Structure and reduction device

Abstract

Provided are a structure and a reduction device capable of more efficiently generating hydride ions. A structure according to an embodiment of the present invention comprises a first electrode, a second electrode, and an electrolyte. The first electrode and the second electrode are porous and allow a fluid to pass therethrough. The electrolyte is a solid disposed between the first electrode and the second electrode. The electrolyte is electrically connected to the first electrode and the second electrode. Hydride ions can move through the electrolyte.

Description

Structure and reduction device

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a structure and a reduction device.

[0002] There are solids that can generate hydride ions and allow the hydride ions to migrate. There is a demand for a technology that can generate hydride ions more efficiently from these solids.

[0003] Japanese Patent Application Laid-Open No. 2023-071811

[0004] An object of the present invention is to provide a structure and a reduction device that can generate hydride ions more efficiently.

[0005] The structure according to the embodiment includes a first electrode, a second electrode, and an electrolyte. The first electrode and the second electrode are porous and permeable to a fluid. The electrolyte is a solid provided between the first electrode and the second electrode. The electrolyte is electrically connected to the first electrode and the second electrode. The electrolyte allows hydride ions to move.

[0006] Fig. 1 is a cross-sectional view showing a structure according to a first embodiment; Fig. 2 is a cross-sectional view showing a structure according to a second embodiment; Fig. 3 is a cross-sectional view showing a structure according to a third embodiment; Fig. 4 is a cross-sectional view showing a reduction device according to an example; Fig. 5 is a cross-sectional view showing a reduction device according to an example.

[0007] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and each drawing, elements similar to those already described are designated by the same reference numerals, and detailed description will be omitted as appropriate.

[0008] First Embodiment Fig. 1 is a cross-sectional view showing a structure according to a first embodiment. As shown in Fig. 1, the structure 1 according to the first embodiment includes an electrolyte 10, a first electrode 11, and a second electrode 12. For the sake of explanation, the direction connecting the first electrode 11 and the second electrode 12 is defined as the Z direction (first direction). Directions that are perpendicular to the Z direction and orthogonal to each other are defined as the X direction and the Y direction.

[0009] The first electrode 11 and the second electrode 12 are conductive porous members. The electrolyte 10 is provided between the first electrode 11 and the second electrode 12 in the Z direction. The electrolyte 10 is solid and electrically connected to the first electrode 11 and the second electrode 12.

[0010] The fluid can pass through the first electrode 11 in the Z direction through the pores included in the first electrode 11. Similarly, the fluid can pass through the second electrode 12 in the Z direction through the pores included in the second electrode 12. In addition, the electrolyte 10 can absorb hydride ions (H － When hydride ions are generated from a fluid supplied through one of the first electrode 11 and the second electrode 12, the hydride ions move in the Z direction through the electrolyte 10 toward the other of the first electrode 11 and the second electrode 12. The fluid may be a gas or a liquid.

[0011] In the illustrated example, the first electrode 11 has a first surface 11a in contact with the electrolyte 10 and a second surface 11b opposite the first surface 11a. The second electrode 12 has a third surface 12c in contact with the electrolyte 10 and a fourth surface 12d opposite the third surface 12c. For example, a fluid containing hydrogen is supplied to the second surface 11b. The fluid passes through the pores of the first electrode 11 and moves toward the electrolyte 10 while diffusing in the X and Y directions. Another fluid is supplied to the fourth surface 12d. The fluid passes through the pores of the second electrode 12 and moves toward the electrolyte 10 while diffusing in the X and Y directions.

[0012] When a positive voltage is applied to the second electrode 12 relative to the first electrode 11, hydride ions are generated from the hydrogen-containing fluid near the interface between the electrolyte 10 and the first electrode 11. The hydride ions pass through the electrolyte 10 and move to the interface between the electrolyte 10 and the second electrode 12. The hydride ions react with another fluid supplied to the second electrode 12, and the other fluid is reduced by the hydride ions.

[0013] The material of the electrolyte 10 is arbitrary as long as hydride ions can migrate through the electrolyte 10. For example, the electrolyte 10 is a compound containing a first element and hydrogen. The first element is at least one selected from the group consisting of Ba, La, Sr, Ca, Na, Li, Co, and Ti. More preferably, the first element is at least one selected from the group consisting of Ba, Sr, and Ca. The electrolyte 10 may contain oxygen in addition to the first element and hydrogen. Furthermore, in order to increase the mobility of hydride ions, the electrolyte 10 preferably has a perovskite structure.

[0014] For example, the electrolyte 10 may be MH ２ The electrolyte 10 is an alkaline earth metal hydride having a perovskite structure, represented by the formula (M=Ca, Sr, or Ba). ２－ｘ－ｙ Sr ｘ＋ｙ LiH １－ｘ＋ｙ O ３－ｙ As a specific example, the electrolyte 10 is an oxyhydride of Ba １．８ LiH ２．８ O ０．９　 (BLHO).

[0015] The first electrode 11 and the second electrode 12 may be made of any material as long as a voltage can be applied to the first electrode 11 and the second electrode 12. For example, the first electrode 11 and the second electrode 12 include at least one selected from the group consisting of copper, aluminum, titanium, gold, silver, nickel, palladium, and chromium. The first electrode 11 and the second electrode 12 may include a compound of these metals.

[0016] As an example, the first electrode 11 and the second electrode 12 are made of a metal mesh. The first electrode 11 and the second electrode 12 include a large number of holes formed by regularly or irregularly arranging thin wires of copper, aluminum, or the like. As the metal mesh, a copper mesh (mesh: 200, thread diameter: 0.05 mm, opening size: 0.77 mm, thickness: 0.1 mm, opening ratio: 36.8%) can be used.

[0017] In another example, a film containing two or more metals is first formed. The film is formed by sputtering, chemical vapor deposition, vacuum deposition, or plating. Next, some of the metals contained in the film are removed by wet etching or dry etching. As a result, other metals remain in the film, and pores are formed in the removed portions. As a specific example, a film containing tin and at least one selected from the group consisting of gold, silver, nickel, and chromium is formed by vapor deposition. By supplying nitric acid to this film, the tin contained in the film is selectively removed, leaving a porous film.

[0018] In yet another example, a slurry containing a metal powder is formed and this slurry is impregnated into a foam such as polyurethane. The metal powder can be aluminum or titanium. The slurry is dried and then fired to remove the polyurethane. The metal contained in the slurry remains, forming pores in the removed areas.

[0019] The dimensions of each component of the structure 1 can be designed as appropriate. As an example, the thickness of the electrolyte 10 (dimension in the Z direction) is approximately 1 mm to 5 mm. The width of the electrolyte 10 (dimension in the X or Y direction) is approximately 3 mm to 100 mm. The thicknesses of the first electrode 11 and the second electrode 12 are designed to allow sufficient diffusion of the fluid in the XY plane. For example, when a copper mesh (mesh: 200, thread diameter: 0.05 mm, mesh size: 0.77 mm, thickness: 0.1 mm, aperture ratio: 36.8%) is used, the thicknesses of the first electrode 11 and the second electrode 12 are designed to be approximately 1 mm to 5 mm. It is preferable that the width of the first electrode 11 and the width of the second electrode 12 be the same as or wider than the width of the electrolyte 10.

[0020] The shape of the structure 1 when viewed from the Z direction is arbitrary. The shape may be polygonal or circular. The dimension of the structure 1 in the X direction may be the same as or different from the dimension of the structure 1 in the Y direction.

[0021] The advantages of the embodiment will be described. The electrolyte 10 can generate hydride ions. The generated hydride ions can move through the electrolyte 10. To generate hydride ions in the electrolyte 10 and move the hydride ions, it is necessary to apply a voltage to the electrolyte 10. For example, in order to apply a voltage uniformly in the XY plane with a simple structure, it is preferable to provide electrodes on both sides of the electrolyte 10. On the other hand, if a general metal film is provided as an electrode on each side of the electrolyte 10, the fluid cannot pass through the metal film, and hydride ions cannot be generated in the electrolyte 10.

[0022] In response to this problem, in the first embodiment, a first electrode 11 and a second electrode 12 are provided on both sides of the electrolyte 10, respectively. The first electrode 11 and the second electrode 12 are porous. Therefore, the fluid can pass through the first electrode 11 and the second electrode 12. Furthermore, the first electrode 11 and the second electrode 12 are electrically connected to the electrolyte 10. Therefore, a voltage can be applied to the electrolyte 10 while supplying the fluid to the electrolyte 10 through the first electrode 11 and the second electrode 12. According to the first embodiment, hydride ions can be generated in the electrolyte 10 more efficiently.

[0023] Second Embodiment Fig. 2 is a cross-sectional view showing a structure according to a second embodiment. The structure 2 according to the second embodiment shown in Fig. 2 further includes a first intermediate layer 21 and a second intermediate layer 22 compared to the structure 1 shown in Fig. 1.

[0024] The first intermediate layer 21 is provided between the electrolyte 10 and the first electrode 11 in the Z direction. The first intermediate layer 21 includes at least one selected from the group consisting of a metal oxide and a metal nitride, and is configured to allow hydrogen to permeate through the first intermediate layer 21 in the Z direction.

[0025] The second intermediate layer 22 is provided between the electrolyte 10 and the second electrode 12 in the Z direction. The second intermediate layer 22 includes at least one selected from the group consisting of a metal oxide and a metal nitride, and is configured to allow hydrogen to permeate through the second intermediate layer 22 in the Z direction.

[0026] For example, the first intermediate layer 21 and the second intermediate layer 22 contain one or more nitrides or oxides selected from the group consisting of titanium, tantalum, and silicon. Preferably, the first intermediate layer 21 and the second intermediate layer 22 contain one or more selected from the group consisting of titanium nitride, tantalum nitride, silicon oxide, and titanium nitride. The material contained in the first intermediate layer 21 may be different from the material contained in the second intermediate layer 22.

[0027] The first intermediate layer 21 and the second intermediate layer 22 are preferably not excessively thick so that hydrogen can permeate through the first intermediate layer 21 and the second intermediate layer 22. For example, the thickness of the first intermediate layer 21 and the second intermediate layer 22 is designed to be 500 nm or less.

[0028] The first intermediate layer 21 may be conductive, semiconductive, or insulating. If the first intermediate layer 21 is insulating, the thickness of the first intermediate layer 21 is preferably small so that the electrolyte 10 and the first electrode 11 can be electrically connected. Similarly, if the second intermediate layer 22 is insulating, the thickness of the second intermediate layer 22 is preferably small so that the electrolyte 10 and the second electrode 12 can be electrically connected. If the first intermediate layer 21 or the second intermediate layer 22 is insulating, the thickness thereof is preferably 10 nm or less.

[0029] Materials capable of hydride ion conductivity have high reducing properties. Therefore, if the electrolyte 10 is in direct contact with the first electrode 11 or the second electrode 12, the material contained in the first electrode 11 or the second electrode 12 may be reduced, possibly deteriorating the characteristics of the first electrode 11 or the second electrode 12. According to the second embodiment, a first intermediate layer 21 is provided between the electrolyte 10 and the first electrode 11, and a second intermediate layer 22 is provided between the electrolyte 10 and the second electrode 12. The first intermediate layer 21 and the second intermediate layer 22 contain a metal oxide or metal nitride that is less reactive with the electrolyte 10. The provision of the first intermediate layer 21 and the second intermediate layer 22 can suppress the reduction of the first electrode 11 and the second electrode 12. Furthermore, the first intermediate layer 21 and the second intermediate layer 22 are permeable to hydrogen. Therefore, even when the first intermediate layer 21 and the second intermediate layer 22 are provided, hydrogen can be supplied to the electrolyte 10 from the first electrode 11 or the second electrode 12.

[0030] 3 is a cross-sectional view showing a structure according to a third embodiment. Compared to the structure 2 shown in FIG. 2, the structure 3 according to the third embodiment shown in FIG. 3 further includes an insulator 30, a first conductive member 31, a second conductive member 32, a pipe 41 a, a pipe 41 b, a pipe 42 a, and a pipe 42 b.

[0031] The electrolyte 10, the first electrode 11, the second electrode 12, the first intermediate layer 21, and the second intermediate layer 22 are located between the first conductive member 31 and the second conductive member 32 in the Z direction. The first electrode 11 and the first intermediate layer 21 are located between the electrolyte 10 and the first conductive member 31. The second electrode 12 and the second intermediate layer 22 are located between the electrolyte 10 and the second conductive member 32. The first conductive member 31 is conductive and is electrically connected to the first electrode 11. The second conductive member 32 is conductive and is electrically connected to the second electrode 12.

[0032] As long as the first conductive member 31 and the second conductive member 32 are conductive, the material of the first conductive member 31 and the material of the second conductive member 32 are arbitrary. For example, the first conductive member 31 and the second conductive member 32 include at least one selected from the group consisting of copper and aluminum.

[0033] The insulator 30 is provided around the electrolyte 10, the first electrode 11, the second electrode 12, the first intermediate layer 21, the second intermediate layer 22, a portion of the first conductive member 31, and a portion of the second conductive member 32 in the XY plane perpendicular to the Z direction. The material of the insulator 30 is arbitrary as long as the insulator 30 has insulating properties and the reactivity between the electrolyte 10 and the insulator 30 is low. For example, the insulator 30 includes aluminum oxide or stainless steel.

[0034] The pipes 41a and 41b are provided inside the first conductive member 31. The pipes 41a and 41b are examples of first pipes. One end of the pipe 41a and one end of the pipe 41b are connected to the first electrode 11. When a fluid is supplied from the pipe 41a or the pipe 41b, the fluid flows from the pipe 41a or the pipe 41b to the hole of the first electrode 11. For example, the fluid is supplied from one of the pipes 41a and 41b to the first electrode 11. The fluid supplied to the first electrode 11 is discharged from the other of the pipes 41a and 41b.

[0035] The pipes 42a and 42b are provided inside the second conductive member 32. The pipes 42a and 42b are examples of second pipes. One end of the pipe 42a and one end of the pipe 42b are connected to the second electrode 12. When a fluid is supplied from the pipe 42a or the pipe 42b, the fluid flows from the pipe 42a or the pipe 42b to the hole in the second electrode 12. For example, the fluid is supplied from one of the pipes 42a and 42b to the second electrode 12. The fluid supplied to the second electrode 12 is discharged from the other of the pipes 42a and 42b.

[0036] Materials capable of hydride ion conductivity are deliquescent. When the electrolyte 10 comes into contact with air, the electrolyte 10 may absorb moisture in the air and dissolve. By covering the electrolyte 10 on the X-Y plane with the insulator 30, the electrolyte 10 is less likely to come into contact with air. According to the third embodiment, deliquescence of the electrolyte 10 can be suppressed.

[0037] Furthermore, by providing the first conductive member 31 and the second conductive member 32, a voltage can be applied more uniformly to the first electrode 11 and the second electrode 12 in the XY plane. Even when the first conductive member 31 is provided, by providing a pipe 41a or a pipe 41b connected to the first electrode 11, a fluid can be supplied to the first electrode 11. Similarly, even when the second conductive member 32 is provided, by providing a pipe 42a or a pipe 42b connected to the second electrode 12, a fluid can be supplied to the second electrode 12.

[0038] The structures according to the above-described embodiments can be used as reduction devices that cause a reduction reaction in any fluid.

[0039] 4 and 5 are cross-sectional views showing a reduction device according to an embodiment. In the reduction device 4 shown in FIG. 4, ammonia is generated using hydride ions. First, the electrolyte 10, the first electrode 11, and the second electrode 12 are heated to a temperature at which hydride ions can be generated. For example, when the electrolyte 10 is Ba, １．８ LiH ２．８ O ０．９　 When the electrolyte 10 contains (BLHO), the electrolyte 10, the first electrode 11, and the second electrode 12 are heated to approximately 300° C. to 340° C. Furthermore, a positive voltage is applied to the second conductive member 32 with respect to the first conductive member 31 by the power source 60.

[0040] The pipe 41a is connected to a gas source 51a. Hydrogen (H ２ ) gas (an example of a first fluid) is supplied to the pipe 41b. The pipe 41b is connected to an exhaust device 51b. The hydrogen gas passes through the first electrode 11 and is exhausted from the pipe 41b. The hydrogen contained in the gas permeates the first intermediate layer 21 and moves to the electrolyte 10. The electrolyte 10 takes in hydrogen molecules and generates hydride ions. The reaction at this time can be expressed by the following formula: H ２ +2e － -> 2H －

[0041] The pipe 42a is connected to a gas source 52a. Nitrogen (N ２) gas (an example of a second fluid) is supplied to the second electrode 12. The pipe 42b is connected to an exhaust device 52b. The nitrogen gas passes through the second electrode 12 and is exhausted from the pipe 42b. The nitrogen contained in the gas permeates the second intermediate layer 22 and moves to the electrolyte 10. In the electrolyte 10, the nitrogen reacts with hydride ions to produce methane. This reaction can be expressed by the following formula: N ２ +6H － -> 2NH ３ +3e －

[0042] 5 , hydrogen is produced from hydrocarbons. First, similar to the reduction device 4, the electrolyte 10 is heated to approximately 300°C to 340°C. Furthermore, a power source 60 applies a positive voltage to the second conductive member 32 relative to the first conductive member 31.

[0043] Oxygen (O ２ ) gas is supplied to the second electrode 12 through the pipe 42a. At the same time, methylcyclohexane (MCH) is supplied from the gas source 52a to the second electrode 12 through the pipe 42a. In the electrolyte 10, MCH is decomposed and oxygen reacts with carbon. This reaction can be expressed by the following formula. As a result, carbon dioxide (CO ２ ) is discharged from the pipe 42b, and hydrogen (H ２ ) is discharged. ７ H １４ +70 ２ +e － -> 7CO ２ +2H － 2H -> H ２ +2e －

[0044] As used herein, "or" indicates that "at least one or more" of the items listed in the sentence may be employed.

[0045] Embodiments of the present invention include the following features: (Feature 1) A structure comprising: first and second electrodes, each porous and permeable to a fluid; a solid electrolyte provided between the first and second electrodes, electrically connected to the first and second electrodes, and allowing hydride ions to move; a first intermediate layer provided between the first electrode and the electrolyte, the first intermediate layer containing at least one selected from the group consisting of a metal oxide and a metal nitride, and allowing hydrogen to permeate; a second intermediate layer provided between the second electrode and the electrolyte, the second intermediate layer containing at least one selected from the group, and allowing hydrogen to permeate; and an insulator provided around the electrolyte on a plane perpendicular to a first direction connecting the first and second electrodes. (Feature 2) The structure according to Feature 1, further comprising: a first pipe connected to the first electrode; and a second pipe connected to the second electrode. (Feature 3) The structure according to Feature 2, further comprising: a first conductive member electrically connected to the first electrode; and a second conductive member electrically connected to the second electrode, wherein the first electrode, the second electrode, and the electrolyte are located between the first conductive member and the second conductive member, the first pipe is provided in the first conductive member, and the second pipe is provided in the second conductive member. (Feature 4) The structure according to any one of Features 1 to 3, wherein the electrolyte includes a compound consisting of a first element and hydrogen, and the first element is at least one selected from the group consisting of Ba, La, Sr, Ca, Na, Li, Co, and Ti. (Feature 5) A reduction device including the structure according to any one of Features 1 to 4, comprising: applying a voltage to one of the first electrode and the second electrode relative to the other of the first electrode and the second electrode; supplying a first fluid containing hydrogen to the electrolyte through the first electrode; supplying a second fluid to the electrolyte through the second electrode; and reacting hydride ions generated from the first fluid with the second fluid.

[0046] According to the embodiments described above, a structure capable of generating hydride ions more efficiently is provided, and according to the examples, a reduction device capable of efficiently reducing any fluid is provided.

[0047] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other.

Claims

1. A structure comprising: first and second electrodes that are porous and permeable to a fluid; a solid electrolyte disposed between the first and second electrodes, electrically connected to the first and second electrodes, and allowing hydride ions to move; a first intermediate layer disposed between the first electrode and the electrolyte, comprising at least one selected from the group consisting of metal oxides and metal nitrides, and allowing hydrogen to permeate; a second intermediate layer disposed between the second electrode and the electrolyte, comprising at least one selected from the group, and allowing hydrogen to permeate; and an insulator disposed around the electrolyte on a plane perpendicular to a first direction connecting the first and second electrodes.

2. The structure of claim 1, further comprising: a first pipe connected to said first electrode; and a second pipe connected to said second electrode.

3. The structure of claim 2, further comprising: a first conductive member electrically connected to the first electrode; and a second conductive member electrically connected to the second electrode, wherein the first electrode, the second electrode, and the electrolyte are located between the first conductive member and the second conductive member, the first piping is provided within the first conductive member, and the second piping is provided within the second conductive member.

4. The structure of claim 1, wherein the electrolyte contains a compound consisting of a first element and hydrogen, and the first element is at least one selected from the group consisting of Ba, La, Sr, Ca, Na, Li, Co, and Ti.

5. A reduction device comprising the structure according to any one of claims 1 to 4, comprising: applying a voltage to one of the first electrode and the second electrode relative to the other of the first electrode and the second electrode; supplying a first fluid containing hydrogen to the electrolyte through the first electrode; supplying a second fluid to the electrolyte through the second electrode; and reacting hydride ions generated from the first fluid with the second fluid.

Images