Porous Magnesium Structure for Hydrogen Storage, Manufacturing Method, and Hydrogen Storage Method

Abstract

Provided are a porous magnesium structure for hydrogen storage, which includes a magnesium skeleton and pores, has a three-dimensional porous structure, and has an average thickness of the magnesium skeleton of more than 0 nm and 200 nm or less, a method for producing the same, and a hydrogen storage method.

Description

Technical Field

[0001] The present invention relates to a porous magnesium structure for hydrogen storage, a method for manufacturing the same, and a hydrogen storage method.

Background Art

[0002] Currently, commercially available hydrogen storage methods are physical storage methods in which hydrogen is compressed at high pressure or stored at ultra-low temperature. However, physical hydrogen storage methods have problems such as large energy loss during storage, low volume storage density, and the use of expensive carbon fibers.

[0003] To solve this problem, metal hydrides, complex hydrides, etc. have been widely studied as solid hydrogen storage materials with high energy density and high safety, but they have drawbacks such as too high hydrogen absorption / desorption required temperature and too slow absorption / desorption rate.

Summary of the Invention

Problems to be Solved by the Invention

[0004] One embodiment provides a porous magnesium structure for hydrogen storage capable of absorbing and releasing hydrogen at low temperature and high speed.

[0005] Another embodiment provides an environmentally friendly and simple method for manufacturing the porous magnesium structure for hydrogen storage.

[0006] Still another embodiment provides a hydrogen storage method using the porous magnesium structure for hydrogen storage.

Means for Solving the Problems

[0007] According to one embodiment, there is provided a porous magnesium structure for hydrogen storage, which includes a magnesium skeleton and pores, has a three-dimensional porous structure, and the average thickness of the magnesium skeleton is more than 0 nm and 200 nm or less.

[0008] The magnesium skeleton body can include a magnesium body and an oxide film located on the surface of the magnesium body.

[0009] The oxide film contains magnesium oxide, and the magnesium oxide can contain MgO.

[0010] The magnesium body and the oxide film can have a molar ratio of 1:1 to 1:5.

[0011] The average diameter of the pores may be 20 nm to 200 nm.

[0012] The specific surface area of the porous magnesium structure may be 20 m 2 / g to 40 m 2 / g.

[0013] The porous magnesium structure can have a diffraction peak at 2θ of 35° to 40° in the XRD pattern.

[0014] The surface of the magnesium skeleton body can further include a transition metal, and the transition metal can include a metal with a standard reduction potential higher than that of magnesium.

[0015] Another embodiment includes a step of manufacturing a porous magnesium structure including a magnesium skeleton body and pores by introducing a magnesium-alkali metal alloy into a solution and performing dealloying. The solution provides a method for manufacturing a porous magnesium structure for hydrogen storage in which an aromatic compound is dissolved in an organic solvent.

[0016] The aromatic compound may include naphthalene, biphenyl, phenanthrene, anthracene, or a combination thereof.

[0017] The dealloying may be such that an alkali metal is desorbed from the magnesium-alkali metal alloy.

[0018] The desorbed alkali metal can react with the aromatic compound in the solution to form a by-product.

[0019] After the step of manufacturing the porous magnesium structure, the method may further include a step of mixing the manufactured porous magnesium structure with a transition metal-containing precursor to manufacture a porous magnesium structure further containing a transition metal.

[0020] The transition metal-containing precursor may include a chloride of a transition metal, a complex compound of a transition metal, or a combination thereof.

[0021] The transition metal-containing precursor can be mixed in an amount of 1 part by weight to 10 parts by weight with respect to 100 parts by weight of the manufactured porous magnesium structure.

[0022] The porous magnesium structure further containing a transition metal may be such that the transition metal is located on the surface of the magnesium skeleton.

[0023] According to another embodiment, there is provided a hydrogen storage method including a step of causing the porous magnesium structure for hydrogen storage to absorb hydrogen gas to obtain magnesium hydride; and a step of reversibly releasing hydrogen gas from the magnesium hydride.

[0024] The absorption can be performed at a temperature of 150°C to 200°C.

[0025] The release can be performed at a temperature of 250°C to 300°C.

Advantages of the Invention

[0026] The porous magnesium structure for hydrogen storage according to one embodiment can absorb and release hydrogen at low temperature and high speed, and thus can be usefully used as a hydrogen storage material. In addition, the porous magnesium structure for hydrogen storage is environmentally friendly and can be manufactured by a simple method, so it can contribute to accelerating the advent of a hydrogen economy.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement them. The present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0036] In order to clearly explain the present invention, parts not related to the description are omitted, and the same or similar components throughout the specification are denoted by the same reference numerals.

[0037] Also, the sizes and thicknesses of the respective configurations shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, the thicknesses are enlarged to clearly represent a plurality of layers and regions. And, in the drawings, for convenience of explanation, the thicknesses of some layers and regions are exaggerated.

[0038] Also, when a part such as a layer, film, region, plate, etc. is "above" or "on top of" another part, this includes not only the case where it is immediately above the other part, but also the case where there are other parts in between. Conversely, when a part is "immediately above" another part, it means that there are no other parts in between. Also, being "above" or "on top of" a reference part means being located above or below the reference part, and does not necessarily mean being located "above" or "on top of" in the direction opposite to gravity.

[0039] Also, throughout the specification, when a part "includes" a certain component, this means that, unless otherwise stated to the contrary, it does not exclude other components and can further include other components.

[0040] A porous magnesium structure for hydrogen storage according to an embodiment will be described with reference to FIG. 1.

[0041] FIG. 1 is a schematic view showing a porous magnesium structure for hydrogen storage according to an embodiment.

[0042] Referring to FIG. 1, a porous magnesium structure (10) for hydrogen storage according to an embodiment has a three-dimensional porous structure and includes a magnesium skeleton (11) and pores (12). The magnesium skeleton (11) has an average thickness (t) exceeding 0 nm and not exceeding 200 nm.

[0043] According to one embodiment, in the porous magnesium structure (10) for hydrogen storage, when storing hydrogen, hydrogen gas rapidly diffuses into the interior through pores (12), dissociates from the surface of the magnesium skeleton (11), and diffuses into the magnesium lattice in the form of hydrogen atoms. As a result, due to the short diffusion distance of the nanostructured magnesium skeleton (11), that is, the crystal structure is nanostructured, hydrogen absorption and release are possible rapidly and at low temperature. Further, the porous magnesium structure (10) is manufactured by a method of nanostructuring magnesium itself without using other composite materials as in the manufacturing method described later, and thus has a high energy density.

[0044] The average thickness (t) of the magnesium skeleton (11) may be more than 0 nm and 200 nm or less, for example, 1 nm to 200 nm, 1 nm to 150 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 45 nm, 1 nm to 40 nm, 5 nm to 35 nm, 5 nm to 30 nm. When the magnesium skeleton (11) has an average thickness (t) within the above range, during hydrogen absorption and release, the diffusion distance of hydrogen atoms inside the lattice is reduced, and hydrogen gas also diffuses smoothly through the pores, enabling high-speed hydrogen absorption and release.

[0045] The magnesium skeleton (11) can include a magnesium body and an oxide film located on the surface of the magnesium body.

[0046] The oxide film can include magnesium oxide. Magnesium oxide may include MgO, Mg(OH)2, or a combination thereof.

[0047] The magnesium body and the oxide film can have a molar ratio of 1:1 to 1:5, for example, can have a molar ratio of 1:1 to 1:4. The molar ratio may be measured in a region near the surface of the magnesium framework, specifically, may be measured in a region where the depth from the surface of the magnesium framework to the inside is 1 nm to 10 nm. When the molar ratio of the magnesium body and the oxide film is within the above range, by having a thin oxide film, a metallic surface that is very advantageous for hydrogen storage can be obtained, and a magnesium framework with successful nanostructuring can be obtained. Thereby, a porous magnesium structure in which hydrogen absorption and release proceed at low temperature and high speed can be ensured.

[0048] The average diameter of the pores (12) may be 20 nm to 200 nm, for example, may be 25 nm to 150 nm, 30 nm to 100 nm, 30 nm to 80 nm, 35 nm to 65 nm, 40 nm to 60 nm. When the average diameter of the pores is within the above range, due to the short diffusion distance of the nanostructured magnesium framework (11), hydrogen absorption and release become possible at high speed and low temperature. Here, the average diameter of the pores means the diameter of the major axis of the pores.

[0049] The specific surface area of the porous magnesium structure (10) is 20 m 2 / g to 40 m 2 / g, for example, may be 20 m 2 / g to 30 m 2 / g. When the specific surface area of the porous magnesium structure (10) is within the above range, more magnesium can be exposed to the hydrogen gas phase, hydrogen absorption and release at high speed and low temperature are possible, and it can be usefully used as a hydrogen storage material.

[0050] The porous magnesium structure (10) can have diffraction peaks at 2θ of 35° to 40°, for example, 2θ of 36° to 39° in the XRD (X-ray diffraction) pattern. The characteristics of the XRD pattern mean that the porous magnesium structure (10) is made of pure magnesium containing almost no impurities. When the porous magnesium structure (10) has the XRD pattern, it is possible to absorb and release hydrogen at high speed and low temperature, and it can be usefully used as a hydrogen storage material.

[0051] The porous magnesium structure (10) can further contain a transition metal located on the surface of the magnesium skeleton (11).

[0052] Since the transition metal can play a role as a catalyst in the hydrogen absorption and release reaction, introduction of the transition metal into the porous magnesium structure (10) enables more rapid hydrogen absorption and release. Further, as will be described later, the porous magnesium structure according to one embodiment is manufactured in a non-corrosive reaction environment. Therefore, in such an environment, since it has a metallic magnesium surface advantageous for introduction of the transition metal, the transition metal that plays a role as a catalyst can be easily introduced into the porous magnesium structure (10).

[0053] Any transition metal can be used as long as its standard reduction potential is higher than that of magnesium. For example, it may include, but is not limited to, Ni, Ti, Co, or a combination thereof.

[0054] Hereinafter, a method for manufacturing the above-described porous magnesium structure (10) will be described.

[0055] The porous magnesium structure (10) according to one embodiment is manufactured in a non-corrosive solution phase. Specifically, it is manufactured by including a step of putting a magnesium-alkali metal alloy into a solution and performing dealloying. At this time, as the solution, a solution in which an aromatic compound is dissolved in an organic solvent is used.

[0056] Dealloying means that alkali metals are selectively desorbed from a magnesium-alkali metal alloy, and the remaining magnesium atoms grow through a self-assembly process into a porous magnesium structure (10) composed of a magnesium skeleton (11) having a nano-size, i.e., a thickness at the nanometer level, and pores (12) having a diameter at the nanometer level.

[0057] Conventional methods for forming porous metals mainly involve dealloying from alloys using highly corrosive strong acid substances, mainly targeting noble metals and transition metals. The use of corrosive substances is not only environmentally unfriendly but also inapplicable to elements with a high oxidation tendency such as magnesium. Magnesium is an element vulnerable to oxidation, and the oxidation or passivation of the magnesium surface has an adverse effect on the hydrogen storage performance of magnesium. Therefore, it is important to minimize this to manufacture a porous magnesium structure. When manufacturing a porous magnesium structure by dealloying using a highly corrosive strong acid substance or by desorbing lithium with an oxidation electrode, etc., there is a problem that the surface is greatly oxidized, reducing the hydrogen storage performance due to the vulnerability of magnesium to oxidation.

[0058] In one embodiment, different from the conventional porous metal synthesis method, synthesis was carried out in a non-corrosive solution phase, and successful synthesis of a porous metal structure was achieved even with magnesium. According to one embodiment, the porous magnesium structure (10) is manufactured by causing dealloying in a reducing reaction environment in a non-corrosive solution. This is manufactured without the corrosive substances and electrochemical equipment generally used for causing dealloying, so it is environmentally friendly and can be manufactured by a simple process, thereby contributing to the acceleration of the advent of the hydrogen economy.

[0059] In addition, while transition metals that play the role of catalysts for hydrogen absorption and release reactions cannot be introduced in a corrosive environment, in a reductive reaction environment in a non-corrosive solution according to one embodiment, the transition metals do not desorb. Therefore, the transition metals can be introduced into the porous magnesium structure (10) in the same process without an additional process. Accordingly, the porous magnesium structure (10) into which the transition metals are introduced can further accelerate hydrogen absorption and release.

[0060] In the magnesium-alkali metal alloy used as a raw material, the alkali metal can be, for example, Li, Na, K, etc., but is not limited thereto.

[0061] In a solution in which an aromatic compound is dissolved in an organic solvent, the aromatic compound may be, for example, a compound having two or more aromatic rings. Specifically, the aromatic compound may include, for example, naphthalene, biphenyl, phenanthrene, anthracene, or a combination thereof, but is not limited thereto.

[0062] In a solution in which an aromatic compound is dissolved in an organic solvent, the organic solvent is not particularly limited as long as it can dissolve the aromatic compound and can be used. Examples of the organic solvent include tetrahydrofuran (THF), diethyl ether, hexamethylphosphoramide (HMPA), 1,2-dimethoxyethane, and the like.

[0063] The alkali metal desorbed by dealloying can react with the aromatic compound in the solution to form a by-product. The formed by-product can serve to protect the porous magnesium structure (10) from oxidation as a reducing agent. Further, the by-product can be further utilized in processes such as the synthesis of nanoparticles as a reducing agent.

[0064] As a specific example, a method for manufacturing a porous magnesium structure (10) according to an embodiment will be described with reference to FIG. 2. FIG. 2 is a specific example for assisting the explanation, and the method for manufacturing a porous magnesium structure according to an embodiment is not limited thereto.

[0065] FIG. 2 is a schematic diagram showing a method for manufacturing a porous magnesium structure for hydrogen storage according to an embodiment.

[0066] Referring to FIG. 2, a porous magnesium structure (10) according to an embodiment can be manufactured by introducing a magnesium-lithium alloy processed in the form of chunks with a size of 1 mm to 5 mm into a solution in which naphthalene is dissolved in a THF solvent and performing dealloying. Specifically, only lithium inside the crystal of the magnesium-lithium alloy is selectively desorbed, and the remaining magnesium atoms grow into a nanosized porous magnesium structure (10) through a self-assembly process. At this time, the desorbed lithium can react with naphthalene to form lithium naphthalenide. The formed lithium naphthalenide can serve to protect the porous magnesium structure (10) from oxidation as a reducing agent.

[0067] In the dealloying process, the reaction between the magnesium-lithium alloy and the solution can be carried out for 2 days to 14 days. When reacting for a time within the above range, a porous magnesium structure composed of a magnesium skeleton having a predetermined average thickness range and pores having a predetermined average diameter range according to an embodiment can be manufactured.

[0068] According to another embodiment, as described above, after manufacturing a porous magnesium structure by dealloying, a step of mixing the manufactured porous magnesium structure (10) with a transition metal-containing precursor can be further performed. By further performing the above process, a porous magnesium structure further containing a transition metal can be manufactured.

[0069] The transition metal-containing precursor may include a chloride of a transition metal, a complex compound of a transition metal, or a combination thereof. At this time, the transition metal may include Ni, Ti, Co, or a combination thereof.

[0070] The complex compound of a transition metal can be a compound in which a ligand such as cyclopentadiene is strongly bonded to a central metal.

[0071] The transition metal-containing precursor can be mixed in an amount of 1 to 10 parts by weight, for example, 2 to 9 parts by weight, based on 100 parts by weight of the porous magnesium structure produced by dealloying in the previous step. When the transition metal-containing precursor is mixed within the above range, the transition metal does not desorb and can be stably introduced into the porous magnesium structure, thereby ensuring a porous magnesium structure capable of absorbing and releasing hydrogen at a higher speed.

[0072] The porous magnesium structure further containing a transition metal produced by the above-described method specifically includes a magnesium skeleton (11) and pores (12), and can have a structure in which the transition metal is located on the surface of the magnesium skeleton (11).

[0073] The porous magnesium structure according to one embodiment is produced by a solution-phase reaction at room temperature, so it can be easily mass-produced, and mass production is also easy. Also, according to one embodiment, since dealloying can be easily caused by a method of putting a magnesium-alkali metal alloy into a solution and stirring it, the production method is easy and simple.

[0074] Hereinafter, a method for storing hydrogen using the above-described porous magnesium structure (10) will be described.

[0075] The hydrogen storage method according to one embodiment is carried out in the process of absorbing hydrogen into the aforementioned porous magnesium structure (10) and reversibly releasing it. Specifically, when hydrogen gas is added to the aforementioned porous magnesium structure (10) at a predetermined temperature, hydrogen is absorbed to obtain magnesium hydride, and then when the temperature is raised and the hydrogen gas is removed, the hydrogen gas can be reversibly released from the magnesium hydride.

[0076] The absorption of hydrogen gas can be carried out at a temperature of 150°C to 200°C, for example, at a temperature of 160°C to 190°C. The release of hydrogen gas can be carried out at a temperature of 250°C to 300°C, for example, at a temperature of 260°C to 290°C. Like the aforementioned temperature range, since hydrogen absorption and release are possible at high speeds even at low temperatures, the porous magnesium structure according to one embodiment can be usefully used as a hydrogen storage material.

[0077] The porous magnesium structure according to one embodiment can absorb and release about 5% hydrogen within 40 minutes with respect to the total weight of the porous magnesium structure.

[0078] Hereinafter, the aforementioned embodiments will be described in more detail through examples. However, the following examples are for illustrative purposes only and do not limit the scope of the rights.

[0079] (Manufacture of Porous Magnesium Structure) Example 1 Mg-Li alloy (Mg 15 Li 85 , Nibco Corporation) was put into 110 mL of a solution in which 0.16 M naphthalene was dissolved in a tetrahydrofuran (THF) solvent per 100 mg of the alloy and stirred, and reacted for 5 days for dealloying to manufacture a porous magnesium structure.

[0080] Comparative Example 1 A porous magnesium structure was fabricated by arranging an Mg-Li alloy foil as the positive electrode and a Li foil as the negative electrode, applying a voltage of 1.5 V, and performing dealloying by an electrochemical method. Specifically, when the voltage was applied, Li was selectively removed from the Mg-Li alloy at the positive electrode to form a porous magnesium structure, and the removed Li grew dendritically at the negative electrode.

[0081] Evaluation 1: SEM analysis To confirm the structures of the porous magnesium structures according to Example 1 and Comparative Example 1, SEM (scanning electron microscope) analysis was performed, and the results are shown in FIGS. 3 to 4b.

[0082] FIG. 3 is an SEM (scanning electron microscope) image of the porous magnesium structure for hydrogen storage according to Example 1.

[0083] Referring to FIG. 3, it can be confirmed that the porous magnesium structure according to one embodiment includes a magnesium skeleton and pores, has a three-dimensional porous structure, and the average thickness of the magnesium skeleton is 50 nm or less.

[0084] FIG. 4a is an SEM image of the porous magnesium structure for hydrogen storage according to Example 1, and FIG. 4b is an SEM image of the porous magnesium structure for hydrogen storage according to Comparative Example 1.

[0085] Referring to FIGS. 4a and 4b, it can be seen that the porous magnesium structure according to Example 1 has all the sizes of the magnesium skeleton and pores at the nanolevel, while in the case of Comparative Example 1, the pores are very large with sizes exceeding the nanolevel, and the deviation in the pore sizes is also very large.

[0086] Evaluation 2: XRD analysis To confirm the crystal structures of the porous magnesium structures according to Example 1 and Comparative Example 1, XRD (X-ray diffraction) analysis was performed, and the results are shown in FIG. 5.

[0087] Figure 5 is an XRD analysis graph of the porous magnesium structure for hydrogen storage according to Example 1 and Comparative Example 1.

[0088] Referring to Figure 5, the porous magnesium structure according to one embodiment has a diffraction peak at 2θ of 35° to 40° in the XRD pattern, indicating that the crystal structure of Mg is well formed.

[0089] Evaluation 3: Specific surface area analysis The specific surface area of the porous magnesium structure according to Example 1 was measured by the BET (Brunauer - Emmett - Teller; BET) method, and the results are shown in FIGS. 6a to 6c.

[0090] FIG. 6a is an N2 adsorption curve of the porous magnesium structure for hydrogen storage according to Example 1, FIG. 6b is a pore size distribution curve of the porous magnesium structure for hydrogen storage according to Example 1, and FIG. 6c is a BET analysis graph of the porous magnesium structure for hydrogen storage according to Example 1.

[0091] Referring to FIGS. 6a to 6c, the porous magnesium structure according to one embodiment has a specific surface area in the range of 20 m 2 / g to 40 m 2 / g, indicating that hydrogen absorption and release can be achieved rapidly and at low temperature.

[0092] Evaluation 4: XPS analysis To confirm the oxide film structure in the porous magnesium structures according to Example 1 and Comparative Example 1, XPS (X - ray photoelectron spectroscopy) analysis (Mg 2p XPS) was performed, and the results are shown in FIGS. 7a and 7b.

[0093] FIG. 7a is an XPS analysis graph of the porous magnesium structure for hydrogen storage according to Example 1, and FIG. 7b is an XPS analysis graph of the porous magnesium structure for hydrogen storage according to Comparative Example 1.

[0094] Referring to FIGS. 7a and 7b, it can be seen that the porous magnesium structure according to one embodiment includes both a magnesium body and an oxide film located on its surface. Also, in the case of Example 1, in the region where the depth from the surface to the inside of the magnesium skeleton is 1 nm to 10 nm, the content of the molar ratio of the magnesium body to the oxide film is about 1:2, and it can be seen that it is within the range of the molar ratio of 1:1 to 1:5 according to one embodiment. On the other hand, in the case of Comparative Example 1, it was found that the content of the molar ratio of the magnesium body to the oxide film was about 1:6. From this, it can be seen that the porous magnesium structure according to one embodiment has a relatively thin oxide film, and thus it can be predicted that hydrogen absorption and release are possible at low temperature and high speed.

[0095] Evaluation 5: Hydrogen absorption and desorption rate Regarding the porous magnesium structures according to Example 1 and Comparative Example 1, the hydrogen absorption and release rates were confirmed, and the results are shown in FIGS. 8a and 8b.

[0096] Measurement was carried out using a Sievert apparatus with a pressure / volume-based measurement method. Hydrogen absorption was carried out in a hydrogen pressurized environment at 200 °C and 16 bar, and hydrogen release was carried out in a static vacuum environment at 300 °C and 0 bar.

[0097] FIG. 8a is a hydrogen absorption curve of the porous magnesium structure for hydrogen storage according to Example 1 and Comparative Example 1, and FIG. 8b is a hydrogen release curve of the porous magnesium structure for hydrogen storage according to Example 1 and Comparative Example 1.

[0098] Referring to FIGS. 8a and 8b, in the case of the porous magnesium structure according to Example 1, it can be confirmed that both hydrogen absorption and release are possible at a higher speed compared to Comparative Example 1.

[0099] As described above, the preferred embodiments of the present invention have been described in detail. However, the scope of the rights of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts of the present invention defined in the following claims also belong to the scope of the rights of the present invention.

Claims

1. A porous magnesium structure for hydrogen storage, comprising a magnesium skeleton and pores, having a three-dimensional porous structure, wherein the average thickness of the magnesium skeleton is more than 0 nm and not more than 200 nm.

2. The porous magnesium structure for hydrogen storage according to Claim 1, wherein the magnesium skeleton comprises a magnesium body and an oxide film located on the surface of the magnesium body.

3. The oxide film contains magnesium oxide, and the magnesium oxide contains MgO. The porous magnesium structure for hydrogen storage according to Claim 2.

4. The porous magnesium structure for hydrogen storage according to Claim 2, wherein the magnesium body and the oxide film have a molar ratio of 1:1 to 1:

5.

5. The porous magnesium structure for hydrogen storage according to Claim 1, wherein the average diameter of the pores is 20 nm to 200 nm.

6. The specific surface area of the porous magnesium structure is 30 m 2 / g to 40 m 2 / g. The porous magnesium structure for hydrogen storage according to claim 1.

7. The porous magnesium structure for hydrogen storage according to Claim 1, which has a diffraction peak at 2θ of 35° to 40° in the XRD pattern.

8. The porous magnesium structure for hydrogen storage according to Claim 1, further comprising a transition metal located on the surface of the magnesium skeleton. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The method for producing a porous magnesium structure for hydrogen storage according to claim 12, wherein the detached alkali metal reacts with the aromatic compound in the solution to form a by-product.

14. After the step of manufacturing the porous magnesium structure, The method for producing a porous magnesium structure for hydrogen storage according to claim 10, further comprising a step of mixing the produced porous magnesium structure and a transition metal-containing precursor to produce a porous magnesium structure further containing a transition metal.

15. The method for producing a porous magnesium structure for hydrogen storage according to claim 14, wherein the transition metal-containing precursor includes a chloride of a transition metal, a complex compound of a transition metal, or a combination thereof.

16. The method for producing a porous magnesium structure for hydrogen storage according to claim 14, wherein the transition metal-containing precursor is mixed in an amount of 1 part by weight to 10 parts by weight based on 100 parts by weight of the produced porous magnesium structure.

17. The method for producing a porous magnesium structure for hydrogen storage according to claim 14, wherein in the porous magnesium structure further containing a transition metal, the transition metal is located on the surface of the magnesium skeleton.

18. A step of absorbing hydrogen gas into the porous magnesium structure for hydrogen storage according to any one of claims 1 to 9 to obtain magnesium hydride; and A hydrogen storage method including a step of reversibly releasing hydrogen gas from the magnesium hydride.

19. The hydrogen storage method according to claim 18, wherein the absorption is performed at a temperature of 150°C to 200°C.

20. The hydrogen storage method according to claim 18, wherein the release is performed at a temperature of 250°C to 300°C.

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