A magnesium-based porous hydrogen storage material and its preparation method

Abstract

The present invention relates to the field of C22C23 / 00, specifically a magnesium-based porous hydrogen storage material and a preparation method thereof. Using 20-30 parts of magnesium-based material, 5-15 parts of porous material, 1-5 parts of expanded powder, and 5-10 parts of composite metal, a magnesium-based porous low-pressure hydrogen storage material with a high hydrogen mass fraction, a large volume density of hydrogen storage, fast absorption and release kinetics, a long cycle service life, and high safety performance is provided. It can achieve a hydrogen storage capacity of more than 15wt% under the condition of 1-2MPa, with a fast hydrogen absorption and release rate and high cycle stability. While greatly improving the hydrogen storage safety, it ensures a high hydrogen storage capacity, enabling the provided magnesium-based porous hydrogen storage material to meet the usage requirements of on-vehicle hydrogen storage.

Description

Technical Field

[0001] The present invention relates to the field of C22C23 / 00, and specifically provides a magnesium-based porous hydrogen storage material and a preparation method thereof. Background Art

[0002] In recent years, with the development of industry, the global demand for energy and the pursuit of sustainable development have been increasing. Hydrogen is clean, safe, efficient, and renewable. Against the backdrop of the rapid deterioration of the global climate, it has prompted people to further study the development and utilization of hydrogen energy. Currently, hydrogen storage methods mainly include high-pressure compression hydrogen storage, liquid hydrogen storage, metal hydride hydrogen storage, physical adsorption hydrogen storage, and complex hydrogen storage technologies. Hydrogen storage technology is mainly considered comprehensively from several aspects such as hydrogen storage cost, hydrogen storage density, and hydrogen storage safety. Although the hydrogen storage effects of high-pressure compression hydrogen storage technology and liquid hydrogen storage technology are relatively good, their costs are high, energy consumption is large, and there are certain safety risks under high-pressure conditions.

[0003] Chinese Patent CN103014384A discloses a preparation method of a magnesium-silver hydrogen storage material. By induction melting a magnesium-silver alloy and then adding a certain amount of titanium trifluoride for ball milling, hydrogen storage activation is not required, and it has certain cycle stability, but the thermodynamic and kinetic properties of hydrogen absorption and desorption need to be improved; Chinese Patent CN111940719 discloses a nano magnesium-based hydrogen storage material and a preparation method thereof, which are mainly prepared by hydrogenation combustion of magnesium, a catalyst of graphene-supported titanium dioxide and scandium sesquioxide, making the prepared nano magnesium-based hydrogen storage material have high activity, but the cycle retention rate of hydrogen storage and release needs to be further improved.

[0004] Therefore, there is provided a magnesium-based porous low-pressure hydrogen storage material with a high hydrogen mass fraction, a large volumetric density of hydrogen storage, fast absorption and release kinetics, a long cycle service life, and high safety performance, which can achieve a hydrogen storage capacity of more than 15 wt% under the condition of 1 - 2 MPa, has a fast hydrogen absorption and desorption rate and high cycle stability, greatly improving the hydrogen storage safety while ensuring a high hydrogen storage capacity. Summary of the Invention

[0005] On the one hand, the present invention provides a magnesium-based porous hydrogen storage material. By weight, its preparation raw materials at least include: 20 - 30 parts of magnesium-based material, 5 - 15 parts of porous material, 1 - 5 parts of expanded powder, and 5 - 10 parts of composite metal.

[0006] As a preferred technical solution, the magnesium-based material is selected from at least one of metallic magnesium, magnesium hydride, nano magnesium hydroxide, and magnesium-aluminum layered double hydroxide; preferably, the magnesium-based material is a combination of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide, which can effectively save costs while enabling the provided magnesium-based porous hydrogen storage material to have an increased hydrogen storage volume density; during the experimental exploration process of this application, it was found that when controlling the mass ratio of the metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide to be (10-15):(2-5):(5-10), especially when using the self-prepared magnesium-aluminum layered double hydroxide, in combination with the porous material in the system, the cycle stability of hydrogen storage and release can be improved, and the thermodynamics and kinetics of hydrogen absorption and release of the magnesium-based porous hydrogen storage material can be significantly improved, realizing low-pressure hydrogen storage. The reason may be that the structure of the self-prepared magnesium-aluminum layered double hydroxide is a flaky structure with slit pores, and its high specific surface area and interlayer pore channels contribute to the compatibility of metallic magnesium, magnesium hydride, and composite metals, improving the cycle stability of hydrogen storage and release, significantly improving the thermodynamics and kinetics of hydrogen absorption and release of the magnesium-based porous hydrogen storage material, and realizing low-pressure hydrogen storage.

[0007] As a preferred technical solution, by weight, the raw materials for preparing the magnesium-aluminum layered double hydroxide include 30-35 parts of magnesium nitrate hexahydrate, 20-28 parts of aluminum nitrate nonahydrate, 15-20 parts of sodium hydroxide, 20-25 parts of sodium carbonate, and 205-220 parts of deionized water;

[0008] The preparation method of the magnesium-aluminum layered double hydroxide at least includes the following steps:

[0009] (1) By weight, add magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to two-fifths of the deionized water to prepare a mixed metal salt solution;

[0010] (2) By weight, add sodium hydroxide and sodium carbonate to the remaining deionized water to prepare a mixed alkali solution;

[0011] (3) Under stirring conditions, drip the mixed metal salt solution into the mixed alkali solution using a peristaltic pump, controlling the dripping rate at 2-3 drops / second and the stirring speed at 500-800 rpm.

[0012] (4) After the dripping is completed, control the heating rate at 5-15 °C / min, heat to 70 °C, keep warm for 12 h, and then obtain the metal composite oxide through washing with water, washing with alcohol, drying, and calcination;

[0013] (5) Add the metal composite oxide to the post-treatment solution, stir for 5-10 min, then place it in a constant temperature box at 4-8 °C and stir for 24 h, and continue washing with water, washing with alcohol, and drying to obtain the magnesium-aluminum layered double hydroxide.

[0014] The post-treatment liquid is a 1 mol / L sodium carbonate solution, and the preparation method of the 1 mol / L sodium carbonate solution is to add sodium carbonate into deionized water to prepare a 1 mol / L sodium carbonate solution.

[0015] As a preferred technical solution, the porous material is selected from one or a combination of several of zeolite molecular sieves, metal-organic frameworks, activated carbon, carbon nanotubes, tourmaline, zirconia, holmium oxide, and neodymium oxide; preferably, the porous material is a combination of zirconia, metal-organic framework, and activated carbon; preferably, the mass ratio of zirconia, metal-organic framework, and activated carbon is (1 - 3):(0.8 - 1.5):(5 - 8); preferably, the metal-organic framework is selected from at least one of ZIF-8, ZIF-67, MOF-74, UIO-66, MIL-101(Cr), and MIL-101(Fe); preferably, the metal-organic framework is UIO-66, and the particle size of the UIO-66 is 300 - 600 nm, and the pore size is 0.6 - 1.1 nm. In this application, by using zirconia, metal-organic framework, and activated carbon with a mass ratio of (1 - 3):(0.8 - 1.5):(5 - 8) as the porous material, the hydrogen storage mass density, hydrogen storage capacity, and dehydrogenation rate of the magnesium-based porous hydrogen storage material are improved. Especially by using the metal-organic framework UIO-66 with a particle size of 300 - 600 nm and a pore size of 0.6 - 1.1 nm, and zirconia with a particle size of 50 nm, it is easy to achieve good composite with the magnesium-based material in the system, synergistically further improve the cycle stability of hydrogen storage and release, ensure the safety of hydrogen storage and release, and make the provided magnesium-based porous hydrogen storage material meet the usage requirements of on-vehicle hydrogen storage.

[0016] The zirconia is purchased from Zhejiang Asia-America Nano-Tech Co., Ltd.; the metal-organic framework UIO-66 is purchased from Nanjing Xianfeng Nano Materials Technology Co., Ltd.

[0017] As a preferred technical solution, the expanded powder is expanded graphite powder; preferably, the expansion multiple of the expanded graphite powder is 400 times. In this application, by adding expanded graphite powder with an expansion multiple of 400 times, the composite between the magnesium-based material, composite metal, and porous material in the system is significantly improved, and at the same time, the hydrogen storage capacity of the magnesium-based porous hydrogen storage material is increased, and the cycle service life of the magnesium-based porous hydrogen storage material is prolonged.

[0018] The expanded graphite powder is purchased from Nanjing Xianfeng Nano Materials Technology Co., Ltd.

[0019] As a preferred technical solution, the composite metal is selected from at least one of zirconium, titanium, iron, manganese, cobalt, nickel, and aluminum; preferably, the composite metal is nickel, and preferably, the particle size of the nickel is 60-200 nm; during the exploration process of this application, it was unexpectedly found that when nickel with a particle size of 60-200 nm is introduced as the composite metal of the magnesium-based material, while not affecting the adsorption capacity of the magnesium-based material, it can achieve good combination with the magnesium-based material and the porous material, improve the hydrogen absorption and desorption rate and the cycle stability, greatly improve the hydrogen storage safety while ensuring a relatively high hydrogen storage capacity.

[0020] On the other hand, this application provides a preparation method of a magnesium-based porous low-pressure hydrogen storage material, which at least includes the following steps:

[0021] (1) By weight, put the magnesium-based material and the composite metal into a container filled with absolute ethanol, disperse them ultrasonically for 5-10 min, and then place them in a vacuum drying oven at 50-80 °C for drying for 30-60 min to obtain mixture A;

[0022] (2) By weight, put the magnesium-based material and the composite metal into a container filled with methanol, disperse them ultrasonically for 10-20 min, and then place them in a vacuum drying oven at 50-80 °C for drying for 30-60 min to obtain mixture B;

[0023] (3) Mix mixture A and mixture B evenly, and then ball mill them under normal pressure in an inert atmosphere to obtain a mixed powder;

[0024] (4) After pressing the mixed powder into a sheet sample, heat it under vacuum conditions to cause a hydrogen desorption reaction, and then the magnesium-based hydrogen storage material is obtained;

[0025] As a preferred technical solution, the inert atmosphere in step (3) is a hydrogen atmosphere. Preferably, the conditions for ball milling under normal pressure in step (3) are: the ball-to-material ratio is (18-22):1, the rotation speed is 200-300 rpm, and the ball milling mixing time is 4-6 h.

[0026] As a preferred technical solution, the heating temperature in step (4) is 300-350 °C.

[0027] Beneficial effects:

[0028] 1. This invention provides a magnesium-based porous low-pressure hydrogen storage material with a high hydrogen mass fraction, a large hydrogen storage volume density, fast absorption and release kinetics, a long cycle service life, and high safety performance. It can achieve a hydrogen storage capacity of more than 15 wt% under the condition of 1-2 MPa, with a fast hydrogen absorption and desorption rate and high cycle stability, greatly improving the hydrogen storage safety while ensuring a relatively high hydrogen storage capacity.

[0029] 2. The present application adopts magnesium metal, magnesium hydride, and magnesium-aluminum layered double hydroxide in a mass ratio of (10-15): (2-5): (5-10), especially when self-prepared magnesium-aluminum layered double hydroxide is used, and cooperates with porous materials in the system to improve the stability of hydrogen storage and dehydrogenation cycles, significantly improve the thermodynamic and kinetic properties of hydrogen absorption and desorption of magnesium-based porous hydrogen storage materials, and achieve low-pressure hydrogen storage.

[0030] 3. In the present application, zirconium oxide, metal organic framework and activated carbon with a mass ratio of (1-3): (0.8-1.5): (5-8) are used as porous materials to improve the hydrogen storage mass density, hydrogen storage capacity and dehydrogenation rate of the magnesium-based porous hydrogen storage material. In particular, the metal organic framework UIO-66 with a particle size of 300-600nm and a pore size of 0.6-1.1nm and zirconium dioxide with a particle size of 50nm are easily composited with the magnesium-based material in the system, and synergistically further improve the stability of the hydrogen storage and dehydrogenation cycles, ensure the safety of hydrogen storage and dehydrogenation, and make the provided magnesium-based porous hydrogen storage material meet the use requirements of vehicle-mounted hydrogen storage.

[0031] 4. In this application, nickel with a particle size of 60-200nm is introduced as a composite metal of the magnesium-based material. Without affecting the adsorption capacity of the magnesium-based material, it achieves good composite with the magnesium-based material and the porous material, improves the hydrogen absorption and desorption rate and the cycle stability, greatly improves the safety of hydrogen storage, and ensures a higher hydrogen storage capacity. DETAILED DESCRIPTION

[0032] Example 1

[0033] Embodiment 1 of the present invention provides a magnesium-based porous hydrogen storage material, wherein the raw materials for its preparation include, by weight: 23 parts of magnesium-based material, 10 parts of porous material, 3 parts of expanded powder, and 8 parts of composite metal.

[0034] The magnesium-based material is a combination of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide, and the mass ratio of the metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide is 12:3:8.

[0035] In parts by weight, the raw materials for preparing the magnesium aluminum layered double hydroxide include 32 parts of magnesium nitrate hexahydrate, 25 parts of aluminum nitrate nonahydrate, 18 parts of sodium hydroxide, 22 parts of sodium carbonate, and 213 parts of deionized water;

[0036] The preparation method of the magnesium aluminum layered double hydroxide comprises the following steps:

[0037] (1) adding magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to two-fifths of deionized water to prepare a mixed metal salt solution;

[0038] (2) adding sodium hydroxide and sodium carbonate according to weight to the remaining deionized water to prepare a mixed alkaline solution;

[0039] (3) Under stirring conditions, the mixed metal salt solution is added dropwise to the mixed alkali solution by a peristaltic pump, controlling the dropping rate to be 2 drops / second and the stirring speed to be 600 rpm.

[0040] (4) After the dropping is completed, control the heating rate to be 10 °C / min, heat to 70 °C, keep warm for 12 h, and then obtain the metal composite oxide through water washing, alcohol washing, drying, and calcination;

[0041] (5) Add the metal composite oxide to the post-treatment solution, stir for 8 min, then place it in a constant temperature oven at 6 °C and stir for 24 h, and continue with water washing, alcohol washing, and drying to obtain the magnesium-aluminum layered double hydroxide.

[0042] The post-treatment solution is a 1 mol / L sodium carbonate solution, and the preparation method of the 1 mol / L sodium carbonate solution is to add sodium carbonate to deionized water to prepare a 1 mol / L sodium carbonate solution.

[0043] The porous material is a combination of zirconia, metal-organic framework, and activated carbon; the mass ratio of zirconia, metal-organic framework, and activated carbon is 2:1.2:6; the metal-organic framework is UIO-66, and the particle size of UIO-66 is 300 - 600 nm, and the pore size is 0.6 - 1.1 nm.

[0044] The zirconia is purchased from Zhejiang Yamei Nano Technology Co., Ltd.; the metal-organic framework UIO-66 is purchased from Nanjing Xianfeng Nano Material Technology Co., Ltd.

[0045] The expanded powder is expanded graphite powder; the expansion multiple of the expanded graphite powder is 400 times.

[0046] The expanded graphite powder is purchased from Nanjing Xianfeng Nano Material Technology Co., Ltd.

[0047] The composite metal is nickel, and the particle size of the nickel is 100 nm. The metallic nickel is purchased from Zhejiang Yamei Nano Technology Co., Ltd.

[0048] On the other hand, Example 1 of this application provides a preparation method of a magnesium-based porous low-pressure hydrogen storage material, including the following steps:

[0049] (1) By weight, put the magnesium-based material and the composite metal into a container filled with anhydrous ethanol, disperse ultrasonically for 8 min, and then place it in a vacuum drying oven at 60 °C and dry for 40 min to obtain mixture A;

[0050] (2) By weight, put the magnesium-based material and the composite metal into a container filled with methanol, disperse ultrasonically for 15 min, and then place it in a vacuum drying oven at 60 °C and dry for 40 min to obtain mixture B;

[0051] (3) After mixing mixture A and mixture B evenly, ball-mill them under normal pressure in an inert atmosphere to obtain mixed powder;

[0052] (4) After pressing the mixed powder into a flaky sample, heat it under vacuum conditions to undergo a hydrogen release reaction, thus obtaining the magnesium-based hydrogen storage material;

[0053] In step (3), the inert atmosphere is a hydrogen atmosphere, and the conditions for ball-milling under normal pressure in step (3) are: the ball-to-material ratio is 20:1, the rotation speed is 250 rpm, and the ball-milling mixing time is 5 h.

[0054] In step (4), the heating temperature is 350 °C.

[0055] Example 2

[0056] On the one hand, Example 2 of the present invention provides a magnesium-based porous hydrogen storage material. By weight, its preparation raw materials include: 25 parts of magnesium-based material, 12 parts of porous material, 5 parts of expanded powder, and 10 parts of composite metal.

[0057] The magnesium-based material is a combination of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide, and the mass ratio of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide is 15:2:8.

[0058] By weight, the preparation raw materials of the magnesium-aluminum layered double hydroxide include 32 parts of magnesium nitrate hexahydrate, 25 parts of aluminum nitrate nonahydrate, 18 parts of sodium hydroxide, 22 parts of sodium carbonate, and 213 parts of deionized water;

[0059] The preparation method of the magnesium-aluminum layered double hydroxide includes the following steps:

[0060] (1) By weight, add magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to two-fifths of the deionized water to prepare a mixed metal salt solution;

[0061] (2) By weight, add sodium hydroxide and sodium carbonate to the remaining deionized water to prepare a mixed alkali solution;

[0062] (3) Under stirring conditions, drop the mixed metal salt solution into the mixed alkali solution using a peristaltic pump, and control the dropping rate to be 2 drops / second and the stirring speed to be 600 rpm.

[0063] (4) After the dropping is completed, control the heating rate to be 10 °C / min, heat to 70 °C, keep it warm for 12 h, and then obtain the metal composite oxide through washing with water, washing with alcohol, drying, and calcination;

[0064] (5) Add the metal composite oxide to the post-treatment solution, stir for 8 min, then place it in a constant temperature oven at 6 °C and stir for 24 h, and continue to wash with water, wash with alcohol, and dry to obtain the magnesium-aluminum layered double hydroxide.

[0065] The post-treatment liquid is a 1 mol / L sodium carbonate solution, and the preparation method of the 1 mol / L sodium carbonate solution is to add sodium carbonate into deionized water to prepare the 1 mol / L sodium carbonate solution.

[0066] The porous material is a combination of zirconia, metal-organic framework, and activated carbon; the mass ratio of zirconia, metal-organic framework, and activated carbon is 3:1.5:8; the metal-organic framework is UIO-66, and the particle size of UIO-66 is 300 - 600 nm, and the pore size is 0.6 - 1.1 nm.

[0067] The zirconia is purchased from Zhejiang Yamei Nano Technology Co., Ltd.; the metal-organic framework UIO-66 is purchased from Nanjing Xianfeng Nano Materials Technology Co., Ltd.

[0068] The expanded powder is expanded graphite powder; the expansion multiple of the expanded graphite powder is 400 times.

[0069] The expanded graphite powder is purchased from Nanjing Xianfeng Nano Materials Technology Co., Ltd.

[0070] The composite metal is nickel, and the particle size of the nickel is 100 nm. The metallic nickel is purchased from Zhejiang Yamei Nano Technology Co., Ltd.

[0071] On the other hand, Example 2 of the present application provides a preparation method of a magnesium-based porous low-pressure hydrogen storage material, including the following steps:

[0072] (1) By weight, put the magnesium-based material and the composite metal into a container containing anhydrous ethanol, ultrasonically disperse for 8 min, and then place it in a vacuum drying oven at 60 °C for 40 min to obtain mixture A;

[0073] (2) By weight, put the magnesium-based material and the composite metal into a container containing methanol, ultrasonically disperse for 15 min, and then place it in a vacuum drying oven at 60 °C for 40 min to obtain mixture B;

[0074] (3) After mixing mixture A and mixture B, perform ball milling under normal pressure in an inert atmosphere to obtain a mixed powder;

[0075] (4) After pressing the mixed powder into a sheet-like sample, heat it under vacuum conditions to cause a hydrogen release reaction, and thus obtain the magnesium-based hydrogen storage material;

[0076] The inert atmosphere in step (3) is a hydrogen atmosphere, and the normal pressure ball milling conditions in step (3) are: the ball-to-material ratio is 20:1, the rotation speed is 250 rpm, and the ball milling mixing time is 5 h.

[0077] The heating temperature in step (4) is 350 °C.

[0078] Example 3

[0079] Example 3 of the present invention provides a magnesium-based porous hydrogen storage material. By weight, its preparation raw materials include: 22 parts of magnesium-based material, 8 parts of porous material, 2 parts of expanded powder, and 6 parts of composite metal.

[0080] The magnesium-based material is a combination of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide, and the mass ratio of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide is 12:2:8.

[0081] By weight, the preparation raw materials of the magnesium-aluminum layered double hydroxide include 32 parts of magnesium nitrate hexahydrate, 25 parts of aluminum nitrate nonahydrate, 18 parts of sodium hydroxide, 22 parts of sodium carbonate, and 213 parts of deionized water;

[0082] The preparation method of the magnesium-aluminum layered double hydroxide includes the following steps:

[0083] (1) By weight, add magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to two-fifths of the deionized water to prepare a mixed metal salt solution;

[0084] (2) By weight, add sodium hydroxide and sodium carbonate to the remaining deionized water to prepare a mixed alkali solution;

[0085] (3) Under stirring conditions, drop the mixed metal salt solution into the mixed alkali solution using a peristaltic pump, control the dropping rate at 2 drops / second, and the stirring speed at 600 rpm.

[0086] (4) After the dropping is completed, control the heating rate at 10 °C / min, heat to 70 °C, keep warm for 12 h, and then obtain a metal composite oxide through water washing, alcohol washing, drying, and calcination;

[0087] (5) Add the metal composite oxide to the post-treatment solution, stir for 8 min, then place it in a constant temperature box at 6 °C and stir for 24 h, and continue with water washing, alcohol washing, and drying to obtain the magnesium-aluminum layered double hydroxide.

[0088] The post-treatment solution is a 1 mol / L sodium carbonate solution, and the preparation method of the 1 mol / L sodium carbonate solution is to add sodium carbonate to deionized water to prepare a 1 mol / L sodium carbonate solution.

[0089] The porous material is a combination of zirconia, metal-organic framework, and activated carbon; the mass ratio of zirconia, metal-organic framework, and activated carbon is 1:1:5; the metal-organic framework is UIO-66, and the particle size of UIO-66 is 300 - 600 nm, and the pore size is 0.6 - 1.1 nm.

[0090] The zirconia was purchased from Zhejiang Asia-America Nano Technology Co., Ltd.; the metal-organic framework UIO-66 was purchased from Nanjing Xianfeng Nano Material Technology Co., Ltd.

[0091] The expanded powder is expanded graphite powder; the expansion multiple of the expanded graphite powder is 400 times.

[0092] The expanded graphite powder was purchased from Nanjing Xianfeng Nano Material Technology Co., Ltd.

[0093] The composite metal is nickel, and the particle size of the nickel is 100 nm. The metallic nickel was purchased from Zhejiang Asia-America Nano Technology Co., Ltd.

[0094] On the other hand, Example 3 of the present application provides a method for preparing a magnesium-based porous low-pressure hydrogen storage material, including the following steps:

[0095] (1) By weight, put the magnesium-based material and the composite metal into a container filled with absolute ethanol, disperse them ultrasonically for 8 min, and then dry them in a vacuum drying oven at 60 °C for 40 min to obtain mixture A;

[0096] (2) By weight, put the magnesium-based material and the composite metal into a container filled with methanol, disperse them ultrasonically for 15 min, and then dry them in a vacuum drying oven at 60 °C for 40 min to obtain mixture B;

[0097] (3) After mixing mixture A and mixture B, perform ball milling at normal pressure in an inert atmosphere to obtain a mixed powder;

[0098] (4) After pressing the mixed powder into a sheet-like sample, heat it under vacuum conditions to cause a hydrogen release reaction, thus obtaining the magnesium-based hydrogen storage material;

[0099] The inert atmosphere in step (3) is a hydrogen atmosphere, and the conditions for ball milling at normal pressure in step (3) are: the ball-to-material ratio is 20:1, the rotation speed is 250 rpm, and the ball milling mixing time is 5 h.

[0100] The heating temperature in step (4) is 350 °C.

[0101] Comparative Example 1

[0102] Comparative Example 1 of the present invention provides a magnesium-based porous hydrogen storage material, and its specific implementation manner is the same as that of Example 1, except that the mass ratio of the metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide is 21:1:1.

[0103] Comparative Example 2

[0104] Comparative Example 2 of the present invention provides a magnesium-based porous hydrogen storage material, and its specific implementation manner is the same as that of Example 1, except that the porous material is activated carbon.

[0105] Comparative Example 3

[0106] Comparative Example 3 of the present invention provides a magnesium-based porous hydrogen storage material. Its specific implementation manner is the same as that of Example 1, except that the raw materials for preparing the magnesium-based porous hydrogen storage material do not include the expanded powder.

[0107] Comparative Example 4

[0108] Comparative Example 4 of the present invention provides a magnesium-based porous hydrogen storage material. Its specific implementation manner is the same as that of Example 1, except that the composite metal is iron.

[0109] Performance test method

[0110] (1) Hydrogen storage performance: The magnesium-based porous low-pressure hydrogen storage materials prepared in the examples and comparative examples are placed in a volumetric hydrogen storage device. After evacuation, 20 bar of hydrogen is introduced, and the temperature is raised to 350 °C. After the magnesium-based porous low-pressure hydrogen storage material absorbs hydrogen for 30 min, the hydrogen storage capacity of the magnesium-based porous low-pressure hydrogen storage material is measured.

[0111] (2) Dehydrogenation performance: The magnesium-based porous low-pressure hydrogen storage materials prepared in the examples and comparative examples are placed in a volumetric hydrogen storage device. After evacuation, 20 bar of hydrogen is introduced, and the temperature is raised to 350 °C. After the magnesium-based porous low-pressure hydrogen storage material absorbs hydrogen for 30 min, the temperature is lowered to 320 °C. When hydrogen is released for 10 min, the dehydrogenation amount of the magnesium-based porous low-pressure hydrogen storage material is measured.

[0112] (3) Cycling stability: The magnesium-based porous low-pressure hydrogen storage materials prepared in the examples and comparative examples are placed in a volumetric hydrogen storage device. After evacuation, 20 bar of hydrogen is introduced, and the temperature is raised to 350 °C. After the magnesium-based porous low-pressure hydrogen storage material absorbs hydrogen for 1 h, the temperature is lowered to 320 °C, and hydrogen is released for 2 h. A 50-cycle hydrogen storage and release test is carried out. The cycling retention rate is calculated by the formula cycling retention rate = the hydrogen storage amount of the 50th cycle / the hydrogen storage amount of the first cycle * 100%, and the cycling retention rate of the magnesium-based porous low-pressure hydrogen storage material after 50 hydrogen storage and release cycles is calculated.

[0113] Hydrogen storage capacity (wt%) Dehydrogenation capacity (wt%) Cycle retention rate (%) Example 1 15.8 4.3 91 Example 2 15.5 4.2 90 Example 3 15.3 4.0 90 Comparative Example 1 12 3.6 85 Comparative Example 2 10 3.3 80 Comparative Example 3 13 3.5 83 Comparative Example 4 14 3.7 88

Claims

1. A magnesium-based porous hydrogen storage material, characterized in that, By weight, the preparation raw materials at least include: 20-30 parts of magnesium-based material, 5-15 parts of porous material, 1-5 parts of expanded powder, and 5-10 parts of composite metal; The magnesium-based material is a combination of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide, and the mass ratio of metallic magnesium, magnesium hydride, and magnesium-aluminum layered double hydroxide is (10-15):(2-5):(5-10); By weight, the preparation raw materials of the magnesium-aluminum layered double hydroxide include 30-35 parts of magnesium nitrate hexahydrate, 20-28 parts of aluminum nitrate nonahydrate, 15-20 parts of sodium hydroxide, 20-25 parts of sodium carbonate, and 205-220 parts of deionized water; The porous material is a combination of zirconia, metal-organic framework, and activated carbon, and the mass ratio of zirconia, metal-organic framework, and activated carbon is (1-3):(0.8-1.5):(5-8). The metal-organic framework is UIO-66, and the particle size of UIO-66 is 300-600 nm, and the pore size is 0.6-1.1 nm; The expanded powder is expanded graphite powder, and the expansion multiple of the expanded graphite powder is 400 times; The composite metal is nickel, and the particle size of the nickel is 60-200 nm.