Hydrogen generating apparatus and hydrogen generating method

Abstract

To provide an efficient hydrogen generating apparatus.SOLUTION: The problem is solved by a hydrogen generating apparatus having a plurality of cells divided by a partition wall of the present invention. Each cell includes a light guide unit, the light guide unit is arranged so as to irradiate the partition wall with light, sunlight is supplied to the light guide unit by an optical fiber, the partition wall has a hydrogen boride sheet, and each cell is interconnected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] TECHNICAL FIELD The present invention relates to a hydrogen generating device and a hydrogen generating method. [Background technology]

[0002] Hydrogen is a secondary energy source that does not emit carbon dioxide when used and can be stored and transported. On the other hand, hydrogen has a lower energy density per volume than natural gas. Therefore, it is stored as compressed hydrogen gas in high-pressure tanks. However, high pressure is costly. Furthermore, the cost of building and maintaining a hydrogen station is higher than the cost of building and maintaining a gas station. Therefore, hydrogen vehicles that use hydrogen as energy are not as widespread as gasoline vehicles. A method using a borohydride sheet has been developed as a method for storing a large amount of hydrogen at normal pressure (Patent Documents 1-3, and Non-Patent Documents 1-2). A technology has been developed in which hydrogen is released by irradiating a borohydride sheet with ultraviolet light (Patent Document 2, and Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 074518 [Patent Document 2] JP 2019-218251 A [Patent Document 3] JP 2016-185899 A [Non-patent literature]

[0004] [Non-Patent Document 1] Nature Communications (UK) 2019, Vol. 10, p. 4880- [Non-Patent Document 2] Journal of the American Chemical Society (USA) 2017, Vol. 139, p13761-13769 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 2, hydrogen is released using an LED as a light source, but because an LED is a point light source, there are areas where the light is irradiated and areas where the light is not irradiated, making the efficiency of light irradiation of the hydrogen boride sheet poor. SUMMARY OF THE PRESENT EMBODIMENT It is therefore an object of the present invention to provide an efficient hydrogen generating apparatus. [Means for solving the problem]

[0006] The present inventors have carried out extensive research into an efficient hydrogen generation device and have surprisingly discovered that hydrogen can be efficiently extracted from a borohydride sheet by using sunlight and a light guide unit. The present invention is based on these findings. Thus, the present invention provides [1] A hydrogen generation device having a plurality of cells separated by partitions, each cell including a light guide unit, the light guide unit being arranged so as to be able to irradiate light onto the partitions, sunlight being supplied to the light guide unit by optical fibers, the partitions having borohydride sheets, and each cell being in communication with the other; [2] The hydrogen generation device according to [1], wherein the light guiding unit is a light guiding rod and / or a light guiding plate; and [3] A method for generating hydrogen using the hydrogen generation device according to [1] or [2], comprising: (1) a step of irradiating a partition wall having a borohydride sheet with sunlight supplied to a light-guiding unit by an optical fiber, thereby releasing hydrogen from the borohydride sheet; and (2) a hydrogen recovery step of recovering the hydrogen released from the borohydride sheet from each of the cells connected thereto, and taking it out from a hydrogen outlet. Regarding. Effect of the Invention

[0007] According to the hydrogen generation device and hydrogen generation method of the present invention, hydrogen can be efficiently extracted from the borohydride sheet. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the appearance of a rectangular parallelepiped embodiment of the hydrogen generation device of the present invention. [Diagram 2] 1A and 1B are a top view and a cross-sectional view, respectively, of a rectangular embodiment of a hydrogen generation device of the present invention. [Diagram 3] FIG. 1 is a perspective view of a rectangular embodiment of the hydrogen generation apparatus of the present invention. [Figure 4] FIG. 2 is a diagram showing the structure of the solar concentrating lens, optical fiber, light guiding rod, and light guiding plate in a rectangular parallelepiped embodiment of the hydrogen generation device of the present invention. [Diagram 5] FIG. 2 is a diagram showing the appearance of a cylindrical embodiment of the hydrogen generation device of the present invention. [Figure 6] 1A and 1B are a top view and a cross-sectional view, respectively, of a cylindrical embodiment of a hydrogen generation device of the present invention. [Figure 7] (A) is a three-dimensional diagram of a boron-hydrogen sheet structure composed of boron and hydrogen, and (B) is a schematic diagram of a boron-hydrogen sheet structure containing boron, hydrogen, and oxygen. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [1] Hydrogen generator The hydrogen generation device of the present invention is a hydrogen generation device having a plurality of cells separated by partitions, each cell including a light-guiding unit, the light-guiding unit being arranged so as to be able to irradiate light onto the partitions, sunlight being supplied to the light-guiding unit by optical fibers, the partitions including boron hydride sheets, and each cell being connected to each other.

[0010] 《Case》 The hydrogen generation device of the present invention has a housing (container) containing a plurality of cells. The shape of the housing is not particularly limited as long as it can contain a plurality of cells, but examples of the shape include a rectangular parallelepiped, a cuboid, a cylindrical body, and a prismatic body. For example, in the case of the rectangular parallelepiped shown in Figs. 1 to 4, rectangular parallelepiped cells including light guide units (e.g., light guide bars and light guide plates) and partition walls may be stacked as shown in Fig. 2B. In the case of the cylindrical body shown in Figs. 5 and 6, hexagonal prism cells including light guide units (e.g., light guide bars) and partition walls may be aligned in a honeycomb shape as shown in Fig. 6. The cylindrical body may include cylindrical cells, and the prismatic body may include prismatic cells or cylindrical cells. Furthermore, the rectangular parallelepiped body may include prismatic cells or cylindrical cells. The housing (container) may be provided with a handle for easy portability. In addition, a water vapor intake port may be provided to re-store hydrogen using water vapor. A structure for distributing the taken-in water vapor to each cell may also be provided.

[0011] The hydrogen generating device of the present invention is intended to recover hydrogen, but the mixture of oxygen and hydrogen can be dangerous. Therefore, the container (the housing containing the cell) may be filled with an inert gas. Examples of the inert gas include nitrogen gas and argon gas.

[0012] "cell" The hydrogen generation device of the present invention includes a plurality of cells 12 separated by partitions in a container (housing 4). The cells are not particularly limited as long as they include a light guide unit and a partition. The shape (cross-sectional shape) of the cells is also not particularly limited, and examples thereof include a rectangular parallelepiped, a cuboid, a cylinder, and a prismatic shape (for example, a triangular prism, a quadrangular prism, a pentagonal prism, a hexagonal prism, a heptagonal prism, an octagonal prism, a nonagonal prism, and a decagonal prism). The rectangular parallelepiped cell 12 shown in Fig. 2B has a rectangular cross section. A rectangular light guide plate 6 can be arranged vertically and horizontally in the center of the cross section of the rectangular parallelepiped cell, and partition walls 7 can be arranged on both sides of the light guide plate 6. In this case, although not limited thereto, it is preferable to arrange a light guide rod 5 on the upper side of the light guide plate 6. Sunlight can be introduced into the light guide plate from the light guide rod. One end of the light guide rod can be directly connected to an optical fiber. 5A and 5B has a hexagonal cross section. A light guiding rod 5 can be disposed at the center of the cross section of the hexagonal cross section of the cell, and a partition wall 7 can be disposed around the light guiding rod 5. One end of the light guiding rod can be directly connected to an optical fiber.

[0013] The number of cells in the hydrogen generating device of the present invention is not particularly limited as long as the effects of the present invention can be obtained. That is, the number of cells in which a light guide unit and a partition wall to which the light is irradiated are combined can be included in the hydrogen generating device up to the upper limit that can be physically installed. However, for example, the upper limit is 100 or less, preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less. The lower limit is also not limited, but is 1 or more, preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more. The upper and lower limits can be appropriately combined.

[0014] <Light guide unit> The light guide unit is not particularly limited as long as it is arranged to irradiate the partition with light. Specific examples of the light guide unit include a light guide rod or a light guide plate, and examples thereof include only a light guide rod, only a light guide plate, or a combination of a light guide rod and a light guide plate. These light guiding units can be used to irradiate the borohydride sheet with sunlight, thereby recovering hydrogen from the borohydride sheet. When the light guiding unit is a combination of a light guiding rod and a light guiding plate, it can be configured as shown in Fig. 4, although this is not limited thereto. A light guiding rod 5 is disposed under a window 8 of the housing, and the light guiding rod 5 is disposed on the upper edge of the light guiding plate 6, and sunlight can be introduced from the upper edge of the light guiding plate to the light guiding plate 6 using an optical fiber. When the light-guiding unit is only a light-guiding rod, although this is not limited to this, as shown in Figures 5 and 6, a light-guiding rod 5 can be placed at the center of a cylindrical or prismatic cell from above, and sunlight can be introduced into the light-guiding rod from an optical fiber.

[0015] (light guide rod) The light guide rod is not particularly limited as long as it can introduce sunlight, but ultraviolet light is necessary to recover hydrogen from the borohydride sheet, and the light guide rod has the ability to transmit ultraviolet light. Examples of the material of the light guide rod include quartz glass, optical glass, and resin. Examples of the resin include acrylic resin, polycarbonate resin, and polystyrene resin. As shown in Figures 5 and 6, when a light guiding bar 5 is placed at the center of a cylindrical or prismatic cell from above, sunlight is irradiated in all directions around the light guiding bar, so a structure in which sunlight is emitted from the entire surface of the light guiding bar is preferable. On the other hand, when sunlight is introduced from a light guiding bar to a light guiding plate as shown in Figure 4, a structure in which sunlight is introduced from below the light guiding bar to the upper side of the light guiding plate may also be used. In other words, a light guiding bar that controls the light emission direction may also be used.

[0016] The length of the light guide rod can be appropriately determined depending on the size of the cell. For example, as shown in Fig. 4, when sunlight is introduced from the light guide rod to the light guide plate, the length of the light guide rod can be determined depending on the length of the upper side of the light guide plate. Also, as shown in Figs. 5 and 6, when the light guide rod 5 is disposed at the center of a cylindrical or prismatic cell from above, the length of the light guide rod can be determined depending on the length (depth) of the cell. The diameter of the light guide rod is not particularly limited, but the upper limit is 10 mm or less, preferably 8 mm or less, and more preferably 5 mm or less. The lower limit is also not particularly limited as long as the effect of the present invention can be obtained, but is 0.1 mm or more, preferably 0.5 mm or more, and more preferably 1 mm or more. The upper and lower limits can be appropriately combined.

[0017] The shape of the light guiding rod is not particularly limited as long as the effects of the present invention can be obtained, but for example, a cylindrical or prismatic light guiding rod (for example, a triangular prism, a square prism, a pentagonal prism, a hexagonal prism, a heptagonal prism, an octagonal prism, a nonagonal prism, or a decagonal prism) can be used. As a commercially available light guiding rod, a light guiding bar (Fukumi Chemical Industry) can be used.

[0018] (light guide plate) The light guide plate is not particularly limited as long as it can introduce sunlight, but ultraviolet light is necessary to recover hydrogen from the borohydride sheet, and the light guide plate has the ability to transmit ultraviolet light. Examples of the material for the light guide plate include quartz glass, optical glass, and resin. Examples of the resin include acrylic resin, polycarbonate resin, polystyrene resin, and a resin mixture of an acrylic resin and a styrene resin. A light guide plate is a processed glass or resin plate that receives light from its end face and emits light. The light guide plate may be a one-sided light emitting plate or a two-sided light emitting plate, but is preferably a two-sided light emitting plate. The light guide plate may be an embossed panel or a dot panel. A commercially available light guide plate that can be used is a Treiteras panel (Tri-Teras Corporation).

[0019] As shown in Fig. 4, when sunlight is introduced from the light guiding rod to the light guiding plate, it is possible to introduce sunlight from below the light guiding rod to the upper side of the light guiding plate 6, and emit light from both sides of the light guiding plate 6. The sunlight emitted from the light guiding plate 6 is radiated to the boron hydride sheets of the partition walls that make up the cells, as shown in Fig. 2B, and hydrogen can be released. The size of the light guide plate can be appropriately determined according to the size of the cell. For example, as shown in Fig. 3 or 4, the length and width of the light guide plate can be determined according to the length and width of the rectangular parallelepiped cell. The thickness of the light guide plate is not particularly limited, but the upper limit is 10 mm or less, preferably 8 mm or less, and more preferably 5 mm or less. The lower limit is also not particularly limited as long as the effects of the present invention can be obtained, but is 0.1 mm or more, preferably 0.5 mm or more, and more preferably 1 mm or more. The upper and lower limits can be appropriately combined.

[0020] (Fiber optics) Sunlight is supplied to the light guide unit through the optical fiber. Optical fiber is a transmission line that transmits light to distant locations. Optical fiber generally has a triple structure consisting of a core, an outer cladding, and a coating that covers them. By making the refractive index of the core higher than that of the cladding, the structure allows light to propagate to the central core through total reflection and refraction. The core and cladding are made of quartz glass or plastic, which have very high light transmittance. The state of only the core and cladding without a coating is simply called "optical fiber." Optical fiber with the surface coated with silicone resin is called "optical fiber strand," optical fiber with nylon fiber coating is called "optical fiber core," and optical fiber core coated with high tensile fiber and outer sheath is called "optical fiber cord."

[0021] In the present invention, the shape, size (diameter), material, and structure of the optical fiber are not particularly limited, but the size (diameter) of the optical fiber is preferably 15 μm or more and 1,000 μm or less, and more preferably 20 μm or more and 800 μm or less. The transmission wavelength range of the material of the optical fiber is not particularly limited and can be appropriately selected, but is preferably from 200 nm to 2,100 nm, and more preferably from 250 nm to 800 nm.

[0022] (Solar collecting lens) In the hydrogen generation device of the present invention, although not limited thereto, sunlight can be collected by a sunlight collecting lens 10. As shown in Fig. 4, the sunlight collected by the sunlight collecting lens 10 can be transmitted by an optical fiber 11 and introduced into the light guide unit.

[0023] In the hydrogen generation device of the present invention, sunlight can be introduced using multiple condenser lenses and multiple optical fibers. Also, light from multiple condenser lenses can be transmitted through a single optical fiber having a bundle structure. Furthermore, single optical fibers having a bundle structure can be bundled together and transmitted through multiple optical fibers.

[0024] The optical fiber 11 is introduced into the hydrogen generation device from the optical fiber connection port 2 in Fig. 1 or the optical fiber connection port 2 in Fig. 5. The optical fiber introduced into the hydrogen generation device supplies sunlight to the light guide unit.

[0025] 《Bulkhead》 The cell is divided into a plurality of cells by partition walls. The shape of the partition walls can be appropriately determined according to the shape of the cell. For example, in the case of a rectangular parallelepiped cell as shown in FIG. 3, the partition walls can be rectangular in shape according to the shape of the light guide plate. In the case of a hexagonal columnar cell as shown in FIG. 6, the partition walls can be hexagonal columnar so as to surround the light guide bar. The material of the partition is not particularly limited, but examples thereof include metals (iron, etc.), alloys (stainless steel, etc.), ceramics, glass, plastics (thermoplastic resins, thermosetting resins, fiber-reinforced plastics, etc.), and porous materials. The partition may be a substrate to which a borohydride sheet is applied.

[0026] The partition wall (substrate) has a borohydride sheet. For example, the borohydride sheet can be applied to the partition wall, but is not limited thereto. The method for applying the borohydride sheet to the partition wall is not particularly limited, but can be, for example, applied as follows. A liquid in which borohydride sheet powder is dissolved in a solvent is applied to the partition wall and dried. The partition wall is impregnated with a liquid in which borohydride sheet powder is dissolved in a solvent, and the partition wall is pulled up and dried.

[0027] The distance between the partition wall and the light guide unit is not particularly limited as long as hydrogen is released. However, it is preferable to set the distance appropriately so as not to increase the hydrogen release efficiency and the cell volume. For example, the upper limit is 10 mm or less, preferably 8 mm or less, and more preferably 5 mm or less. The lower limit is also not particularly limited, but is 0.1 mm or more, preferably 0.5 mm or more, and more preferably 1 mm or more. The upper and lower limits can be combined as appropriate.

[0028] The borohydride sheet is not limited in location and form as long as it is present at the light irradiated portion. In addition to the method of applying the borohydride sheet to the partition wall, another method is to support the borohydride sheet on a transparent porous carrier and fill the gaps in the cells. For example, the carrier can be expanded alumina, alumina nanoparticles, or quartz (quartz wool, porous quartz glass). As another method, it is also possible to fill each cell with a borohydride sheet dispersed in a solvent. For example, the solvent is water or an organic solvent. The organic solvent is not particularly limited, but examples thereof include amide-based solvents, alcohol-based solvents, ester-based solvents, ketone-based solvents, nitrile-based solvents, aromatic hydrocarbon-based solvents, halogenated hydrocarbons, ethers, amides, carbonates, hydrocarbons, and nitromethane. Examples of nitrile-based solvents include acetonitrile, isobutyronitrile, and propylonitrile, and examples of alcohol-based solvents include methanol, ethanol, and propanol. The solvents are used alone or in combination of two or more.

[0029] {Hydrogen borate sheet} The borohydride sheet used in the present invention is not particularly limited as long as it contains boron and hydrogen, and any borohydride sheet used in this field can be used without any limitations. For example, an ideal boron hydride sheet consisting of only boron and hydrogen has a three-dimensional structure shown in FIG. 7(A). Some boron hydride sheets also contain oxygen. That is, a boron hydride sheet containing boron, hydrogen, and oxygen, having BHB bonds, BH bonds, and B-OH bonds shown in FIG. 7(B), and having a structure of (BH)n(BOH)m in which BH and BOH are combined, can be used. That is, a part of the hydrogen (H) in FIG. 7(A) is replaced with a hydroxyl group (OH), and the structure is BHn(OH)m (n+m=1).

[0030] The thickness of the borohydride sheet is not particularly limited, but is 0.23 nm to 0.50 nm. In the borohydride sheet, the length in at least one direction (for example, the length in the X direction or Y direction in FIG. 7A) is preferably 100 nm or more. In the structure of the present invention, if the length in at least one direction is 100 nm or more, the borohydride sheet can be effectively used as a hydrogen storage material. The size (area) of the borohydride sheet is not particularly limited, and the size of the borohydride sheet can be formed to any size depending on the method for producing the borohydride sheet.

[0031] The borohydride sheet is a substance having a crystalline structure. In addition, in the boron boride sheet, the bonding strength between the boron atoms (B) forming the hexagonal rings and between the boron atoms (B) and the hydrogen atoms (H) is strong. Therefore, even if the structure of the present invention forms a crystal (aggregate) consisting of multiple layers during production, it can be easily cleaved along the crystal planes in the same way as graphite, and separated (recovered) as a single layer two-dimensional sheet.

[0032] In addition, since the borohydride sheet absorbs only ultraviolet light, a substance that absorbs visible light may be added to the borohydride sheet in order to efficiently utilize solar energy. Suitable examples of substances that absorb visible light include cis-di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) (hereinafter also referred to as "N3"), cis-di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) bis-TBA salt (hereinafter also referred to as "N719"), cis-di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) tetra-TBA salt (hereinafter also referred to as "N712"), tri(thiocyanato)-(4,4',4'' ruthenium-based sensitizing dyes such as tris-tetrabutylammonium salt of cis-tricarboxy-2,2':6',2''-terpyridine)ruthenium (hereinafter also referred to as "N749"), mono-tetrabutylammonium salt of cis-di(thiocyanato)-(2,2'-bipyridyl-4,4'-dicarboxylic acid)(4,4'-bis(5'-hexylthio-5-(2,2'-bithienyl))bipyridyl)ruthenium(II) (hereinafter also referred to as "black dye"), and C106; and iridium-based sensitizing dyes such as tris(2-pyridylphenyl)iridium(III). Furthermore, various organic sensitizing dyes such as coumarin-based, polyene-based, cyanine-based, hemicyanine-based, thiophene-based, indoline-based, xanthene-based, carbazole-based, perylene-based, porphyrin-based, phthalocyanine-based, merocyanine-based, catechol-based, azo-based, azine-based, and squarylium-based dyes are also suitable. In addition, donor-acceptor composite sensitizing dyes that combine these sensitizing dyes may be used. The dyes may be used alone or in combination of two or more. The dyes preferably include at least one of N3, N719, N712, and C106.

[0033] [2] Hydrogen generation method The hydrogen generation method of the present invention is a method using the hydrogen generation device of the present invention, and includes the steps of (1) irradiating a partition wall having a borohydride sheet with sunlight supplied to a light guide unit by an optical fiber to release hydrogen from the borohydride sheet, and (2) recovering the hydrogen released from the borohydride sheet from each of the connected cells and taking it out from a hydrogen outlet.

[0034] <Hydrogen release process (1)> In the hydrogen releasing step (1), sunlight supplied to the light guide unit by an optical fiber is irradiated onto a partition wall having a boron boride sheet, causing hydrogen to be released from the boron boride sheet. The optical fiber may be, but is not limited to, for example, sunlight collected by a solar light collecting lens, which is then introduced and transferred. The transferred sunlight releases hydrogen from the optical fiber connection port or the boron boride sheet, enters the hydrogen generating device, and is introduced into the introduction unit. For example, when the housing shown in Figures 1 to 4 is a rectangular parallelepiped, sunlight can be irradiated from the light guide plate to the boron boride sheet included in the partition wall, causing hydrogen to be released from the boron boride sheet, as shown in Figures 2B and 3. When the housing shown in Figures 5 to 6 is a cylinder, sunlight can be irradiated from the guide rod to the boron boride sheet included in the partition wall, causing hydrogen to be released from the boron boride sheet.

[0035] <Hydrogen recovery process (2)> In the hydrogen recovery step (2), hydrogen released from the borohydride sheet is recovered from each of the connected cells and taken out from the hydrogen outlet. When the housing is a rectangular parallelepiped, as shown in Figures 2B and 3, hydrogen released from the borohydride sheet can be taken out from the hydrogen outlet 3 along the hydrogen flow 9 through the communication port 13. When the housing is a cylinder, as shown in Figure 6B, hydrogen released from the borohydride sheet can be taken out from the hydrogen outlet 3 along the hydrogen flow 9 through the communication port 13. [Industrial Applicability]

[0036] The hydrogen generating device of the present invention can be used for transporting or storing hydrogen. [Explanation of symbols]

[0037] 1. Hydrogen generator; 2···Fiber optic connection port; 3 Hydrogen outlet; 4. Housing; 5...Light guide rod; 6...Light guide plate; 7...bulkhead; 8 · · · Window; 9···Hydrogen flow; 10...Solar concentrating lens; 11···Optical fiber; 12···cell; 13···Communication port;

Claims

1. A hydrogen generation device having a plurality of cells separated by a partition, A hydrogen generating device in which each cell includes a light-guiding unit, the light-guiding unit is arranged so as to irradiate light onto the partition wall, sunlight is supplied to the light-guiding unit by an optical fiber, the partition wall has a borohydride sheet, and each cell is connected to each other.

2. The hydrogen generation apparatus according to claim 1 , wherein the light guiding unit is a light guiding rod and / or a light guiding plate.

3. A method for generating hydrogen using the hydrogen generating device according to claim 1 or 2, (1) a step of irradiating a partition wall having a borohydride sheet with sunlight supplied to a light-guiding unit through an optical fiber to release hydrogen from the borohydride sheet; (2) a hydrogen recovery step of recovering hydrogen released from the borohydride sheet from each of the connected cells and removing the hydrogen from a hydrogen outlet; A method for generating hydrogen comprising the steps of:

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