Hydrogen production method

Abstract

A hydrogen production method according to the present disclosure includes a supply step for supplying water to a hydrogen boride member containing a two-dimensional arrangement of hydrogen boride, wherein hydrogen is generated as a result of the water contacting the hydrogen boride member.

Description

Hydrogen production methods

[0001] This disclosure relates to a method for producing hydrogen. This application claims priority based on Japanese Patent Application No. 2025-009527, filed with the Japan Patent Office on January 23, 2025, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 describes a two-dimensional borohydride sheet that releases hydrogen when heated to 200°C to 350°C, while adsorbing hydrogen when water is supplied at a temperature of 0°C to 200°C.

[0003] Patent No. 7485287

[0004] However, the method described in Patent Document 1 requires repeated heating and cooling of the two-dimensional boric acid sheet in order to repeatedly release hydrogen from the sheet and adsorb hydrogen onto the sheet. Since hydrogen is not released while water is being supplied to the cooled two-dimensional boric acid sheet (while hydrogen is being adsorbed), there is a problem in that the amount of hydrogen generated per unit time is small.

[0005] In view of the circumstances described above, at least one embodiment of this disclosure aims to provide a hydrogen production method capable of increasing the amount of hydrogen produced per unit time.

[0006] To achieve the above objective, the hydrogen production method according to this disclosure includes a supply step of supplying water to a borohydride member containing a two-dimensional arrangement of borohydride molecules, wherein hydrogen is generated when the water comes into contact with the borohydride member.

[0007] According to the hydrogen production method of this disclosure, since hydrogen is generated when water comes into contact with the hydrogen boride component, it is not necessary to repeatedly heat and cool the hydrogen boride component to repeat the release of hydrogen from the hydrogen boride component and the adsorption of hydrogen onto the hydrogen boride component, and as a result, the amount of hydrogen generated per unit time can be increased.

[0008] It is a conceptual diagram for explaining a hydrogen production method according to one embodiment constituting the present disclosure. It is a conceptual diagram for explaining a hydrogen production method according to another embodiment constituting the present disclosure. It is a diagram showing an exemplary specific configuration of a hydrogen production apparatus for executing a hydrogen production method according to some embodiments constituting the present disclosure. It is a graph showing the change over time of the ion current value of hydrogen in the gas generated by supplying water to the borohydride member in the experiment of Example 1. It is a graph showing the experimental results of Example 1. It is a graph showing the experimental results of Examples 2 to 11. It is a graph showing the experimental results of Examples 1, 4, 5, and 8.

[0009] Hereinafter, a hydrogen production method according to some embodiments constituting the present disclosure will be described based on the drawings. The embodiments described below show one aspect of the present disclosure, do not limit this disclosure, and can be arbitrarily changed within the scope of the technical idea of the present disclosure.

[0010] As shown in FIG. 1, a hydrogen production method according to one embodiment among some embodiments constituting the present disclosure includes a supply step of supplying water 4 to a borohydride member 1. Note that the water 4 is not limited to liquid water and may be water vapor. The borohydride member 1 contains a two-dimensional array of borohydride represented by the chemical formula B ｍ H ｎ When hydrogen is adsorbed on the borohydride member 1, the stoichiometric ratio m:n is from 1:1 to 3:4 (for example, BH, BH ２ , BH ３ , BH ４ , B ２ H ３ , B ３ H ４ ). (m and n are not limited to integers and may be non-integers).

[0011] Water 4 supplied to the borohydride component 1 in the supply step generates hydrogen 5 upon contact with the borohydride component 1. The generated hydrogen 5 may be stored in a storage facility 6 such as a tank (storage step), or it may be transferred to a facility 7 that consumes the hydrogen 5 (transfer step). Alternatively, a portion of the generated hydrogen 5 may be transferred to the facility 7 and the remainder stored in the storage facility 6. Furthermore, the hydrogen 5' stored in the storage facility 6 may be transferred to the facility 7. Since the gas transferred to the storage facility 6 or facility 7 contains components other than hydrogen 5 (water and oxygen), a hydrogen purification device may be installed between the borohydride component 1 and the storage facility 6 or facility 7 to increase the hydrogen concentration in the gas.

[0012] In another embodiment of the hydrogen production method, a heating step may be included before the supply step, in which the borohydride member 1 is heated. The heating step is performed by a heating device 2 adding heat H to the borohydride member 1. In the heating step, hydrogen 5 is released from the borohydride member 1 as it is heated. In this embodiment, compared to embodiments that do not include the heating step (for example, the embodiment in Figure 1), water 4 comes into contact with the borohydride member 1, which contains many boron atoms not bonded to hydrogen atoms, in the supply step, so the hydrogen production reaction can be brought about more quickly. The temperature range of the borohydride member 1 heated in the heating step is 20°C to 1000°C, more preferably 125°C to 1000°C, and most preferably 150°C to 1000°C.

[0013] The supply step, which follows the heating step, is performed at a temperature higher than the temperature at which the heating step was performed. However, to avoid the need to change the temperature, it is preferable to maintain the temperature at the same level as the heating step during the supply step. When water 4 is supplied from the water supply member 3 to the borohydride member 1, hydrogen 5 is generated when the water 4 comes into contact with the borohydride member 1. If the temperature of the borohydride member 1 is below 150°C, boric acid is generated, reducing the active sites of borohydride and thus decreasing the amount of hydrogen generated. However, if water 4 is supplied to the borohydride member 1 at a temperature of 150°C to 1000°C, the generated boric acid decomposes, thus suppressing the generation of boric acid.

[0014] By removing water vapor, oxygen, and other substances from the products generated in the supply step using known methods, hydrogen can be continuously produced. This increases the amount of hydrogen produced per unit time compared to the case where the hydrogen borohydride member 1 is repeatedly heated and cooled in order to repeatedly release hydrogen from the hydrogen borohydride member 1 and adsorb hydrogen onto the hydrogen borohydride member 1.

[0015] When supplying water 4 to the borohydride component 1, the amount of water 4 supplied per gram of borohydride component 1 is preferably 0.01 ml / min to 206.4 ml / min. Under these conditions, a suitable flow rate of water 4 is supplied relative to the mass of the borohydride component 1, so the hydrogen production rate can be appropriately controlled.

[0016] The borohydride component 1 can be used in any form, for example, as a powder, a solution, supported on a carrier, or contained inside a cartridge (details are disclosed in Japanese Patent Application Publication No. 2023-30975, filed with the applicant of this disclosure) in which both ends of a porous cylindrical component are sealed with lids. This makes it possible to use the borohydride component 1 in an appropriate form in hydrogen production equipment of various configurations. As the carrier on which the borohydride component is supported, silica, alumina, zeolite, titania, magnesia, zirconia, ceria, niobia, manganese oxide, manganese carbonate, activated carbon, carbon black, etc. can be used.

[0017] Figure 3 shows non-limiting specific examples for implementing the hydrogen production methods of Figures 1 and 2. In the non-limiting specific example for implementing the manufacturing method of Figure 1, a water supply member 3, such as a pump, is connected to the housing 10 that houses the hydrogen boride member 1 via piping 12. The housing 10 is also provided with an outlet 13 for releasing the gas (gas containing hydrogen 5) inside the housing 10. In the non-limiting specific example for implementing the manufacturing method of Figure 2, in addition to the above configuration, a flow path 2a through which a fluid 11 containing heat H flows is provided inside the housing 10 as an example of a heating device 2. As an alternative example of the heating device 2, an electric heater or the like that heats the housing 10.

[0018] (Example 1) <Confirmation experiment for hydrogen generation> Under a nitrogen atmosphere, 5 g of magnesium diboride and 300 ml of ion exchange resin were mixed in 250 ml of acetonitrile and stirred for 72 hours at 30°C. The resulting mixed solution was filtered, and the solution obtained by filtration was dried at a temperature of 50°C to obtain a hydrogen boride component powder.

[0019] Using an X-ray photoelectron spectrometer (product name: JPS9010TR) manufactured by JEOL Corporation, the surface of the powder was irradiated with X-rays, and the energy of the photoelectrons generated at that time was measured to analyze the constituent elements of the powder and their electronic states. This analysis revealed that almost no photoelectron energy originating from the magnesium element constituting the raw material magnesium diboride was detected, and only the photoelectron energy originating from boron and hydrogen was detected. Therefore, it was confirmed that the powder was composed almost entirely of boron and hydrogen, that is, that a boron hydrogen component powder had been prepared. Furthermore, when the powder was observed using a transmission electron microscope (TEM) manufactured by JEOL Corporation, a film-like (sheet-like) substance was observed, confirming that the powder was a two-dimensional sheet-like substance. From the above, it was confirmed that a two-dimensional sheet-like boron hydrogen component had been manufactured.

[0020] The effectiveness of the hydrogen production method disclosed herein was confirmed by the following experiment using the above-mentioned powder. 5 mg of the above-mentioned powder was placed in the heating chamber of a heated vacuum diffuse reflectance analyzer (Heat Chamber Type-1000°C / DiffusIR, S.T. Japan Co., Ltd.) under an argon atmosphere. The powder was heated to 175°C using a heater built into the apparatus. Thirty minutes after the start of heating the powder, saturated water vapor at 5°C was supplied to the heating chamber at a flow rate of 30 ml / min. After 200 minutes from the start of heating the powder, the supply of saturated water vapor was stopped and the experiment was terminated.

[0021] During the above experiment, the ion current value of the gas flowing out of the heating chamber was measured using a mass spectrometer (BELMASS II, Microtrac-Bel Co., Ltd.) connected to the heating chamber. The change in ion current value over time during the experiment is shown in Figure 4. The ion current value on the vertical axis of Figure 4 is normalized by the argon current value. Prior to the above experiment, a blank experiment was conducted to obtain the change in hydrogen ion current value over time by adjusting the temperature inside the heating chamber to 175°C and supplying saturated steam at 5°C without containing the boron component powder inside the heating chamber. The change in hydrogen ion current value over time was obtained by subtracting the change in hydrogen ion current value obtained in the blank experiment from the change in hydrogen ion current value obtained in the above experiment, and this result is shown in Figure 4 as the change in hydrogen ion current value over time.

[0022] When saturated steam was supplied to the heating chamber 30 minutes after the start of heating the powder, the hydrogen ion current value increased, and then remained almost constant or showed a gradual upward trend until the end of the experiment. This result indicates that hydrogen is present in the gas flowing out of the heating chamber. Since the hydrogen ion current value remained almost constant for approximately 30 minutes after the start of heating the powder, the increase in the hydrogen ion current value after the start of saturated steam supply, and the subsequent almost constant or gradual upward trend in the hydrogen ion current value, is considered to indicate that hydrogen is being generated.

[0023] The results from Example 1 confirmed that hydrogen is generated while water is supplied to the powder at a temperature of 175°C. This means that the amount of hydrogen generated per unit time can be increased compared to the case where the hydrogen boric acid component is repeatedly heated and cooled in order to repeatedly release hydrogen from the component and adsorb hydrogen onto the component.

[0024] <Relationship between water supply and hydrogen production> Next, several experiments were conducted in which saturated water vapor at 5°C was supplied at different rates to the above-mentioned experiment. For each experiment, the cumulative amount of hydrogen produced while saturated water vapor was supplied was measured, and the amount of hydrogen produced was calculated from this cumulative amount and the time for which saturated water vapor was supplied. The results are shown in Figure 5. From these results, it was confirmed that hydrogen is produced at a temperature of 175°C if the water supply rate per gram of powder is in the range of 0.01 ml / min to 206.4 ml / min. Furthermore, from the viewpoint of hydrogen production, it is preferable that the water supply rate per gram of powder be between 0.59 ml / min and 8 ml / min.

[0025] (Examples 2-11) <Relationship between temperature of borohydride component and amount of hydrogen produced> Experiments in Examples 2-8 were conducted using the powder prepared in Example 1. Experiments in Examples 9 and 10 were conducted using an aqueous solution prepared by dissolving the powder prepared in Example 1 in water to a concentration of 13 g / L. Experiment in Example 11 was conducted using the powder prepared in Example 1 impregnated and supported on silica powder. However, in the experiments in Examples 2-11, unlike the experiment in Example 1 in which water vapor was continuously supplied, water was supplied to the borohydride component in a batch manner. The borohydride component used in Example 11 was prepared by adding 9 g of silica powder to 500 ml of acetonitrile in which 1 g of the powder prepared in Example 1 was dissolved, and then evaporating the acetonitrile to dryness at 50°C. The borohydride content in the borohydride compound impregnated and supported on the silica powder prepared in this way was 10% by mass.

[0026] Each of the experiments in Examples 2 to 11 was carried out using the apparatus used in Example 1. The form of the boron material used in each experiment, the mass of the boron, the temperature of the boron material when supplying water to the heating chamber, and the amount of water supplied per gram of boron material are summarized in Table 1 below.

[0027]

[0028] Based on the experimental results of Examples 2 to 11, the relationship between the temperature of the boronide component and the amount of hydrogen produced was obtained. The graph is shown in Figure 6. According to Figure 6, it was confirmed that hydrogen is produced by supplying water when the temperature of the boronide component is between 20°C and 1000°C. However, from the viewpoint of the amount of hydrogen produced, the temperature of the boronide component is preferably between 125°C and 1000°C, and more preferably between 150°C and 1000°C. Furthermore, from these results, the temperature of the boronide component while water is being supplied is not limited to being the same as the temperature of the boronide component before water is supplied; within the above temperature range, the former temperature may be higher than the latter temperature.

[0029] In the experiments of Examples 1, 4, 5, and 8, infrared radiation was irradiated onto a hydrogen boride component at multiple different times while saturated steam at 5°C was supplied to the heating chamber, and spectra were obtained. No significant time differences were observed between the multiple spectra obtained in each experiment. Therefore, based on the spectra obtained in each experiment (spectrums obtained 60 minutes after the start of saturated steam supply), the Kuberker-Munk function, that is, an index corresponding to the increment in the peak intensity of boric acid, was calculated, and the relationship between the temperature of the hydrogen boride component and this index is shown in Figure 7.

[0030] According to Figure 7, when the temperature of the boric acid component is 125°C, a relatively large amount of boric acid is produced. However, when the temperature of the boric acid component is between 150°C and 1000°C, the amount of boric acid produced is almost constant. It is generally known that boric acid decomposes above 150°C, and if the temperature of the boric acid component is above 150°C, even if boric acid is produced by the supply of water, it will decompose, thus suppressing the production of boric acid. Therefore, by supplying water under conditions where the temperature of the boric acid component is between 150°C and 1000°C, hydrogen can be produced while suppressing the production of boric acid.

[0031] The contents described in each of the above embodiments can be understood, for example, as follows:

[0032] [1] The hydrogen production method according to one aspect includes a supply step of supplying water (4) to a borohydride member (1) containing a two-dimensional array of borohydride, and hydrogen is generated by the water (4) contacting the borohydride member (1).

[0033] According to the hydrogen production method of the present disclosure, since hydrogen is generated when water contacts the borohydride member, it is not necessary to repeatedly heat and cool the borohydride member to repeatedly release hydrogen from the borohydride member and adsorb hydrogen to the borohydride member. As a result, the amount of hydrogen generated per unit time can be increased.

[0034] [2] The hydrogen production method according to another aspect is the hydrogen production method of [1], further including a heating step of heating the borohydride member (1) before the supply step, and performing the supply step at a temperature not lower than the temperature at which the heating step is performed.

[0035] According to such a method, compared with the case where the heating step is not included, water contacts the borohydride member containing many boron atoms not bonded to hydrogen atoms in the supply step, so that the hydrogen generation reaction can occur rapidly.

[0036] [3] The hydrogen production method according to still another aspect is the hydrogen production method of [1] or [2], further including a storage step of storing the generated hydrogen.

[0037] According to such a method, the hydrogen generated more than necessary can be used in the equipment where hydrogen is required.

[0038] [4] The hydrogen production method according to still another aspect is the hydrogen production method of any one of [1] to [3], further including a transfer step of transferring the generated hydrogen to equipment that consumes hydrogen.

[0039] According to such a method, the equipment for storing the generated hydrogen becomes unnecessary.

[0040] [5] The hydrogen production method according to still another aspect is the hydrogen production method of any one of [1] to [4], and the supply step is performed at a temperature of 20°C to 1000°C.

[0041] According to such a method, since hydrogen is generated when water comes into contact with the borohydride member, there is no need to repeatedly heat and cool the borohydride member in order to repeatedly release hydrogen from the borohydride member and adsorb hydrogen to the borohydride member. As a result, the amount of hydrogen generated per unit time can be increased.

[0042] [6] A hydrogen production method according to yet another aspect is the hydrogen production method according to any one of [1] to [4], wherein the supply step is performed at a temperature of 150°C to 1000°C.

[0043] When water is supplied to a borohydride member at a temperature lower than 150°C, boric acid is generated and the active sites of the borohydride decrease, so that the amount of hydrogen generated decreases. On the other hand, according to such a method, even if boric acid is generated, it decomposes with heat of 150°C or higher, so that the generation of boric acid can be suppressed.

[0044] [7] A hydrogen production method according to yet another aspect is the hydrogen production method according to any one of [1] to [6], wherein the supply amount of the water (4) per 1 g of the borohydride member (1) is 0.01 ml / min to 206.4 ml / min.

[0045] According to such a method, water with a flow rate suitable for the mass of the borohydride member is supplied, so that the hydrogen generation rate can be appropriately controlled.

[0046] [8] A hydrogen production method according to yet another aspect is the hydrogen production method according to any one of [1] to [7], wherein the borohydride member (1) is used in any of a powder form, a solution form, a form supported on a carrier, and a form accommodated inside a cartridge in which both ends of a porous cylindrical member are closed with lids.

[0047] According to such a method, it becomes possible to use a borohydride member in an appropriate form in a hydrogen production apparatus having various configurations.

[0048] 1 Borohydride member 4 Water

Claims

1. A hydrogen production method comprising a supply step of supplying water to a hydrogen boride component containing a two-dimensional arrangement of hydrogen boride, wherein hydrogen is produced when the water comes into contact with the hydrogen boride component.

2. The hydrogen production method according to claim 1, further comprising a heating step of heating the borohydride component before the supply step, and performing the supply step at a temperature equal to or higher than the temperature at which the heating step was performed.

3. A method for producing hydrogen according to claim 1 or 2, further comprising a storage step of storing the generated hydrogen.

4. The hydrogen production method according to claim 1 or 2, further comprising a transfer step of transferring the generated hydrogen to equipment that consumes hydrogen.

5. The hydrogen production method according to claim 1 or 2, wherein the supply step is performed at a temperature of 20°C to 1000°C.

6. The hydrogen production method according to claim 1 or 2, wherein the supply step is performed at a temperature of 150°C to 1000°C.

7. The hydrogen production method according to claim 1 or 2, wherein the amount of water supplied per gram of the boric acid member is 0.01 ml / min to 206.4 ml / min.

8. The hydrogen production method according to claim 1 or 2, wherein the borohydride component is used in any of the following forms: in the form of a powder, in the form of a solution, in the form supported on a carrier, or in the form contained inside a cartridge in which both ends of a porous cylindrical member are sealed with lids.

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