Composition, hydrogen generating agent, and hydrogen generating method

Abstract

To provide a composition for use in a hydrogen generating agent that exhibits excellent storage stability and ensures safety, and further to provide a hydrogen generating agent containing the composition and a hydrogen generating method employing the hydrogen generating agent.SOLUTION: A composition includes a metal hydride and a water-soluble organic solvent. A hydrogen generating agent contains the composition. A hydrogen generating method comprises a first mixing step of yielding a first mixture by mixing the hydrogen generating agent with water, and a first heating step of generating hydrogen by heating the first mixture.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] A fuel cell vehicle (FCV) rotates its motor using electrical energy generated by reacting hydrogen and oxygen in a fuel cell. One example of a hydrogen supply source for a fuel cell is a hydrogen generating agent that generates hydrogen by reacting metal hydride with water. A known example of a conventional hydrogen generating agent is a suspension in which powder of the hydrogen generating agent is dispersed in water (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-177580 Summary of the Invention [Problem to be solved by the invention]

[0004] When a hydrogen generating agent is prepared by suspending a metal hydride in water, hydrogen is generated when the temperature of the hydrogen generating agent rises during storage. Therefore, when a hydrogen generating agent is a suspension of a metal hydride and water, storage stability is low, and there are safety concerns due to unexpected generation of hydrogen.

[0005] Therefore, one aspect of the present invention aims to provide a composition for use in a hydrogen generating agent that has excellent storage stability and ensures safety. Another aspect of the present invention aims to provide a hydrogen generating agent containing the composition, and a method for generating hydrogen using the hydrogen generating agent. [Means for solving the problem]

[0006] The present invention includes the following [1] to [9]. [1] A composition containing a metal hydride and a water-soluble organic solvent. [2] The composition according to [1], wherein the metal hydride is magnesium hydride. [3] The composition according to [1] or [2], wherein the organic solvent is a polyhydric alcohol. [4] The composition according to any one of [1] to [3], wherein the organic solvent is glycerin. [5] The composition according to any one of [1] to [4], wherein the content of the metal salt in the composition is 40 mass % or less based on the total amount of the composition. [6] The composition according to any one of [1] to [5], which is in a paste form. [7] A hydrogen generating agent containing the composition according to any one of [1] to [6]. [8] A first mixing step of mixing the hydrogen generating agent according to [7] with water to obtain a first mixture; a first heating step of heating the first mixture to generate hydrogen; A method for generating hydrogen, comprising: [9] The method according to [8], wherein in the first mixing step, the hydrogen generating agent is mixed with the water using a dispenser.

[10] a power generation step of supplying the hydrogen generated in the first heating step to a fuel cell to generate power and obtain water and heat; a second mixing step of mixing the water obtained in the power generating step with a hydrogen generating agent including a composition containing magnesium hydride and a water-soluble organic solvent to obtain a second mixture; a second heating step of heating the second mixture to generate hydrogen; Including, The method according to [8] or [9], wherein the heat obtained in the power generation step is utilized in the second heating step. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a composition used for a hydrogen generating agent that has excellent storage stability and ensures safety. Furthermore, according to the present invention, it is possible to provide a hydrogen generating agent containing the composition and a method for generating hydrogen using the hydrogen generating agent. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present invention will be described in detail below.

[0009] [Composition] One embodiment of the present invention is a composition containing a metal hydride and a water-soluble organic solvent. The composition according to one embodiment can provide a composition used for a hydrogen generating agent that has excellent storage stability and ensures safety.

[0010] The present invention speculates that the reason for this is as follows. 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 composition, 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. For these reasons, the present invention makes it possible to provide a hydrogen generating agent that has excellent storage stability and ensures safety using the composition.

[0011] (metal hydride) The composition contains a metal hydride. The metal hydride may be an alkali metal hydride or an alkaline earth metal hydride. The composition may contain a single metal hydride or two or more metal hydrides.

[0012] 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 even better storage stability.

[0013] 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 + H20 → H2 + M(OH) (1)

[0014] 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+2H20→2H2+M(OH)2···(2)

[0015] The metal hydride may be in a powder form. The average particle size of the metal hydride may be 1 to 1000 μm, 5 to 500 μm, or 10 to 100 μm, from the viewpoint of excellent dispersibility when mixed with water and efficient hydrogen generation. The average particle size of the metal hydride may be D 50 This means that the chromatic aberration can be measured by laser diffraction and scattering.

[0016] The content of the metal hydride may be 10% by mass or more, 20% by mass or more, or 30% by mass or more based on the total amount of the composition, from the viewpoints of excellent dispersibility when mixed with water and efficient hydrogen generation. The content of the metal hydride may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, from the viewpoints of excellent storage stability and easier safety assurance. From these viewpoints, the content of the metal hydride may be 10 to 90% by mass, 20 to 80% by mass, or 30 to 70% by mass.

[0017] (Water-soluble organic solvent) The composition contains a water-soluble organic solvent. The composition may contain one kind of water-soluble organic solvent alone, or may contain two or more kinds of water-soluble organic solvents.

[0018] The water-soluble organic solvent means an organic solvent having a solubility of 20 g or more in 100 g of water at 90° C. The water-soluble organic solvent is preferably one that is unreactive with metal hydrides and water.

[0019] 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 having superior storage stability, making it easier to ensure safety, and being easily dissolved in water and capable of efficiently generating hydrogen.

[0020] The solubility of the water-soluble organic solvent in 100 g of water at 90°C may be 25 g or more, 50 g or more, or 75 g or more, from the viewpoint of being able to efficiently generate hydrogen when mixed with water.

[0021] The flash point of the water-soluble organic solvent may be 70° C. or higher, 900° C. or higher, or 110° C. or higher, from the viewpoint of more easily ensuring safety.

[0022] The boiling point of the water-soluble organic solvent may be 100°C or higher, 1500°C or higher, 180°C or higher, or 200°C or higher, from the viewpoint of achieving better storage stability.

[0023] The molecular weight of the water-soluble organic solvent may be 30-500, 60-200, or 70-100.

[0024] The viscosity of the water-soluble organic solvent at 20° C. may be 0.02 Pa·s or more, 0.1 Pa·s or more, or 0.5 Pa·s or more.

[0025] The content of the water-soluble organic solvent may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more based on the total amount of the composition, from the viewpoints of achieving better storage stability and making it easier to ensure safety. The content of the water-soluble organic solvent may be 90% by mass or less, 70% by mass or less, or 50% by mass or less, from the viewpoint of being able to efficiently generate hydrogen when mixed with water. From these viewpoints, the content of the water-soluble organic solvent may be 10 to 90% by mass, 20 to 70% by mass, or 30 to 50% by mass.

[0026] 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 3 or more, 5 or more, or 10 or more from the viewpoint of achieving better storage stability and making it easier to ensure safety, and may be 0.4 or less, 0.2 or less, or 0.1 or less from the viewpoint of being able to efficiently generate hydrogen when mixed with water.

[0027] The composition may contain components other than the metal hydride and the water-soluble organic solvent, such as pigments, dyes, antioxidants, dispersants, thickeners, and pH adjusters.

[0028] The composition may or may not contain a metal salt. Examples of the metal in the metal salt include calcium, magnesium, aluminum, zinc, tin, iron, titanium, gallium, and zirconium. The metal in the metal salt may be the same as the metal in the metal hydride, from the viewpoint of achieving better storage stability and making it easier to ensure safety. The metal salt may be a metal salt having a divalent or higher metal cation, and the composition may not contain such a metal salt.

[0029] The metal salt may be, for example, a chloride, fluoride, bromide, nitrate, amide, sulfate, hydrogen sulfate, acetate, butyrate, formate, lactate, malonate, pyruvate, tartrate, or citrate salt of the metal.

[0030] Specific examples of metal salts include zirconium(IV) chloride, zirconium(IV) acetate, zirconium(IV) citrate, zirconium(IV) formate, titanium(III) chloride, ferrous chloride, ferrous acetate, ferrous citrate, ferrous formate, iron chloride, magnesium chloride, magnesium acetate, magnesium nitrate, magnesium formate, calcium chloride, potassium chloride, sodium chloride, zinc chloride, zinc acetate, zinc nitrate, and zinc formate.

[0031] The content of the metal salt may be 40% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, based on the total amount of the composition. The composition may be substantially free of metal salts (the content of metal salts is substantially 0% by mass).

[0032] The content of the metal salt may be 1 mol or less, 0.5 mol or less, or 0.1 mol or less per 1 mol of the metal hydride.

[0033] The composition may be in a paste form at room temperature (20° C.) When the composition is in a paste form, it is easy to handle.

[0034] The viscosity of the composition at 20°C may be 0.02 to 10 Pa·s, or 0.1 to 5 Pa·s.

[0035] [Hydrogen generating agent] The above-described composition can be used as a hydrogen generating agent. That is, another embodiment of the present invention is a hydrogen generating agent containing the above-described composition.

[0036] The hydrogen generating agent can generate hydrogen by mixing it with water and then heating the mixture of the hydrogen generating agent and water. When the hydrogen generating agent is mixed with water, the water-soluble organic solvent in the hydrogen generating agent dissolves in the water. This removes the water-soluble organic solvent that had been covering the metal hydride, allowing the metal hydride to come into contact with water. When the metal hydride and water are heated, the reaction of the above-mentioned formula (1) or formula (2) proceeds, and hydrogen is generated.

[0037] The temperature at which the mixture is heated can be appropriately adjusted depending on the type of metal hydride, the content of metal hydride in the hydrogen generating agent, etc. The temperature at which the mixture is heated may be, for example, 60°C or higher, 70°C or higher, or 80°C or higher.

[0038] The amount of the hydrogen generating agent added to the water may be 50% by mass or less, 30% by mass or less, or 10% by mass or less, based on the total mass of the water.

[0039] The amount of metal hydride added to water may be 0.01 mass% or more, 0.1 mass% or more, or 1 mass% or more, relative to the total mass of water, and may be 70 mass% or less, 50 mass% or less, or 30 mass% or less, or may be 0.01 to 70 mass%, 0.1 to 50 mass%, or 1 to 30 mass%.

[0040] [How to generate hydrogen] After mixing the hydrogen generating agent with water to obtain a mixture, hydrogen can be generated by heating the mixture. That is, another embodiment of the present invention is a hydrogen generation method including a first mixing step of mixing the hydrogen generating agent with water to obtain a first mixture, and a first heating step of heating the first mixture to generate hydrogen.

[0041] In the first mixing step, the hydrogen generating agent and water are mixed to obtain a first mixture. 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 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 using a stirrer to obtain the first mixture.

[0042] In the first heating step, the first mixture is heated to generate hydrogen. The first heating step may be performed simultaneously with the first mixing step. That is, the hydrogen generation method may include a step of heating the first mixture while mixing the hydrogen generating agent and water to obtain the first mixture.

[0043] In the first heating step, the temperature at which the first mixture is heated can be appropriately adjusted depending on the type of metal hydride, the content of metal hydride in the hydrogen generating agent, etc. The temperature at which the first mixture is heated may be, for example, 60°C or higher, 70°C or higher, or 80°C or higher.

[0044] The hydrogen generation method may further include a power generation step of supplying the hydrogen generated in the first heating step to a fuel cell to generate electricity and obtain water and heat. The electricity generated in the power generation step is used, for example, in an FCV.

[0045] 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 second mixing step of mixing the water produced in the power generation step with a hydrogen generating agent including a composition containing magnesium hydride and a water-soluble organic solvent to obtain a second mixture.

[0046] The second mixture obtained in the second mixing step is heated to generate hydrogen. That is, the hydrogen generation method may further include a second heating step of heating the second mixture to generate hydrogen. The heat obtained in the power generation step may be utilized in the second heating step.

[0047] A hydrogen generation method according to one embodiment repeats a first mixing step, a first heating step, a power generation step, a second mixing step, and a second heating step, thereby generating electricity while efficiently using the water and heat produced by power generation. [Example]

[0048] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0049] Example 1 Six grams of glycerin (Kanto Chemical, Grade 1), 3 grams of magnesium hydride (Fujifilm Wako Pure Chemical Industries, Ltd.), and 1 gram of magnesium chloride (Kanto Chemical, Grade 1) were weighed and added to a polypropylene container. The polypropylene container was placed in a paste mixer, and the mixture inside the container was mixed. To prevent heat generation during mixing, the mixture was mixed for 30 seconds, then stopped until the temperature inside the container fell below 30°C. Once the temperature had fallen below 30°C, the mixture was mixed again for 30 seconds. The composition was prepared by mixing the mixture until the viscosity reached 0.3 Pa·S.

[0050] Example 2 Six grams of glycerin (Kanto Chemical, Grade 1) and 3 grams of magnesium hydride (Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed and added to a polypropylene container. The polypropylene container was placed in a paste mixer, and the mixture inside the polypropylene container was mixed. To prevent heat generation during mixing, the mixture was mixed for 30 seconds, then stopped until the temperature inside the container fell below 30°C. Once the temperature had fallen below 30°C, the mixture was mixed again for 30 seconds. The composition was prepared by mixing the mixture until the viscosity reached 0.2 Pa·S.

[0051] When 1 g of the composition immediately after preparation in each example was added to water and heated to 80°C or higher while mixing, hydrogen was generated. This is thought to be due to the organic solvent dissolving in water and the magnesium hydride coming into contact with water, causing a reaction to proceed. Next, after preparing the composition in each example, the composition was stored in an air atmosphere at room temperature (25°C) for 30 days. After that, 1 g of the composition after storage was added to water and heated to 80°C or higher while mixing, and hydrogen was generated to the same extent as before storage. These results demonstrate that the compositions prepared in each example have excellent storage stability. Furthermore, since the amount of hydrogen generated did not change before and after storage, the reaction of magnesium hydride did not proceed during storage, and unexpected hydrogen generation was suppressed, resulting in excellent safety.

Claims

1. A composition comprising a metal hydride and a water-soluble organic solvent.

2. 2. The composition of claim 1 wherein the metal hydride is magnesium hydride.

3. The composition of claim 1 , wherein the organic solvent is a polyhydric alcohol compound.

4. The composition of claim 1 , wherein the organic solvent is glycerin.

5. The composition according to claim 1 , wherein the content of the metal salt in the composition is 40 mass % or less based on the total amount of the composition.

6. The composition of claim 1 in the form of a paste.

7. A hydrogen generating agent comprising the composition according to any one of claims 1 to 6.

8. a first mixing step of mixing the hydrogen generating agent according to claim 7 with water to obtain a first mixture; a first heating step of heating the first mixture to generate hydrogen; A method for generating hydrogen, comprising:

9. The method according to claim 8, wherein in the first mixing step, the hydrogen generating agent is mixed with the water using a dispenser.

10. a power generation step of supplying the hydrogen generated in the first heating step to a fuel cell to generate power and obtain water and heat; a second mixing step of mixing the water obtained in the power generating step with a hydrogen generating agent including a composition containing magnesium hydride and a water-soluble organic solvent to obtain a second mixture; a second heating step of heating the second mixture to generate hydrogen; Including, The method according to claim 8 , wherein the second heating step utilizes the heat obtained in the power generation step.