Photocatalytic decomposition device

Abstract

To provide a photocatalytic decomposition apparatus that achieves efficient supply and evaporation of water decomposed with a photocatalyst.SOLUTION: A photocatalytic decomposition apparatus 100 of the invention is a water decomposition apparatus using a photocatalyst, and includes: a vapor generation part 102 that includes a hole for sucking up water, and generates heat by absorbing light 105 supplied from a light source; and a photocatalytic decomposition part 103 where vapor generated by the vapor generation part 102 and the photocatalyst come into contact with each other, and the light supplied from the light source is irradiated to the photocatalyst.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to a photocatalytic decomposition device.

Background Art

[0002] In recent years, artificial photosynthesis systems have attracted attention as a clean energy generation method because they can synthesize compounds that become other energy carriers such as hydrogen without emitting CO2 using solar energy. As one means of continuously generating hydrogen and the like, there is a method that uses renewable energy such as sunlight and seawater that has not been effectively utilized.

[0003] As an example of such a technology, for example, there is Patent Document 1. Patent Document 1 discloses a water photocatalytic decomposition device including a casing 1 having a light transmission window 12 that transmits sunlight L, and a photocatalytic layer 5 provided on the casing 1. This photocatalytic decomposition device is installed in a floating state in an aqueous layer 9. By irradiating with sunlight L, water vapor evaporates from the aqueous layer 9, and this water vapor is introduced into the photocatalytic layer 5. In the photocatalytic layer 5, photocatalytic particles 52 are excited by sunlight L, and the introduced water vapor is decomposed into Basic water and oxygen do and the configuration is disclosed. According to the configuration of Patent Document 1, it is said that hydrogen and oxygen can be efficiently obtained by suppressing the reverse reaction, and furthermore, a water photocatalytic decomposition device that can promote the photocatalytic decomposition of water by effectively using solar energy can be provided.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In conventional artificial photosynthesis systems, when seawater is directly decomposed, chloride ions in the seawater are released as hypochlorous acid and toxic chlorine gas, which can lead to corrosion and deterioration of the equipment and environmental pollution.

[0006] Furthermore, while chloride ions can be removed by vaporizing seawater, this requires a mechanism to efficiently supply seawater to the device and efficiently vaporize it. For these reasons, there has been a need to investigate configurations that can supply and vaporize seawater even more efficiently than conventional technologies such as those described in Patent Document 1.

[0007] In view of the above circumstances, the present invention aims to provide a photocatalytic decomposition apparatus that can efficiently supply and vaporize water to be decomposed by a photocatalyst. [Means for solving the problem]

[0008] One aspect of the present invention, which solves the above problems, uses a photocatalyst A photocatalyst that decomposes water into hydrogen and oxygen. A decomposition device having a void for drawing up water, and absorbing light supplied from a light source. hand Fever And, generate steam from water. A steam generation unit, Equipped with a photocatalyst, The steam generated in the steam generation section comes into contact with the photocatalyst, and the photocatalyst is supplied with light from the light source. Ta Light is shone , decomposes the steam into hydrogen and oxygen It comprises a photocatalytic decomposition unit and A photocatalytic decomposition section is provided so as to be in contact with the surface of the housing into which light enters, and the light that has passed through the photocatalytic decomposition section is supplied to the vapor generation section. This is a photocatalytic decomposition device characterized by [the following].

[0009] A more specific configuration of the present invention is described in the claims. [Effects of the Invention]

[0010] According to the present invention, a photocatalytic decomposition apparatus can be provided that can efficiently supply and vaporize water to be decomposed by a photocatalyst.

[0011] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0012] [Figure 1A] Figure schematically showing the photocatalytic decomposition apparatus of Example 1 [Figure 1B] Figure enlarging the vapor generation section of Fig. 1A [Figure 2] Figure schematically showing the photocatalytic decomposition apparatus of Example 2 [Figure 3] Figure schematically showing the photocatalytic decomposition apparatus of Example 3 [Figure 4] Figure schematically showing the photocatalytic decomposition apparatus of Example 4

Mode for Carrying Out the Invention

[0013] Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings.

Examples

[0014] Fig. 1A is a figure schematically showing the photocatalytic decomposition apparatus of Example 1. As shown in Fig. 1A, the photocatalytic decomposition apparatus 100 of the present invention includes a vapor generation section 102 that absorbs light 105 supplied from a light source and generates heat to generate vapor 106 from water obtained from an aqueous layer 107, a photocatalytic decomposition section 103 that has a photocatalyst and causes the light 105 supplied from the light source and the vapor 106 generated by the vapor generation section 102 to react with the photocatalyst to decompose the vapor 106, and a housing 101 that houses the vapor generation section 102 and the photocatalytic decomposition section 103. In this example, the sun is used as the light source, and seawater is used as the aqueous layer 107. Hereinafter, each configuration will be described in detail.

[0015] (1) Housing The housing 101 is made of a material that transmits the light 105 incident from a light source such as the sun. (2) Vapor generation section

[0016] Fig. 1B is a figure enlarging the vapor generation section 102 of Fig. 1A. As shown in Fig. 1B, the vapor generation section 102 is made of a material having a large number of pores (pores penetrating from the upper end to the lower end of the vapor generation section 102) 120, and the aqueous layer 107 causes the capillary action of these pores 120 ThinDue to the capillary phenomenon, water can be efficiently sucked up in the direction of the black arrow in Fig. 1B. Further, the steam generation unit 102 is heated by the light 105 and can efficiently vaporize the water sucked up from the water layer 107 and remaining on the surface.

[0017] As the material constituting the steam generation unit 102, carbon-based materials such as graphite, graphene, carbon nanotubes, etc. are preferable.

[0018] Steam generation unit 102 The porosity (the volume ratio of pores in the steam generation unit 102) is preferably 10% volume or more and 90% volume or less. If the porosity is less than 10%, it becomes difficult to provide pores penetrating from the upper end to the lower end of the steam generation unit 102, and it is impossible to suck up enough water to efficiently supply water to the photocatalytic Decomposition unit 103. On the other hand, if the porosity exceeds 90%, the strength is insufficient and it becomes difficult to continuously perform water decomposition due to breakage.

[0019] (3) Photocatalytic decomposition unit 103 The photocatalytic decomposition unit 103 has a photocatalytic material and decomposes the steam generated by the steam generation unit 102 and the water obtained by cooling and liquefying the steam into hydrogen (H2) and oxygen (O2) by the light 105 and the photocatalyst.

[0020] The photocatalytic material is not particularly limited as long as it is a material that absorbs light and excites electrons. For example, TiO2, SrTiO3, SrTiO2N, BaTaO2N, NaTaO3, WO3, ZnO, Fe2O3, CuO, Ta2O5, Bi2O3, SnO2, BiVO4, Y2Ti2O5S2, etc. can be mentioned. In order to promote the reaction Photocatalytic materials the surface may be appropriately modified with a material that can serve as a cocatalyst. Representative cocatalyst materials include, for example, Pt, Ru, Rh, Au, etc. Also, the photocatalytic material may be supported by a substrate. Further, the photocatalytic material may be a mixture of powders, a compacted powder, or a sheet that functions as an anode and a cathode. Also, a photoelectrode structure in which the anode part and the cathode part are separated may be used.

[0021] The gas (product gas: H2 and O2) generated by the photocatalytic decomposition unit 103 can be recovered through the recovery port 104. It is desirable that the recovery port 104 be equipped with a mechanism, such as a Liebig condenser, that can trap excess water vapor, although this mechanism is not shown. After trapping the water vapor, the product gas is pumped 109a and discharged into piping 108 Inside It is desirable to have a mechanism that transfers the water, separates gases other than H2 and O2, exhausts the exhaust gas 110, and further separates it from H2 and O2 using a pump 109b. It is also desirable to have a mechanism that uses trapped fresh water to remove some of the salt precipitated in the steam generation unit 102.

[0022] According to the photocatalytic decomposition apparatus 100 of the above embodiment, in the vapor generation section 102 having pores 120 ,light 105 is converted into heat to turn water into steam, and the steam or the fresh water produced when the steam cools is used as a photocatalyst. Decomposition By performing water splitting in section 103, water can be split more efficiently than in conventional methods. Since the water in the water layer 107 is first vaporized before being split in the photocatalytic decomposition section 103, for example, in the case of seawater, the generation of chloride ions and hypochlorous acid can be suppressed in the photocatalytic decomposition section 103, making it possible to continuously split seawater without generating harmful or toxic substances contained in seawater.

[0023] The photocatalytic decomposition apparatus 100 of this embodiment is not limited to applications that decompose water to generate only H2 and O2. For example, it can also be used to decompose CO2 or nitrogen oxides (NOx). x It is also possible to introduce these gases and use them in the reduction reaction in the cathode section. In that case, the gas species to be reacted can be introduced into the container by providing a separate gas introduction section. In addition, it can be used for the synthesis of organic compounds such as formic acid, ethanol, methanol, and methyl. [Examples]

[0024] Figure 2 is a schematic diagram of the photocatalytic decomposition apparatus of Example 2. Figure 2 shows the housing 201 of the photocatalytic decomposition apparatus 200 and its internal structure. As shown in Figure 2, in this embodiment, a horizontally inclined inclined section 205 is provided on the upper surface of the housing 201, so that the water vapor generated in the steam generation section 202 travels along the inclined section 205, is cooled to fresh water, and is introduced into the photocatalytic decomposition section 203. The fresh water introduced into the photocatalytic decomposition section 203 is decomposed by a photocatalytic reaction, similar to the water vapor.

[0025] By using this configuration, minutes The water to be decomposed can be supplied to the photocatalytic decomposition unit 203 more efficiently than by supplying water vapor, and the entire apparatus can perform photocatalytic decomposition even more efficiently than in Example 1. [Examples]

[0026] Figure 3 is a schematic diagram of the photocatalytic decomposition apparatus of Example 3. Figure 3 shows the housing 301 of the photocatalytic decomposition apparatus 300 and its internal structure. As shown in Figure 3, in this embodiment, a black body section 305 is provided on the upper surface of the steam generation section 302, which absorbs light supplied from a light source and whose temperature rises. The black body section 305 is made of a material that absorbs more heat than the steam generation section 302. With this configuration, water from the aqueous layer is processed more efficiently. High Furthermore, the entire apparatus can perform photocatalytic decomposition even more efficiently than in Example 1. [Examples]

[0027] Figure 4 is a schematic diagram of the photocatalytic decomposition apparatus of Example 4. Figure 4 illustrates the housing 401 of the photocatalytic decomposition apparatus 400 and its internal structure. As shown in Figure 4, in this embodiment, the photocatalytic decomposition unit 403 is provided so as to be in contact with the surface of the housing 401 into which light enters. The substrate holding the catalyst in the photocatalytic decomposition unit 403 is made of a material that transmits at least infrared light. The transmitted infrared light is absorbed by the steam generation unit 402, raising the temperature of the steam generation unit 402. The ultraviolet light and visible light that do not pass through the photocatalytic decomposition unit 403 are absorbed by the photocatalytic material of the photocatalytic decomposition unit 403 and are used in the photocatalytic reaction, contributing to water splitting.

[0028] With this configuration, the light from the light source is used for heating the water and for other purposes. catalyst By separating the excitation process, heat generation and decomposition can be performed more efficiently, and the entire apparatus can perform photocatalytic decomposition even more efficiently than in Example 1.

[0029] As explained above, the present invention provides a photocatalytic decomposition apparatus that can efficiently supply and vaporize water to be decomposed by a photocatalyst.

[0030] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of Symbols]

[0031] 100, 200, 300, 400…Photocatalytic decomposition device, 101, 201, 301, 401…Housing, 102, 202, 302, 402…Steam generation unit, 103, 203, 303, 403…Photocatalytic decomposition unit, 104…Recovery port, 105 …light 106...Steam, 107...Water layer, 108...Piping, 109a,109b...Pump, 110...Exhaust gas, 120...Vacuum, 205...Inclined section, 305...Black body section.

Claims

1. A photocatalytic decomposition device that uses a photocatalyst to decompose water into hydrogen and oxygen, A steam generating unit having a void for drawing up the water, and which absorbs light supplied from a light source to generate heat and produce steam from the water, The photocatalytic decomposition unit comprises the photocatalyst described above, wherein the steam generated in the steam generation unit comes into contact with the photocatalyst, and the photocatalyst is irradiated with light supplied from the light source, thereby decomposing the steam into hydrogen and oxygen. A photocatalytic decomposition apparatus characterized in that the photocatalytic decomposition unit is provided so as to be in contact with the surface of the housing into which the light is incident, and the light that has passed through the photocatalytic decomposition unit is supplied to the vapor generation unit.

2. A photocatalytic decomposition apparatus according to claim 1, wherein the steam generation unit is in contact with the water, and the pores draw up the water by capillary action.

3. A photocatalytic decomposition apparatus according to claim 1, characterized in that the porosity of the vapor generation section is 10 volume% or more and 90 volume% or less.

4. A photocatalytic decomposition apparatus according to claim 1, characterized in that the upper surface of the steam generation section has a black body section that absorbs more heat than the steam generation section.

5. A photocatalytic decomposition apparatus according to Claim 1, characterized in that the water is seawater.

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