Hydrogen generating method

Abstract

To provide a hydrogen generating method that allows efficient generation of hydrogen from a metal hydride.SOLUTION: A hydrogen generating method includes the steps of: preparing a first container charged with a hydrogen generating agent comprising a metal hydride; heating while mixing the hydrogen generating agent with water to yield hydrogen and a composition including a metal hydroxide; and charging the composition into a second container, the second container having a shape substantially the same as that of the first container.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for generating hydrogen. [Background technology]

[0002] Fuel cell vehicles (FCVs) use electrical energy generated by the reaction of hydrogen and oxygen in a fuel cell to power their motors. One example of a hydrogen source for a fuel cell is a hydrogen generator, which generates hydrogen by reacting metal hydride with water.

[0003] Furthermore, from the viewpoint of environmental conservation, recycling of used hydrogen generating agents (particularly, metal hydrides in the hydrogen generating agents) has been considered. For example, Patent Document 1 discloses a magnesium hydroxide recycling method in which magnesium hydroxide produced by hydrolysis is recovered from a fuel cell system that generates power by generating hydrogen gas through the hydrolysis of magnesium hydride, and the recovered magnesium hydroxide is recycled (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-234829 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 discloses that hydrogen is generated by supplying water to a cartridge filled with magnesium hydride. However, since the amount of water is small compared to the amount of magnesium hydride, magnesium hydroxide formed on the surface of the magnesium hydride may inhibit the progress of the reaction.

[0006] Therefore, an object of the present invention is to provide a method for generating hydrogen that can efficiently generate hydrogen from a metal hydride. [Means for solving the problem]

[0007] The present invention includes the following [1] to

[10] . [1] A step of preparing a first container filled with a hydrogen generating agent containing a metal hydride; a step of adding the hydrogen generating agent to water, mixing and heating the mixture, and generating hydrogen while obtaining a composition containing a metal hydroxide; and filling the composition into a second container; A method for generating hydrogen, wherein the shape of the second container is substantially the same as the shape of the first container. [2] a step of reacting the metal hydroxide with carbon dioxide to obtain a metal carbonate; decomposing the metal carbonate into a metal oxide and carbon dioxide; a step of reducing and hydrogenating the metal oxide to obtain a metal hydride; producing a hydrogen generating agent using the metal hydride and filling the hydrogen generating agent into a third container, The hydrogen generation method according to [1], wherein the shape of the third container is substantially the same as the shape of the first container. [3] The method for generating hydrogen according to [1] or [2], wherein the metal hydride includes magnesium hydride. [4] The hydrogen generation method according to any one of [1] to [3], wherein the hydrogen generating agent further contains a water-soluble organic solvent. [5] The method for generating hydrogen according to [4], wherein the organic solvent is a polyhydric alcohol. [6] The method for generating hydrogen according to [4] or [5], wherein the organic solvent is glycerin. [7] The method for generating hydrogen according to any one of [1] to [6], wherein the content of the metal salt in the hydrogen generating agent is 10 mass % or less based on the total amount of the hydrogen generating agent. [8] The hydrogen generating method according to any one of [1] to [7], wherein the hydrogen generating agent is in a paste form. [9] The method for generating hydrogen according to any one of [1] to [8], wherein the hydrogen generating agent is brought into contact with the water using a dispenser.

[10] A step of supplying the hydrogen to a fuel cell to generate electricity and obtain water and heat; a step of mixing the water produced during the power generation with a hydrogen generating agent containing a metal hydride to obtain a mixture; heating the mixture while utilizing the heat to generate hydrogen; The hydrogen generation method according to any one of [1] to [9], further comprising: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a hydrogen generation method that can efficiently generate hydrogen from a metal hydride. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flow diagram illustrating a method for generating hydrogen. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0011] One embodiment of the present invention is a hydrogen generation method comprising the steps of: preparing a first container filled with a hydrogen generating agent containing a metal hydride (preparation step); adding the hydrogen generating agent to water, mixing and heating the mixture to generate hydrogen, and obtaining a composition containing a metal hydroxide (hydrogen generation step); and filling the composition into a second container (composition filling step). In the hydrogen generation method according to this embodiment, the shape of the second container is substantially the same as the shape of the first container.

[0012] According to the present invention, hydrogen can be efficiently generated by pouring the hydrogen generating agent filled in the first container into water. Furthermore, by making the shapes of the first container and the second container substantially identical, the first container, which has been emptied by discharging the hydrogen generating agent, can be reused as a second container to be filled with a composition containing a metal hydroxide. This eliminates the need to secure a separate space for recovering the composition containing a metal hydroxide, thereby realizing space savings within a facility or device (e.g., an FCV) that generates hydrogen.

[0013] In this specification, "the shape of the second container is substantially the same as the shape of the first container" means that when comparing the shape of the first container and the shape of the second container, although there are differences in shape due to scratches, dents, etc., the two are in a relationship in which they can be substituted when installing the first container or the second container in equipment or a device, etc. Hereinafter, similar expressions will be defined in the same way as above.

[0014] <Preparation process> In the preparation step, a first container filled with a hydrogen generating agent containing a metal hydride is prepared. In Fig. 1, in the preparation step, a first container 1 filled with a hydrogen generating agent containing a metal hydride is prepared.

[0015] The hydrogen generating agent contains at least a metal hydride. Examples of the metal hydride include alkali metal hydrides and alkaline earth metal hydrides. The hydrogen generating agent may contain one type of metal hydride alone or two or more types of metal hydrides.

[0016] Examples of alkali metal hydrides include lithium hydride (LiH), sodium hydride (NaH), potassium hydride (KH), etc. Examples of alkaline earth metal hydrides include magnesium hydride (MgH), calcium hydride (CaH), barium hydride (BaH), beryllium hydride (BeH), strontium hydride (SrH), etc. The metal hydride may be magnesium hydride, which is stable in air and has excellent storage stability.

[0017] When the metal hydride is an alkali metal hydride, contact with water causes the reaction represented by the following formula (1): In formula (1), M represents an alkali metal. MH + H2O → H2 + M(OH) (1)

[0018] When the metal hydride is an alkaline earth metal hydride, the reaction shown in formula (2) below occurs upon contact with water: In formula (2), M represents an alkaline earth metal. MH2+2H2O→2H2+M(OH)2···(2)

[0019] The metal hydride may be in the form of a powder. The average particle size of the metal hydride may be 0.01 to 500 μm, 0.1 to 100 μm, or 1 to 10 μm, from the viewpoint of excellent dispersibility when mixed with water and enabling more efficient hydrogen generation. The average particle size of the metal hydride is D 50 This means that the chromatic aberration can be measured by laser diffraction and scattering.

[0020] The content of the metal hydride may be 1% by mass or more, 5% by mass or more, or 10% by mass or more based on the total amount of the hydrogen generating agent, from the viewpoints of excellent dispersibility when mixed with water and enabling more efficient hydrogen generation. The content of the metal hydride may be 90% by mass or less, 70% by mass or less, or 50% by mass or less, from the viewpoints of excellent storage stability and easy assurance of safety. From these viewpoints, the content of the metal hydride may be 1 to 90% by mass, 5 to 70% by mass, or 10 to 50% by mass.

[0021] The hydrogen generating agent may further contain a water-soluble organic solvent. By further containing a water-soluble organic solvent, the storage stability of the hydrogen generating agent is improved and safety is more easily ensured. The present invention presumes the reason for this as follows.

[0022] That is, by mixing the metal hydride with a water-soluble organic solvent, the metal hydride is coated with the organic solvent. This makes it difficult for the metal hydride to come into contact with trace amounts of moisture present in the air, etc., and hydrogen generation can be suppressed. On the other hand, when a sufficient amount of water is mixed with the hydrogen generating agent, the organic solvent that coated the metal hydride dissolves in water because the organic solvent is water-soluble, and hydrogen can be generated by the metal hydride coming into contact with water.

[0023] The water-soluble organic solvent means an organic solvent having a solubility of 20 g or more in 100 g of water at 20° C. The water-soluble organic solvent is preferably one that is unreactive with metal hydrides and water.

[0024] Examples of water-soluble organic solvents include monohydric alcohol compounds such as methanol, ethanol, propanol, and butanol; polyhydric alcohol compounds such as ethylene glycol and glycerin; ether compounds such as dimethoxyethane, tetrahydrofuran, and dioxane; carboxylic acid compounds such as acetic acid; ketone compounds such as acetone; and nitrogen-containing compounds such as acetonitrile, hexamethylphosphoric triamide, triethylamine, and pyridine. The water-soluble organic solvent may be a monohydric alcohol compound or a polyhydric alcohol compound, or may be glycerin, from the viewpoints of excellent storage stability, easy safety assurance, and easy dissolution in water and efficient hydrogen generation when mixed with water. The hydrogen generator may contain one water-soluble organic solvent alone, or may contain two or more water-soluble organic solvents.

[0025] The solubility of the water-soluble organic solvent in 100 g of water at 20°C may be 50 g or more, 100 g or more, or 150 g or more, from the viewpoint of enabling more efficient generation of hydrogen when mixed with water.

[0026] From the viewpoint of easily ensuring safety, the flash point of the water-soluble organic solvent may be 100°C or higher, 120°C or higher, 140°C or higher, or 150°C or higher.

[0027] The boiling point of the water-soluble organic solvent may be 40°C or higher, 60°C or higher, 80°C or higher, or 100°C or higher, from the viewpoint of excellent storage stability.

[0028] The molecular weight of the water-soluble organic solvent may be 30-200, 50-150, or 80-120.

[0029] The viscosity of the water-soluble organic solvent at 20° C. may be 1 Pa·s or more, 1.1 Pa·s or more, 1.2 Pa·s or more, or 1.3 Pa·s or more.

[0030] The content of the water-soluble organic solvent may be 1% by mass or more, 5% by mass or more, or 10% by mass or more based on the total amount of the hydrogen generating agent, from the viewpoints of excellent storage stability and easy safety assurance. The content of the water-soluble organic solvent may be 99% by mass or less, 90% by mass or less, or 70% by mass or less, from the viewpoint of more efficient hydrogen generation when mixed with water. From these viewpoints, the content of the water-soluble organic solvent may be 1 to 99% by mass, 5 to 90% by mass, or 10 to 70% by mass.

[0031] The ratio of the content of the water-soluble organic solvent to the content of the metal hydride (content of water-soluble organic solvent / content of metal hydride) may be 0.1 or more, 0.3 or more, or 1 or more from the viewpoint of excellent storage stability and easy assurance of safety, and may be 10 or less, 5 or less, or 2 or less from the viewpoint of more efficient generation of hydrogen when mixed with water.

[0032] The hydrogen generating agent may contain components other than the metal hydride and the water-soluble organic solvent, such as pigments, dyes, antioxidants, dispersants, thickeners, and pH adjusters.

[0033] The hydrogen generating agent may or may not contain a metal salt. Examples of the metal in the metal salt include calcium, magnesium, aluminum, zinc, tin, iron, titanium, and gallium.

[0034] The content of the metal salt may be 10% by mass or less, 5% by mass or less, or 1% by mass or less based on the total amount of the hydrogen generating agent. The hydrogen generating agent may be in an embodiment that does not substantially contain a metal salt (the content of the metal salt is substantially 0% by mass).

[0035] The hydrogen generating agent may be in a paste form at room temperature (20° C.). When the hydrogen generating agent is in a paste form, it is easy to handle.

[0036] The viscosity of the hydrogen generating agent at 20°C may be 0.02 Pa·s or more, 0.1 Pa·s or more, or 0.5 Pa·s or more.

[0037] The first container has at least an outlet for discharging the hydrogen generating agent. In the hydrogen generating step, the hydrogen generating agent discharged from the first container is mixed with water and then heated to generate hydrogen.

[0038] The shape of the first container is not particularly limited and can be appropriately adjusted depending on the device in which the first container is placed, etc. The shape of the first container may be, for example, a substantially cylindrical shape or a substantially prismatic shape.

[0039] The capacity of the first container is not particularly limited and can be adjusted appropriately depending on the device in which the first container is placed, etc. The capacity of the first container may be, for example, 0.5 to 100 L, 2 to 50 L, or 5 to 10 L.

[0040] The material of the first container is preferably a material that is inert to the components contained in the hydrogen generating agent and is difficult for moisture to permeate. The material of the first container may be, for example, a metal, and more specifically, may be an alloy containing iron as a main component.

[0041] <Hydrogen generation process> In the hydrogen generation step, a hydrogen generating agent is added to water and heated while being mixed to generate hydrogen and obtain a composition containing a metal hydroxide. In Fig. 1, in the hydrogen generation step, the hydrogen generating agent supplied from the first container 1 through a line L11 is added to a mixing tank 10 containing water supplied through a line L12 and heated while being mixed, whereby hydrogen is discharged through a line L13 and a composition containing a metal hydroxide is discharged through a line L14.

[0042] The amount of the hydrogen generating agent added to water may be 100% by mass or less, 50% by mass or less, or 10% by mass or less, or may be 0.01 to 100% by mass, 0.1 to 50% by mass, or 1 to 10% by mass, relative to the total mass of water.

[0043] The amount of metal hydride added to water may be 10% by mass or less, 30% by mass or less, or 50% by mass or less, or may be 0.01 to 100% by mass or more, 0.1 to 30% by mass, or 1 to 50% by mass, based on the total mass of water.

[0044] The method for mixing the hydrogen generating agent and water is not particularly limited and may be a known method. For example, the hydrogen generating agent discharged from the first container may be added to water using a dispenser, an inkjet device, or the like, and then the hydrogen generating agent and water may be stirred with a stirrer to obtain a mixture. The amount of the hydrogen generating agent discharged from the first container may be adjusted depending on the demand for hydrogen.

[0045] The temperature at which the mixture of the hydrogen generating agent and water is heated can be appropriately adjusted depending on the type of metal hydride, the content of the metal hydride in the hydrogen generating agent, etc. The temperature at which the mixture is heated may be, for example, 60°C or higher, 80°C or higher, or 90°C or higher.

[0046] By heating the mixture of the hydrogen generating agent and water, the reaction of the above formula (1) and / or formula (2) proceeds, and hydrogen and metal hydroxide are generated. The hydrogen generated in the hydrogen generating step may be supplied to a fuel cell.

[0047] The type of metal hydroxide generated in the hydrogen generation step is determined depending on the type of metal hydride in the hydrogen generating agent. Examples of metal hydroxides include hydroxides of alkali metals and hydroxides of alkaline earth metals. Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. Examples of alkaline earth metal hydroxides include magnesium hydroxide, calcium hydroxide, barium hydroxide, beryllium hydroxide, strontium hydroxide, etc. The metal hydroxide may be magnesium hydroxide from the viewpoint of stability in the atmosphere.

[0048] The solubility of the metal hydroxide in 100 g of water at 20° C. may be 0.1 g or less, 0.05 g or less, or 0.01 g or less, from the viewpoint of ease of separation from water.

[0049] <Power generation process> When hydrogen is supplied to the fuel cell to generate electricity, water and heat are obtained. That is, the hydrogen generation method may further include a step of supplying hydrogen to the fuel cell to generate electricity and obtaining water and heat (power generation step). The electricity generated in the power generation step is used, for example, in an FCV.

[0050] <Mixing process> The water produced in the power generation step may be used as water to be mixed with the hydrogen generating agent. That is, the hydrogen generation method may further include a step (mixing step) of mixing the water produced in the power generation step with a hydrogen generating agent containing a metal hydride to obtain a mixture. For example, the water produced in the power generation step may be supplied to the mixing tank 10 through the line L12.

[0051] <Second hydrogen generation step> The mixture obtained in the mixing step is heated to generate hydrogen. That is, the hydrogen generation method may further include a step of heating the mixture to generate hydrogen (second hydrogen generation step). In the second hydrogen generation step, the heat obtained in the power generation step may be utilized.

[0052] <Composition filling process> In the composition charging step, the composition obtained in the hydrogen generation step is charged into a second container. The shape of the second container is substantially the same as that of the first container. In FIG. 1, in the composition charging step, the composition containing the metal hydroxide discharged through line L14 is charged into second container 2.

[0053] The shape of the second container is substantially the same as the shape of the first container, but the material of the second container may be substantially the same as or different from the material of the first container. The second container may be the first container that has been emptied after the hydrogen generating agent has been discharged, or may be a container other than the first container.

[0054] The method for filling the composition into the second container may be a known method. For example, a mixture (composition) of the metal hydroxide and water may be collected and filled into the second container, or the metal hydroxide and water may be separated by a known method, and then the composition containing the metal hydroxide may be filled into the second container.

[0055] <Metal carbonate production process> After the composition filling step, the metal hydroxide in the composition filled in the second container may react with carbon dioxide to form a metal carbonate. That is, the hydrogen generation method may further include a step of reacting the metal hydroxide with carbon dioxide to obtain a metal carbonate (metal carbonate generation step). In FIG. 1, in the metal carbonate generation step, the metal hydroxide in the composition filled in the second container 2 is supplied through line L21 and reacts with carbon dioxide supplied through line L22, and water is discharged through line L23 and the metal carbonate is discharged through line L24. The empty second container may be reused as the third container described below. The metal carbonate generation step may be performed without removing the metal hydroxide from the second container.

[0056] The type of metal carbonate produced in the metal carbonate production step is determined depending on the type of metal hydroxide produced in the hydrogen generation step. When the reaction of formula (1) above proceeds in the hydrogen generation step, the reaction of formula (3) below proceeds in the metal carbonate production step, and when the reaction of formula (2) above proceeds in the hydrogen generation step, the reaction of formula (4) below proceeds in the metal carbonate production step. In formula (3), M represents an alkali metal, and in formula (4), M represents an alkaline earth metal. 2M(OH)+CO2→M2CO3+H2O ···(3) M(OH)2+CO2→MCO3+H2O ···(4)

[0057] Examples of metal carbonates include alkali metal carbonates and alkaline earth metal carbonates. Examples of alkali metal carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Examples of alkaline earth metal carbonates include magnesium carbonate, calcium carbonate, barium carbonate, beryllium carbonate, and strontium carbonate. The metal carbonate may be magnesium carbonate.

[0058] When the metal hydroxide is magnesium hydroxide, magnesium carbonate can be obtained by contacting the magnesium hydroxide with carbon dioxide.

[0059] The metal carbonate is decomposed into the metal oxide and carbon dioxide in the metal oxide production step described below. When the carbon dioxide generated in the metal oxide production step is discharged underground, the metal carbonate may be transported to a carbon dioxide storage site. The carbon dioxide storage site may be a region, country, etc. that emits less carbon dioxide than the location where the metal carbonate is produced, or may be a region, country, etc. that can store more carbon dioxide than the location where the metal carbonate is produced.

[0060] The amount of carbon dioxide supplied may be in excess of the amount of metal hydroxide, from the viewpoint of facilitating the reaction between the metal hydroxide and carbon dioxide, and may be, for example, 1 to 10 mol per 1 mol of the metal hydroxide.

[0061] <Metal oxide generation process> The metal carbonate produced through the metal carbonate production step may be decomposed into metal oxide and carbon dioxide by heating or the like. That is, the hydrogen generation method may further include a step of decomposing the metal carbonate into metal oxide and carbon dioxide (metal oxide production step). In FIG. 1, in the metal oxide production step, the metal carbonate supplied through line L24 is decomposed, and carbon dioxide is discharged through line L25 and the metal oxide is discharged through line L26. If the metal carbonate production step is performed without removing the metal hydroxide from the second container, the metal carbonate may be decomposed into metal oxide and carbon dioxide after removing the metal carbonate from the second container.

[0062] The type of metal oxide produced in the metal oxide production step is determined depending on the type of metal carbonate produced in the metal carbonate production step. When the reaction of formula (3) above proceeds in the metal carbonate production step, the reaction of formula (5) below proceeds in the metal oxide production step. When the reaction of formula (4) above proceeds in the metal carbonate production step, the reaction of formula (6) below proceeds in the metal oxide production step. In formula (5), M represents an alkali metal, and in formula (6), M represents an alkaline earth metal. M2CO3 → M2O + CO2 (5) MCO3 → MO + CO2 (6)

[0063] Examples of metal oxides include oxides of alkali metals and oxides of alkaline earth metals. Examples of alkali metal oxides include lithium oxide, sodium oxide, and potassium oxide. Examples of alkaline earth metal oxides include magnesium oxide, calcium oxide, barium oxide, beryllium oxide, and strontium oxide. The metal oxide may be magnesium oxide.

[0064] The method for decomposing the metal carbonate into the metal oxide and carbon dioxide may be a known method. For example, when the metal carbonate is magnesium carbonate, the magnesium carbonate can be decomposed into magnesium oxide and carbon dioxide by heating it to 400 to 700°C.

[0065] The carbon dioxide generated in the metal oxide production step may be discharged underground. That is, the hydrogen generation method may further include a step of discharging the carbon dioxide generated in the metal oxide production step underground. This makes it possible to suppress the emission of carbon dioxide into the atmosphere. Known methods can be applied as a method for discharging carbon dioxide underground (a method for storing carbon dioxide). In order to increase the purity of the carbon dioxide, the carbon dioxide may be supplied to a separator or the like before being discharged underground.

[0066] <Metal hydride generation process> Metal hydride and water can be obtained by reducing and hydrogenating the metal oxide produced through the metal oxide production step. That is, the hydrogen generation method may further include a step of reducing and hydrogenating the metal oxide to obtain a metal hydride (metal hydride production step). In Fig. 1, in the metal hydride production step, metal carbonate supplied through line L26 is reduced and hydrogenated with hydrogen supplied through line L27, and the metal hydride is discharged through line L28.

[0067] The type of metal hydride produced in the metal hydride production step is determined depending on the type of metal oxide produced in the metal oxide production step. When the reaction of formula (5) above proceeds in the metal oxide production step, the reaction of formula (7) below proceeds in the metal hydride production step. When the reaction of formula (6) above proceeds in the metal oxide production step, the reaction of formula (8) below proceeds in the metal hydride production step. In formula (7), M represents an alkali metal, and in formula (8), M represents an alkaline earth metal. M2O+2H2→2MH+H2O (7) MO+2H2→MH2+H2O (8)

[0068] Examples of the metal hydride include alkali metal hydrides and alkaline earth metal hydrides. Specific examples of the alkali metal hydrides and alkaline earth metal hydrides are as described above. The metal hydride may be magnesium hydride.

[0069] The method for reducing and hydrogenating the metal oxide may be a known method. For example, when the metal oxide is magnesium oxide, magnesium hydride can be obtained by mixing the magnesium oxide with hydrogen and subjecting the mixture to a thermal plasma treatment.

[0070] The amount of hydrogen supplied may be in excess of the amount of metal oxide, from the viewpoint of facilitating the reaction between the metal oxide and hydrogen, for example, 1 to 10 mol per 1 mol of metal oxide.

[0071] <Hydrogen generating agent filling process> The metal hydride produced through the metal hydride production step is used, for example, to produce a hydrogen generating agent. When the metal hydride is used to produce a hydrogen generating agent, the produced hydrogen generating agent may be filled into a third container having substantially the same shape as the first container. That is, the hydrogen generation method may further include a step of producing a hydrogen generating agent using the metal hydride and filling the hydrogen generating agent into a third container (hydrogen generating agent filling step). In FIG. 1, in the hydrogen generating agent filling step, a hydrogen generating agent is produced from a hydrogen generating agent supplied through a line L28, and the hydrogen generating agent is filled into a third container 3.

[0072] The components and properties of the hydrogen generating agent produced in the hydrogen generating agent filling step can be appropriately referred to the descriptions regarding the hydrogen generating agent described above. The hydrogen generating agent produced in the hydrogen generating agent filling step may have substantially the same composition as the hydrogen generating agent filled in the first container, or may have a different composition from the hydrogen generating agent filled in the first container.

[0073] The third container filled with a hydrogen generating agent can be used in the same manner as the first container. That is, the hydrogen generating agent filled in the third container may be heated while being mixed with water to generate hydrogen and obtain a composition containing a metal hydroxide. In FIG. 1, the hydrogen generating agent supplied from the third container 3 through line L31 and water supplied through line L12 are mixed and heated in a mixing tank 10, whereby hydrogen is discharged through line L13 and the composition containing a metal hydroxide is discharged through line L14. In this way, the series of steps from the preparation step to the hydrogen generating agent filling step are repeated to recycle the metal hydride. [Explanation of symbols]

[0074] 1...first container, 2...second container, 3...third container, 10...mixing tank.

Claims

1. providing a first container filled with a hydrogen generating agent containing a metal hydride; a step of adding the hydrogen generating agent to water, mixing and heating the mixture, and generating hydrogen while obtaining a composition containing a metal hydroxide; and filling the composition into a second container; A method for generating hydrogen, wherein the shape of the second container is substantially the same as the shape of the first container.

2. reacting the metal hydroxide with carbon dioxide to obtain a metal carbonate; decomposing the metal carbonate into a metal oxide and carbon dioxide; a step of reducing and hydrogenating the metal oxide to obtain a metal hydride; producing a hydrogen generating agent using the metal hydride and filling the hydrogen generating agent into a third container, The method for generating hydrogen according to claim 1 , wherein the shape of the third container is substantially the same as the shape of the first container.

3. The method of generating hydrogen according to claim 1 , wherein the metal hydride comprises magnesium hydride.

4. The hydrogen generating method according to claim 1 , wherein the hydrogen generating agent further comprises a water-soluble organic solvent.

5. The method for generating hydrogen according to claim 4 , wherein the organic solvent is a polyhydric alcohol.

6. The method for generating hydrogen according to claim 4 , wherein the organic solvent is glycerin.

7. 2. The method for generating hydrogen according to claim 1, wherein the content of the metal salt in the hydrogen generating agent is 10 mass % or less based on the total amount of the hydrogen generating agent.

8. The method for generating hydrogen according to claim 1 , wherein the hydrogen generating agent is in a paste form.

9. The method for generating hydrogen according to claim 1 , wherein the hydrogen generating agent is brought into contact with the water using a dispenser.

10. supplying the hydrogen to a fuel cell to generate electricity and obtain water and heat; a step of mixing the water produced during the power generation with a hydrogen generating agent containing a metal hydride to obtain a mixture; heating the mixture while utilizing the heat to generate hydrogen; The method of generating hydrogen according to claim 1 , further comprising:

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