Apparatus and method for hydrogen production by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials

Abstract

The application provides a device and method for preparing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage material. The hydrogen preparation device comprises a hydrolysis unit, a drying unit, a pyrolysis unit, a water storage unit and a gas storage unit, the outlet of the water storage unit is communicated with the inlet of the hydrolysis unit, the outlet of the hydrolysis unit is communicated with the inlet of the drying unit, the outlet of the drying unit is communicated with the inlet of the pyrolysis unit, the outlet of the pyrolysis unit is communicated with the inlet of the gas storage unit, and the gas storage unit provides a carrier gas for the hydrolysis unit. Magnesium hydride is filled in the hydrolysis unit, the drying unit and the pyrolysis unit. The application uses the hydrolysis of the hydrolysis unit to prepare part of hydrogen, and uses the reaction heat as a heat source to realize the pyrolysis of the pyrolysis unit, and further prepare hydrogen. The coupling of the hydrolysis process and the pyrolysis process realizes high hydrogen storage density, continuous and stable hydrogen release of the hydrogen preparation device.

Description

Technical Field

[0001] This invention relates to hydrogen production technology, and more particularly to an apparatus and method for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. Background Technology

[0002] Magnesium hydride (MgH2) is an excellent hydrogen storage material and can be used as a hydrogen source for various stationary and mobile hydrogen production processes. There are two main technologies for producing hydrogen from magnesium hydride: pyrolysis and hydrolysis. The current challenge is that magnesium hydride pyrolysis requires an external heat source, while magnesium hydride hydrolysis releases a significant amount of heat that needs to be promptly dissipated. Therefore, there is a feasibility and necessity for process coupling between these two processes to improve energy utilization in the hydrogen production process. Summary of the Invention

[0003] The purpose of this invention is to address the low thermal efficiency of current magnesium hydride hydrogen production technology by proposing a device for the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials to produce hydrogen. This device combines the heat-releasing properties of magnesium hydride hydrolysis and the heat-endothermic properties of pyrolysis to achieve efficient energy utilization. Using magnesium hydride as a carrier, the device utilizes the heat of hydrolysis to promote the thermal decomposition reaction, resulting in a high hydrogen storage density and continuous, stable hydrogen release device.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: an apparatus for preparing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials, comprising a hydrolysis unit, a drying unit and a pyrolysis unit, wherein the outlet of the hydrolysis unit is connected to the inlet of the drying unit, the outlet of the drying unit is connected to the inlet of the pyrolysis unit, and magnesium hydride is filled in the hydrolysis unit, the drying unit and the pyrolysis unit.

[0005] The hydrolysis unit is wrapped around the outside of the pyrolysis unit; or, the pyrolysis unit is wrapped around the outside of the hydrolysis unit.

[0006] The hydrolysis unit and the pyrolysis unit are connected by a thermally conductive material.

[0007] Furthermore, the apparatus for preparing hydrogen by coupling hydrolysis and pyrolysis of the magnesium-based hydrogen storage material also includes a water storage unit and a gas storage unit. The outlet of the water storage unit is connected to the inlet of the hydrolysis unit, the outlet of the pyrolysis unit is connected to the inlet of the gas storage unit, the first outlet of the gas storage unit is connected to the inlet of the hydrolysis unit, and the second outlet of the gas storage unit is connected to the downstream hydrogen-using device.

[0008] Furthermore, the apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of the magnesium-based hydrogen storage material also includes a heat exchanger. The heat exchanger has two refrigerant inlets, which are respectively connected to the outlet of the water storage unit and the first gas storage unit. The refrigerant outlet of the heat exchanger is connected to the inlet of the hydrolysis unit, the heat medium inlet of the heat exchanger is connected to the outlet of the pyrolysis unit, and the heat medium outlet of the heat exchanger is connected to the inlet of the gas storage unit.

[0009] Furthermore, the heat exchanger includes a refrigerant inlet, and the pipeline after the first outlet of the gas storage unit and the outlet of the water storage unit merge is connected to the refrigerant inlet of the heat exchanger. That is, the hydrogen gas flowing out of the first outlet of the gas storage unit serves as a carrier gas and flows through the heat exchanger together with the water from the water storage unit. After being heated, it flows into the hydrolysis unit.

[0010] Furthermore, the inlet and outlet of the hydrolysis unit are respectively located below and above the hydrolysis unit.

[0011] Furthermore, the hydrolysis unit is provided with a material replacement port for quick replacement of the packing material, and the material replacement port is sealed with a flange and a gasket.

[0012] Furthermore, the drying unit is provided with a material replacement port for quick replacement of the packing material, and the material replacement port is sealed with a flange and a gasket.

[0013] After the hydrolysis and pyrolysis units finish releasing hydrogen, the hydrolysis product magnesium hydroxide is removed from the hydrolysis unit and replaced with new magnesium hydride, which can be done through the feed changer. The product in the pyrolysis unit is metallic magnesium. Hydrogen gas is introduced into the pyrolysis unit through the hydrogen outlet, causing the reaction Mg + H₂ → MgH₂ to regenerate magnesium hydride. Alternatively, the metallic magnesium product can be removed, hydrogenated at a fixed hydrogen refueling station, and then reintroduced into the pyrolysis unit. The drying unit absorbs water vapor from the hydrogen gas. When the reaction reaches approximately 80%, it needs to be replaced, using a flange and gasket connection for sealing.

[0014] Furthermore, the drying unit is positioned above the hydrolysis unit and the pyrolysis unit.

[0015] Furthermore, the drying unit is equipped with a flow channel plate, which allows the water vapor entrained in the hydrogen to come into full contact with the magnesium hydride inside the drying unit.

[0016] Furthermore, the pyrolysis unit inlet and the pyrolysis unit outlet are respectively located above and below the pyrolysis unit.

[0017] Furthermore, the inner wall of the pyrolysis unit is provided with metal fins to facilitate heat conduction.

[0018] Furthermore, the mass ratio of magnesium hydride filled in the hydrolysis unit, the magnesium hydride filled in the pyrolysis unit, and the magnesium hydride filled in the drying unit is 1-3:3:0.5-2.

[0019] Furthermore, the volume ratio of the hydrolysis unit, the pyrolysis unit, and the drying unit is 3-8:4:1-5, preferably 4:3:1.

[0020] Furthermore, the hydrolysis unit is filled with magnesium hydride and a catalyst that promotes hydrolysis;

[0021] And / or, the drying unit is filled with magnesium hydride and a catalyst that promotes hydrolysis;

[0022] And / or, the pyrolysis unit is filled with magnesium hydride and a catalyst that promotes the pyrolysis reaction.

[0023] This invention, based on the reaction characteristics of different units, adds different catalysts to magnesium hydride to fully utilize the potential of the raw materials. Different catalysts are added to the magnesium hydride in the hydrolysis and pyrolysis units. For example, the magnesium hydride in the hydrolysis unit is mixed with a catalyst that promotes the hydrolysis reaction, allowing the magnesium hydroxide generated during the reaction to be stripped; the magnesium hydride in the pyrolysis unit is mixed with a catalyst that promotes the pyrolysis reaction, and the magnesium hydride repeatedly absorbs and releases hydrogen; the magnesium hydride in the drying unit (can be without a catalyst or with a catalyst that promotes hydrolysis) has a catalyst that promotes hydrolysis, allowing high-temperature water vapor to enter the drying unit, and the hydrolysis reaction occurs preferentially.

[0024] Furthermore, pressure gauges and thermometers are installed in the hydrolysis unit, drying unit, and pyrolysis unit to monitor the pressure and temperature inside the reaction chamber in real time.

[0025] Another objective of this invention is to disclose a method for preparing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. This method effectively utilizes the heat generated by the hydrolysis of magnesium hydride to heat the magnesium hydride pyrolysis and release hydrogen, thus making full use of the heat generated by the hydrolysis of magnesium hydride.

[0026] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing hydrogen through the coupling of hydrolysis and pyrolysis of magnesium-based hydrogen storage materials, comprising the following steps: a hydrogen carrier gas provided by a gas storage unit carries water provided by a water storage unit into a hydrolysis unit. As the hydrolysis reaction proceeds, the generated hydrogen, along with the carrier gas, enters a drying unit through a pipeline. The water vapor entrained in the hydrogen reacts with magnesium hydride in the drying unit to produce hydrogen, while releasing heat. The hydrogen in the drying unit (hydrogen carrier gas, hydrogen generated by the hydrolysis unit, and hydrogen generated by the drying unit) enters a pyrolysis unit through a pipeline, transferring heat to magnesium hydride in the pyrolysis unit. The magnesium hydride pyrolyzes to produce hydrogen. Finally, the hydrogen carrier gas, the hydrogen generated by the hydrolysis unit, the hydrogen generated by the drying unit, and the hydrogen generated by the pyrolysis unit are all discharged from the outlet of the pyrolysis unit and enter the gas storage unit.

[0027] Furthermore, the hydrogen gas discharged from the pyrolysis unit has a temperature as high as 200-300℃, which cannot be directly used in fuel cells. In this invention, the high-temperature hydrogen gas from the pyrolysis unit outlet exchanges heat with water from the water storage unit and hydrogen carrier gas from the gas storage unit. This preheats the carrier gas and heats the water into steam before it enters the hydrolysis unit, which is conducive to the occurrence of the hydrolysis reaction. At the same time, the high-temperature hydrogen gas flowing out of the pyrolysis unit is cooled to 70-80℃ and flows into the gas storage unit. The gas storage unit supplies hydrogen to downstream hydrogen-using devices (such as fuel cells).

[0028] This invention proposes an apparatus and method for producing hydrogen through the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. Using magnesium hydride as a carrier, the heat of hydrolysis is utilized to promote the thermal decomposition reaction, resulting in a high hydrogen storage density and a continuously stable hydrogen release device. The heat generated during magnesium hydride hydrolysis is effectively used to heat the magnesium hydride and release hydrogen, ensuring full utilization of the heat from magnesium hydride hydrolysis. Compared with existing technologies, this invention has the following advantages:

[0029] 1) For hydrogen-based fuel cells, the moisture content in the fuel hydrogen must not exceed 10 ppm. Excessive moisture can easily cause cathode flooding, hindering the transport of reactant gases and severely impacting the fuel cell's efficiency. This invention uses magnesium hydride instead of traditional desiccants, effectively removing moisture from the hydrogen while also increasing hydrogen production.

[0030] 2) This invention solves the problem of needing an external heat source for magnesium hydride pyrolysis hydrogen production by effectively utilizing the reaction heat of hydrolysis: the heat generated by the hydrolysis of magnesium hydride in the hydrolysis unit is directly transferred to the magnesium hydride in the pyrolysis unit through the heat-conducting material between the hydrolysis unit and the pyrolysis unit, realizing solid-solid heat transfer; the hydrogen carrier gas, the water vapor generated by the hydrolysis of magnesium hydride in the hydrolysis unit, and the hydrogen gas enter the drying unit together, which dries the hydrogen gas on the one hand, and the water vapor reacts with magnesium hydride to generate heat, further heating the hydrogen gas; the high-temperature hydrogen gas with moisture removed in the drying unit enters the pyrolysis unit, and the heat is transferred to the magnesium hydride in the pyrolysis unit, realizing gas-solid heat transfer; the hydrogen gas temperature at the outlet of the pyrolysis unit is 200℃-300℃, and this heat exchanges with the water from the water storage unit and the hydrogen carrier gas from the gas storage unit, turning the water into water vapor, which is conducive to the occurrence of the hydrolysis reaction in the hydrolysis unit;

[0031] 3) The reaction process of this invention is as follows:

[0032] In the hydrolysis unit, magnesium hydride undergoes a hydrolysis reaction (water is in liquid or gaseous state), releasing heat. Part of this heat is transferred to the pyrolysis unit through the vessel wall, and the rest is carried away by hydrogen into the drying unit. In the drying unit, the hydrogen is dried, and any remaining moisture in the hydrogen is absorbed by the magnesium hydride. High-temperature hydrogen enters the pyrolysis unit. In the pyrolysis unit, magnesium hydride decomposes. Based on the enthalpy of the reaction and the heat loss during the reaction, the ratio of magnesium hydride in the hydrolysis unit: magnesium hydride in the pyrolysis unit: magnesium hydride in the drying unit is 1–3:3:0.5–2. Attached Figure Description

[0033] Figure 1 Schematic diagram of an apparatus for producing hydrogen through the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. Figure 1 ;

[0034] Figure 2 Schematic diagram of an apparatus for producing hydrogen through the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. Figure 2;

[0035] Figure 3 Schematic diagram of an apparatus for producing hydrogen through the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. Figure 3 . Detailed Implementation

[0036] The present invention will be further described below with reference to the embodiments:

[0037] Example 1

[0038] This embodiment discloses a device for producing hydrogen through the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. It has a circular nested structure, such as... Figure 1 As shown, the system includes a hydrolysis unit 1, a drying unit 2, a pyrolysis unit 3, a water storage unit 4, a gas storage unit 5, and a heat exchanger. The hydrolysis unit 1 covers the outside of the pyrolysis unit 3. The sidewalls of the pyrolysis unit 3 are made of thermally conductive material. The inner and outer walls of the hydrolysis unit 1 are made of thermally conductive material and thermally insulating material, respectively. In this invention, the inner wall of the hydrolysis unit 1 refers to the sidewall close to the pyrolysis unit 3, and the outer wall of the hydrolysis unit 1 refers to the sidewall away from the pyrolysis unit 3. The drying unit 2 is located above the hydrolysis unit 1 and the pyrolysis unit 3. The outlet of the hydrolysis unit 1 is connected to the inlet of the drying unit 2, and the outlet of the drying unit 2 is connected to the inlet of the pyrolysis unit 3. The refrigerant inlet of the heat exchanger is connected to the outlet of the water storage unit 4 and the first outlet of the gas storage unit 5. The refrigerant outlet of the heat exchanger is connected to the inlet of the hydrolysis unit 1, the heat medium inlet of the heat exchanger is connected to the outlet of the pyrolysis unit 3, and the heat medium outlet of the heat exchanger is connected to the inlet of the gas storage unit 5. The hydrogen gas flowing out of the first outlet of the gas storage unit 5 serves as a carrier gas and flows together with the water from the water storage unit 4 through the heat exchanger, and finally flows into the hydrolysis unit 1.

[0039] The inlet and outlet of the hydrolysis unit 1 are respectively located below and above the hydrolysis unit 1. The hydrolysis unit 1 is provided with a material replacement port for quick replacement of the packing material, and the material replacement port is sealed by a flange and a gasket.

[0040] The drying unit 2 is equipped with a material replacement port for quick packing replacement, which is sealed by a flange and gasket. The drying unit 2 also contains a flow channel plate to ensure sufficient contact between the water vapor entrained in the hydrogen and the magnesium hydride within the drying unit 2.

[0041] The inlet and outlet of the pyrolysis unit 3 are respectively located above and below the pyrolysis unit 3. Metal fins are provided on the inner wall of the pyrolysis unit 3 to facilitate heat conduction. In this invention, the inner wall of the pyrolysis unit 3 refers to the inner side of the reaction chamber sidewall.

[0042] After hydrogen release from hydrolysis unit 1 and pyrolysis unit 3, the hydrolysis product magnesium hydroxide in hydrolysis unit 1 is removed and replaced with new magnesium hydride, which can be done through the feed inlet. The product in the pyrolysis unit is metallic magnesium. Hydrogen gas is introduced into the pyrolysis unit through the hydrogen outlet, and the reaction Mg + H₂ → MgH₂ occurs, regenerating the hydrogen storage material magnesium hydride. The drying unit absorbs water vapor from the hydrogen gas. After the reaction is complete, it needs to be replaced, and a flange and gasket connection is used for sealing.

[0043] The volumes of the hydrolysis unit 1, the drying unit 2, and the pyrolysis unit 3 are 4L, 1L, and 3L, respectively. All three units are filled with magnesium hydride; the masses of magnesium hydride in the hydrolysis unit 1, drying unit 2, and pyrolysis unit 3 are 1.2kg, 0.5kg, and 1.8kg, respectively. The hydrolysis unit 1 contains magnesium hydride and a catalyst to promote its hydrolysis; the drying unit 2 contains magnesium hydride and a catalyst to promote its hydrolysis; and the pyrolysis unit 3 contains magnesium hydride and a catalyst to promote its pyrolysis reaction. The water consumption for each hydrolysis unit is 1.7kg.

[0044] In the embodiments described, different catalysts were added to the magnesium hydride in the hydrolysis unit and the pyrolysis unit. For example, the magnesium hydride in the hydrolysis unit was mixed with a catalyst that promotes the hydrolysis reaction, so that the magnesium hydroxide generated during the reaction could be stripped off; the magnesium hydride in the pyrolysis unit was mixed with a catalyst that promotes the pyrolysis reaction, and the magnesium hydride repeatedly absorbed and released hydrogen; the magnesium hydride in the drying unit (can be without a catalyst or with a catalyst that promotes hydrolysis) can have a catalyst that promotes hydrolysis added, so that high-temperature water vapor can enter the drying unit, and the hydrolysis reaction will occur preferentially.

[0045] Pressure gauges and thermometers are installed in the hydrolysis unit 1, drying unit 2 and pyrolysis unit 3 to monitor the pressure and temperature of the reaction chamber in real time.

[0046] The method for preparing hydrogen using the apparatus for the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials in this embodiment includes the following steps: At the start of the reaction, a portion of the hydrogen from the gas storage unit 5 carries water from the water storage unit 4 as a carrier gas. After passing through a heat exchanger, it flows into the hydrolysis unit 1 for hydrolysis to produce hydrogen. The hydrogen accumulated in the hydrolysis unit 1 (the hydrogen carrier gas provided by the gas storage unit 5 and the hydrogen generated during the hydrolysis process) enters the drying unit 2 through a pipeline. The water vapor entrained in the hydrogen reacts with magnesium hydride in the drying unit 2 to produce hydrogen, while releasing heat. After the hydrogen removes moisture in the drying unit 2, it enters the pyrolysis unit 3 through a pipeline, transferring heat to the magnesium hydride in the pyrolysis unit. The magnesium hydride is then pyrolyzed to produce hydrogen. Finally, the hydrogen carrier gas provided by the gas storage unit 5, the hydrogen generated by the hydrolysis unit 1, the hydrogen generated by the drying unit 2, and the hydrogen generated by the pyrolysis unit 3 all flow out from the outlet of the pyrolysis unit 3 and enter the gas storage unit 5.

[0047] The hydrogen gas discharged from the outlet of the pyrolysis unit 3 has a temperature as high as 200-300℃, which cannot be directly used in fuel cells. In this invention, the high-temperature hydrogen gas from the outlet of the pyrolysis unit 3 is exchanged with water from the water storage unit 4 and hydrogen carrier gas provided by the gas storage unit 5 to heat the water into water vapor, which then enters the hydrolysis unit 1, which is conducive to the occurrence of the hydrolysis reaction.

[0048] Example 2

[0049] This embodiment discloses a device for producing hydrogen through the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. Its structure is basically the same as that of Embodiment 1, being a circular nested structure, as shown below. Figure 2 As shown. The difference is that the pyrolysis unit 3 is wrapped around the outside of the hydrolysis unit 1. The sidewall of the hydrolysis unit 1 is made of thermally conductive material, while the inner and outer walls of the pyrolysis unit 3 are made of thermally conductive material and thermally insulating material, respectively.

[0050] Example 3

[0051] This embodiment discloses an apparatus for producing hydrogen through the coupled hydrolysis and pyrolysis of magnesium-based hydrogen storage materials. The hydrogen production method is basically the same as in Embodiment 1: water is carried by a hydrogen carrier gas through a heat exchanger and flows into the hydrolysis unit to produce hydrogen, releasing heat of reaction. This heat of reaction heats the pyrolysis unit through the solid boundary, such as... Figure 3 The hydrogen carrier gas and the hydrogen generated in the hydrolysis unit flow into the drying unit, where moisture is removed and the temperature is further increased before flowing into the pyrolysis unit. In the pyrolysis unit, the magnesium hydride receives heat from the high-temperature hydrogen in the drying unit and heat transferred from the solid boundary between the drying unit and the hydrolysis unit, and then decomposes to release hydrogen. Finally, the hydrogen carrier gas and the hydrogen generated in the hydrolysis unit, drying unit, and pyrolysis unit flow together into the gas storage unit.

[0052] The difference between Example 3 and Example 1 is that Example 3 adopts a square combined structure, with the outer layer being a hydrolysis unit and the middle layer being a pyrolysis unit. A hydrogen flow channel is provided in the pyrolysis unit to ensure uniform heating of the magnesium hydride within the pyrolysis unit by high-temperature hydrogen from the drying unit. Furthermore, the square hydrolysis unit, drying unit, and pyrolysis unit adopt a modular design, allowing them to be disassembled into independent parts after the hydrogen production process is completed. In particular, the pyrolysis unit can be disassembled into an independent part and sent to a fixed hydrogen refueling station for hydrogen refueling.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of a magnesium-based hydrogen storage material, characterized in that, It includes a hydrolysis unit (1), a drying unit (2) and a pyrolysis unit (3). The outlet of the hydrolysis unit (1) is connected to the inlet of the drying unit (2), and the outlet of the drying unit (2) is connected to the inlet of the pyrolysis unit (3). The hydrolysis unit (1), the drying unit (2) and the pyrolysis unit (3) are all filled with magnesium hydride. The hydrolysis unit (1) is wrapped around the outside of the pyrolysis unit (3); or, the pyrolysis unit (3) is wrapped around the outside of the hydrolysis unit (1); The hydrolysis unit (1) and the pyrolysis unit (3) are connected by a thermally conductive material; The apparatus for preparing hydrogen by coupling hydrolysis and pyrolysis of the magnesium-based hydrogen storage material further includes a water storage unit (4) and a gas storage unit (5). The outlet of the water storage unit (4) is connected to the inlet of the hydrolysis unit (1), the outlet of the pyrolysis unit (3) is connected to the inlet of the gas storage unit (5), the first outlet of the gas storage unit (5) is connected to the inlet of the hydrolysis unit (1), and the second outlet of the gas storage unit (5) is connected to the downstream hydrogen-using device. The mass ratio of magnesium hydride filled in the hydrolysis unit (1), the pyrolysis unit (3), and the drying unit (2) is 1~3:3:0.5~2.

2. The apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials according to claim 1, characterized in that, It also includes a heat exchanger, which has two refrigerant inlets connected to the outlet of the water storage unit (4) and the first outlet of the gas storage unit (5), respectively. The refrigerant outlet of the heat exchanger is connected to the inlet of the hydrolysis unit (1), the heat inlet of the heat exchanger is connected to the outlet of the pyrolysis unit (3), and the heat outlet of the heat exchanger is connected to the inlet of the gas storage unit (5).

3. The apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials according to claim 2, characterized in that, It also includes a heat exchanger, which has a refrigerant inlet, and the pipeline after the first outlet of the gas storage unit (5) and the outlet of the water storage unit (4) merge is connected to the refrigerant inlet of the heat exchanger.

4. The apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials according to claim 1, characterized in that, The drying unit (2) is equipped with a flow channel plate.

5. The apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials according to claim 1, characterized in that, The volume ratio of the hydrolysis unit (1), the pyrolysis unit (3), and the drying unit (2) is 3~8:4:1~5.

6. The apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials according to claim 1, characterized in that, The hydrolysis unit (1) is filled with magnesium hydride and a catalyst that promotes hydrolysis.

7. The apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials according to claim 1, characterized in that, The drying unit (2) is filled with magnesium hydride and a catalyst that promotes hydrolysis.

8. The apparatus for producing hydrogen by coupling hydrolysis and pyrolysis of magnesium-based hydrogen storage materials according to claim 1, characterized in that, The pyrolysis unit (3) is filled with magnesium hydride and a catalyst that promotes the pyrolysis reaction.

9. A method for preparing hydrogen through the coupled hydrolysis and pyrolysis of a magnesium-based hydrogen storage material, characterized in that, Includes the following steps: The hydrogen carrier gas provided by the gas storage unit carries the water provided by the water storage unit into the hydrolysis unit. As the hydrolysis reaction proceeds, the generated hydrogen, along with the carrier gas, enters the drying unit through a pipeline. The water vapor entrained in the hydrogen reacts with the magnesium hydride in the drying unit to produce hydrogen, while releasing heat. The hydrogen in the drying unit enters the pyrolysis unit through a pipeline, transferring heat to the magnesium hydride in the pyrolysis unit, where the magnesium hydride pyrolyzes to produce hydrogen. Finally, the hydrogen carrier gas, the hydrogen produced by the hydrolysis unit, the hydrogen produced by the drying unit, and the hydrogen produced by the pyrolysis unit are all discharged from the outlet of the pyrolysis unit and enter the gas storage unit.

10. The method for preparing hydrogen by coupling hydrolysis and pyrolysis of the magnesium-based hydrogen storage material according to claim 9, characterized in that, The high-temperature hydrogen gas exiting the pyrolysis unit exchanges heat with water from the water storage unit and carrier gas from the gas storage unit to preheat the carrier gas and heat the water into steam before entering the hydrolysis unit. At the same time, the high-temperature hydrogen gas exiting the pyrolysis unit is cooled to 70-80°C and flows into the gas storage unit. The gas storage unit supplies hydrogen to downstream hydrogen-using units.

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