JP7354469B1 - hydrogen storage container - Google Patents

Abstract

An object of the present invention is to easily store and release hydrogen gas, and to easily increase the amount of hydrogen gas stored. SOLUTION: A hydrogen storage container 10 has a container for storing hydrogen gas and a hydrogen gas-soluble liquid 20 filled in the container, and the hydrogen gas-soluble liquid 20 is aprotic. Contains at least one of a polar solvent and a nonionic surfactant. [Selection diagram] Figure 1

Description

The present invention relates to hydrogen storage containers.

Patent Document 1 describes a high pressure hydrogen storage tank. When using a high-pressure hydrogen storage tank at a hydrogen station, it is stated that the pressure inside the tank is usually set at 30 to 90 MPa, and the temperature is set at about -20 to 70°C.

Patent Document 2 describes a hydrogen storage method. Hydrogen molecular compounds are formed by bringing an organic compound into contact with hydrogen gas under pressure. By storing this hydrogen molecular compound, hydrogen can be stored in a stable state even under conditions close to normal temperature and normal pressure. When releasing hydrogen gas, the hydrogen molecular compound is heated.

Japanese Patent Application Publication No. 2016-44702 International Publication No. 2004/000857

By the way, hydrogen storage containers, also called hydrogen storage tanks, are required to further increase the amount of hydrogen gas that can be stored. Generally, in order to increase the amount of hydrogen gas stored, the pressure of hydrogen gas filled into a hydrogen storage container is increased. However, increasing the pressure of hydrogen gas as in Patent Document 1 places an additional pressure load on incidental equipment and leads to an increase in work costs. In addition, it is necessary to carry out work with greater consideration to safety. Therefore, it is not easy to increase the amount of hydrogen gas stored.

Further, in the hydrogen storage method of Patent Document 2, it is necessary to hold an organic compound and hydrogen gas under pressure for a certain period of time to form a hydrogen molecular compound. Further, since the hydrogen compound is composed of a hydrogen molecular compound, it is necessary to heat the hydrogen compound in order to separate the hydrogen molecules from the hydrogen molecular compound when releasing hydrogen gas. Therefore, it has not been possible to easily store and release hydrogen gas.

The hydrogen storage container of aspect 1 includes a container for storing hydrogen gas and a hydrogen gas-soluble liquid filled in the container, and the hydrogen gas-soluble liquid is an aprotic polar solvent. , and a nonionic surfactant.

According to this configuration, the storage amount of hydrogen gas can be easily increased by dissolving hydrogen gas in at least one of the aprotic polar solvent and the nonionic surfactant in the container. . Furthermore, hydrogen gas can be easily stored and released.

Aspect 2 is the hydrogen storage container of Aspect 1, wherein the nonionic surfactant is glycerin.
Aspect 3 is the hydrogen storage container of Aspect 1 or 2, wherein the hydrogen gas-soluble liquid contains water, and when the total mass of the hydrogen gas-soluble liquid in the container is 100% by mass, The water content is less than 50% by mass. According to this configuration, since the hydrogen gas-soluble liquid contains water in the above numerical range, the amount of hydrogen gas stored can be increased compared to a hydrogen gas-soluble liquid containing 50% or more of water. The stability of soluble liquids can be improved.

Aspect 4 is the hydrogen storage container according to any one of Aspects 1 to 3, in which when the volume of the container is 100% by volume, the amount of the hydrogen gas-soluble liquid filled in the container is 10% by volume. It is not less than 100% by volume. According to this configuration, the dissolution effect is likely to be obtained when the filling amount of the hydrogen gas-soluble liquid is within the above numerical range.

Aspect 5 is the hydrogen storage container according to any one of Aspects 1 to 4, wherein the container is filled with hydrogen gas, and in the container, the hydrogen gas is applied to a pressure of 0.001 MPa or more and 20 MPa or less. I'm under pressure. According to this configuration, more hydrogen gas can be dissolved in the hydrogen gas-soluble liquid while suppressing an increase in work costs.

Aspect 6 is the hydrogen storage container according to any one of Aspects 1 to 5, in which the hydrogen gas-soluble liquid is stored in a state where the hydrogen gas concentration in the container is 99% and the hydrogen gas pressure is 1 MPa. After maintaining the pressure for more than a minute, when the pressure inside the container is brought to normal pressure, the concentration of dissolved hydrogen in the hydrogen gas-soluble liquid becomes less than 10 ppm. According to this configuration, hydrogen gas can be easily released without waste by lowering the pressure inside the container, and efficient repeated filling can be performed.

According to the hydrogen storage container of the present invention, hydrogen gas can be easily stored and released, and the amount of hydrogen gas stored can be easily increased.

FIG. 1 is a cross-sectional view of a hydrogen storage container. FIG. 2 is a schematic diagram showing a dissolution/release model between liquid and gas. FIG. 3 is a simulation three-dimensional model diagram of one hydrogen molecule and one water molecule. FIG. 4 is a simulation three-dimensional model diagram of one hydrogen molecule and two water molecules. FIG. 5 is a simulation three-dimensional model diagram of one acetylene molecule and two acetone molecules. FIG. 6 is a graph of interaction energy and dissolved amount in hydrogen and water, an acetone solution, and acetylene gas dissolved in water. FIG. 7 is a graph in which the interaction energy range calculated for hydrogen-glycerin is added to FIG. 6. FIG. 8 is a graph plotting the solubility of glycerin obtained from the experiment in FIG. FIG. 9 is a graph showing changes in hydrogen storage amount with respect to gas phase pressure in Examples and Comparative Examples.

An embodiment of a hydrogen storage container will be described.
As shown in FIG. 1, the hydrogen storage container 10 includes a cylindrical container body (hereinafter also simply referred to as a container) 11 for storing hydrogen gas, and a hydrogen gas-soluble liquid 20 filled in the container 11. and has. The shape of the container 11 is not particularly limited as long as it has a pressure-resistant shape for storing hydrogen gas. Hydrogen storage container 10 has a valve 12 connected to container 11 and a pressure gauge 13.

The details of the hydrogen storage container 10 will be described below.
<Container>
As shown in FIG. 1, the container 11 has a cylindrical peripheral wall 11a. The container 11 has a top wall 11b connected to the peripheral wall 11a at one end in the axial direction of the peripheral wall 11a, and a bottom wall 11c connected to the peripheral wall 11a at the other end. The container 11 has a cylindrical socket 11d that protrudes from the center of the top wall 11b along the axial direction of the peripheral wall 11a. The inside of the socket 11d communicates with the inside of the peripheral wall 11a, and the socket 11d functions as an opening of the container 11. A bulb 12 is attached to the socket 11d. The container 11 has a space inside the peripheral wall 11a, and this space is filled with a hydrogen gas-soluble liquid 20.

The internal volume of the hydrogen storage container 10 is the internal volume of the container 11 which forms a closed circuit when the valve 12 is closed, and the internal volume of the socket 11d from the valve body of the valve 12 to the socket 11d and the connecting pipes. , the internal volume of the pipe connecting the pressure gauge 13 to the container 11 is included.

The materials of the peripheral wall 11a, the top wall 11b, the bottom wall 11c, and the socket 11d are not particularly limited, and known materials used for pressure-resistant members can be appropriately employed. Known materials used for pressure-resistant members include metals and resins.

Specific examples of metals include light alloys such as aluminum alloys and magnesium alloys, stainless steel, and the like.
As the resin, a resin having excellent gas barrier properties against hydrogen gas and pressure resistance can be used. Specific examples of the resin include thermoplastic resins such as polyamide resins and polyolefin resins. The resin may be reinforced with fibers. That is, it may be a fiber reinforcement material. The fibers used for fiber reinforcement may include carbon fibers, glass fibers, or resin-made reinforcing fibers.

(valve)
As shown in FIG. 1, the bulb 12 is attached to the socket 11d of the container 11. The valve 12 is used to open and close the opening. Having the valve 12 allows the vessel 11 to be used as a pressure vessel. The material of the valve 12 may be metal or resin in consideration of pressure resistance and hydrogen embrittlement resistance.

(Pressure gauge)
The hydrogen storage container 10 has a pressure gauge 13 for measuring the pressure inside the container 11. This pressure gauge 13 is attached at a position where it can measure the pressure of the gas phase within the container 11. As for the type of pressure gauge 13, a pressure gauge 13 that takes pressure resistance and hydrogen embrittlement resistance into consideration can be used. Note that in the following description, pressure means gauge pressure.

Further, the hydrogen storage container 10 may include a pressure regulating valve (not shown) for adjusting the discharge pressure when discharging the gas in the container 11.
<Hydrogen gas soluble liquid>
As shown in FIG. 1, the hydrogen storage container 10 has a hydrogen gas-soluble liquid 20 filled in the container 11. As shown in FIG. Further, the hydrogen gas-soluble liquid 20 contains at least one of an aprotic polar solvent and a nonionic surfactant.

Aprotic polar solvents and nonionic surfactants have the property of easily dissolving hydrogen gas. Therefore, since the hydrogen gas-soluble liquid 20 contains at least one of an aprotic polar solvent and a nonionic surfactant, the hydrogen gas filled in the container 11 becomes the hydrogen gas-soluble liquid 20. It tends to be in a molten state.

Specific examples of aprotic polar solvents include acetone, acetonitrile, dimethyl sulfoxide (DMSO), nitromethane, 1,3-dimethyl-2-imidazolidinone, ethyl acetate, perfluorohexane, α,α,α- Trifluorotoluene, pentane, methylcyclohexane, decalin, dioxane, diisopropyl ether, t-butyl methyl ether (MTBE), 1,2-dimethoxyethane, tetrahydrofuran (THF), pyridine, methyl ethyl ketone (2-butanone) (MEK) , N-methylpyrrolidone, sulfolane, propylene carbonate, tetramethylene sulfoxide, acetylpyrrolidine, methylal or dimethoxymethane, methylnaphthodioxane, methyl formate, methyl acetate, ethyl formate, 1-formylpyrrolidine, ethylene oxide, trimethyl orthoacetate, trimethyl borate , acetal, N-nitrosopyrrolidine, methyl benzoate, propionaldehyde, methylene diacetate, ethyl butyrate, ethyl perfluorobutyrate, triethyl orthoformate, dimethylaniline, methyl n-propyl ketone (MPK), dimethylformamide, dichloromethane, Examples include propylene acetate.

Specific examples of nonionic surfactants include glycerin, glycerin fatty acid ester, acylglycerin (acylglyceride), glycerin alkanoate, fatty acid glycerin, lipophilic monofatty acid glycerin, sorbitol, sorbitan fatty acid ester, sorbitan alkanate, Fatty acid sorbitan, alkanoyl sorbitan, sucrose fatty acid ester, acyl sucrose, sugar ester, fatty acid sucrose ester, sucrose ester type, polyoxyethylene alkyl ether, alkyl polyoxyethylene ether, polyoxyethylene alkyl, alkyl poly Ethoxyethanol, POE alkyl ether, polyoxyethylene alkylphenyl ether, alkylphenyl polyoxyethylene ether, polyoxyethylene alkylphenyl, alkylphenyl polyethoxyethanol, POE alkylphenyl ether, polyoxyethylene polyoxypropylene, polyoxyalkylene block polymer Ether types such as fatty acid polyethylene glycol, polyoxyethylene alkanoate, alkylcarbonyloxypolyoxyethylene, fatty acid polyoxyethylene sorbitan, acyl polyoxyethylene sorbitan, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitan alkano Examples include ester/ether types such as ester, polyoxyethylene hexitane fatty acid ester, and POE sorbitan fatty acid ester, and alkyl glycosides such as octyl glucoside, decyl glucoside, and lauryl glucoside.

Among these, glycerin can be obtained relatively inexpensively. Some are also used as food additives, which are preferable because they can be used safely.
The above-mentioned aprotic polar solvent and nonionic surfactant may each be used singly or in an appropriate combination of two or more.

The content of at least one of the aprotic polar solvent and the nonionic surfactant in the hydrogen gas-soluble liquid 20 is not particularly limited. The content of at least one of the aprotic polar solvent and the nonionic surfactant in the hydrogen gas-soluble liquid 20 is preferably 10% by mass or more, more preferably 60% by mass or more, and Preferably it is 70% by mass or more. Moreover, it is preferably 100% by mass or less.

Although there are differences depending on the type of solvent or the amount of hydrogen gas dissolved, since hydrogen molecules enter between solvent molecules, the density of the solution decreases compared to before the hydrogen molecules enter. In other words, it is expected that the volume of the solution will expand and that bubbles will occur when it becomes a solution. It is necessary to ensure spaces in the hydrogen storage container 10 for the solution expansion and air bubbles. When creating a hydrogen gas-soluble liquid 20 in which hydrogen gas is dissolved in the hydrogen storage container 10, and then connecting the pipe to another hydrogen storage container 10 and transferring and filling the hydrogen gas-soluble liquid 20 in which hydrogen gas is dissolved, a separate process is required. There is no need to consider the voids in the hydrogen storage container 10.

The amount of hydrogen gas-soluble liquid 20 filled in hydrogen storage container 10 is not particularly limited. Assuming that the volume of the hydrogen storage container 10 is 100% by volume, the filling amount of the hydrogen gas-soluble liquid 20 in the hydrogen storage container 10 is preferably 10% by volume or more, more preferably 20% by volume or more, and Preferably it is 30% by volume or more. Moreover, it is preferably 100 volume% or less, more preferably 60 volume% or less, still more preferably 50 volume% or less, and most preferably 40 volume% or less. The filling amount of the hydrogen gas-soluble liquid 20 is determined in consideration of volume expansion due to gas dissolution in the hydrogen gas-soluble liquid 20.

When the filling amount of the hydrogen gas-soluble liquid 20 in the hydrogen storage container 10 is within the above numerical range, hydrogen gas can be easily dissolved in the hydrogen gas-soluble liquid 20.
<Other ingredients>
The hydrogen gas-soluble liquid 20 contains other components other than the aprotic polar solvent and nonionic surfactant described above, such as an oil agent, a thickener, a bactericide, an antibacterial agent, a wetting agent, a stabilizer, and a preservative. , a pH adjuster, an antioxidant, a fragrance, a coloring agent, an aprotic polar solvent, a solvent other than a nonionic surfactant, etc. may be blended. These components may be used alone or in combination of two or more.

In addition, when the hydrogen gas-soluble liquid 20 of the present invention contains other components in addition to the aprotic polar solvent and nonionic surfactant, the aprotic polar solvent and nonionic surfactant may be mixed together. The other components will be collectively referred to as the hydrogen gas-soluble liquid 20. Further, the other components are not limited to being uniformly blended as a liquid, but may be dispersed in an aprotic polar solvent or a nonionic surfactant as a particulate solid or a colloidal liquid.

(Solvents other than aprotic polar solvents and nonionic surfactants)
Specific examples of solvents other than aprotic polar solvents and nonionic surfactants include nonpolar solvents, protic polar solvents, and the like. Specific examples of nonpolar solvents include hexane, benzene, toluene, diethyl ether, and the like. Specific examples of protic polar solvents include water, ethanol, methanol, acetic acid, and the like.

When water is contained as a solvent other than the aprotic polar solvent or the nonionic surfactant, the stability of the hydrogen gas-soluble liquid 20 can be improved. However, since the hydrogen gas solubility of the hydrogen gas-soluble liquid 20 decreases, it is better to contain as little water as possible. However, when used as a so-called hydrogen increasing additive for hydrogen water, it can also be used for water with a content close to 100% by mass.

The content of the above-mentioned other components contained in the hydrogen gas-soluble liquid 20 is not particularly limited. The content of other components is preferably 0% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass, when the mass of the entire hydrogen gas-soluble liquid 20 is 100% by mass. That's all. Further, it is preferably less than 50% by mass, more preferably 30% by mass or less, and still more preferably 20% by mass or less.

In addition, when the hydrogen gas-soluble liquid 20 contains water as a solvent, it is preferable that the numerical range of the water content is less than 50% by mass of the whole.
Since the hydrogen gas soluble liquid 20 contains water in the above numerical range, the hydrogen gas soluble liquid 20 can increase the storage amount of hydrogen gas compared to the hydrogen gas soluble liquid 20 containing 50% or more of water. 20 stability can be improved.

<Uses of container>
The use of the hydrogen storage container 10 is not particularly limited, and can be used appropriately for storing and utilizing hydrogen gas.

The hydrogen storage container 10 can be used, for example, as a container for filling compositions such as pharmaceuticals, designated quasi-drugs, quasi-drugs, or cosmetics. That is, hydrogen gas may be used alone or in combination with the hydrogen gas-soluble liquid and other components in the composition. Hydrogen gas is said to have antioxidant effects, beautifying skin effects, anti-stress effects, etc., and can be used as a container filled with compositions having these effects.

The dosage form of the above composition is not particularly limited, and it can be used, for example, as an ointment, emulsion, spray, lotion, etc.
The uses of the above composition are not particularly limited, and include, for example, humectants, disinfectants, alcohol disinfectants, skin external preparations, and the like.

When the hydrogen storage container 10 is used as a container filled with the above composition, the size of the hydrogen storage container 10 may be small enough to be easily carried or portable. . It can also be applied to ordinary compressed hydrogen cylinders.

Other uses of the hydrogen storage container 10 include hydrogen vehicles that use hydrogen gas as fuel, such as fuel cell vehicles and hydrogen engine vehicles. It can be used by being mounted on a hydrogen vehicle, or it can be installed at a hydrogen station or the like to supply hydrogen gas to a hydrogen vehicle. It can also be used as a tank for power generation equipment that uses hydrogen gas as fuel.

<Action and effect>
The operation of this embodiment will be described.
As shown in FIG. 2, a molecular model for dissolution and release between a liquid solvent and a gas solute in a general container can be explained as follows. When A consisting of gaseous solute molecules A (hereinafter simply referred to as A) is filled into the gas phase portion of a container containing a certain amount of B consisting of liquid solvent molecules B (hereinafter also simply referred to as B), the liquid A gas (gas solute molecule A) having a stronger entropy than (liquid solvent molecule B) diffuses into the liquid from the interface with the liquid. When A and B are in an attractive relationship due to hydrogen bonding, etc., the energy level of the interaction that occurs between solute molecule A and solvent molecule B in a liquid is higher than when solute molecule A and solvent molecule B are in their own states. The solute molecule A is dissolved between the solvent molecules B in a stable state. As solute molecule A dissolves in solvent molecule B, the pressure of the gas phase decreases. This is considered to be because when A is dissolved in a solvent, the number of molecules of A in the gas phase, which is a factor of pressure, decreases, and the disorder, also known as entropy, decreases. In a solution where there are changes in molecular weight, intermolecular position, and molecular rotation between A and B, various stable states can exist depending on the entropy within the solution. Therefore, the dissolution in the solution becomes a gas-liquid equilibrium state that follows the pressure change of the gas A, and various stable states of A are formed in the solution from a low concentration to a high concentration of A.

The dissolution of A into B and the decrease in the pressure of the gas phase within the container can be interpreted as further increasing the amount of A filled in the container, making it possible to store more A in the container. .
In the release operation, when A in the gas phase inside the container is released outside the container and the pressure of the gas phase is reduced, molecules A are released from the liquid phase into the gas phase by the opposite mechanism of dissolution, and the gas phase When released until it reaches normal pressure, it dissolves in a vapor-liquid equilibrium state at normal pressure.

As mentioned above, the ease with which A dissolves in B and the ease with which A is released from B change depending on the balance between the energy level due to the interaction between A and B and the entropy of A. do.

Here, the structure of the hydrogen molecule, which is the gas solute molecule A, has a pair of electrons that form a covalent bond in the 1S orbit. These paired electrons act to cancel each other's spin quantum numbers, so hydrogen molecules are difficult to magnetize and hydrogen molecules are considered to be a material that is difficult to interact with the solvent. In other words, it can be said that hydrogen molecules have a low solvent affinity and therefore are difficult to dissolve in liquids.

The aprotic polar solvent and nonionic surfactant of this embodiment are polar solvents that do not have proton donating property, also called hydrogen ion donating property. Proton-donating property refers to the property of releasing hydrogen atoms as protons, and means that by releasing protons, the polarity of the molecule appears to be neutralized. By not having proton-donating properties, aprotic polar solvents and nonionic surfactants maintain the polarity of their molecules and magnetize hydrogen molecules, which are difficult to magnetize due to the polarity of a single or multiple molecules. Furthermore, it is thought that it is possible to generate an interaction with hydrogen molecules and bring it into a stable state due to a decrease in free energy. That is, aprotic polar solvents and nonionic surfactants have the property of easily attracting hydrogen molecules, and are thought to easily dissolve hydrogen molecules by attracting hydrogen molecules.

Furthermore, interactions between hydrogen molecules and aprotic polar solvents, interactions between hydrogen molecules and nonionic surfactants, interactions between aprotic polar solvents, and interactions between nonionic surfactants. are not strong bonds like ionic and covalent bonds. Therefore, it is relatively easy to release these interactions and release hydrogen molecules dissolved in at least one of the aprotic polar solvent and the nonionic surfactant into the gas phase. can.

According to the hydrogen storage container 10 of this embodiment, when the gas phase pressure of hydrogen molecules filled in the hydrogen storage container 10 is increased, at least one of the aprotic polar solvent and the nonionic surfactant Due to the interaction of hydrogen molecules, more hydrogen molecules can be dissolved in an aprotic polar solvent or a nonionic surfactant. Therefore, compared to the case where the hydrogen storage container 10 does not contain the hydrogen gas-soluble liquid 20, it is possible to increase the amount of hydrogen gas stored.

Further, according to the hydrogen storage container 10 of the present embodiment, the pressure of hydrogen gas in the hydrogen storage container 10 is approximately the same as in the case where the hydrogen storage container 10 does not contain the hydrogen gas-soluble liquid 20. If so, it becomes possible to store more hydrogen gas. Furthermore, by discharging the hydrogen gas in the hydrogen storage container 10 to the outside of the hydrogen storage container 10 and lowering the pressure, hydrogen gas in the aprotic polar solvent or nonionic surfactant can be easily removed from the hydrogen storage container 10. It becomes possible to release 10 gaseous phases.

Note that the pressure within the hydrogen storage container 10 when hydrogen gas is dissolved in an aprotic polar solvent or a nonionic surfactant is not particularly limited, and is determined by the pressure resistance performance of the hydrogen storage container 10.

The pressure inside the hydrogen storage container 10 when hydrogen gas is dissolved in an aprotic polar solvent or a nonionic surfactant is not particularly limited, but is preferably 0.001 MPa or more and 100 MPa or less, and 0.001 MPa or more and 20 MPa or less. It is more preferable that it is below. In other words, in the hydrogen storage container 10, the hydrogen gas is preferably pressurized to 0.001 MPa or more and 100 MPa or less, more preferably 0.001 MPa or more and 20 MPa or less.

Further, the temperature inside the hydrogen storage container 10 when dissolving hydrogen gas in at least one of an aprotic polar solvent and a nonionic surfactant is not particularly limited, and is equal to or higher than the melting point of the solvent in the operating pressure range. , below the boiling point. Preferably, in order to suppress the vapor pressure of the solvent, the boiling point at the operating pressure is more preferably -50° C. or less.

The hydrogen gas stored in the hydrogen storage container 10 is not particularly limited, and commercially known hydrogen gas can be used.
The effects of this embodiment will be described.

(1) The hydrogen storage container 10 includes a hydrogen storage container 10 for storing hydrogen gas and a hydrogen gas-soluble liquid 20 filled in the hydrogen storage container 10. contains at least one of an aprotic polar solvent and a nonionic surfactant.

Therefore, by dissolving hydrogen gas in at least one of an aprotic polar solvent and a nonionic surfactant in the hydrogen storage container 10, hydrogen gas can be easily stored and released. Furthermore, the amount of hydrogen gas stored can be easily increased.

(2) The nonionic surfactant is glycerin. Therefore, it can be used relatively inexpensively and safely.
(3) The hydrogen gas-soluble liquid 20 may contain water, and when the total mass of the hydrogen gas-soluble liquid 20 in the hydrogen storage container 10 is 100% by mass, the water content is 50% by mass. less than %. Therefore, when the hydrogen gas soluble liquid 20 contains water in the range of the above numerical value, the hydrogen gas soluble liquid 20 can increase the storage amount of hydrogen gas and improve hydrogen gas solubility compared to the hydrogen gas soluble liquid 20 containing 50% or more of water. The stability of the liquid 20 can be improved.

(4) If the volume of the hydrogen storage container 10 is 100% by volume, the amount of hydrogen gas-soluble liquid 20 filled in the hydrogen storage container 10 is 10% by volume or more and 100% by volume or less. When the filling amount of the hydrogen gas-soluble liquid 20 is within the above numerical range, a dissolving effect can be easily obtained.

(5) The hydrogen storage container 10 is filled with hydrogen gas, and the hydrogen gas-soluble liquid 20 has bubbles containing hydrogen gas. The hydrogen gas pressure inside the bubble becomes higher than the pressure in the other gas phase. Therefore, it is considered that the amount of hydrogen gas stored is increased.

(6) The hydrogen storage container 10 is filled with hydrogen gas, and the hydrogen gas is pressurized to 0.001 MPa or more and 20 MPa or less. Therefore, more hydrogen gas can be dissolved in the hydrogen gas-soluble liquid 20 while suppressing an increase in work costs.

(7) The hydrogen gas-soluble liquid 20 releases the gas phase in the hydrogen storage container 10 after maintaining the hydrogen gas concentration in the hydrogen storage container 10 at 99% or more and the hydrogen gas pressure at 1 MPa for 5 minutes or more. When the pressure is brought to normal pressure, the dissolved hydrogen concentration becomes less than 10 ppm. Therefore, hydrogen gas can be easily released by lowering the pressure inside the hydrogen storage container 10.

<Example of change>
This embodiment can be modified and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

- In this embodiment, the hydrogen storage container 10 had the valve 12 connected to the container 11 and the pressure gauge 13, but the hydrogen storage container 10 is not limited to this aspect. At least one of the valve 12 and the pressure gauge 13 may be omitted. For example, a pipe for supplying hydrogen gas may be attached to the socket 11d of the container 11, and the container 11 may be configured to be used as a pressure vessel with the pipe attached.

- Although in this embodiment, the container 11 had the peripheral wall 11a, the top wall 11b, the bottom wall 11c, and the socket 11d, it is not limited to this aspect. The shape of the container 11 is not particularly limited, and any known container, cylinder, tank, etc. that can store hydrogen gas can be used.

- When the hydrogen storage container 10 is filled with hydrogen gas, the hydrogen gas-soluble liquid 20 does not need to have bubbles containing hydrogen gas.
・The hydrogen gas soluble liquid becomes soluble when the hydrogen storage container 10 is brought to normal pressure after maintaining the hydrogen gas concentration in the hydrogen storage container 10 at 99% and the hydrogen gas pressure at 1 MPa for 5 minutes or more. The hydrogen concentration in the liquid may be 10 ppm or more.

Examples that further embody the above embodiment will be described below.
First, using the known solubility of gas and solution, we investigated the relationship between solubility and interaction energy between gas and liquid, which was determined by quantum chemical calculation simulation (hereinafter also referred to as simulation). Note that interaction energy means the difference in free energy at the time of stabilization with respect to the sum of free energies possessed by individual molecules.

(How to calculate interaction energy)
The simulation was performed using the plane wave pseudopotential method using the known first principles pseudopotential band calculation software "PHASE/0". The cutoff energy was set to a wave function of 25 Ryd and an electrification density of 230 Ryd. It was assumed that the absolute temperature was 0°K and that entropy could be ignored.

For the simulation, combinations of hydrogen-water (see Figures 3 and 4), acetylene-acetone (see Figure 5), and acetylene-water with known solubility were selected. Dissolution of carbon dioxide in water is also known, but since dissolution of carbon dioxide in water involves a carbonation reaction, it was excluded from this purpose. In the notation in the result graph, for example, 1 hydrogen molecule and 1 water molecule (hereinafter also referred to as "hydrogen 1 water 1"), 1 hydrogen molecule and 2 water molecules (hereinafter also referred to as "hydrogen 1 water 2") ), two acetylene molecules and one acetone molecule (hereinafter also referred to as "acetylene 2 acetone 1"), one acetylene molecule and two acetone molecules (hereinafter also referred to as "acetylene 1 acetone 2"), It is shown as one acetylene molecule and one water molecule (hereinafter also referred to as "one acetylene one water").

In addition, in FIGS. 3 to 5, "O", "C", and "H" mean oxygen atom, carbon atom, and hydrogen atom, respectively, and reflect the positions in the stabilized state, that is, the local minimum. be.

The interaction between hydrogen molecules and water molecules does not occur only between one hydrogen molecule and one water molecule. Therefore, as shown in FIG. 4, we also conducted a simulation with one hydrogen molecule and two water molecules, so that we could evaluate interactions in a more realistic state (see numbers 1 to 5 in Table 1).

Next, the interaction energy between hydrogen molecules and glycerin, dimethylformamide, dimethoxymethane, acetone, a mixture of acetone and fluorocarbons, or a mixture of acetone and water was also calculated. The above simulations were assigned numbers 6-12. The results of the simulation are shown in Table 1.

(Relationship between interaction energy and solubility)
The interaction energies calculated for hydrogen molecules and water molecules, which are numbers 1 and 2 in Table 1, and the solubility of hydrogen gas in water; similarly, the acetylene molecules and water molecules, which are numbers 3 to 5 in Table 1, Alternatively, FIG. 6 shows a plot of the correlation line between interaction energy and solubility calculated for acetylene molecules and acetone molecules.

The amount of hydrogen gas dissolved in water, and the amount of acetylene gas dissolved in acetone and water, can be found in the solubility literature ("Acetylene Technical Data", Dissolved Acetylene Association, 1976, "Chemical Engineering Handbook", Revised 6th Edition, Japan Society of Chemical Engineers). The physical property formula shown in Maruzen Publishing (1999) was used. Solubility was determined under conditions of 0.3 MPa and 20°C.

Note that the amount of solubility, also called solubility, is calculated by the following formula (1). The unit of "amount" below is mol.
Solubility (mol%) = amount of dissolved solute/(amount of dissolved solute + amount of solvent) (1).

In Figure 6, the horizontal axis represents the calculated interaction energy, and the vertical axis represents the solubility of each solvent, hydrogen gas, and acetylene gas, and it is possible that there is a correlation between solubility and interaction energy. sex was suggested.

FIG. 7 shows the interaction energy range calculated for "hydrogen 1 glycerin 2", number 6 in Table 1, added to FIG. 6.
As shown by the arrow in FIG. 7, the interaction energy calculated for "hydrogen 1 glycerin 2" is 0.21 (eV), and high dissolution of hydrogen gas in glycerin can be expected.

(Production of hydrogen storage container)
As shown in Table 2, the hydrogen storage containers 10 were filled with a liquid such as the hydrogen gas-soluble liquid 20, and the hydrogen storage containers of Example 1 and Comparative Examples 1 and 2 were produced.

In Example 1, glycerin (concentrated glycerin manufactured by Kanto Kagaku, product containing 95% by mass or more of glycerin), which is a nonionic surfactant, was used as the hydrogen gas-soluble liquid 20. In Comparative Example 1, the hydrogen storage container 10 was not filled with the hydrogen gas-soluble liquid 20 and was used empty. This simulates a normal compressed hydrogen gas charge. In Comparative Example 2, the hydrogen storage container 10 was filled with ion-exchanged water. This uses water, which is a solution with low interaction energy with hydrogen gas. The container 11 used was made of stainless steel (SUS316) and had an inner diameter of 60.9 mm, a wall thickness of 4.3 mm, and a depth of 110 mm.

(Evaluation test)
The hydrogen storage containers of Example 1 and Comparative Examples 1 and 2 were evaluated for the storage amount of hydrogen gas. The evaluation method and evaluation results are shown below.

Furthermore, FIG. 8 shows a plot of the solubility obtained from the experiment in the interaction energy region of "hydrogen 1 glycerin 2" in FIG. 7.
As shown in FIG. 8, the solubility of hydrogen in glycerin was 0.02 1 mol%, which was obtained from the experiment. This is the intersection region of the correlation line between known solubility and interaction energy shown in FIG. 7 and the area calculated from the interaction energy range for "hydrogen 1 glycerin 2". Even when this value is added, it was found that the solubility of various gases in various solutions has a strong relationship with the magnitude of their interaction energy.

Note that the hydrogen solubility in glycerin in Figure 8 is 0.02 1 mol%, which can be calculated by formula (1) as follows from the results of Figure 9, where the gas phase pressure is 0.3 MPa and the hydrogen mass based on the cavity volume is 0.41 mg/mL. It was calculated using

(i) Total hydrogen gas mass (mol) in hydrogen storage container 10 = ((mass including hydrogen storage container 10 and internal glycerin, hydrogen gas) - (mass of hydrogen storage container 10 and glycerin)) ÷ hydrogen molecular weight...・=0.066mol
(ii) Hydrogen gas mass (mol) in the gas phase inside the hydrogen storage container 10 = (inner volume of the hydrogen storage container 10 - solution volume (tentatively substituted with glycerin volume)) × gas phase pressure inside the hydrogen storage container 10 (absolute pressure here) × 273÷(273+20)÷22400...=0.0 3 7mol
(iii) Mass of dissolved hydrogen gas (mol)=mass of total hydrogen gas in hydrogen storage container 10 (mol)−mass of hydrogen gas in gas phase in hydrogen storage container 10 (mol)...0.0 2 9=0. 066-0.0 3 7
(iv) The solubility of hydrogen in glycerin is determined by the above formula (1).

0.02 1 = 0.0 2 9 ÷ (0.0 2 9 + 1.356) (1)
The conditions are that the inside and outside of the hydrogen ^storage container 10 and the glycerin temperature in FIG. (l/mol).

(Evaluation method of hydrogen gas storage amount)
The mass W0 of the empty hydrogen storage container 10 (container body 11, socket 11d, valve 12, and pressure gauge 13 connected) was measured at a room temperature of 20°C. Next, while making sure that no air bubbles remain in the hydrogen storage container 10, fill the valve 12 with water at 20°C to the top, close the valve 12, remove water outside the closed system, and fill the hydrogen storage container with water. The mass W1 of 10 was measured. The capacity of the hydrogen storage container 10 was calculated by dividing the difference between the mass W1 and the mass W0 by the density of water at 20° C., 0.9982. The volume of hydrogen storage container 10 was 324 mL.

Next, the valve 12 was opened to drain the water inside the hydrogen storage container 10 to empty the hydrogen storage container 10, and then the hydrogen storage container 10 was placed in a dryer at 50° C. to dry the inside of the hydrogen storage container 10. After drying, the hydrogen storage container 10 was left at room temperature to return to room temperature, and the mass W0 was confirmed. For each of Example 1 and Comparative Examples 1 and 2, after the containers were washed, dried, and left at room temperature, the mass W0 was confirmed. The liquids of Example 1 and Comparative Examples 1 and 2 were filled in the amounts shown in Table 2. The temperature of each liquid was 20°C. A pipe (not shown) was attached to the socket 11d, which is the opening of the hydrogen storage container 10, and nitrogen gas was introduced into the hydrogen storage container 10 through the pipe. Pressurizing the nitrogen gas to a pressure of 0.5 MPa and then evacuation were repeated five times to reduce the oxygen concentration in the hydrogen storage container 10 to 100 ppm or less. Note that the oxygen concentration in the hydrogen storage container 10 was measured using an oxygen concentration measuring device (Oxygen analyzer LC750 manufactured by TORAY).

Next, the gas introduced from the pipe was switched to commercially available hydrogen gas with a concentration of 99% or more. Pressurizing the hydrogen gas to a pressure of 0.5 MPa and then evacuation were repeated five times. The hydrogen gas concentration in the hydrogen storage container 10 was measured using a hydrogen gas concentration meter (XP-3340II Hydrogen, manufactured by Shin Cosmos Electric), and the hydrogen gas concentration was confirmed to be 99% or more. Thereafter, the hydrogen gas in the hydrogen storage container 10 was released to reduce the pressure to 0.001 MPa or less. After closing the valve 12 and removing the hydrogen storage container 10 from the pipe, the mass W2 of the hydrogen storage container 10 was measured. The mass W2 of the hydrogen storage container 10 was taken as the reference mass.

After attaching the hydrogen storage container 10 to the pipe again, the valve 12 is opened with the pressure of the hydrogen gas supplied from the pipe reaching a predetermined pressure, approximately 0.6 MPa in Example 1, and the inside of the hydrogen storage container 10 is was filled with hydrogen gas. After 5 minutes, the valve 12 was closed and the hydrogen storage container 10 filled with hydrogen gas was removed from the pipe. After that, the mass W3 of the hydrogen storage container 10 was measured.

After attaching the hydrogen storage container 10 to the pipe again, the valve 12 is opened with the pressure of the hydrogen gas supplied from the pipe reaching a predetermined pressure, approximately 1 MPa in Example 1, and hydrogen gas is introduced into the hydrogen storage container 10. Filled. After 5 minutes, the valve 12 was closed and the hydrogen storage container 10 filled with hydrogen gas was removed from the pipe. After that, the mass W4 of the hydrogen storage container 10 was measured.

After attaching the hydrogen storage container 10 to the exhaust pipe again, the valve 12 is opened with the pressure of hydrogen gas in the container at a predetermined pressure, approximately 0.6 MPa in Example 1, and hydrogen gas is discharged from inside the hydrogen storage container 10. was exhausted. After 5 minutes, the valve 12 was closed and the hydrogen storage container 10 filled with hydrogen gas was removed from the pipe. After that, the mass W5 of the hydrogen storage container 10 was measured.

After attaching the hydrogen storage container 10 to the exhaust pipe again, the valve 12 is opened with the pressure of hydrogen gas in the container at a predetermined pressure, approximately 0.3 MPa in Example 1, and hydrogen gas is discharged from inside the hydrogen storage container 10. was exhausted. After 5 minutes, the valve 12 was closed and the hydrogen storage container 10 filled with hydrogen gas was removed from the pipe. After that, the mass W6 of the hydrogen storage container 10 was measured.

After attaching the hydrogen storage container 10 to the exhaust pipe again, the valve 12 is opened with the pressure of hydrogen gas in the container at a predetermined pressure, approximately 0.001 MPa in Example 1, and hydrogen gas is discharged from inside the hydrogen storage container 10. was exhausted. After 5 minutes, the valve 12 was closed and the hydrogen storage container 10 filled with hydrogen gas was removed from the pipe. After that, the mass W7 of the hydrogen storage container 10 was measured.

Based on the mass W2 of the hydrogen storage container 10, the amount of change (unit: mg) in the mass W3 to W7 of the hydrogen storage container 10 was determined. By dividing these changes by the volume of the hydrogen storage container 10 (324 mL), the amount of change in mass per unit volume of the hydrogen storage container 10 (hereinafter also referred to as "cylinder volume-based hydrogen mass") was determined. . In addition, in Comparative Examples 1 and 2, the hydrogen mass based on the cylinder volume was determined by the same method as in Example 1 at each pressure shown in FIG. The unit of hydrogen mass based on cavity volume is mg/mL. The results are shown in FIG.

(Evaluation results of hydrogen gas storage amount)
As shown in FIG. 9, in Comparative Example 1 in which the hydrogen storage container 10 is not filled with the hydrogen gas-soluble liquid 20, as the pressure inside the hydrogen storage container 10 increases, the hydrogen mass based on the cylinder volume also increases in proportion. It was increasing. When the pressure inside the hydrogen storage container 10 was about 1 MPa, the hydrogen mass based on the cylinder volume was about 0.9 mg/mL. It was confirmed that this result complies with Boyle's law.

In Comparative Example 2, in which the hydrogen storage container 10 was filled with 24% by volume of water, as the pressure inside the hydrogen storage container 10 increased, the hydrogen mass based on the cylinder volume also increased substantially proportionally. When the pressure inside the hydrogen storage container 10 was about 1 MPa, the hydrogen mass based on the cylinder volume was about 0.6 mg/mL. Since the amount of hydrogen dissolved in water is only a few ppm, it is thought that the effective volume inside the hydrogen storage container 10 is reduced by the volume of water, and the gas is compressed in the remaining space, causing the pressure and amount of hydrogen to decrease. It was confirmed.

On the other hand, in Example 1, which was filled with 32% by volume of glycerin, as the pressure inside the hydrogen storage container 10 increased, the hydrogen mass based on the cylinder volume also increased in proportion. It was confirmed that when the pressure inside the hydrogen storage container 10 was about 1 MPa, the hydrogen mass based on the cavity volume was about 1.2 mg/mL, which was increased compared to Comparative Examples 1 and 2. Furthermore, as shown by the arrows in FIG. 9, in Example 1, the hydrogen mass based on the cavity volume when the pressure increases and the hydrogen mass based on the cavity volume when the pressure decreases change to approximately the same value. was. That is, hydrogen gas, which was dissolved in glycerin and stored in the hydrogen storage container 10 when the pressure was increased, was released without remaining in the glycerin when the pressure was decreased. Further, after returning the hydrogen storage container 10 whose mass W7 was measured to normal pressure, the glycerin in the hydrogen storage container 10 is recovered, and the dissolved hydrogen concentration, also called the residual hydrogen concentration, contained in the glycerin is measured using a gas chromatograph mass spectrometer. (also referred to as GC-MS). As a result, the dissolved hydrogen concentration was less than 10 ppm. It was confirmed that when the pressure was set to normal pressure of 0.001 MPa or less, almost all of the hydrogen gas dissolved in glycerin was released. In addition, 1-propanol, 2-propanol, 1,2-propanediol, and 1,3-propanediol, which are supposed to be produced by decomposition with hydrogen at high temperatures (500° C. or higher), were not detected.

Further, under the same conditions as in Example 1, the gas phase pressure of the hydrogen storage container 10 was set to approximately 0.6 MPa, and piping was installed in a separate container with an observation window that was maintained at the same hydrogen gas pressure of 0.6 MPa as the hydrogen storage container 10. A portion of the hydrogen gas dissolved solution in the hydrogen storage container 10 was transferred to another container with an observation window by opening the valve. When the liquid surface was observed through the observation window, many air bubbles were observed inside and on the surface of the glycerin liquid. Specifically, three bubbles with an average diameter of 12 μm were observed within a field of view of 2 mm×2 mm in glycerin. In Comparative Example 2, no bubbles were observed. Note that the method for observing bubbles is not particularly limited, but can be carried out by observing the inside of a separate container with an observation window using a microscope (VHX-700 manufactured by Keyence Corporation).

It was confirmed that Example 1 could store more hydrogen gas than Comparative Examples 1 and 2 at the same pressure. In other words, Example 1 can store the same amount of hydrogen gas as Comparative Examples 1 and 2 at a lower pressure. Example 1 has a simple configuration in which a hydrogen storage container 10 is filled with a hydrogen gas-soluble liquid 20 containing at least one of an aprotic polar solvent and a nonionic surfactant. Storage capacity can be increased more easily. Moreover, with a simple configuration in which the pressure of the hydrogen storage container 10 is increased or decreased by pressurizing or releasing the hydrogen gas in the hydrogen storage container 10, it is possible to easily store and release hydrogen gas.

10... Hydrogen storage container 11... Container body 11a... Peripheral wall 11b... Top wall 11c... Bottom wall 11d... Socket 12... Valve 13... Pressure gauge 20... Hydrogen gas soluble liquid

Claims (5)

a container for storing hydrogen gas;
and a hydrogen gas-soluble liquid filled in the container,
The hydrogen gas-soluble liquid contains at least one of an aprotic polar solvent and a nonionic surfactant,
the hydrogen gas-soluble liquid contains water,
A hydrogen storage container characterized in that the water content is less than 50% by mass when the total mass of the hydrogen gas-soluble liquid in the container is 100% by mass. a container for storing hydrogen gas;
and a hydrogen gas-soluble liquid filled in the container,
The hydrogen gas-soluble liquid contains at least one of an aprotic polar solvent and a nonionic surfactant,
The hydrogen gas-soluble liquid is dissolved when the hydrogen gas concentration in the container is maintained at 99% and the hydrogen gas pressure is maintained at 1 MPa for 5 minutes or more, and then when the inside of the container is brought to normal pressure. A hydrogen storage container characterized in that the hydrogen concentration therein is less than 10 ppm . The hydrogen storage container according to claim 1 or 2 , wherein the nonionic surfactant is glycerin. 3. The hydrogen storage container according to claim 1, wherein when the volume of the container is 100% by volume, the amount of the hydrogen gas-soluble liquid filled in the container is 10% by volume or more and 100% by volume or less. The container is filled with hydrogen gas,
The hydrogen storage container according to claim 1 or 2 , wherein the hydrogen gas is pressurized to 0.001 MPa or more and 20 MPa or less in the container.

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