Preparation method of metal hydride block, block obtained by preparation method and hydrogen storage equipment

Abstract

The invention discloses a preparation method of a metal hydride block, the block obtained through the preparation method and hydrogen storage equipment, and relates to the field of hydrogen storage and transportation and medium preparation. The preparation method of the metal hydride block comprises the following steps: uniformly mixing powder or filaments of crushed hydrogen storage metal / metal alloy and heat-conducting metal and / or nonmetal, and carrying out cold pressing in a preset mold to obtain a block; and carrying out high-temperature hydrogenation on the pressed and molded block in a hydrogenation reactor to obtain the metal hydride block. According to the method, hydrogenation is conducted after pressing, the problems that in an existing magnesium powder hydrogenation process, powder particles are prone to agglomeration and sintering, the safety risk is large, and heat and mass transfer is slow are solved, the method has better heat conductivity and higher porosity, and safe and efficient large-scale metal hydride preparation is better achieved.

Description

Technical Field

[0001] This invention relates to the fields of hydrogen storage and transportation and hydrogen storage medium preparation, specifically to a method for preparing a metal hydride block, the resulting block, and a hydrogen storage device. Background Technology

[0002] Magnesium is a highly promising hydrogen storage alloy system. Its hydride (MgH2) boasts a theoretical mass hydrogen storage density of up to 7.6 wt% H2 and an energy density as high as 9 MJ / kg Mg. Furthermore, magnesium is abundant in nature and possesses advantages such as low cost and non-toxicity. Consequently, the research and application of magnesium as a solid-state hydrogen storage material have rapidly developed in recent years, especially in the field of large-scale hydrogen storage and transportation.

[0003] However, in practical applications, one of the challenges facing magnesium hydrogen storage materials is how to prepare magnesium hydride powder on a large scale, which may encounter the following difficulties:

[0004] 1. Particle agglomeration and sintering: Under high temperature and pressure for a long time, magnesium powder particles are prone to sintering, resulting in particle growth and a decrease in specific surface area, which in turn worsens the kinetics of subsequent reactions.

[0005] 2. Powdering and volume expansion: When Mg is converted to MgH2, the crystal structure changes from hexagonal close-packed to tetragonal rutile structure, accompanied by significant volume expansion (about 30%).

[0006] 3. Heat and mass transfer issues: These are not significant in small-scale experiments, but when scaled up to the kilogram level or larger, heat transfer and hydrogen diffusion within the reactor become bottlenecks. Ensuring uniform temperature in the reaction bed and rapid hydrogen delivery to each magnesium powder particle presents a significant challenge.

[0007] 4. Increased safety risks: Magnesium powder has high chemical reactivity. Large quantities of magnesium powder are handled in a high-temperature, high-pressure hydrogen environment, which places extremely high demands on explosion-proof, leak-proof, and fire-proof measures.

[0008] 5. Cost control: High-purity hydrogen, high-pressure and high-temperature equipment, high energy consumption, and possible pre-treatment / post-treatment steps all increase the preparation cost.

[0009] In conclusion, there is still a great need and room for improvement in developing a safe and efficient process and equipment for preparing magnesium hydride, and in addressing the current shortcomings and deficiencies. Summary of the Invention

[0010] In view of this, the main objective of the present invention is to provide a method for preparing a metal hydride bulk, the resulting bulk and a hydrogen storage device, in order to at least partially solve the above-mentioned technical problems.

[0011] To achieve the above objectives, as a first aspect of the present invention, a method for preparing a bulk metal hydride is provided, comprising the following steps:

[0012] The pulverized hydrogen storage metal / alloy is mixed evenly with the first component and / or the second component, and then cold-pressed into a block in a preset mold; wherein, the first component is a thermally conductive non-metallic powder, and the second component is a thermally conductive metal powder or filament;

[0013] The pressed block is hydrogenated at high temperature in a hydrogenation reactor to obtain a metal hydride block.

[0014] As a second aspect of the present invention, a metal hydride bulk material prepared according to the preparation method of the metal hydride bulk material as described above is also provided.

[0015] As a third aspect of the invention, a hydrogen storage device employing the metal hydride block as described above is also proposed.

[0016] Based on the above technical solution, it can be seen that the method for preparing the metal hydride bulk of the present invention, the resulting bulk and the hydrogen storage device, have at least one of the following beneficial effects compared with the prior art:

[0017] 1. This invention overcomes the problems of easy agglomeration and sintering of powder particles, low powder bulk density, amplified safety risks, and slow heat and mass transfer in the existing magnesium powder hydrogenation process for preparing magnesium hydride. The magnesium / magnesium alloy block containing expanded graphite or metal wire of this invention has better thermal conductivity and higher porosity, which can solve the problem of slow heat and mass transfer of powder. The compressed metal block has high bulk density and reduces the volume expansion during alloy powder hydrogenation.

[0018] 2. The magnesium / magnesium alloy bulk material containing expanded graphite or metal wire of the present invention has low raw material cost and low equipment requirements, which is more conducive to the safe and efficient large-scale preparation of metal hydrides. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.

[0020] Figure 1 This is a schematic diagram of the process for preparing the metal hydride bulk material according to the present invention;

[0021] Figure 2 Mg is an embodiment of the present invention 96 Hydrogen absorption curve of Ni3Nd2 + 2wt% EG (Expandable Graphite) + 1.33wt% Cu bulk material;

[0022] Figure 3For example, Mg is a comparative sample of the present invention. 96 Hydrogen absorption curve of Ni3Nd2 bulk material. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of the invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0025] Traditional magnesium-based hydrogen storage material preparation involves hydrogenating magnesium powder before molding it into bulk materials. This process is prone to problems such as particle agglomeration and sintering, heat and mass transfer issues, and safety risks. By using magnesium alloy powder as the raw material, along with small amounts of expanded graphite and metal powder / wires, and mixing them uniformly, a cold-pressing process is used to obtain magnesium alloy bulk materials. These bulk materials are then hydrogenated in a hydrogen atmosphere at high temperature to obtain hydrogenated magnesium briquettes. This method solves the aforementioned problems of existing technologies. Therefore, a method for preparing metal hydride bulk materials that can be applied to most hydrogen storage metals is proposed, such as… Figure 1 As shown, it includes the following steps:

[0026] The pulverized hydrogen storage metal / alloy is mixed evenly with the first component and / or the second component, and then cold-pressed into a block in a preset mold; wherein, the first component is a thermally conductive non-metallic powder, and the second component is a thermally conductive metal powder or filament;

[0027] The pressed block is hydrogenated at high temperature in a hydrogenation reactor to obtain a metal hydride block.

[0028] The hydrogen storage metal / alloy is selected from magnesium-based, titanium-based, vanadium-based, rare earth metals, or alloys of the above metals.

[0029] The particle size range of the pulverized hydrogen storage metal / alloy is, for example, between 20 and 200 mesh, i.e., between 0.075 and 0.85 mm, preferably between 20 and 40 mesh, i.e. between 0.425 and 0.85 mm, and more preferably between 30 mesh, i.e., 0.6 mm pore size.

[0030] The thermally conductive metal is selected from copper or aluminum, and the thermally conductive non-metal is selected from expanded graphite (EG). The particle size of the thermally conductive metal and non-metal powders ranges from 20 to 300 mesh, i.e., 0.05 to 0.85 mm, preferably from 20 to 100 mesh, i.e., 0.15 to 0.85 mm. The diameter of the thermally conductive metal filaments is, for example, less than 1 mm, and the length is, for example, less than 5 mm.

[0031] The amount of the thermally conductive nonmetal, such as expanded graphite, added is, for example, between 0 and 10 wt%.

[0032] The amount of the thermally conductive metal, such as copper or aluminum powder or filament, added is, for example, between 0 and 10 wt%.

[0033] The pressing pressure for cold pressing the block into shape in the preset mold is, for example, 50~500 MPa.

[0034] The cross-sectional shape of the preset mold includes, but is not limited to, a circle (disc-shaped), a square, or a trapezoid.

[0035] The conditions for hydrogenating the pressed metal block in the hydrogenation reactor are, for example, a temperature range of 100~350℃ and a hydrogen pressure range of 0.2~3 MPa.

[0036] Currently, the advantage of metal powder hydrogenation is that it yields hydrogenated alloy products at moderate temperatures and within short hydrogenation reaction times. However, the powder hydrogenation process has extremely stringent requirements for equipment, environment, and safety, resulting in higher production costs. Compared to existing technologies that hydrogenate powder first and then press it, this invention employs a process of first pressing it into blocks and then hydrogenating it. Since the hydrogenation process no longer involves powder, the risk of explosion is greatly reduced, the block volume density is higher, and the production capacity of metal hydrides per batch is significantly increased. Simultaneously, this invention uses powders or filaments incorporating thermally conductive metals and / or non-metals to ensure the alloy blocks have superior porosity, facilitating hydrogen diffusion. It also overcomes the problem of excessive heat accumulation during conventional alloy block hydrogenation and avoids powder particle sintering, thereby improving the hydrogenation rate of the blocks. Commercial magnesium hydride powder is currently mainly used in the chemical industry, primarily in powder form, and the overall scale is relatively small. In the current hydrogen storage field, since powder has a faster hydrogenation rate, the research on alloy hydrides is mainly based on powder. However, for large-scale production of alloy hydrides, the alloy briquette hydrogenation method overcomes the above-mentioned shortcomings of existing technologies, has unique advantages, and opens up a new preparation route.

[0037] The present invention also proposes a metal hydride bulk material prepared according to the preparation method of the metal hydride bulk material as described above.

[0038] The present invention also proposes a hydrogen storage device using the metal hydride block as described above, wherein the hydrogen storage device is, for example, a solid hydrogen storage rod, a solid hydrogen storage tank, etc.

[0039] The present invention will be further illustrated below through specific embodiments. It should be noted that the following embodiments are merely illustrative and not intended to limit the present invention.

[0040] Example 1

[0041] Weigh out 14.5 g of Mg 96 Ni3Nd2 (atomic ratio), 0.3 g expanded graphite (50 mesh), and 0.2 g copper powder (100 mesh) were mechanically stirred to obtain a homogeneous mixture of magnesium alloy, expanded graphite, and copper powder. The mixture was poured into a 30 mm diameter circular mold and pressed under 100 MPa pressure to obtain magnesium alloy blocks with a diameter of 30 mm. Thirteen of these 15 g magnesium alloy blocks were placed in a hydrogenation reactor and hydrogenated at 350 °C and 3 MPa pressure. The resulting magnesium alloy blocks absorbed hydrogen for 2 hours, and the hydrogen absorption curve is shown below. Figure 2 As shown.

[0042] Example 2

[0043] Weigh out 14.5 g of Mg 96 Ni3Nd2 (atomic ratio) and 0.5 g of expanded graphite (100 mesh) were mixed to obtain a homogeneous magnesium alloy / expanded graphite powder by mechanical stirring. The powder was poured into a 40 mm diameter circular mold and pressed under 500 MPa pressure to obtain a 40 mm diameter magnesium alloy block. The magnesium alloy block was then placed in a hydrogenation reactor and hydrogenated at 300 °C and 2 MPa pressure.

[0044] Example 3

[0045] Weigh out 29.1 g of Mg 96 Ni3Nd2 (atomic ratio) and 0.9 g of expanded graphite (300 mesh) were mechanically stirred to obtain a homogeneous magnesium alloy / expanded graphite mixed powder. The mixed powder was poured into a 40 mm diameter circular mold and pressed into a 40 mm diameter magnesium alloy block under a pressure of 150 MPa. The magnesium alloy block was then placed in a hydrogenation reactor and hydrogenated at 350 °C and 2 MPa.

[0046] Examples 4-9

[0047] The specific experimental steps are the same as in Example 1, except that some of the experimental conditions are shown in Table 1.

[0048] Table 1. List of experimental parameters for Examples 1-9

[0049]

[0050] Comparative Example 1

[0051] Weigh 15 g of Mg 96 Ni3Nd2 (atomic ratio) was poured into a 30 mm diameter circular mold and pressed under 100 MPa pressure to obtain magnesium alloy blocks with a diameter of 30 mm. Thirteen of these blocks, each weighing 15 g, were placed in a hydrogenation reactor and hydrogenated at 350 °C and 3 MPa pressure. After absorbing hydrogen for 5 hours, the magnesium alloy blocks were then subjected to a hydrogen release test. The hydrogen absorption curve is shown below. Figure 3 As shown.

[0052] Comparing Examples 1-9 with existing compressed blocks obtained by first hydrogenating powder and then pressing, it can be found that the preparation method of the present invention is safer, and the hydrogenation conditions and protective measures of the hydrogenation reactor can be appropriately reduced, resulting in higher safety.

[0053] Comparing Example 1 with Comparative Example 1 reveals that, compared to the briquettes of Comparative Example 1 without the addition of expanded graphite and copper powder, the briquettes of Example 1 with the addition of expanded graphite and copper powder exhibit a faster hydrogenation rate and a higher hydrogen storage capacity. Furthermore, the briquettes do not experience overheating during preparation, resulting in core melting and reduced porosity.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a bulk metal hydride, characterized in that, Includes the following steps: The pulverized hydrogen storage metal / alloy is mixed evenly with the first component and / or the second component, and then cold-pressed into a block in a preset mold; wherein, the first component is a thermally conductive non-metallic powder, and the second component is a thermally conductive metal powder or filament; The pressed block is hydrogenated at high temperature in a hydrogenation reactor to obtain a metal hydride block.

2. The preparation method according to claim 1, characterized in that, The hydrogen storage metal / alloy is selected from magnesium-based, titanium-based, vanadium-based, rare earth metals, or alloys of the above metals; and / or The thermally conductive metal is selected from copper or aluminum; and / or The thermally conductive nonmetal is selected from expanded graphite or carbon fiber.

3. The preparation method according to claim 1, characterized in that, The particle size of the pulverized hydrogen storage metal / alloy is between 20 and 200 mesh; and / or The particle size range of the thermally conductive metal and thermally conductive non-metal powders is between 20 and 300 mesh; and / or The diameter of the thermally conductive metal or thermally conductive non-metal filament is less than 1 mm and the length is less than 5 mm.

4. The preparation method according to claim 3, characterized in that, The particle size of the pulverized hydrogen storage metal / alloy is between 20 and 40 mesh; and / or The particle size range of the thermally conductive metal and thermally conductive non-metal powders is between 20 and 100 mesh.

5. The preparation method according to claim 1, characterized in that, The amount of the thermally conductive nonmetal added is between 0 and 10 wt%.

6. The preparation method according to claim 1, characterized in that, The amount of thermally conductive metal added is between 0 and 10 wt%.

7. The preparation method according to claim 1, characterized in that, The pressing pressure for cold pressing the block into shape in a pre-set mold is 50~500 MPa; and / or The cross-sectional shape of the preset mold includes a circle, a square, or a trapezoid.

8. The preparation method according to claim 1, characterized in that, The conditions for hydrogenating the pressed metal block in the hydrogenation reactor are: temperature range 100~350℃, hydrogen pressure range 0.2~3 MPa.

9. A metal hydride bulk obtained by the method for preparing a metal hydride bulk according to any one of claims 1-8.

10. A hydrogen storage device employing the metal hydride bulk material as described in claim 9.

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