Methane reactor

Abstract

To provide a methane reactor that allows methane and a chlorine dioxide-based material to chemically react with each other efficiently.SOLUTION: A methane reactor allows methane and a chlorine dioxide-based material to chemically react with each other in solvent to oxide methane, where the methane reactor comprises: a first dissolving part which dissolves chlorine dioxide-based material as a first solute into the solvent; a second dissolving part which is at a position apart from the first dissolving part, and dissolves the methane as a second solute into the solvent, in which a vapor phase of the methane is formed separate from the first dissolving part in the second dissolving part; and a light irradiation part which is at a position apart from the first dissolving part and the second dissolving part, and irradiates mixture containing the first solute and the second solute with light from the light source.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001] The present invention relates to a methane reactor. [Background technology]

[0002] Methods for using light to promote chemical reactions of materials dissolved in liquid are known in various fields. For example, Patent Document 1 describes a technique for decomposing dioxins by mixing and stirring dioxins with alcohol and irradiating the mixture with ultraviolet light (UV250nm) from a low-pressure mercury lamp. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-068227 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have conducted extensive research into the chemical reaction that occurs when methane and a chlorine oxide-based material are used, and have investigated a highly efficient methane reaction device that is suitable for this chemical reaction.

[0005] This section explains why we investigated a methane reactor. For example, methane gas, which is produced in large quantities from food waste and livestock excrement, is known as a greenhouse gas that causes global warming. If released directly into the atmosphere, its global warming potential is said to be 25 times that of carbon dioxide. Even if methane gas is burned before being released, a large amount of carbon dioxide will be released into the atmosphere. Furthermore, methane gas is a gas at room temperature and pressure, but transporting it as a gas is inefficient and difficult to store. Immobilizing methane gas reduces greenhouse gas emissions, improves its transport efficiency and storage ease, and contributes to global warming countermeasures.

[0006] In addition, when chlorine oxide-based materials are used as the substance to react with methane, it is expected that the methane can be immobilized and converted into industrially useful substances. The profits that can be gained by converting methane into industrially useful substances and providing them to the market can attract investment in the introduction of equipment for immobilizing methane. In other words, methane immobilization can be a viable business.

[0007] The present invention aims to provide a methane reactor that efficiently chemically reacts methane with a chlorine oxide-based material. Providing a methane reactor and using the provided methane reactor to fix methane will contribute to achieving Goal 13 of the United Nations' Sustainable Development Goals (SDGs), which is to "take urgent action to combat climate change and its impacts." [Means for solving the problem]

[0008] The methane reaction apparatus of the present invention is a methane reaction apparatus that oxidizes methane by chemically reacting methane with a chlorine oxide-based material in a solvent, and the methane reaction apparatus comprises: a first dissolving section for dissolving a chlorine oxide-based material as a first solute in the solvent; a second dissolution zone located at a position distant from the first dissolution zone and dissolving the methane as a second solute in the solvent, wherein a gas phase of the methane is formed in the second dissolution zone separately from the first dissolution zone; a light irradiation unit that is located away from the first dissolution unit and the second dissolution unit and that irradiates light from a light source onto a mixed solution containing the first solute and the second solute; Equipped with.

[0009] The inventors' background in devising the methane reaction apparatus will be explained below. Methane dissolves in fluorous solvents. Chlorine oxide-based materials are easily soluble in solvents such as water and aqueous hydrogen chloride solutions. During the dissolution process of a chlorine oxide-based material (e.g., sodium chlorite), chlorine dioxide (chlorine dioxide radicals) is generated as a chlorine oxide-based material. This chlorine dioxide is also easily dissolved in fluorous solvents. Therefore, by using both a solvent that dissolves the chlorine oxide-based material and a fluorous solvent, both methane and the chlorine oxide-based material can be dissolved in the solvent. Then, as will be described in detail later, a mixed solution in which both methane and the chlorine oxide-based material are dissolved in the solvent is prepared, and the mixed solution in a container is irradiated with light to generate chlorine radicals, which then oxidize the methane. The oxidized methane is ultimately converted into industrially useful substances, namely, methanol and formic acid.

[0010] In order to efficiently chemically react a mixed liquid containing methane and a chlorine oxide-based material in a container, it is conceivable that the chlorine oxide-based material in the mixed liquid should be at a high concentration. However, as a result of intensive research by the present inventors, the following has been discovered.

[0011] Inside the container, there is a gas phase containing methane gas that did not completely dissolve in the container, or methane gas that was once dissolved but then vapor-deposited and re-gasified. On the other hand, if the chlorine oxide-based material is made highly concentrated, there is a risk that the gaseous chlorine oxide-based material that does not completely dissolve in the solvent will be mixed into the methane gas phase. When light energy is irradiated onto the gas phase containing the gasified chlorine oxide-based material and methane gas, there is a high risk of abnormal reactions, such as fires or explosions, triggered by the application of light energy. Therefore, in consideration of safely carrying out the chemical reaction, there is a limit to how highly concentrated the chlorine oxide-based material can be.

[0012] To address this issue, the inventors devised a configuration in which the first and second dissolving sections are located at separate positions, and the methane gas phase formed in the second dissolving section is separated from the first dissolving section. In the methane reaction apparatus, the first and second dissolving sections are located at separate positions, and the methane gas phase formed in the second dissolving section is separated from the first dissolving section via a solvent. This effectively prevents the gaseous (including mist-like) chlorine oxide material generated in the first dissolving section from mixing with the methane gas phase generated in the second dissolving section. As long as the chlorine oxide material and methane are not mixed in the gas phase, the risk of abnormal reactions of methane gas does not increase even if the chlorine oxide material is highly concentrated. Therefore, by increasing the concentration of the chlorine oxide material, the chlorine oxide material can be efficiently chemically reacted with methane. As will be described in detail in the detailed description of the preferred embodiment, sodium chlorite (NaClO), a precursor of chlorine dioxide that generates chlorine radicals, is supplied as the chlorine oxide material supplied in the first dissolving section. The chlorine dioxide precursor is a reactant for obtaining chlorine dioxide through a chemical reaction. However, chlorine dioxide itself may be supplied as the chlorine oxide-based material supplied to the first dissolution zone.

[0013] In the methane reaction apparatus, the light irradiation unit is also located away from the first and second melting units. When the light irradiation unit is located away from the first and second melting units, the light energy of the light irradiation unit is not applied to the gas phase of the first melting unit where the chlorine oxide-based material is present or the gas phase of the second melting unit where methane is present. This prevents an increase in the risk of abnormal reactions triggered by the application of light energy.

[0014] the methane reaction apparatus includes an oxygen dissolving unit that dissolves oxygen as a third solute in the solvent; In the light irradiation unit, the light may be irradiated onto a mixed solution containing the first solute, the second solute, and the third solute. Dissolving oxygen in the mixed solution can promote a chemical reaction between methane and the chlorine oxide-based material. If gaseous oxygen is mixed into methane in the gas phase, the risk of an abnormal reaction increases. However, even if a solvent in which oxygen is dissolved comes into contact with a solvent in which methane is dissolved, the risk of an abnormal reaction does not increase. In addition, in the methane reaction device, oxygen may be dissolved in the solvent at a location away from the methane reaction device, and then the oxygen-containing solution in which oxygen is dissolved may be mixed with the solvent in the methane reaction device.

[0015] The light irradiation unit may be located in a pipe connected to a vessel containing the second dissolving unit or downstream of the pipe. Details of the light irradiation unit being located in a pipe connected to a vessel containing the second dissolving unit or downstream of the pipe are described in the second embodiment (FIG. 4).

[0016] The methane reaction device may include a bubble removal unit upstream of the light irradiation unit for removing bubbles contained in the mixed liquid. Details of the bubble removal unit are described in the fourth embodiment (FIG. 6).

[0017] The methane reaction apparatus may include a first return flow path that supplies the bubbles removed by the bubble removal section to the first dissolution section. Details of the first return flow path are described in the fourth embodiment (FIG. 6).

[0018] The methane reaction apparatus may include a second return flow path that supplies the mixed solution discharged from the light irradiation section to the first dissolution section. Details of the second return flow path are described in the fifth embodiment (FIG. 7). The sixth embodiment (FIG. 8) and the seventh embodiment (FIG. 9) also maintain the second return flow path.

[0019] The first dissolving section may be provided with a stirring bar.

[0020] The second dissolving section may include at least one of a stirrer, a methane bubble-containing liquid supply port, and / or a pressure-boosting mechanism. The methane bubble-containing liquid supply port is connected to a methane bubble generator. The bubbles generated by the methane bubble generator may be fine bubbles or bubbles with a diameter larger than that of fine bubbles.

[0021] The oxygen dissolving unit may include at least one of a stirrer provided in the dissolving area, an oxygen bubble-containing liquid supply port, and / or a pressure increasing mechanism. The oxygen bubble-containing liquid supply port is connected to an oxygen bubble generator. The bubbles generated by the oxygen bubble generator may be fine bubbles or bubbles with a diameter larger than that of fine bubbles.

[0022] The first dissolution section may be located in a container integrated with the container in which the second dissolution section is provided. Embodiments in which the first dissolution section is located in a container integrated with the container in which the second dissolution section is provided are disclosed in the first embodiment (FIG. 1) to the fourth embodiment (FIG. 6). The first dissolution section and the oxygen dissolver may be located in a container integrated with the container in which the second dissolution section is provided. Embodiments in which the first dissolution section and the oxygen dissolver are located in a container integrated with the container in which the second dissolution section is provided are disclosed in the third embodiment (FIG. 5) to the fourth embodiment (FIG. 6). The first dissolution section and the oxygen dissolver may be located in a container separate from the container in which the second dissolution section is provided. Embodiments in which the first dissolution section and the oxygen dissolver are located in a container separate from the container in which the second dissolution section is provided are disclosed in the sixth embodiment (FIG. 8) and onwards. The first dissolution section and the oxygen dissolver may be located both inside and outside the container. An embodiment in which the first dissolving section and the oxygen dissolving section are provided across the inside and outside of the container is disclosed in a fifth embodiment (FIG. 7).

[0023] A mixing section in which the solution having the first solute dissolved therein and the solution having the second solute dissolved therein are mixed may be provided at a location different from the first dissolving section and the second dissolving section. The first to fifth embodiments (FIGS. 1 to 7) disclose a methane reactor having a mixing section in which the solution having the first solute and the solution having the second solute flow in and are mixed at a location different from the first dissolving section and the second dissolving section.

[0024] A solution containing the first solute is passed through the second dissolution section, In the second dissolution section, a mixed solution containing the first solute and the second solute may be formed. This methane reactor is disclosed in the sixth embodiment (FIG. 8) and thereafter.

[0025] The light source may emit light having a dominant wavelength of 365 nm. [Effects of the Invention]

[0026] This makes it possible to provide a methane reaction device that efficiently chemically reacts methane with a chlorine oxide-based material. [Brief explanation of the drawings]

[0027] [Figure 1A] FIG. 1 shows a first embodiment of a methane reactor. [Figure 1B] FIG. 1 shows a first embodiment of a methane reactor. [Figure 2] FIG. 1 illustrates the main chemical reactions. [Figure 3] FIG. 1 shows a variant of the first embodiment of the methane reactor. [Figure 4] FIG. 1 shows a second embodiment of a methane reactor. [Figure 5] FIG. 10 shows a third embodiment of a methane reactor. [Figure 6] FIG. 10 shows a fourth embodiment of a methane reactor. [Figure 7] FIG. 10 is a diagram showing a fifth embodiment of a methane reaction device. [Figure 8] FIG. 10 is a diagram showing a sixth embodiment of a methane reaction device. [Figure 9] FIG. 10 is a diagram showing a seventh embodiment of a methane reaction device. [Figure 10] FIG. 10 shows a variant of the seventh embodiment of the methane reactor. [Figure 11] FIG. 10 shows an eighth embodiment of a methane reactor. DETAILED DESCRIPTION OF THE INVENTION

[0028] The embodiments will be described with reference to the drawings as appropriate. Note that all drawings are schematic, and the dimensional ratios in the drawings do not necessarily correspond to the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily correspond to the actual dimensional ratios.

[0029] In this specification, descriptions will be made with reference to drawings showing an XYZ coordinate system as appropriate. In this specification, when a direction is expressed and a distinction is made between positive and negative directions, it is described with a positive or negative sign, such as "+X direction" and "-X direction." In addition, when a direction is expressed without distinguishing between positive and negative directions, it is simply described as "X direction." In other words, in this specification, when simply referring to "X direction," it includes both "+X direction" and "-X direction." The same applies to the Y direction and Z direction. In this embodiment, the X direction and Y direction are horizontal directions, and the -Z direction is the direction of gravity.

[0030] First Embodiment [Outline of methane reactor] FIG. 1A is a diagram showing a first embodiment of a methane reactor. The methane reactor 100 is an apparatus for chemically reacting methane with a chlorine oxide-based material. The methane reactor 100 of this embodiment includes one container 10. A solvent for dissolving a solute injected from the outside of the methane reactor is stored in the container 10. In this embodiment, the container 10 has a shape formed by bending an expanded-diameter pipe into a U-shape. The container 10 is arranged so that both ends of the U-shape face upward (+Z direction).

[0031] The methane reactor 100 has stirrers (5a, 5b) for stirring a solution in which a solute is dissolved in a solvent. The methane reactor 100 shown in FIG. 1A shows a state in which the stirrers (5a, 5b) are left stationary for a while without rotating. A layer of a first solution S1 (the region darkly hatched with high-density diagonal lines in FIG. 1A) mainly composed of a solvent that dissolves a chlorine oxide-based material exists separately from a layer of a second solution S2 (the region lightly hatched with low-density diagonal lines in FIG. 1A) mainly composed of a solvent that dissolves methane. Because the specific gravity of the first solution S1 is lower than that of the second solution S2, the first solution S1 is located above the second solution S2. The second solution S2 occupies most of the container 10 (e.g., more than 80% of the total volume of the container 10).

[0032] FIG. 1B shows the state in which the stirrers (5a, 5b) are being rotated in the methane reaction apparatus 100 shown in FIG. 1A. When the stirrer 5a is rotated in the first dissolving section 10a, the first solution S1 is stirred into the second solution S2, and the first solute (here, chlorine dioxide) in the first solution S1 is easily dissolved in the second solution S2. As a result, a second solution S2 in which the first solute is also dissolved is formed in the first dissolving section 10a. When the stirrer 5b is rotated in the second dissolving section 10b, methane is dissolved in the second solution S2, and a second solution S2 in which a larger amount of the second solute is dissolved is formed in the second dissolving section 10b. In the mixing section, a mixed liquid is formed in which the second solution S2 containing the first solute formed in the first dissolving section 10a and the second solution S2 in which the second solute is dissolved in the second dissolving section 10b are mixed.

[0033] As shown in FIGS. 1A and 1B, the container 10 of this embodiment has three regions within it: a first dissolving section 10a for dissolving a chlorine oxide-based material in a solvent; a second dissolving section 10b for dissolving methane in a solvent; and a light irradiation section 10c. To facilitate visualization of the regions (10a, 10b, 10c), lines are drawn in FIGS. 1A and 1B to indicate the regions (10a, 10b, 10c). However, the positions and sizes of the regions (10a, 10b, 10c) shown in FIGS. 1A and 1B are merely examples and are not intended to be limiting. Within the container 10, the first dissolving section 10a, the second dissolving section 10b, and the light irradiation section 10c are located apart from one another. A mixed solution containing the first solute and the second solute is present in the region between the first dissolving section 10a and the second dissolving section 10b, including the light irradiation section 10c.

[0034] The first dissolving section 10a is a region intended to dissolve a chlorine oxide-based material as a first solute in the solvent. The first dissolving section 10a has a gas phase 6a in the upper portion (near the +Z end of the first dissolving section 10a). The gas phase 6a contains the chlorine oxide-based material (mainly chlorine dioxide) that was not completely dissolved in the solvent in a gaseous or mist state. When the stirring bar 5a is rotated, the chlorine oxide-based material in the gas phase 6a dissolves into the first solution S1. In FIG. 1B, spheres 8a around the stirring bar 5a represent the first solution S1 temporarily dispersed in the second solution S2 by stirring, or bubbles composed of components of the gas phase 6a. Here, the first solution S1 does not mix with the second solution S2, so the first solution S1 and the second solution S2 remain separate.

[0035] The second dissolving section 10b is a region intended to dissolve methane as a second solute in the solvent. The second dissolving section 10b has a gas phase 6b in the upper portion of the second dissolving section 10b (near the +Z end of the second dissolving section 10b). The gas phase 6b contains methane gas that was not completely dissolved in the solvent. When the stirring bar 5b is rotated, the methane gas in the gas phase 6b dissolves in the second solution S2. In FIG. 1B, the spheres 8b surrounding the stirring bar 5b represent bubbles composed of components of the gas phase 6b.

[0036] The light irradiation unit 10c is an area intended to irradiate the mixed solution containing the first solute and the second solute with light L1 from the light source 4. In the light irradiation unit 10c, the mixed solution in which methane (second solute) and a chlorine oxide-based material (first solute) are dissolved is irradiated with light, causing a chemical reaction between the methane and the chlorine oxide-based material.

[0037] [Chemical reaction mechanism] Before describing each region (10a, 10b, 10c), we will explain the estimated chemical reaction mechanism of the methane reactor 100. Figure 2 is a diagram illustrating the main chemical reactions that occur in the methane reactor 100 of this embodiment.

[0038] First, sodium chlorite (NaClO2), a chlorine oxide-based material, is supplied into the first dissolving section 10a. The solvent contains a hydrogen chloride (HCl) aqueous solution, i.e., hydrochloric acid, that dissolves the sodium chlorite. As shown by chemical reaction R1 in Figure 2, it is believed that chlorine dioxide (ClO2), a chlorine oxide-based material, is produced from sodium chlorite (NaClO2) and hydrogen chloride (HCl). In the specification, chemical reaction R1 is also shown as equation (1). 5NaClO2+4HCl → 4ClO2+5NaCl+2H2O ···(1)

[0039] The following chemical reaction R2 will be explained. The generated chlorine dioxide (ClO2) easily absorbs the light L1 emitted by the light source 4 of the light irradiation unit 10c. When the energy of the light L1 is applied to chlorine dioxide, it is thought to generate chlorine radicals (Cl), which are active species of chlorine atoms. This chemical reaction is shown in equation (2). ClO2 → Cl+O2 (2)

[0040] The photochemical reaction in equation (2) is thought to be the initial reaction, which then triggers a chain reaction of subsequent reactions. Chemical reaction R3 is a process in which a chlorine radical abstracts a hydrogen atom from methane, producing a methyl radical (hereafter simply referred to as "methyl"), which is an active species of the methane molecule. This chemical reaction is shown in equation (3). Cl + CH4 → CH3 + HCl (3)

[0041] Chemical reaction R3 occurs in the mixed solution containing the first solute and the second solute in the light irradiation region of light irradiation unit 10c. In particular, chlorine radicals generated by the initial reaction in light irradiation unit 10c react with methane (CH4) in second solution S2 to generate methyl (CH3) and hydrogen chloride (HCl). The generated hydrogen chloride reacts with additional sodium chlorite (NaClO2) to regenerate chlorine dioxide.

[0042] The methyl produced combines with oxygen molecules (O2) in the second solution S2 in chemical reaction R4, producing the intermediate methylperoxy radical (CH3O2). Chemical reaction R4 is shown in equation (4). CH3 + O2 → CH3O2 (4)

[0043] Methylperoxy radicals are intermediates that play an important role in the oxidation of methane. When methylperoxy radicals (CH3O2) come into contact with each other in a solution, they produce methanol (CH3OH) and formaldehyde (HCHO) according to equation (5). Formaldehyde gradually combines with oxygen atoms contained in oxygen molecules in the reaction vessel in an oxidation reaction to produce formic acid (HCOOH). The reaction that produces methanol and formaldehyde from methylperoxy radicals is chemical reaction R5. 2CH3O2→ CH3OH+HCHO+O2···(5)

[0044] In some cases, methylperoxy radicals (CH3O2) come into contact with each other in a solution, and through chemical reaction R6, oxygen molecules are released to produce methoxy radicals (CH3O). Chemical reaction R6 is shown in equation (6). 2CH3O2 → 2CH3O+O2 (6)

[0045] The methoxy radical obtained in equation (6) is converted to methanol by reacting with methane, and then converted to formic acid by reacting with oxygen to form formaldehyde. Figure 2 shows chemical reaction R7, which converts methoxy radical to methanol. It is assumed that there are other chemical reactions converting methoxy radical to formic acid besides chemical reaction R7, but we will not describe these other assumed chemical reactions here. CH3O+CH4→ CH3OH+CH3...(7)

[0046] The above-described series of chemical reaction mechanisms continues by additionally adding methane and a chlorine oxide-based material (e.g., sodium chlorite (NaClO2)) to the vessel 10. Furthermore, by controlling the amount of sodium chlorite (NaClO2) added according to the amount of methane added to the vessel 10, the chemical reaction is efficiently promoted, and more methane is converted into methanol or formic acid.

[0047] [First melting section] Returning to FIG. 1A, the first dissolving section 10a in which a chlorine oxide-based material as a first solute is dissolved in a solvent will be described in detail.

[0048] The photochemical reaction (chemical reaction R3) that produces methyl from methane mentioned above is also a reaction that consumes chlorine radicals (Cl) produced by light L1. To continuously produce methyl, it is necessary to produce and store a large amount of chlorine radicals so that the number does not decrease.

[0049] However, chlorine radicals cannot be produced and stored in large quantities because, as the amount of chlorine radicals in the solution increases, the chances that chlorine radicals will come into contact with other chlorine radicals before coming into contact with methane molecules increase, resulting in the production of chlorine molecules (Cl2), and the target products, methanol or formic acid, cannot be obtained.

[0050] Since it is not possible to produce and store a large amount of chlorine radicals, it is necessary to continuously supply chlorine radicals to prevent the chlorine radical concentration from decreasing. To do this, it is necessary to maintain a high concentration of chlorine dioxide, the raw material for chlorine radicals, in the liquid.

[0051] In order to maintain a high concentration of chlorine dioxide in the liquid, a chlorine oxide-based material is dissolved in a solvent in the first dissolving section 10a. In this embodiment, chlorine dioxide is replenished not by supplying chlorine dioxide itself, but by additionally supplying sodium chlorite (NaClO2), a precursor of chlorine dioxide. The supplied sodium chlorite quickly reacts with the aqueous hydrogen chloride solution in the aqueous solution to generate chlorine dioxide (ClO2), which is a radical. Chlorine dioxide (ClO2) dissolves in solvents such as water or aqueous hydrogen chloride solution (hydrochloric acid). Chlorine dioxide dissolved in a solvent can also dissolve in solvents that dissolve methane (e.g., fluorous solvents).

[0052] The first dissolving section 10a contains a first solution S1 (water or hydrochloric acid) that dissolves the chlorine oxide-based material and a second solution S2 (e.g., a fluorous solvent) that dissolves methane. However, the first solution S1 that dissolves the chlorine oxide-based material and the second solution S2 that dissolves methane do not maintain an evenly mixed state. Therefore, if the solvent in the first dissolving section 10a is left standing without stirring, it separates into a layer of the first solution S1 that dissolves the chlorine oxide-based material and a layer of the second solution S2 that dissolves methane, as shown in FIG. 1A. Because the specific gravity of the first solution S1 is lower than that of the second solution S2, the layers are separated with the layer of the first solution S1 located above the layer of the second solution S2. However, by stirring with the stirrer 5a, the first solute, the chlorine oxide material (chlorine dioxide), also dissolves in the second solution S2, forming a mixed liquid (second solution S2) containing the first solute (chlorine oxide-based material) and the second solute (methane).

[0053] In this embodiment, an aqueous solution containing water or a hydrogen chloride aqueous solution is used as the first solution S1 for dissolving the chlorine oxide-based material. The aqueous solution may also be an aqueous solution containing formic acid, methanol, or the like. A fluorous solvent is used as the second solution S2 for dissolving methane. A solvent containing perfluorooctane (hereinafter sometimes referred to as "PFO") is used as the fluorous solvent. Substances other than PFO, such as perfluorohexane, perfluoroheptane, perfluorononane, and perfluorodecalin, as well as isomers of these substances, may also be used. The solute is preferably a substance without an unsaturated bond. For example, it may be ethane or propane. The solute is preferably a substance that is gaseous at room temperature and normal pressure.

[0054] The methane reaction apparatus 100 has a precursor supply unit 11 and a precursor supply pump 12 that delivers a solution containing a precursor. The precursor supply unit 11 has a reservoir tank for a sodium chlorite (NaClO2) aqueous solution 7. The sodium chlorite aqueous solution 7 is additionally supplied to the first dissolving unit 10a from the reservoir tank of the precursor supply unit 11 using the precursor supply pump 12. In FIG. 1B, the sodium chlorite aqueous solution 7 is supplied in the form of droplets in order to precisely control the amount of sodium chlorite aqueous solution 7 added. However, when the amount of sodium chlorite aqueous solution 7 added is large, the sodium chlorite aqueous solution 7 may be supplied so as to form a continuous outflow stream.

[0055] The sodium chlorite aqueous solution 7 may be fed into the first dissolving section 10a until the chlorine dioxide reaches a predetermined upper limit. The chlorine dioxide in the mixed solution is consumed by a chemical reaction, and the chlorine dioxide concentration decreases, which promotes dissolution of the sodium chlorite aqueous solution 7 fed into the first dissolving section 10a and the chlorine dioxide in the gas phase 6a into the solvent.

[0056] [Second melting section] The second dissolving section 10b, which dissolves methane as a second solute in a solvent, will now be described in detail. In this embodiment, methane is dissolved in PFO in the second dissolving section 10b. Methane is supplied in gaseous form from a methane supply source 9. By rotating the stirring bar 5b, the methane gas and PFO are mixed, and the methane gas is dissolved in the PFO.

[0057] Gas phase 6b exists in the upper part of second dissolving section 10b (near the +Z side end of second dissolving section 10b). Gas phase 6b contains methane gas that was not completely dissolved in the solvent. As the methane in second solution S2 is consumed by a chemical reaction and the methane concentration decreases, the methane in gas phase 6b dissolves into second solution S2. Stir bar 5b promotes the dissolution of methane gas in gas phase 6b into second solution S2.

[0058] The first dissolution zone 10a and the second dissolution zone 10b are located apart from each other. As a result, although the first dissolution zone 10a and the second dissolution zone 10b are located with the second solution S2 sandwiched between them, chlorine dioxide, which is a component of the gas phase 6a in the first dissolution zone 10a, rarely comes into contact with methane gas, which is a component of the gas phase 6b in the second dissolution zone 10b. This reduces the risk of an abnormal reaction occurring when chlorine dioxide mixes with methane.

[0059] [Light irradiation unit] The light irradiation unit 10c will be described in detail with reference to FIG. 1B. The methane reaction apparatus 100 includes a light source 4 and a light guide 3. The light source 4 and the light guide 3 are disposed in the light irradiation unit 10c. Light L1 from the light source 4, disposed outside the vessel 10, is irradiated onto the mixed solution (second solution S2 containing a first solute and a second solute) in the light irradiation unit 10c. The light irradiation unit 10c is located away from the first dissolution unit 10a and the second dissolution unit 10b. Therefore, the light L1 from the light irradiation unit 10c reaches the mixed solution in the light irradiation unit 10c, but does not reach the first dissolution unit 10a or the second dissolution unit 10b. Therefore, light energy is not applied to the gas phase 6a in the first dissolution unit 10a or the gas phase 6b in the second dissolution unit 10b, thereby reducing the risk of an abnormal reaction triggered by the application of light energy. When the mixed liquid is irradiated with the light L1, the mixed liquid may be irradiated with the light while being continuously stirred with the stirring bars (5a, 5b).

[0060] After the light irradiation, the mixed solution is discharged through the discharge pipe 15 by opening the discharge valve 14. The methanol and formic acid produced in the mixed solution are recovered downstream of the discharge pipe 15. After the mixed solution is discharged, the discharge valve 14 is closed. Then, the hydrogen chloride aqueous solution and PFO are supplied as solvents, and sodium chlorite is supplied to the first dissolving section 10a and methane gas is supplied to the second dissolving section 10b, followed by stirring, and the mixture is again irradiated with light L1. This process is repeated.

[0061] Chlorine dioxide (ClO2) exhibits high absorbance at 360 nm. Therefore, it is preferable to use light having a wavelength of 360 nm as the light L1 for generating chlorine radicals from chlorine dioxide. Therefore, it is particularly preferable to use a light source that emits light having a dominant wavelength of 300 to 380 nm as the light source 4. For example, an LED light source that emits light having a dominant wavelength of 365 nm can be used as the light source 4 that emits light in this wavelength range. Note that, in this specification, the dominant wavelength of the light source 4 refers to the wavelength with the highest intensity in the emission spectrum of the light source 4. The light source 4 is not limited to an LED light source, and may be another solid-state light source such as an LD, or may be a discharge lamp.

[0062] There is no particular limitation on the number of light sources in one unit of light source 4 or the number of units of light source 4. Also, Fig. 1 shows a state in which light source 4 disposed outside container 10 emits light L1 and the light L1 enters container 10 via a light guide 3 provided in the wall of container 10. However, light source 4 may be disposed inside container 10, or light source 4 may be incorporated into the wall of the container.

[0063] In the light irradiation unit 10c, a reflective film that reflects the light L1 may be formed on the inner wall of the container 10 onto which the light L1 is irradiated. The light L1 reflected by the reflective film again imparts light energy to the mixed liquid (second solution S2 containing the first solute and the second solute). The reflective film may be formed, for example, by vapor deposition of an aluminum-based material. If the aluminum-based material does not have sufficient corrosion resistance against chlorine-based substances (chlorine dioxide and chlorine radicals), the vapor deposition surface of the aluminum-based material may be protected with glass to prevent the aluminum-based material from coming into contact with the liquid in the reaction container. However, the reflective film is not an essential component.

[0064] [Modification of the light irradiation unit] FIG. 3 is a diagram showing a modified embodiment of the first embodiment. In a methane reaction apparatus 150, which is a modified embodiment of the first embodiment, a light source 4 is disposed inside a U-shaped container 10. Light L1 is emitted downward (in the -Z direction), which is the outside. The first molten portion 10a and the second molten portion 10b are located above the light irradiating portion 10c (in the +Z direction), on the opposite side to the direction in which light L1 is emitted. With this arrangement of the light irradiating portion 10c, even if the divergence angle of light L1 is increased, it is difficult for light L1 to enter the first molten portion 10a and the second molten portion 10b. This further reduces the risk of an abnormal reaction triggered by the application of light energy.

[0065] [container] It is preferable that the container 10 be made of a material that has excellent corrosion resistance against chlorine-based substances (chlorine dioxide and chlorine radicals). Regarding the shape of the container 10, a U-shaped container 10 as shown in Figures 1A, 1B, and 2 is suitable for creating a situation in which the first dissolution section 10a, the second dissolution section 10b, and the light irradiation section 10c are located at positions separate from one another. This is because two separate gas phase spaces can be arranged in the upper part of the container 10, while a liquid phase space communicating with the two gas phase spaces can be arranged in the lower part of the container 10.

[0066] However, the vessel 10 does not necessarily have to be U-shaped. When the methane reaction is carried out using a single vessel 10, a shape suitable for the vessel 10 preferably satisfies the following conditions: (1) a common liquid layer is located on the -Z side, (2) the methane gas phase and the chlorine dioxide gas phase are located on the +Z side relative to the common liquid layer, and (3) the methane gas phase and the chlorine dioxide gas phase do not directly contact each other. The U-shape is merely one example that satisfies these conditions. Other shapes that satisfy the above conditions may be used, and vessels with shapes that do not satisfy the above conditions may also be used.

[0067] [Stir bar] The stirrers (5a, 5b) shown in FIGS. 1A and 1B are provided with a power source (not shown) outside the vessel 10 that rotates the stirrers (5a, 5b), and the power source rotates a rotating shaft connected to the stirrers (5a, 5b). The stirrers (5a, 5b) may be of a type that does not have a rotating shaft. For example, a magnetic material may be used as the stirrers (5a, 5b), and an electromagnetic coil located outside the vessel 10 may be used as the power source. In a configuration where a chemical reaction in a closed system is preferred to reduce the risk of explosion, for example, a configuration in which power is supplied to the stirrers 5 without contact, such as by magnetic force, is advantageous. The stirrers (5a, 5b) may have variable rotation speeds or rotate intermittently depending on the situation.

[0068] Here, we have described the stirrer 5a used in the first dissolving section 10a and the stirrer 5b used in the second dissolving section 10b, but the above-mentioned features of the stirrer can also be applied to other stirrers described later.

[0069] Second Embodiment A second embodiment of a methane reaction apparatus will be described with reference to Figure 4. Features different from the previously described embodiments will be mainly described, and features common to the previously described embodiments will not be described in principle. In other words, matters not described in the second embodiment are the same as the features of the previously described embodiments. The third and subsequent embodiments will also be described in a similar format.

[0070] In the methane reaction apparatus 200 of the second embodiment, the light irradiation unit 20 is not present in a part of the container 10 but exists independently from the container 10. The area where the light irradiation unit was present in the first embodiment is a mixing space 10p in which both the chlorine oxide-based material and methane are dissolved. The light irradiation unit 20 is connected to an exhaust pipe 15 located downstream of the mixing space 10p. The light irradiation unit 20 is a light treatment space with a volume larger than that of the piping. The light irradiation unit 20 includes a supply port 20i, an exhaust port 20o, and a light guide unit 3 that guides light L1 from a light source 4 outside the light irradiation unit 20. A reflective film 22 that reflects light L1 is formed on the inner surface of the light irradiation unit 20 facing the light guide unit 3.

[0071] In this embodiment, the mixed solution containing the first solute and the second solute is discharged from the container 10 by opening the discharge valve 14, and is supplied to the light irradiation unit 20 through the discharge pipe 15. The mixed solution is supplied from the supply port 20i of the light irradiation unit 20, irradiated with light L1, and discharged from the discharge port 20o of the light irradiation unit 20. Methanol and formic acid produced and contained in the mixed solution are recovered downstream of the discharge port 20o.

[0072] In this embodiment, the light irradiation unit 20 is separate from the discharge pipe 15, but the light irradiation unit 20 may be integrated with the discharge pipe 15. Specifically, at least a portion of the discharge pipe 15, which is a pipe connected to the container 10, may be made of a transparent material that transmits light L1. Then, light L1 may be irradiated from a light source outside the discharge pipe 15 toward the liquid flowing through the discharge pipe 15 via the transparent material.

[0073] Third Embodiment A third embodiment of a methane reaction apparatus will be described with reference to FIG. 5. The methane reaction apparatus 300 includes an ω-shaped vessel 10. The vessel 10 includes a first dissolving section 10a, a second dissolving section 10b, and an oxygen dissolving section 10d. Oxygen is supplied to the solvent in the oxygen dissolving section 10d. Oxygen gas is supplied from an oxygen gas source 13 into the vessel of the oxygen dissolving section 10d. The area near the stirrer 5d is a dissolving field where oxygen is dissolved in the solvent. In the dissolving field, oxygen gas is dissolved in the solvent by rotating the stirrer 5d. This produces an oxygen-rich mixed solution (a second solution S2 containing a first solute and a second solute). Note that in FIG. 5, the second dissolving section 10b, the oxygen dissolving section 10d, and the first dissolving section 10a are arranged in this order from left to right (i.e., in the +X direction), but the arrangement order of these regions (10b, 10d, 10a) is not limited.

[0074] The oxygen dissolving section 10d of this embodiment has a gas phase 6d. The gas phase 6d contains oxygen that does not dissolve in the dissolving field. The oxygen gas present in the gas phase 6d is located away from the gas phase 6b containing methane gas in the second dissolving section 10b. In this embodiment, it can be said that the dissolving field is located away from the second dissolving section 10b. This prevents oxygen gas from coming into contact with methane gas, thereby reducing the risk of abnormal reactions of methane gas. Note that even if oxygen dissolved in a solvent comes into contact with methane dissolved in the solvent, the risk of abnormal reactions does not increase. The dissolving field is also located away from the first dissolving section 10a and the light irradiation section 20.

[0075] In the chemical reaction mechanism shown in Figure 2, when generating methylperoxy radicals (CH3O2) from methyl, if a large amount of oxygen gas is dissolved in the liquid, chemical reaction R5 is likely to proceed, as shown in chemical reaction R4. Dissolving a large amount of oxygen gas in the mixed liquid (second solution S2 containing the first solute and second solute) can promote a series of chemical reactions.

[0076] In this embodiment, oxygen gas is supplied to the oxygen dissolver 10d, but a gas containing oxygen gas (for example, air) may be supplied to the oxygen dissolver 10d.

[0077] <Fourth embodiment> A fourth embodiment of a methane reaction apparatus will be described with reference to FIG. 6. The methane reaction apparatus 400 has a bubble removal unit 19 located midway through the discharge pipe 15. The bubble removal unit 19 corresponds to the high-level portion (the portion located on the +Z side) of the bent discharge pipe 15. Gas phase components (e.g., chlorine dioxide gas or chlorine gas) may be present as bubbles in the mixed solution (second solution S2 containing a first solute and a second solute) flowing through the discharge pipe 15. If the bubbles flow into the light irradiation unit 20, they will block the light L1, thereby reducing the reaction efficiency of the light L1. Therefore, the bubbles are removed from the mixed solution by capturing them in the bubble removal unit 19 located midway through the discharge pipe 15 upstream of the light irradiation unit 20.

[0078] The bubbles removed from the mixed solution in the bubble removal section 19 are supplied to the first dissolving section 10a together with a small amount of liquid through the first return flow path 17 by the operation of the pump 18. Since the bubble component is chlorine dioxide, in Fig. 6, it is returned to the inside of the first solution S1 to increase the concentration of chlorine dioxide in the first solution S1.

[0079] The methane reaction apparatus 400 of this embodiment has a further feature. The methane reaction apparatus 400 has a pressure boosting mechanism capable of supplying methane gas at a higher pressure than the methane supply source 9 in the first to third embodiments. Various types of pressure boosting mechanisms exist, and FIG. 6 shows an example of such a pressure boosting mechanism. The methane reaction apparatus 400 has a gate valve 16 between the second dissolving section 10b and the mixing space 10p. With the gate valve 16 and the leak valve 42 closed, the methane supply valve 44 is opened to supply high-pressure methane from the methane supply source 9b. This creates a high-pressure environment throughout the second dissolving section 10b, allowing more methane gas to dissolve in the solvent. To release the high-pressure environment, the methane supply valve 44 is closed, the leak valve 42 is opened, and the second dissolving section 10b is returned to the same pressure as the ambient air pressure, and then the gate valve 16 is opened.

[0080] As shown in FIG. 6, the oxygen dissolving section 10d of the methane reaction apparatus 400 may have a pressure-boosting mechanism. The methane reaction apparatus 400 has a gate valve 16 between the oxygen dissolving section 10d and the mixing space 10p. With the gate valve 16 and the leak valve 42 closed, the oxygen supply valve 45 is opened to supply high-pressure oxygen from the oxygen supply source 13b. This creates a high-pressure environment throughout the oxygen dissolving section 10d, allowing more oxygen gas to dissolve in the solvent. To release the high-pressure environment, the oxygen supply valve 45 is closed and the leak valve 42 is opened to return the pressure in the oxygen dissolving section 10d to the same as the ambient air pressure, and then the gate valve 16 is opened.

[0081] Fifth Embodiment A fifth embodiment of the methane reaction apparatus will be described with reference to Fig. 7. The methane reaction apparatus 500 has a second return flow path 41 that supplies the mixed liquid discharged from the light irradiation unit 20 to the first dissolving unit 10a. A pump 43 provided midway along the second return flow path 41 is used to supply the mixed liquid discharged from the light irradiation unit 20 to the first dissolving unit 10a. Chlorine dioxide remaining in the mixed liquid can be dissolved in a solvent to chemically react with methane again.

[0082] Further features of the methane reaction apparatus 500 of this embodiment are shown below. In the methane reaction apparatus 500, the second dissolving section 10b extends to the outside of the container 10. The second dissolving section 10b has a fine bubble generator 59. The fine bubble generator 59 is connected to the methane supply source 9. The fine bubble generator 59 has a suction pipe 54 that sucks up the solvent from the container 10 and a drain pipe 55 that returns the solvent in the fine bubble generator 59 to the container 10. In other words, the fine bubble generator 59 sucks up the solvent, dissolves it in the solvent as fine bubbles of methane gas inside the fine bubble generator 59 located outside the container 10, and returns the liquid with the dissolved fine bubbles to the container 10.

[0083] In this specification, fine bubbles refer to bubbles with a diameter of less than 100 μm. The term "fine bubbles" encompasses microbubbles with a diameter of 1 μm or more but less than 100 μm, and ultrafine bubbles with a diameter of less than 1 μm. Ultrafine bubbles are also called nanobubbles. In particular, when a solute is dissolved in a solvent as ultrafine bubbles, the solute can remain in the liquid for at least a certain period of time. Therefore, even if a mixed solution in which a solute has dissolved in a solvent in the form of bubbles is irradiated with light, a chemical reaction can occur without increasing the risk of abnormal reactions, and therefore, this method is used as a method for dissolving a solute in a solvent.

[0084] The methane reaction apparatus 500 of this embodiment has a further feature. In the methane reaction apparatus 500, the oxygen dissolving section 10d extends outside the vessel 10, similar to the second dissolving section 10b. The oxygen dissolving section 10d has an ultra-fine bubble generator 53. The ultra-fine bubble generator 53 is connected to the oxygen gas supply source 13. The ultra-fine bubble generator 53 has a suction pipe 56 that draws up the solvent from the oxygen dissolving section 10d and a drain pipe 57 that returns the solvent in the ultra-fine bubble generator 53 to the oxygen dissolving section 10d. In other words, the ultra-fine bubble generator 53 draws up the solvent, dissolves it in the solvent as ultra-fine bubbles of oxygen gas inside the ultra-fine bubble generator 53 located outside the vessel 10, and returns the liquid with the dissolved ultra-fine bubbles to the vessel 10.

[0085] In this embodiment, an ultra-fine bubble generator is used in place of a stirring bar in the second dissolving section 10b and the oxygen dissolving section 10d, but a stirring bar and an ultra-fine bubble generator may be used together.

[0086] Sixth Embodiment In the first to fifth embodiments, each dissolution section is arranged in the internal space of a single container. However, in the sixth and subsequent embodiments, a flow-type reaction apparatus is disclosed in which each dissolution section has an independent space (container) and each space (each container) is connected by a pipe.

[0087] A sixth embodiment of the methane reaction apparatus will be described with reference to Fig. 8. The methane reaction apparatus 600 comprises, in order of liquid flow, a first container 31 having a first dissolver, a second container 32 having an oxygen dissolver, a third container 33 having a second dissolver, and a light irradiation section 20. The liquid leaving the light irradiation section 20 is returned to the first container 31 via a second return flow path 41.

[0088] The first container 31 having the first dissolving section will now be described. The supply port 31i is disposed relatively higher (+Z side) of the first container 31, and the discharge port 31o is disposed relatively lower (-Z side) of the first container 31. The precursor supply pump 12 is operated to supply an aqueous sodium chlorite (NaClO2) solution 7 from the precursor supply section 11. The supplied sodium chlorite quickly reacts with the aqueous hydrogen chloride solution in the liquid to produce chlorine dioxide (ClO2).

[0089] A flow control valve (not shown) may be provided at the supply port 31i to control the amount of liquid supplied and set the timing for starting or stopping the supply. Similarly, a flow control valve (not shown) may be provided at the discharge port 31o to control the amount of liquid discharged and set the timing for starting or stopping the discharge.

[0090] The second container 32 having an oxygen dissolver will now be described. The supply port 32i, which is connected to the outlet 31o of the first container 31 via a connecting pipe, is disposed relatively higher (on the +Z side) of the second container 32, and the outlet 32o is disposed relatively lower (on the -Z side) of the second container 32. As described in the third embodiment, a gas containing oxygen gas (e.g., air) may be supplied to the second container 32 having an oxygen dissolver, rather than oxygen gas.

[0091] In this embodiment, the second container 32 having an oxygen dissolving section does not have a stirrer. Instead, a bubble generator 36 is attached to the second container 32. The bubble generator 36 recovers oxygen gas from the gas phase in the second container 32 and blows the recovered oxygen gas into the liquid layer in the second container 32. This causes a larger amount of oxygen to dissolve in the solvent. The bubble generator 36 in this embodiment is not a device that generates fine bubbles such as ultrafine bubbles, but a bubble generator that generates fine bubbles such as ultrafine bubbles may be installed.

[0092] A flow control valve (not shown) may be provided at the supply port 32i to control the amount of liquid supplied and set the timing for starting or stopping the supply. Similarly, a flow control valve (not shown) may be provided at the discharge port 32o to control the amount of liquid discharged and set the timing for starting or stopping the discharge.

[0093] The third container 33 having the second dissolving section will now be described. A supply port 33i connected to an outlet 32o of the second container 32 via a connecting pipe is disposed relatively above (on the +Z side of) the third container 33, and the outlet 33o is disposed relatively below (on the -Z side of) the third container 33. Methane gas is supplied from a methane supply source 9.

[0094] In this embodiment, the third vessel 33 having the second dissolving section does not have a stirrer. Instead, a bubble generator 37 is attached to the third vessel 33. The bubble generator 37 recovers methane gas from the gas phase in the third vessel 33 and blows the recovered methane gas into the liquid layer in the third vessel 33. This causes a larger amount of methane gas to dissolve in the solvent. The bubble generator 37 in this embodiment is not a device that generates fine bubbles such as ultrafine bubbles, but a bubble generator that generates fine bubbles such as ultrafine bubbles may be installed.

[0095] A flow control valve (not shown) may be provided at the supply port 33i to control the amount of liquid supplied and set the timing for starting or stopping the supply. Similarly, a flow control valve (not shown) may be provided at the discharge port 33o to control the amount of liquid discharged and set the timing for starting or stopping the discharge.

[0096] The light irradiation unit 20 includes a supply port 20i, an outlet 20o, and a light guide unit 3 that guides light L1 from a light source 4 outside the light irradiation unit 20. In the light irradiation unit 20, a liquid (liquid mixture) containing dissolved chlorine dioxide (first solute) and methane (second solute) supplied from the supply port 20i is irradiated with light L1 to promote a chemical reaction. The liquid after light irradiation is supplied to the first container 31 through the second return flow path 41. A chemical reaction involving liquid circulation is carried out for a certain period of time to increase the target products, methanol and formic acid, in the liquid. After producing the desired amount of methanol and formic acid, the liquid circulation is stopped, and the produced methanol and formic acid contained in the liquid mixture in the containers (31, 32, 33), the light irradiation unit 20, or the connecting piping are collected.

[0097] Seventh Embodiment A seventh embodiment of a methane reaction apparatus will be described with reference to FIG. 9. In the methane reaction apparatus 700, a pressure-boosting mechanism for creating a high-pressure environment is attached to the third vessel 33 having the second dissolving section. The on-off valves (16i, 16o) and the leak valve 42 are closed to form a closed space, and the methane supply valve 44 is opened to supply high-pressure methane from the methane supply source 9b. This creates a high-pressure environment throughout the second dissolving section 10b, allowing more methane gas to dissolve in the solvent. To release the high-pressure environment, first close the methane supply valve 44 and open the leak valve 42 to return the second dissolving section 10b to the same pressure as the ambient air pressure. Next, open the gate valve 16.

[0098] FIG. 10 shows a modified example of the seventh embodiment. FIG. 10 shows only the second dissolving section of the methane reactor 750. As shown in FIG. 10, the second dissolving section may be composed of two or more vessels, each of which is composed of two third vessels 33 connected in parallel. In this embodiment, the two third vessels 33 are connected to a common high-pressure methane supply source 9. While one vessel is pressurized with high-pressure methane, the other vessel is supplied with and discharged from the vessel. By replacing the vessels after a certain period of time, continuous production of a liquid containing dissolved methane becomes possible.

[0099] Even if the high-pressure methane supply source is not used, if the processing capacity of the second dissolving section is simply inferior to that of the first dissolving section and the oxygen dissolving section, the processing capacity may be improved by connecting multiple third containers 33 in parallel. The water discharged from the outlets 33o of the respective third containers 33 is joined and transferred to the light irradiation section 20.

[0100] The improvement of processing capacity by arranging a plurality of units and connecting them in parallel is not limited to the second dissolving unit. A plurality of first dissolving units, oxygen dissolving units, or light irradiating units may be arranged and connected in parallel to improve the processing capacity of each unit.

[0101] Eighth Embodiment An eighth embodiment of a methane reaction apparatus will be described with reference to Fig. 11. The methane reaction apparatus 800 comprises, in order of liquid flow, a first container 31 having a first dissolver, a second container 32 having an oxygen dissolver, a third container 33 having a second dissolver, and a light irradiation section 20. The liquid leaving the light irradiation section 20 is returned to the first container 31 via a second return flow path 41. Note that Fig. 11 does not show the fluid supply ports, fluid supply sources, and various dissolution mechanisms (such as a stirrer, a bubble generator, or a pressure-boosting mechanism) for the fluids supplied to the containers (31, 32, 33).

[0102] Each of the containers (31, 32, 33) and the light irradiation unit 20 has a flat shape that is wide in the horizontal direction (XY direction) and short in the height direction (Z direction). When the first container 31 has a flat shape, the interface between the first solution S1 and the second solution S2 becomes wide, so the first solute mixes well with both solutions even with gentle stirring. When the containers (32, 33) have a flat shape, the interface between the gas phase and the second solution S2 becomes wide, so the gas phase component can be easily dissolved into the second solution S2 even with gentle stirring. When the light irradiation unit 20 has a flat shape, the area irradiated with light becomes wide, allowing the chemical reaction to occur efficiently.

[0103] The upper portion of the internal space of each container (31, 32, 33) contains a gas phase, while the internal space of the light irradiation unit 20 is preferably filled with the second solution S2. In this embodiment, the containers (31, 32, 33) and the light irradiation unit 20 are stacked in the height direction (Z direction). This reduces the footprint of the methane reaction apparatus. The liquid in each container (31, 32, 33) preferably flows by gravity into the next container (32, 33) or the light irradiation unit 20. A pump 43 is attached to the second return flow path 41 from the light irradiation unit 20 to the first container 31. By operating the pump 43, the second solution S2 (mixed liquid) containing the first solute and the second solute is transferred to the light irradiation unit 20.

[0104] The above describes the embodiments and their modifications of the methane reaction apparatus. The above embodiments and their modifications are merely examples of the present invention, and the present invention is not limited to the above embodiments and their modifications. Various changes or modifications can be made to the above embodiments and their modifications, and the above embodiments and their modifications can be combined as appropriate, without departing from the spirit of the present invention.

[0105] In this specification and drawings, locations where there is an on-off valve but no pump upstream or downstream of it are locations where the inlet pressure of the on-off valve can be set to be higher than the outlet pressure, and liquid will flow out simply by opening the on-off valve without using a pump. A pump may be used instead of an on-off valve where an on-off valve is used. Conversely, an on-off valve set so that the inlet pressure is higher than the outlet pressure may be used instead of a pump where a pump is used. Gravity may be used to make the inlet pressure higher than the outlet pressure. Of course, an on-off valve and a pump may be used together. [Explanation of symbols]

[0106] 3: Light guide section 4:Light source 5,5a,5b,5c: Stirrer 6a, 6b, 6c: Gas phase 7: Sodium chlorite aqueous solution 9,9b: Methane source 10: Container 10a: First melting section 10b:Second melting section 10c: Light irradiation part 10d: Oxygen dissolving section 10p: Mixed space 11: Precursor supply section 12: Precursor supply pump 13, 13b: Oxygen gas supply source 14: Exhaust valve 15: Discharge pipe 16: Gate valve 17: First return flow path 18: Pump 19: Air bubble removal section 20: Light irradiation unit 20i: Supply port (for light irradiation section) 20o: (light irradiation part) exhaust port 22: Reflective film 31:First container 31i: (First container) supply port 31o: (First container) outlet 32:Second container 32i: (Second container) supply port 32o: (Second container) outlet 33:Third container 33i: (Third vessel) supply port 33o: Outlet (of the third container) 36,37: Bubble generator 37: Bubble Generator 41: Second return flow path 42: Leak valve 43: Pump 44: Methane supply valve 45: Oxygen supply valve 53,59:Ultra Fine Bubble Generator 54,56:Liquid suction tube 55,57:Drainage tube 100, 150, 200, 300, 400, 500, 600, 700, 750, 800: Methane reactor L1: light S1: First solution S2: Second solution

Claims

1. A methane reactor that oxidizes methane by chemically reacting methane with a chlorine oxide-based material in a solvent, the methane reactor comprising: a first dissolving section for dissolving a chlorine oxide-based material as a first solute in the solvent; a second dissolution zone located at a position distant from the first dissolution zone and dissolving the methane as a second solute in the solvent, wherein a gas phase of the methane is formed in the second dissolution zone separately from the first dissolution zone; a light irradiation unit that is located away from the first dissolution unit and the second dissolution unit and that irradiates light from a light source onto a mixed solution containing the first solute and the second solute; A methane reaction apparatus comprising:

2. an oxygen dissolving unit that dissolves oxygen as a third solute in the solvent; 2. The methane reaction apparatus according to claim 1, wherein the light irradiation unit irradiates the mixed solution containing the first solute, the second solute, and the third solute with the light.

3. 3. The methane reaction apparatus according to claim 1, wherein the light irradiation unit is located in a pipe connected to a vessel including the second dissolution unit, or downstream of the pipe.

4. 3. The methane reaction apparatus according to claim 1, further comprising a bubble removal section upstream of the light irradiation section, which removes bubbles contained in the mixed liquid.

5. 5. The methane reaction apparatus according to claim 4, further comprising a first return flow path for supplying the bubbles removed in the bubble removal section to the first dissolution section.

6. 3. The methane reaction apparatus according to claim 1, further comprising a second return flow path that supplies the mixed liquid discharged from the light irradiation part to the first dissolution part.

7. The methane reaction apparatus according to claim 1 or 2, wherein the first dissolving section is provided with a stirring bar.

8. 3. The methane reaction apparatus according to claim 1, wherein the second dissolving section comprises at least one of a stirrer, a methane bubble-containing liquid supply port, and a pressure-boosting mechanism.

9. 3. The methane reaction apparatus according to claim 2, wherein the oxygen dissolving section comprises at least one of a stirrer provided in a dissolving field, an oxygen bubble-containing liquid supply port, and a pressure increasing mechanism.

10. 3. The methane reaction apparatus according to claim 1, further comprising a mixing section in which the solution in which the first solute is dissolved and the solution in which the second solute is dissolved are mixed at a location different from the first dissolving section and the second dissolving section.

11. A solution containing the first solute is passed through the second dissolution section, 3. The methane reaction apparatus according to claim 1, wherein a mixed solution containing the first solute and the second solute is formed in the second dissolution section.

12. 3. The reactor according to claim 1, wherein the light source emits light having a dominant wavelength of 365 nm.

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