Chemical conversion materials

Abstract

To provide a chemical transforming member that can use light energy with high efficiency.SOLUTION: A chemical transforming member has a complex including: a light absorber that absorbs ultraviolet light; a chemical transformer where chemical transformation of substance occurs; and a wavelength converter that converts light with a wavelength of 400 nm or more to light with a wavelength of less than 400 nm.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a chemical conversion element. [Background technology]

[0002] Light (typically ultraviolet light) may be used for chemical conversion. For example, Non-Patent Document 1 proposes using a photocatalyst to convert carbon dioxide into methane and reconstruct the stable carbon dioxide molecule into fuel. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Hongwei Zhang et al., "Efficient and Selective Interplay Revealed: CO2 Reduction to CO over ZrO2 by Light with Further Reduction to Methane over NiO by Heat Converted from Light," Angewandte Chemie International Edition, January 20, 2021 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above chemical conversion, the energy of the input light may not be fully utilized.

[0005] In view of the above problems, the main object of the present invention is to provide a chemical conversion member that is excellent in the efficiency of utilizing light energy. [Means for solving the problem]

[0006] The chemical conversion member according to an embodiment of the present invention has a composite part including a light absorption part that absorbs ultraviolet light, a chemical conversion part where chemical conversion of a substance occurs, and a wavelength conversion part that converts light with a wavelength of 400 nm or more into light with a wavelength of less than 400 nm. In one embodiment, at least a part of the composite part is an adsorption part that adsorbs a substance to be chemically converted. In one embodiment, the light absorption part is composed of particles. In one embodiment, the chemical conversion part is composed of particles. In one embodiment, the chemical conversion member performs chemical conversion of carbon dioxide. In one embodiment, the light absorption part adsorbs carbon dioxide. In one embodiment, the chemical conversion member has a support, and the composite part is provided on the support. In one embodiment, the support has translucency in the visible light region (a region with a wavelength of 400 nm to 830 nm).

Advantages of the Invention

[0007] According to an embodiment of the present invention, a chemical conversion member excellent in the utilization efficiency of light energy can be provided.

Brief Description of the Drawings

[0008] [Figure 1] It is a cross-sectional view showing a simplified chemical converter according to one embodiment of the present invention. [Figure 2] It is a cross-sectional view showing an enlarged part of the chemical conversion member shown in FIG. 1.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Also, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the embodiments, but this is merely an example and does not limit the interpretation of the present invention.

[0010] FIG. 1 is a simplified cross-sectional view of a chemical converter according to one embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a portion of the chemical conversion member shown in FIG. 1. The chemical converter 100 has a cylindrical chemical conversion member 10 and a cylindrical container 50 that houses the chemical conversion member 10. The chemical conversion member 10 has a support 1 and a composite portion (composite layer) 2 provided on the surface of the support 1. The composite portion 2 includes a light absorbing portion, a chemical conversion portion, and a wavelength conversion portion. When light is incident on the composite portion 2, chemical conversion can occur using the energy of the light.

[0011] In the illustrated example, the light source 70 is disposed inside the container 50 so as to be able to irradiate light toward the chemical conversion member 10, but the light source 70 (e.g., the sun) may also be disposed outside the container 50. In this case, the container 50 is translucent. For example, it is translucent to visible light and ultraviolet light, or to visible light. A translucent container is made of, for example, glass, resin, or ceramics. As the light source 70 other than the sun, a light source with high luminous efficiency (e.g., a blue LED) can be used. Even if the wavelength of the light emitted by the light source differs from the wavelength of the light required for chemical conversion, the wavelength conversion unit can convert the light emitted by the light source into the light required for chemical conversion (ultraviolet light), so a light source with high luminous efficiency can be selected.

[0012] The support 1 shown in Figure 1 is a member having a honeycomb structure, and has a cylindrical outer wall 11 and partition walls 12. The cylindrical outer wall 11 extends in the longitudinal direction (left and right in Figure 1). The cross-sectional shape of the cylindrical outer wall 11 perpendicular to the longitudinal direction is typically circular, but may be other shapes such as polygonal. The partition walls 12 are provided inside the cylindrical outer wall 11 and form a plurality of cells 13. Specifically, each of the plurality of cells 13 is a space extending in the longitudinal direction. The cross-sectional shape of each cell 13 perpendicular to the longitudinal direction is approximately square in the illustrated example, but may be other shapes such as polygonal or circular.

[0013] The size of the support 1 (cylindrical outer wall 11 and partition wall 12) is not particularly limited as long as the support 1 can have the light transmittance described below. However, the length of the cylindrical outer wall 11 (partition wall 12) is, for example, 50 mm to 600 mm, and the outer diameter of the cylindrical outer wall 11 is, for example, 10 mm to 600 mm. The thickness of the cylindrical outer wall 11 is, for example, 30 μm or more and 1000 μm or less, preferably 50 μm or more and 500 μm or less. The thickness of the partition wall 12 is, for example, 30 μm or more and 1000 μm or less, preferably 50 μm or more and 500 μm or less. The number of cells 13 per unit area in a cross-section perpendicular to the length direction is, for example, 100 cpsi to 1200 cpsi.

[0014] The support 1 (cylindrical outer wall 11 and partition wall 12) preferably has light transmittance. For example, it has light transmittance in the visible light region and the ultraviolet light region, or in the visible light region. According to such a configuration, it can contribute to improving the utilization efficiency of light energy. Specifically, the light that was not utilized by the composite part 2 disposed in the first cell 13 can be utilized by the composite part 2 disposed in the second cell 13, and can contribute to improving the utilization efficiency of light energy. Note that the visible light region refers to, for example, a region with a wavelength of 400 nm to 830 nm.

[0015] The support having the above light transmittance is composed of, for example, an inorganic material such as alumina, zirconia, or quartz glass. According to such a form, the support can be excellent in heat resistance. As another example, the support having the above light transmittance may be composed of a resin.

[0016] As described above, the composite part 2 includes a light absorption part, a chemical conversion part, and a wavelength conversion part. The light absorption part absorbs the light incident on the chemical conversion member 10. In the chemical conversion part, chemical conversion of substances occurs. The wavelength conversion part converts the wavelength of the light incident on the chemical conversion member 10. Preferably, the wavelength conversion part converts light with a wavelength of 400 nm or more (visible light) into light with a wavelength of less than 400 nm (ultraviolet light). In one embodiment, light with a wavelength in the range of 400 nm to 600 nm is converted into light with a wavelength in the range of 350 nm to less than 400 nm. Examples of the constituent material of the wavelength conversion part include a composite of a metal cluster and a fluorescent organic dye. Specific examples of the composite of a metal cluster and a fluorescent organic dye include PtOEP (platinum octaethylporphyrin) / anthracene-encapsulated modified dendrimer, Ir(C6)2(acac) / TIPS-Nph (1,4-bis(triisopropylsilylethynyl)naphthalene). By having such a composite part, the light with the wavelength necessary for chemical conversion can be increased, and the energy of the light incident on the chemical conversion member 10 can be efficiently utilized.

[0017] The composite part (composite layer) 2 can be formed by any suitable method. The composite part (composite layer) 2 is formed, for example, by applying a coating solution containing a material constituting the light absorption part, a material constituting the chemical conversion part, a material constituting the wavelength conversion part, and a solvent to the support 1 (partition wall 12), or by immersing the support 1 (partition wall 12) in the coating solution and then removing (drying) the solvent. As the solvent, for example, water, alcohols such as ethanol and methanol are used. Here, the solvent is a concept that includes a solvent and a dispersion medium. The thickness of the composite part (composite layer) 2 is, for example, 1 μm to 100 μm, preferably 1 μm to 50 μm.

[0018] In one embodiment, the light absorption part is composed of particles, and the particle diameter (primary particle diameter) is, for example, 20 nm to 10 μm. In one embodiment, the chemical conversion part is composed of particles, and the particle diameter is, for example, 1 nm to 10 μm. The wavelength conversion part can be present on the surface of the first particles that can function as the light absorption part and / or the second particles that can function as the chemical conversion part.

[0019] The composite section may contain the material constituting the light-absorbing section, the material constituting the chemical conversion section, and the material constituting the wavelength conversion section, and the shapes and positional relationship of the light-absorbing section, the chemical conversion section, and the wavelength conversion section are not particularly limited. For example, the composite section may be formed by sequentially stacking layers constituting each section on a support. Preferably, in the composite section, the light-absorbing section and the chemical conversion section are arranged adjacent to each other.

[0020] At least a part of the composite part (composite layer) 2 is an adsorption part that adsorbs a substance to be chemically converted. For example, the light absorbing part can function as an adsorption part that adsorbs a substance to be chemically converted.

[0021] In one embodiment, the composite section 2 can function as a hydrocarbon production catalyst. For example, in the light absorbing section, electrons and holes are generated by absorbing ultraviolet light, and carbon monoxide (CO) is produced from carbon dioxide (CO2) adsorbed in the light absorbing section. Specifically, carbon dioxide (CO2) is adsorbed as hydrogen carbonate (HCO3) in the adsorption section of the light absorbing section, and this hydrogen carbonate (HCO3) is reduced by the electrons to produce carbon monoxide (CO). This carbon monoxide (CO) reacts with hydrogen (H2) in the chemical conversion section to produce methane (CH4). The conversion to methane (CH4) in the chemical conversion section can be accelerated by heat converted from visible light. For example, the chemical converter 100 may have a heating section (not shown) that heats the chemical conversion member 10.

[0022] When the composite section 2 is made to function as a hydrocarbon production catalyst, examples of the constituent material of the light absorbing section include oxides such as zirconium oxide, cerium oxide, magnesium oxide, yttrium oxide, aluminum oxide, and titanium oxide. Examples of the constituent material of the chemical converting section include metals such as nickel, ruthenium, cobalt, copper, zinc, manganese, iron, and titanium. These may be used alone or in combination of two or more.

[0023] During the above chemical conversion, the substances to be chemically converted, specifically carbon dioxide (CO2) and hydrogen (H2), are present so as to be in contact with the composite section 2. In the example shown in Figure 1, carbon dioxide (CO2) and hydrogen (H2) are circulated in the direction of the arrows. The flow of the substances to be chemically converted may be carried out in a closed system (for example, by forming a flow path using a container 50) as shown in Figure 1, or in an open system.

[0024] In another embodiment, the composite unit 2 can function as a water splitting catalyst. For example, in the light absorbing unit, electrons and holes are generated by absorbing ultraviolet light, and the holes oxidize water to generate oxygen. The electrons then reduce the protons generated in the process to generate hydrogen. Here, the chemical converting unit can function as a co-catalyst and includes a hydrogen generating unit and an oxygen generating unit.

[0025] When the composite section 2 functions as a water splitting catalyst, for example, strontium titanate (SrTiO3) is used as a constituent material of the light absorbing section. The chemical converting section includes, for example, a first converting section (hydrogen generating section) containing rhodium (Rh) and chromium oxide (Cr2O3) and a second converting section (oxygen generating section) containing cobalt oxyhydroxide (CoOOH).

[0026] During the above chemical conversion, the substance to be chemically converted, specifically water, is placed in contact with the composite part 2. For example, water may be brought into contact with the composite part 2 while flowing in the direction of the arrow in Fig. 1, or the composite part 2 (chemical conversion member 10) may be immersed in water without using the cylindrical container 50 shown in Fig. 1.

[0027] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations shown in the above-described embodiment can be replaced with configurations that are substantially the same as those shown in the above-described embodiment, that have the same effects, or that can achieve the same purpose. [Industrial Applicability]

[0028] The chemical conversion element according to the embodiment of the present invention can be suitably used for, for example, producing hydrocarbons such as methane, decomposing water, and the like. [Explanation of symbols]

[0029] 1 Support 2 Composite section (composite layer) 10 Chemical conversion materials 50 containers 70 light source 100 Chemical Converters

Claims

1. It has a composite part including a light absorption part that absorbs ultraviolet light, a chemical conversion part where chemical conversion of a substance occurs, and a wavelength conversion part that converts light with a wavelength of 400 nm or more into light with a wavelength of less than 400 nm, The chemical conversion part is composed of particles, The chemical conversion part includes a metal selected from nickel, ruthenium, cobalt, copper, zinc, manganese, iron, and titanium, or includes a first conversion part including rhodium and chromium oxide and a second conversion part including cobalt oxyhydroxide, Chemical conversion member.

2. The chemical conversion member according to claim 1, wherein at least a part of the composite part is an adsorption part that adsorbs a substance to be chemically converted.

3. The chemical conversion member according to claim 1 or 2, wherein the light absorption part is composed of particles.

4. The chemical conversion member according to claim 3, wherein the wavelength conversion part is present on the surface of the first particles that are the light absorption part and / or the second particles that are the chemical conversion part.

5. The chemical conversion member according to any one of claims 1 to 4, which performs chemical conversion of carbon dioxide.

6. The chemical conversion member according to any one of claims 1 to 5, wherein the light absorption part adsorbs carbon dioxide.

7. The chemical conversion member according to any one of claims 1 to 6, which has a support, and the composite part is provided on the support.

8. The chemical conversion member according to claim 7, wherein the support has translucency in the visible light region.

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