 66.8 mT, the ammonia conversion rate is close to 100%, and the reaction temperature (T) is also low. IR,mThis process achieves a temperature reduction of over 100°C compared to traditional resistance furnace heating, and its energy efficiency during startup is over 30% higher, significantly reducing energy consumption. In the process, ammonia is decomposed into a mixture of H2 and N2 via a catalyst bed. The product gas is purified through a buffer tank 6 (with a built-in 0.5μm porous ceramic filter membrane), an ammonia absorption bottle 7 containing 10% dilute sulfuric acid, and a drying bottle 8 containing 4A molecular sieves. One path is sent to a gas chromatograph 5 for online analysis, while the other path can be connected to a hydrogen fuel cell. Tests show that the ammonia conversion rate of this system is close to 100%. After 100 start-stop cycles, the catalyst performance remains stable.

[0038] In summary, this invention discloses a cobalt-based catalyst and supporting system for rapid cold start-up of ammonia decomposition driven by magnetic induction heating, belonging to the field of hydrogen energy production and catalysis technology. The catalyst uses Al2O3 as a support and cobalt as the active component, prepared by initial wet impregnation and pre-reduction treatment at a specific temperature. It can achieve delayed heating under an alternating magnetic field. The supporting system includes a magnetic induction heating device, a catalyst bed, a gas path module, and a hydrogen fuel cell integrated unit. This invention achieves a cold start-up time of ≤10s for ammonia decomposition through the synergistic effect of the magnetic hysteresis heating characteristics of cobalt nanoparticles and their catalytic ammonia decomposition activity, improving the start-up efficiency by hundreds of times compared to traditional resistance furnace heating. Furthermore, the catalyst maintains stable performance after 100 cycles. This system can be directly integrated into mobile devices such as ammonia-powered vehicles, providing an efficient solution for on-site hydrogen production and promoting the practical application of ammonia as a hydrogen carrier.

[0039] The above description is merely a preferred embodiment of the present invention. Any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical solution of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A rapid cold start system for ammonia decomposition driven by magnetic induction heating, characterized in that, It includes a gas path unit, a catalyst bed, a detection unit, a magnetic induction heating device (9), and a hydrogen fuel cell integration unit; The gas circuit unit includes an ammonia cylinder (1) for supplying reaction raw materials and an inert gas cylinder (14) for system purging. The catalyst bed includes a quartz reaction tube (10) and a magnetic cobalt-based catalyst (11) filled inside the quartz reaction tube (10). The detection unit includes an infrared thermometer (4) for monitoring the temperature of the catalyst bed and a gas chromatograph (5) for detecting the ammonia conversion rate and analyzing the composition of the products. The magnetic induction heating device (9) generates an alternating magnetic field that acts on the magnetic cobalt-based catalyst (11) of the catalyst bed. The outlet of the gas path unit is connected in sequence to a buffer tank (6), an ammonia absorption bottle (7), and a drying bottle (8). The purified product gas path branch is connected to a gas chromatograph (5) and a hydrogen fuel cell integrated unit.

2. The magnetic induction heating-driven ammonia decomposition rapid cold start system as described in claim 1, characterized in that, The magnetic induction heating device (9) comprises three parts: an induction heating power supply, a magnetic field generating coil, and a magnetic field parameter control unit. The induction heating power supply is a high-frequency power supply with a power of 2.0-3.0kW. The magnetic field generating coil is a solenoid coil wound with copper wire. The magnetic field parameter control unit controls the magnetic field strength by adjusting the coil current.

3. The magnetic induction heating-driven ammonia decomposition rapid cold start system as described in claim 2, characterized in that, The ammonia cylinder (1) and the inlet end of the quartz reaction tube (10) are connected, and a first shut-off valve (2) and a first flow meter (3) are provided on the connecting pipeline; the inert gas cylinder is connected to the outlet end of the quartz reaction tube (10), and a second shut-off valve (13) and a second flow meter (12) are provided on the connecting pipeline; the quartz reaction tube (10) passes through the magnetic field generating coil.

4. The magnetic induction heating-driven rapid cold start system for ammonia decomposition as described in claim 1, characterized in that, The maximum surface temperature of the catalyst bed can be controlled by the magnetic field strength; the magnetic field parameter control unit of the magnetic induction heating device (9) controls the magnetic field strength by adjusting the coil current, thereby controlling the maximum surface temperature of the catalyst bed. The cold start time for ammonia decomposition in the system is ≤10s.

5. The magnetic induction heating-driven rapid cold start system for ammonia decomposition as described in claim 1, characterized in that, The outlet end of the quartz reaction tube (10) is connected to a buffer tank (6), an ammonia absorption bottle (7), and a drying bottle (8) in sequence. The outlet end of the drying bottle (8) is the product gas outlet, and the outlet gas path of the drying bottle (8) is connected to the gas chromatograph (5) and the hydrogen fuel cell integrated unit.

6. The magnetic induction heating-driven rapid cold start system for ammonia decomposition as described in claim 1, characterized in that, The buffer tank (6) is equipped with a porous ceramic filter membrane; the ammonia absorption bottle (7) is filled with dilute sulfuric acid; the drying bottle (8) is filled with 4A molecular sieve; the inert gas bottle is an argon bottle (14).

7. A magnetic cobalt-based catalyst for use in the system according to any one of claims 1-6, characterized in that, Using Al2O3 as a carrier, the active component is metallic Co. 0 The catalyst contains 20%-30% cobalt by mass, and the active component, metallic cobalt, exists in the form of nanoparticles with an average size of 30-35 nm and exposed crystal planes of (0001). The saturation magnetization of the catalyst is not less than 136 A•m. 2 •kg Co -1 .

8. The magnetic cobalt-based catalyst according to claim 7, characterized in that, Its preparation method includes the following steps: S1. The cobalt salt solution is impregnated onto the Al2O3 support using the initial wet impregnation method; S2. Dry the impregnated support at 80-120℃ for 4-8 hours, and then calcine it at 500-600℃ for 3-5 hours to obtain the catalyst precursor; S3. The catalyst precursor is pre-reduced in a hydrogen atmosphere at 500-700℃ for 2-4 hours to obtain the magnetic cobalt-based catalyst (11).

9. The magnetic cobalt-based catalyst as described in claim 8, characterized in that, The cobalt salt is cobalt nitrate or cobalt chloride.

10. A method for rapid cold start of ammonia decomposition driven by magnetic induction heating, using the system described in any one of claims 1-6, characterized in that, Includes the following steps: a) System purging: Open the inert gas cylinder to purge the system gas path, then close it; b) Magnetic induction heating start-up: Start the magnetic induction heating device (9) to raise the temperature of the magnetic cobalt-based catalyst (11) in the quartz reaction tube (10) to above 500°C within 10 seconds; c) Feeding reaction: Open the ammonia cylinder (1) to allow ammonia to enter the inlet of the quartz reaction tube (10) and undergo a decomposition reaction through the heated magnetic cobalt-based catalyst (11); d) Product purification and application: The gas generated by the reaction passes through a buffer tank (6), an ammonia absorption bottle (7), and a drying bottle (8) in sequence before being sent to the hydrogen fuel cell integrated unit.

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