Production method and production apparatus for oxidation reaction product of hydrocarbon or derivative thereof

Abstract

The present invention provides a production method and a production apparatus, with which an oxidation reaction product is efficiently generated. A production method for an oxidation reaction product according to the present disclosure includes: an introduction step for introducing a starting material, which is a hydrocarbon or a derivative thereof, and a chlorine dioxide radical in a gaseous state into a liquid phase; and a reaction step for obtaining an oxidation reaction product of the starting material by irradiating the liquid phase with light.

Description

Method and apparatus for producing oxidation reaction products of hydrocarbons or their derivatives

[0001] The present invention relates to a method and apparatus for producing an oxidation reaction product of a hydrocarbon or its derivative.

[0002] Due to their high industrial utility, alcohols, carboxylic acids, and the like are industrially produced by various methods. For example, a commonly used method for producing methanol is to react carbon monoxide with hydrogen gas at high temperature and pressure. The raw materials, carbon monoxide and hydrogen gas, can be produced, for example, by partial combustion of methane (natural gas) or by steam reforming. Furthermore, alcohols such as ethanol, carboxylic acids, and the like are also commonly produced by biochemical methods such as fermentation.

[0003] Furthermore, in recent years, methods have been proposed for the effective utilization of natural gases such as shale gas by oxidizing hydrocarbons contained in natural gas to produce oxidation reaction products such as alcohols and carboxylic acids. For example, Patent Document 1 discloses a method for producing an oxidation reaction product, which includes a reaction step of irradiating a reaction system containing an organic phase with light in the presence of a hydrocarbon or a derivative thereof and chlorine dioxide radicals. Patent Document 2 discloses a method for producing an oxidation reaction product, which includes a reaction step of reacting a hydrocarbon or a derivative thereof with a compound radical, wherein the reaction system in the reaction step includes a gas phase.

[0004] Japanese Patent Publication No. 2017-155017 Japanese Patent Publication No. 2020-002119

[0005] However, the above-mentioned conventional techniques have room for improvement in terms of efficiently producing oxidation reaction products.

[0006] For example, Patent Document 1 discloses that the reaction system includes an aqueous phase, and that sodium chlorite and an acid are dissolved in the aqueous phase to generate chlorine dioxide radicals. However, in the method using an aqueous phase containing sodium chlorite and an acid as the reaction system, the reaction rate is significantly reduced, and it is sometimes difficult to obtain a high concentration of oxidation reaction product. In addition, the technology described in Patent Document 2 involves a reaction in a gas phase, which causes a low frequency of molecular collisions and raises concerns about low reaction efficiency.

[0007] An object of one aspect of the present invention is to provide a production method and production apparatus that efficiently produce an oxidation reaction product.

[0008] In order to solve the above-mentioned problems, a method for producing an oxidation reaction product according to one embodiment of the present invention includes an introduction step of introducing a raw material that is a hydrocarbon or a derivative thereof and gaseous chlorine dioxide radicals into a liquid phase, and a reaction step of irradiating the liquid phase with light to obtain an oxidation reaction product of the raw material.

[0009] Furthermore, an apparatus for producing an oxidation reaction product according to one embodiment of the present invention includes a liquid phase storage unit for storing a liquid phase, a raw material supply unit for introducing a raw material that is a hydrocarbon or a derivative thereof into the liquid phase, a chlorine dioxide radical supply unit for introducing gaseous chlorine dioxide radicals into the liquid phase, and a reaction unit equipped with a light source for irradiating the liquid phase with light.

[0010] According to one aspect of the present invention, it is possible to provide a production method and a production apparatus for efficiently producing an oxidation reaction product.

[0011] FIG. 1 is a schematic diagram showing the configuration of an apparatus for producing an oxidation reaction product according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of an apparatus for producing an oxidation reaction product according to one embodiment of the present invention. FIG. 3 is a schematic diagram showing the configuration of an apparatus for producing an oxidation reaction product according to one embodiment of the present invention. FIG. 4 is a schematic diagram showing the configuration of an apparatus for producing an oxidation reaction product according to one embodiment of the present invention. FIG. 5 is a diagram showing changes over time in the amount of formic acid produced in Example 1 and Comparative Example 1.

[0012] Hereinafter, one embodiment of the present invention will be described in detail. In this specification, unless otherwise specified, the numerical range "A to B" means "A or more and B or less."

[0013] 1. Method for Producing Oxidation Reaction Product A method for producing an oxidation reaction product according to one embodiment of the present invention includes an introduction step of introducing a raw material, which is a hydrocarbon or a derivative thereof, and gaseous chlorine dioxide radicals into a liquid phase, and a reaction step of irradiating the liquid phase with light to obtain an oxidation reaction product of the raw material.

[0014] According to a production method of one embodiment of the present invention, chlorine dioxide radicals are introduced in a gaseous state into a liquid phase, thereby preventing the generation of unnecessary inorganic salts, which are by-products of chlorine dioxide radical generation, as occurs in the method used in Patent Document 1. In particular, while the influence of inorganic salts is significant when an aqueous phase containing a chlorine dioxide radical source is continuously introduced into a reaction system over a long period of time, the production method of one embodiment of the present invention is not affected by inorganic salts. This prevents a decrease in reaction rate, allowing the reaction to proceed continuously and resulting in a high concentration of oxidation reaction product. Furthermore, when the technology described in Patent Document 1 is applied to mass production, a step of removing inorganic salts from the aqueous phase is required. Alternatively, in the technology described in Patent Document 1, if chlorine dioxide radicals are continuously added to the reaction phase in an aqueous solution state, the volume of the aqueous phase increases, making it impossible to increase the concentration of the oxidation reaction product in the aqueous phase, and therefore a step of concentrating the oxidation reaction product is required. According to a production method of one embodiment of the present invention, a high concentration of oxidation reaction product can be obtained without removing inorganic salts or concentrating the oxidation reaction product.

[0015] Furthermore, in the production method according to one embodiment of the present invention, the reaction is carried out in a liquid phase, which results in a higher frequency of molecular collisions than in a gas phase reaction as in the technology described in Patent Document 2, and therefore the oxidation reaction product can be produced more efficiently. It is possible to carry out the reaction at high pressure using a metallic pressure vessel to promote the reaction in the technology described in Patent Document 2, but since chlorine dioxide radicals are highly corrosive to metals, the durability of metallic pressure vessels becomes an issue, making them unsuitable for practical use. In the production method according to one embodiment of the present invention, the oxidation reaction product can be efficiently produced even at room temperature and atmospheric pressure.

[0016] <1-1. Introduction Step> The introduction step is a step of introducing a raw material, which is a hydrocarbon or its derivative, and gaseous chlorine dioxide radicals into a liquid phase. The raw material may be introduced into the liquid phase in a gaseous, liquid, or solid state. Furthermore, when the raw material is a liquid, the raw material itself may be in the liquid phase. Introducing gaseous chlorine dioxide radicals into the liquid phase means introducing a chlorine dioxide radical gas or mist into the liquid phase. Mist refers to a state in which fine droplets are dispersed in a gas. Therefore, in this specification, mist is included in the gaseous state. Furthermore, the chlorine dioxide radical gas or mist and the raw material may be introduced separately into the liquid phase, or when the raw material is a gas, the chlorine dioxide radical gas or mist and the raw material gas may be introduced into the liquid phase in a mixed state. When the raw material is a liquid, the introduction step may be a step of introducing gaseous chlorine dioxide radicals into the raw material in the liquid phase.

[0017] The feedstock may be a hydrocarbon itself, or a derivative thereof, which may be, for example, non-polymeric.

[0018] The hydrocarbon is not particularly limited, and examples thereof include linear or branched saturated and unsaturated hydrocarbons (e.g., alkanes, alkenes, alkynes, etc.), saturated and unsaturated hydrocarbons containing non-aromatic cyclic structures (e.g., cycloalkanes, cycloalkenes, etc.), and aromatic hydrocarbons. The hydrocarbon may or may not have one or more aromatic or non-aromatic rings in its structure, and may or may not have one or more linear or branched saturated or unsaturated hydrocarbon groups. The hydrocarbon preferably has 1 to 20 carbon atoms, more preferably 1 to 10, even more preferably 1 to 6, and particularly preferably 1 to 3.

[0019] Examples of the hydrocarbon include chain hydrocarbons such as methane, ethane, propane, n-butane, 2-methylpropane, n-pentane, n-hexane, ethylene, propylene, 1,3-butadiene, and acetylene, and cyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, methylcyclohexane, cyclohexene, benzene, toluene, o-xylene, m-xylene, p-xylene, mesitylene, durene, biphenyl, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, anthracene, phenanthrene, pyrene, and styrene. These may be used alone or in combination of two or more.

[0020] In this specification, a "derivative" of a hydrocarbon refers to, for example, an organic compound containing a hetero element (an element other than carbon and hydrogen). The hetero element is not particularly limited, and examples thereof include oxygen (O), nitrogen (N), sulfur (S), and halogens. Examples of the halogens include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0021] The derivative may be a hydrocarbon derivative having a hydrocarbon group. The derivative may be, for example, an organic compound having a structure in which a hydrocarbon group is bonded to an arbitrary substituent or atomic group. The derivative may also be, for example, a compound having a structure in which multiple hydrocarbon groups are bonded by an arbitrary atomic group, and the hydrocarbon group may be substituted with one or more arbitrary substituents, or may not be substituted. The hydrocarbon group portion may then be oxidized by an oxidation reaction in the reaction step to produce an oxidation reaction product of the hydrocarbon derivative.

[0022] The hydrocarbon group is not particularly limited, and examples thereof include monovalent or divalent or higher valent groups derived from the hydrocarbons listed above. The hydrocarbon group may have, for example, one or more carbon atoms substituted with heteroatoms. Specifically, for example, one carbon atom of a phenyl group (and the hydrogen atom bonded thereto) may be substituted with a nitrogen atom to form a pyridyl group. The substituent or atomic group is not particularly limited, and examples thereof include a hydroxy group, a halogen group (e.g., a fluoro group, a chloro group, a bromo group, an iodo group, etc.), an alkoxy group, an aryloxy group (e.g., a phenoxy group, etc.), a carboxy group, an alkoxycarbonyl group, an aryloxycarbonyl group (e.g., a phenoxycarbonyl group, etc.), a mercapto group, an alkylthio group, an arylthio group (e.g., a phenylthio group, etc.), an amino group having or having no substituent (e.g., an amino group, an alkylamino group, a dialkylamino group, etc.), an ether bond (—O—), an ester bond (—CO—O—), a thioether bond (—S—), etc.

[0023] In this specification, chain hydrocarbons (e.g., alkanes, unsaturated aliphatic hydrocarbons, etc.) or chain substituents derived from chain hydrocarbons (e.g., hydrocarbon groups such as alkyl groups, unsaturated aliphatic hydrocarbon groups, etc.) are not particularly limited and may be linear or branched. The number of carbon atoms therein is not particularly limited, and is, for example, preferably 1 to 20, more preferably 1 to 6, and even more preferably 1 to 2 (2 or more in the case of unsaturated hydrocarbon groups). In addition, in this specification, the number of ring members (the number of atoms constituting the ring) of cyclic hydrocarbons (e.g., cyclic saturated hydrocarbons, non-aromatic cyclic unsaturated hydrocarbons, aromatic hydrocarbons, heteroaromatic compounds, etc.) or cyclic substituents derived from cyclic hydrocarbons (e.g., cyclic saturated hydrocarbon groups, non-aromatic cyclic unsaturated hydrocarbon groups, aryl groups, heteroaryl groups, etc.) is not particularly limited, and is, for example, preferably 5 to 20, more preferably 6 to 18, or even more preferably 6 to 10. Furthermore, when isomers exist in a substituent or the like, there are no particular limitations and any isomer may be used. For example, when simply referring to a "naphthyl group," it may be a 1-naphthyl group or a 2-naphthyl group.

[0024] Furthermore, in this specification, any isomer such as a tautomer or a stereoisomer (e.g., a geometric isomer, a conformational isomer, and an optical isomer) can be used as the raw material. When the raw material can form a salt, the salt can also be used without any particular limitation. The salt may be an acid addition salt or a base addition salt. The method for producing the salt is also without any particular limitation, and the salt can be produced, for example, by a method in which an acid or a base is appropriately added to the compound by a known method. In order to efficiently produce the oxidation reaction product, it is preferable that the raw material is not a salt.

[0025] The chlorine dioxide radical gas refers to a gas containing chlorine dioxide radicals. It may be a gas of chlorine dioxide radicals alone, or chlorine dioxide radicals may be present in a carrier gas. The chlorine dioxide radical mist may be generated by dispersing and suspending condensates of chlorine dioxide radical gas, droplets of an aqueous solution containing chlorine dioxide radicals, or droplets of the evaporated material from a radical generating tank containing chlorine dioxide radicals in the chlorine dioxide radical gas. Alternatively, the chlorine dioxide radical mist may be generated by dispersing and suspending condensates of chlorine dioxide radical gas, droplets of an aqueous solution containing chlorine dioxide radicals, or droplets of the evaporated material from a radical generating tank in a carrier gas. Examples of the carrier gas include air, nitrogen, rare gases, oxygen, and combinations thereof. Alternatively, when the raw material is in a gaseous state, a raw material gas containing chlorine dioxide radicals may be generated by using the gaseous raw material as the carrier gas.

[0026] The liquid phase functions as a reaction solvent and may be an aqueous phase, an organic phase, or both an aqueous phase and an organic phase. In this specification, the aqueous phase refers to a water phase, and the organic phase refers to an organic solvent phase. Furthermore, when the raw materials are liquid and only the raw materials are in the liquid phase, the raw materials also function as a reaction solvent.

[0027] The liquid phase may exist in a state where the aqueous phase and the organic phase are separated. The raw material and chlorine dioxide radicals may be dissolved in the organic phase. When the raw material is liquid, the raw material may be an organic phase (organic solvent). If the oxidation reaction product produced in the reaction step described below is water-soluble, it may be dissolved in the aqueous phase. In this case, the water-soluble oxidation reaction product can be recovered from the aqueous phase. When the organic phase has a higher specific gravity than the aqueous phase, the aqueous phase will be the upper layer and the organic phase will be the lower layer in the vertical direction. On the other hand, when the organic phase has a lower specific gravity than the aqueous phase, the organic phase will be the upper layer and the aqueous phase will be the lower layer in the vertical direction.

[0028] The organic solvent may be used alone or in combination of two or more. Examples of the organic solvent include hydrocarbon solvents, halogenated solvents, and fluorous solvents. In order to facilitate recovery of the oxidation reaction product, it is preferable that the organic solvent is less likely to cause side reactions in the reaction system and is easily separable from the aqueous phase. In one embodiment of the present invention, the liquid phase preferably contains a fluorous solvent.

[0029] Examples of hydrocarbon solvents include non-aromatic hydrocarbon solvents, aromatic hydrocarbon solvents, etc. Non-aromatic hydrocarbon solvents such as n-hexane and n-octane are preferred as hydrocarbon solvents because they are less likely to produce by-products such as chlorides.

[0030] In this specification, a halogenated solvent refers to a solvent in which all or most of the hydrogen atoms of a hydrocarbon have been substituted with halogen. The halogenated solvent is, for example, a solvent in which preferably 50% or more, more preferably 80% or more, and even more preferably 90% or more of the number of hydrogen atoms of the hydrocarbon have been substituted with halogen. Examples of the halogenated solvent include methylene chloride, chloroform, carbon tetrachloride, carbon tetrabromide, and the following fluorous solvents.

[0031] In this specification, the term "fluorous solvent" refers to a type of halogenated solvent in which all or most of the hydrogen atoms of a hydrocarbon have been substituted with fluorine atoms. The fluorous solvent is, for example, a solvent in which preferably 50% or more, more preferably 80% or more, and even more preferably 90% or more of the number of hydrogen atoms of the hydrocarbon have been substituted with fluorine atoms.

[0032] Fluorous solvents have the advantage of improving reaction efficiency due to their high solubility of the hydrocarbon raw material or its derivatives. Furthermore, fluorous solvents have the advantage of suppressing or preventing side reactions due to their low reactivity. Examples of such side reactions include oxidation of the solvent, hydrogen abstraction and chlorination reactions of the solvent by chlorine radicals, and reactions between radicals derived from the raw material and the solvent (e.g., reactions between methyl radicals and the solvent when the raw material is methane). Furthermore, fluorous solvents are poorly miscible with water, which allows for easy separation of the reaction system (fluorous phase) and the product recovery system (aqueous phase), thereby suppressing further oxidation of the product.

[0033] Examples of the fluorous solvent include solvents represented by the following formulas (F1) to (F6), and among them, CF in which n=4 in the following formula (F1) ３ (CF ２ ) ４ CF ３ That is, perfluorohexane (PFH) has a viscosity that is easy to handle (kinematic viscosity at 25°C: 0.38 mm ２ / s), which is preferable.

[0034] As the fluorous solvent, perfluoropolyether (PFPE) can also be suitably used. In this specification, perfluoropolyether refers to a compound having a structure in which two or more hydrocarbon groups, in which 90% or more of the hydrogen atoms have been substituted with fluorine atoms, are bonded via ether bonds.

[0035] <1-2. Reaction Step> The reaction step is a step in which the liquid phase is irradiated with light to obtain an oxidation reaction product of the raw material. The chlorine dioxide radicals (ClO ２ ・ ) is given light energy, the chlorine dioxide radical decomposes to chlorine radical (Cl ・ ) and molecular oxygen (O ２) is generated. As a result, the raw material introduced into the liquid phase is oxidized to generate an oxidation reaction product. Examples of oxidation reaction products include, but are not limited to, alcohols, carboxylic acids, aldehydes, and ketones. The amount of chlorine dioxide radicals is preferably 1 / 10,000 to 1,000 equivalents relative to the raw material. In this specification, the liquid phase irradiated with light in the reaction step may be referred to as the reaction phase.

[0036] In the reaction step, the wavelength of the irradiated light is not particularly limited and may be, for example, 200 nm or more and 800 nm or less. The light irradiation time is also not particularly limited and may be, for example, 1 minute or more and 1,000 hours or less. The reaction temperature is also not particularly limited and may be, for example, in the range of 0°C to 100°C. From the viewpoint of reaction efficiency, 40°C or less is preferable. The atmospheric pressure during the reaction is also not particularly limited and may be, for example, in the range of 0.1 MPa to 100 MPa. According to one embodiment of the present invention, for example, as shown in the examples described later, the reaction step or all of the steps including it can be carried out at room temperature (room temperature) and normal pressure (atmospheric pressure) without any heating, pressurization, decompression, or the like. "Room temperature" is not particularly limited and may be, for example, 5 to 35°C. Furthermore, according to one embodiment of the present invention, the reaction step or all of the steps including it can be carried out in the atmosphere without any inert gas replacement or the like.

[0037] The light source used in the light irradiation is not particularly limited, and excitation can be easily achieved by using, for example, visible light contained in natural light such as sunlight. Furthermore, for example, light sources such as xenon lamps, halogen lamps, fluorescent lamps, mercury lamps, and LED lamps may be used as appropriate instead of or in addition to natural light. Furthermore, a filter that cuts off wavelengths other than the required wavelengths may be used as appropriate.

[0038] For example, when methane is used as a raw material, methanol and formic acid may be produced. When ethane is used as a raw material, ethanol and acetic acid may be produced. When propane is used as a raw material, 2-propanol, propionic acid, and acetone may be produced. When cyclohexane is used as a raw material, cyclohexanol and cyclohexanone may be produced. When benzene is used as a raw material, phenol and benzoquinone may be produced. Reaction schemes predicted for these reactions are also disclosed in the aforementioned Patent Documents 1 and 2. The reaction scheme predicted when methane is used as a raw material is shown below.

[0039] The introduction step may be carried out before or simultaneously with the reaction step. That is, the raw material and gaseous chlorine dioxide radicals may be introduced into the liquid phase before light irradiation, or the raw material and gaseous chlorine dioxide radicals may be introduced into the liquid phase while light irradiation is being carried out.

[0040] The reaction step may include a step of adding chlorine dioxide radicals to the liquid phase while irradiating with light. For example, before irradiating with light, the raw material and gaseous chlorine dioxide radicals may be introduced into the liquid phase, and then the raw material and gaseous chlorine dioxide radicals may be introduced into the liquid phase while irradiating with light. By introducing additional reactive materials in this way, the reaction can be further promoted.

[0041] The liquid phase irradiated with light may be circulated and reused as a liquid phase into which the raw material and chlorine dioxide radicals are introduced, thereby enabling the reuse of unreacted raw material, enabling continuous production of the oxidation reaction product, and improving productivity.

[0042] <1-3. Radical Generation Step> The production method may include a step of generating chlorine dioxide radicals. This step is referred to as the radical generation step.

[0043] In the radical generation step, hypochlorous acid (HClO), chlorous acid (HClO ２Chlorine dioxide radicals may be generated from an aqueous solution of chlorous acid or its salt. For example, chlorous acid or its salt may be dissolved in water to spontaneously generate chlorine dioxide radicals from chlorite ions. In this case, the presence of an acid in the water, for example, further promotes the generation of chlorine dioxide radicals. Chlorous acid or its salt, as well as the acid, may be dissolved in water, or may be dispersed or precipitated in water. The mechanism by which chlorite radicals are generated from chlorite ions is presumed to be, for example, the following reaction mechanism. Alternatively, chlorine dioxide radicals may be generated in the gas phase by an electrochemical method. For example, when chlorite ions are used and an acid is added to water, the protons generated by the acid are preferably 0.0001 mol / L to 1 mol / L relative to the chlorite ions.

[0044] For example, hypochlorous acid or its salt can be reacted with acid in an aqueous solution to generate chlorine gas, and the resulting chlorine gas can be reacted with chlorous acid or its salt to generate chlorine dioxide radical.Hypochlorite can be, for example, sodium hypochlorite, potassium hypochlorite, lithium hypochlorite, etc.In order to efficiently generate chlorine dioxide radical, it is preferable to react sodium hypochlorite with hydrochloric acid, which contains about 3% of low salt.

[0045] Examples of salts of chlorous acid include sodium chlorite (NaClO ２ ), lithium chlorite (LiClO ２ ), potassium chlorite (KClO ２ ), magnesium chlorite (Mg(ClO ２ ) ２ ), calcium chlorite (Ca(ClO ２ ) ２ These may be used alone or in combination of two or more. Among them, sodium chlorite (NaClO ２ ) is preferred.

[0046] The acid is not particularly limited and may be, for example, an inorganic acid or an organic acid, or may be a Lewis acid or a Bronsted acid. Examples thereof include trifluoromethanesulfonic acid, trifluoroacetic acid, acetic acid, oxalic acid, citric acid, hydrofluoric acid, hydrochloric acid (hydrochloric acid), hydrobromic acid, hydroiodic acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, phosphoric acid, and phosphorous acid. Examples of easily available, inexpensive raw materials include hydrochloric acid and sulfuric acid.

[0047] Acids that are difficult to vaporize are preferred because they are less likely to be mixed into the reaction system that produces the oxidation reaction product. For example, sulfuric acid is more difficult to vaporize than hydrochloric acid.

[0048] The production method may include a step of generating chlorine dioxide radicals in a reaction system (second reaction system) isolated from a reaction system (first reaction system) that generates the oxidation reaction product of the raw material. For example, in the reaction system isolated from the reaction system that generates the oxidation reaction product of the raw material, chlorine dioxide radicals may be generated from an aqueous solution of chlorous acid or its salt, or chlorine dioxide radicals may be generated by mixing an acid with an aqueous solution of chlorous acid or its salt. In such cases, using a salt of chlorous acid in the chlorine dioxide radical generation step is preferable because inorganic salts do not accumulate in the reaction system that generates the oxidation reaction product of the raw material. An isolated reaction system means that the liquid phase of the first reaction system and the solution of the second reaction system are not in direct contact with each other.

[0049] <1-4. Other Steps> The production method may include a step of introducing oxygen into the liquid phase before the reaction step. By introducing oxygen into the liquid phase, the oxidation reaction of the raw material can be further promoted. Examples of a method for introducing oxygen into the liquid phase include a method of blowing air or oxygen gas into the liquid phase.

[0050] The production method may include a step of recovering the oxidation reaction product of the raw material from the liquid phase irradiated with light. The method for recovering the oxidation reaction product of the raw material from the liquid phase is not particularly limited, and examples thereof include extraction from an aqueous phase, extraction with an organic solvent, distillation, fractional distillation, filtration, crystallization, and the like. When the oxidation reaction product is continuously produced by circulating the liquid phase, it is preferable to recover the oxidation reaction product while continuing or temporarily interrupting the continuous production. This can prevent the oxidation reaction product from being excessively oxidized to produce carbon dioxide and the like, and can improve the yield of the desired oxidation reaction product.

[0051] For example, the step of recovering the oxidation reaction product of the raw material may be a step of separating the irradiated liquid phase into an aqueous phase and an organic phase, and recovering the target substance from the aqueous phase. For example, when the liquid phase contains an aqueous phase and an organic phase, the liquid phase can be allowed to stand to separate the aqueous phase and the organic phase. The water-soluble oxidation reaction product can be recovered from the separated aqueous phase. When the liquid phase contains only an organic phase, the liquid phase can be introduced into water, allowed to stand to separate the aqueous phase and the organic phase, and the oxidation reaction product dissolved in water can be recovered.

[0052] The production method may include a step of stirring the liquid phase into which the raw material and the chlorine dioxide radicals have been introduced. This can further promote the oxidation reaction. Stirring may be performed after the raw material and the chlorine dioxide radicals have been introduced into the liquid phase, or while the raw material and the chlorine dioxide radicals are being introduced into the liquid phase. Stirring may also be performed before irradiating the liquid phase with light, while irradiating the liquid phase with light, or after irradiating the liquid phase with light. The liquid phase may also be stirred while circulating.

[0053] [2. Apparatus for Producing Oxidation Reaction Products] An apparatus for producing oxidation reaction products according to one embodiment of the present invention includes a liquid-phase storage unit for storing a liquid phase, a raw material supply unit for introducing a raw material that is a hydrocarbon or a derivative thereof into the liquid phase, a chlorine dioxide radical supply unit for introducing gaseous chlorine dioxide radicals into the liquid phase, and a reaction unit equipped with a light source for irradiating the liquid phase with light. The production apparatus can implement the above-described method for producing oxidation reaction products. The matters already explained in [1. Method for Producing Oxidation Reaction Products] can be referred to, and therefore will not be explained again below. When the raw material is in a liquid phase, the raw material supply unit introduces the raw material into the liquid-phase storage unit.

[0054] 1 to 5 are schematic diagrams showing the configuration of an apparatus for producing an oxidation reaction product according to one embodiment of the present invention. The following will explain the configuration of the apparatus for producing an oxidation reaction product according to one embodiment of the present invention.

[0055] The manufacturing apparatus 101 shown in FIG. 1 includes a liquid-phase storage section 10, a raw material supply section 20, a chlorine dioxide radical supply section 30, and a light source 40. Here, the liquid-phase storage section 10 also serves as a reaction section. The raw material supply section 20 and the chlorine dioxide radical supply section 30 are each connected to the liquid-phase storage section 10 via piping. This allows the raw material and gaseous chlorine dioxide radicals to be introduced into the liquid phase. The light source 40 is provided at a position where it can irradiate the liquid-phase storage section 10 with light. By irradiating the liquid phase with light using the light source 40, the oxidation reaction of the raw material can be promoted and an oxidation reaction product can be obtained.

[0056] The liquid phase storage section 10 has a space for storing a liquid phase. The liquid phase storage section 10 is a reaction vessel for reacting the raw material with chlorine dioxide radicals, and is made of a material that transmits light from the light source 40. Here, as described above, the liquid phase storage section 10 also serves as a reaction section. The liquid phase storage section 10 may also serve as a product recovery section 60, which will be described later.

[0057] The raw material supply unit 20 may supply the raw material from a cylinder containing a raw material gas. Alternatively, the raw material supply unit 20 may be equipped with a device for generating the raw material gas. The chlorine dioxide radical supply unit 30 may supply chlorine dioxide radicals from a cylinder containing a gas or mist containing chlorine dioxide radicals. Alternatively, the chlorine dioxide radical supply unit 30 may be equipped with a chlorine dioxide radical generator (described below), and the generated chlorine dioxide radicals may be introduced into the liquid phase using a carrier gas. The carrier gas may be nitrogen, oxygen, air, carbon dioxide, methane, or the like.

[0058] The light source 40 is not particularly limited, but examples thereof include a xenon lamp, a halogen lamp, a fluorescent lamp, a mercury lamp, and an LED lamp. The light source 40 may be provided either inside or outside the liquid-phase storage unit 10, but in Fig. 1 it is provided outside the liquid-phase storage unit 10. The light source 40 may be a condensing light source or a surface-irradiating light source.

[0059] The manufacturing apparatus 101 includes an oxygen supply unit 50 for introducing oxygen into the liquid phase. The oxygen supply unit 50 is connected to the liquid phase accommodation unit 10 via a pipe. The oxygen supply unit 50 may supply oxygen from a cylinder containing oxygen gas or air. Alternatively, the oxygen supply unit 50 may include an oxygen gas generating device or an air compressor.

[0060] The production apparatus 101 includes a product recovery section 60 for recovering the oxidation reaction product from the liquid phase irradiated with light. For example, the liquid phase can be separated into an aqueous phase and an organic phase in the liquid phase storage section 10, and the oxidation reaction product can be recovered from the aqueous phase by the product recovery section 60. The product recovery section 60 is connected to the liquid phase storage section 10 via a pipe, and the end of the pipe is located in the aqueous phase. For example, the product recovery section 60 can be a recovery tank that recovers and stores the aqueous phase containing the water-soluble oxidation reaction product from the liquid phase after the reaction.

[0061] The manufacturing apparatus 102 shown in FIG. 2 includes a liquid-phase storage section 10, a light source 40, and a product recovery section 60. In the manufacturing apparatus 102, the chlorine dioxide radical supply section includes a chlorine dioxide radical generation section 31 for generating chlorine dioxide radicals. The chlorine dioxide radical generation section 31 may have a space for accommodating an aqueous solution of chlorous acid or its salt. This allows chlorine dioxide radicals to be generated in a reaction system isolated from a reaction system that generates oxidation reaction products of the raw material. Alternatively, the chlorine dioxide radical generation section 31 may be an apparatus that generates chlorine dioxide radicals in a gas phase by an electrochemical method.

[0062] The chlorine dioxide radical gas generated in the chlorine dioxide radical generating unit 31, or the aqueous solution and mist containing chlorine dioxide radicals, can be supplied to the liquid-phase containing unit 10 using a carrier gas. That is, the gas supplied to the chlorine dioxide radical generating unit can introduce chlorine dioxide radicals in a gaseous state into the liquid phase. In the manufacturing apparatus 102, the raw material supply unit 21 is connected to the chlorine dioxide radical generating unit 31 via a pipe. This allows the raw material gas to be supplied to the chlorine dioxide radical generating unit 31, and chlorine dioxide radicals can be supplied in a gaseous state to the liquid-phase containing unit 10 using the raw material gas as a carrier gas. That is, the raw material gas containing chlorine dioxide radicals can be supplied to the liquid-phase containing unit 10.

[0063] 3 includes a static separation tank 90, a raw material supply unit 20, a chlorine dioxide radical supply unit (chlorine dioxide radical generation unit 31), a light source 40, an oxygen supply unit 50, and a product recovery unit 60. In the production apparatus 103, the static separation tank 90 serves both as a liquid phase storage unit and a reaction unit.

[0064] The manufacturing apparatus 103 includes a flow path 110 (circulation flow path) for circulating the irradiated liquid phase to a liquid-phase storage section (here, the static separation tank 90). The flow path 110 connects the liquid-phase storage section and the reaction section and circulates the liquid phase. A liquid-transfer pump 80 for circulating the liquid phase is provided midway through the flow path 110. The flow path 110 is connected to a raw material supply section 20, a chlorine dioxide radical supply section (chlorine dioxide radical generating section 31), and an oxygen supply section 50. As a result, the liquid phase containing the raw material and chlorine dioxide radicals is supplied to the static separation tank 90. ​​Furthermore, the liquid phase sent from the static separation tank 90 to the flow path 110 circulates through a path that passes through the raw material supply section 20 and the chlorine dioxide radical supply section and returns to the static separation tank 90. ​​This allows the liquid phase after the reaction to be reused as the liquid phase into which the raw material and chlorine dioxide radicals are introduced, thereby also allowing unreacted raw materials to be reused. The raw material gas, carrier gas, and oxygen gas that are not dissolved in the organic phase are released to the outside from the settling separation tank 90. ​​The raw material gas that is not dissolved in the organic phase may be recovered and reused.

[0065] In production apparatus 103, flow path 110 connects the vertically lower portion of still separation tank 90 with the vertically upper portion of still separation tank 90. ​​When the liquid phase contains an aqueous phase and an organic phase having a larger specific gravity than the aqueous phase, the organic phase circulates from the vertically lower portion of still separation tank 90 through flow path 110 and returns to the vertically upper portion of still separation tank 90. ​​The aqueous phase remains in still separation tank 90.

[0066] The manufacturing apparatus 103 has, as light sources 40, light source 40a provided at a position where it can irradiate light onto the flow path 110, and light source 40b provided at a position where it can irradiate light onto the still standing separation tank 90. ​​Light source 40a is provided at a position where it can irradiate light onto the region of the flow path 110 downstream of the raw material supply unit 20 and the chlorine dioxide radical supply unit, up to the still standing separation tank 90. ​​Light source 40b may be provided inside the still standing separation tank 90. ​​Either light source 40a or light source 40b may be used, or both may be used. The flow path and still standing separation tank 90 may be made of a material that transmits light from light source 40. In FIG. 3 , a part of the flow path 110 and the still standing separation tank 90 are the reaction unit.

[0067] When the still separation tank 90 is large, it may be difficult for light to reach the interior using only the light source 40b, and light may reach the interior more easily by using the light source 40a to irradiate the flow path 110. Furthermore, by providing a winding flow path 110 and using a surface-irradiating light source as the light source 40a, the winding flow path 110 can be irradiated with light all at once, thereby lengthening the irradiation time and improving the reaction efficiency.

[0068] In the manufacturing apparatus 103, the chlorine dioxide radical supply unit includes a chlorine dioxide radical generating unit 31, a chlorine dioxide radical generating source storage unit 32 having a space for storing an aqueous solution of chlorous acid or its salt, a liquid pump 33 for supplying the chlorine dioxide radical generating source, and a carrier gas supply unit 34 for supplying a carrier gas. In the manufacturing apparatus 103, the chlorine dioxide radical generating unit 31 stores an aqueous solution of an acid. By using the liquid pump 33 to send the aqueous solution of chlorous acid or its salt from the chlorine dioxide radical generating source storage unit 32 to the chlorine dioxide radical generating unit 31, the chlorous acid or its salt and the acid react to promote the generation of chlorine dioxide radicals. By blowing a carrier gas from the carrier gas supply unit 34 into the chlorine dioxide radical generating unit 31, chlorine dioxide radicals can be supplied in a gaseous state to the flow path 110. The carrier gas supply unit 34 may be a cylinder containing a carrier gas. Because chlorine dioxide radicals are introduced into the liquid phase in a gaseous state, inorganic salts are not contained in the liquid phase. This is preferable because the flow path 110 is not clogged with inorganic salts.

[0069] In the settling separation tank 90, the irradiated liquid phase is allowed to stand, and the product recovery section 60 can recover the oxidation reaction product of the raw material from the liquid phase. The liquid phase may contain an organic phase and an aqueous phase. For example, if the oxidation reaction produces water in addition to the oxidation reaction product, even if the liquid phase contains only the organic phase before the reaction starts, the amount of the aqueous phase will increase as the oxidation reaction progresses. The organic phase and the aqueous phase are separated in the settling separation tank 90. ​​FIG. 3 shows the liquid phase in the settling separation tank as being divided into two layers. If the specific gravity of the organic phase is greater than that of the aqueous phase, the upper layer will be the aqueous phase and the lower layer will be the organic phase. If the oxidation reaction product is more soluble in the aqueous phase than the organic phase, the oxidation reaction product will dissolve in the aqueous phase. Therefore, the product recovery section 60 can use a pump to remove the aqueous phase from the settling separation tank 90 and extract the oxidation reaction product from the aqueous phase. The end of flow path 110 is located below (below the center of) settling separation tank 90, and the organic phase is circulated via flow path 110. The aqueous phase, which is the upper layer, is not circulated and remains in settling separation tank 90, making it easy to remove the aqueous phase from settling separation tank 90 and extract the oxidation products. Water may be replenished into settling separation tank 90 as needed.

[0070] The production apparatus 103 includes an agitator 70 for agitating the liquid phase containing the raw material and chlorine dioxide radicals. The agitator 70 may be an agitator capable of continuous agitation, such as an in-line mixer, or an agitator equipped with a stirring blade. In FIG. 3, the agitator 70 is provided midway through the flow path 110, but it may also be provided inside the liquid phase storage unit.

[0071] The production apparatus 104 shown in Fig. 4 includes a static separation tank 90 that also serves as a liquid phase storage section, a liquid transfer pump 80, a raw material supply section 20, a light source 40, and a product recovery section 60. The production apparatus 104 is mostly the same as the production apparatus 103 in terms of its configuration, but differs in that a chlorine dioxide radical supply section is provided at the position where light from the light source 40 is irradiated on the flow path 110. In Fig. 4, the region of the flow path 110 irradiated with light by the light source 40 is the reaction section. A description of the same apparatus configuration as that of Fig. 3 will be omitted.

[0072] The manufacturing apparatus 104 includes a chlorine dioxide radical supply unit (chlorine dioxide radical generator 31a, chlorine dioxide radical source storage unit 32a, liquid pump 33a, and carrier gas supply unit 34a) that introduces chlorine dioxide radicals upstream of the light source 40, and a chlorine dioxide radical supply unit (chlorine dioxide radical generator 31b, chlorine dioxide radical source storage unit 32b, liquid pump 33b, and carrier gas supply unit 34b) that introduces chlorine dioxide radicals into the region irradiated with light by the light source 40. This allows the raw material and gaseous chlorine dioxide radicals to be introduced into the liquid phase before light irradiation, and further allows chlorine dioxide radicals to be introduced into the liquid phase during light irradiation. This allows chlorine dioxide radicals reduced by the oxidation reaction of the raw material proceeding with light irradiation to be supplied to the reaction phase, thereby efficiently obtaining an oxidation product. Although not shown, a raw material supply unit may be further disposed in the region irradiated with light by the light source 40, similar to the chlorine dioxide radical supply unit.

[0073] The manufacturing apparatus 104 is equipped with an agitator 70a provided upstream of the light source 40 and an agitator 70b provided in an area irradiated with light by the light source 40. This allows the separated gas and solvent to be re-mixed, and the reaction materials introduced at multiple locations to be stirred, thereby further promoting the oxidation reaction. Although not shown in FIG. 4, a light source 40b that irradiates light into the settling separation tank 90 may be installed.

[0074] The manufacturing apparatus may have two or more modules each including the raw material supply unit, the chlorine dioxide radical supply unit, and the light source. The manufacturing apparatus 105 shown in Fig. 5 includes a module 105a including a raw material supply unit 20a, a chlorine dioxide radical supply unit 30a, an agitator 71a, and a light source 41a, and a module 105b including a raw material supply unit 20b, a chlorine dioxide radical supply unit 30b, an agitator 71b, and a light source 41b.

[0075] The manufacturing apparatus 105 includes a flow path 111 that passes through modules 105a and 105b. The raw material supply unit 20a and the chlorine dioxide radical supply unit 30a are connected to the flow path 111. In the flow path 111, an agitator 71a is provided in a region downstream of the raw material supply unit 20a and the chlorine dioxide radical supply unit 30a. The light source 41a is provided in a position in the flow path 111 that allows it to irradiate the region downstream of the agitator 71a with light. The raw material supply unit 20b and the chlorine dioxide radical supply unit 30b are connected to a region downstream of the light source 41a in the flow path 111. The agitator 71b is provided in a region downstream of the raw material supply unit 20b and the chlorine dioxide radical supply unit 30b in the flow path 111. The light source 41b is provided in a position in the flow path 111 that allows it to irradiate the region downstream of the agitator 71b with light. In FIG. 5 , the region of the flow path 111 that is irradiated with light by the light sources 41a and 41b is the reaction zone. Although not shown, only the agitator 71b and the light source 41b may be disposed downstream of the module 105a. By promoting dissolution of the raw materials and chlorine dioxide radicals that have not dissolved in the liquid phase and irradiating them with light, the raw materials and the like can be consumed efficiently.

[0076] Although not shown, one or more oxygen supply units may be connected to flow path 111. Furthermore, as in Figure 3 or 4, one or more liquid phase storage units, product recovery units, or static separation tanks may be connected to flow path 111. For example, a liquid phase storage unit may be connected to the start point of flow path 111, and a product recovery unit or static separation tank may be connected to the end point. Alternatively, a vertically lower portion of a static separation tank that also serves as a liquid phase storage unit and a product recovery unit may be connected to a vertically upper portion by flow path 111, and the liquid phase may be configured to circulate.

[0077] According to one embodiment of the present invention, oxidation reaction products can be efficiently produced using hydrocarbons or their derivatives as raw materials. For example, hydrocarbons or their derivatives can be efficiently converted into oxidation reaction products using a very simple method involving only light irradiation, even under extremely mild conditions such as room temperature and atmospheric pressure. Furthermore, oxidation reaction products with extremely high industrial utility, such as alcohols, carboxylic acids, ketones, phenols, and quinones, can also be efficiently obtained. Furthermore, hydrocarbons such as natural gas can be effectively used as raw materials. Therefore, according to one embodiment of the present invention, compounds that have traditionally been synthesized primarily from feedstocks such as petroleum and coal can be synthesized very simply and efficiently from feedstocks such as natural gas, thereby making a significant contribution to resolving energy issues and the like. Such effects can also contribute to achieving, for example, Goal 7 of the United Nations' Sustainable Development Goals (SDGs), "Ensure access to affordable, reliable, sustainable, and modern energy for all."

[0078] Furthermore, according to one embodiment of the present invention, it is possible to obtain an oxidation reaction product of the raw material without using, for example, a toxic heavy metal catalyst. As described above, this allows the reaction to be carried out under extremely mild conditions, such as room temperature and atmospheric pressure, and also makes it possible to efficiently obtain the oxidation reaction product using a method that places an extremely small burden on the environment. Such effects may also contribute to the achievement of SDGs Goal 14, "Conserve and sustainably use the oceans, seas and marine resources for sustainable development," and Goal 15, "Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss."

[0079] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0080] One embodiment of the present invention may include the following features: <1> A method for producing an oxidation reaction product, comprising: an introduction step of introducing a raw material, which is a hydrocarbon or a derivative thereof, and gaseous chlorine dioxide radicals into a liquid phase; and a reaction step of irradiating the liquid phase with light to obtain an oxidation reaction product of the raw material. <2> A method for producing an oxidation reaction product according to <1>, wherein the light-irradiated liquid phase is circulated and reused as the liquid phase into which the raw material and chlorine dioxide radicals are introduced. <3> A method for producing an oxidation reaction product according to <1> or <2>, comprising a step of producing chlorine dioxide radicals in a reaction system isolated from a reaction system producing an oxidation reaction product of the raw material. <4> A method for producing an oxidation reaction product according to any one of <1> to <3>, comprising a step of separating the light-irradiated liquid phase into an aqueous phase and an organic phase and recovering a target substance from the aqueous phase. <5> A method for producing an oxidation reaction product according to any one of <1> to <4>, wherein the liquid phase contains a fluorous solvent. <6> The method for producing an oxidation reaction product according to any one of <1> to <5>, wherein the reaction step includes a step of adding the chlorine dioxide radicals to the liquid phase while irradiating with light. <7> The method for producing an oxidation reaction product according to any one of <1> to <6>, wherein the reaction step includes a step of introducing oxygen into the liquid phase before the reaction step. <8> An apparatus for producing an oxidation reaction product, comprising: a liquid phase storage unit for storing the liquid phase, a raw material supply unit for introducing a raw material that is a hydrocarbon or a derivative thereof into the liquid phase, a chlorine dioxide radical supply unit for introducing gaseous chlorine dioxide radicals into the liquid phase, and a reaction unit equipped with a light source for irradiating the liquid phase with light. <9> The apparatus for producing an oxidation reaction product according to <8>, comprising a flow path connecting the liquid phase storage unit and the reaction unit and for circulating the liquid phase. <10> The apparatus for producing an oxidation reaction product according to <8> or <9>, wherein the chlorine dioxide radical supply unit includes a chlorine dioxide radical generation unit for generating chlorine dioxide radicals, and the chlorine dioxide radicals are introduced into the liquid phase by a gas supplied to the chlorine dioxide radical generation unit. <11> The apparatus for producing an oxidation reaction product according to any one of <8> to <10>, which includes two or more modules each including the raw material supply unit, the chlorine dioxide radical supply unit, and the light source.<12> The apparatus for producing an oxidation reaction product according to any one of <8> to <11>, further comprising an oxygen supply unit for introducing oxygen into the liquid phase.<13> The apparatus for producing an oxidation reaction product according to any one of <8> to <12>, further comprising a product recovery unit for separating the liquid phase in the liquid phase storage unit into an aqueous phase and an organic phase and recovering the oxidation reaction product from the aqueous phase.<14> The apparatus for producing an oxidation reaction product according to any one of <8> to <13>, further comprising a stirrer for stirring the liquid phase into which the raw material and the chlorine dioxide radicals have been introduced.

[0081] An embodiment of the present invention will be described below.

[0082] [Evaluation method] - Quantitative determination of the product The yield of the oxidation reaction product is determined by the amount of the oxidation reaction product after the reaction. １ H-NMR was measured, and the peak intensity ratios of each component were compared and calculated. NMR measurements were performed using the following equipment and measurement conditions. The amount of oxide produced was quantified using sodium 3-(trimethylsilyl)propionate-2,2,3,3-d4 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as an internal standard for NMR quantification. Equipment: JNM-ECS-400 FT NMR equipment, 400 MHz, manufactured by JEOL Ltd. Measurement conditions Solvent: D ２ O Temperature: 20° C. Number of times accumulated: 16 Example 1 An experiment was carried out using an apparatus having the same configuration as the production apparatus 101 shown in FIG. 1 except that the product recovery section 60 was not provided.

[0083] <Radical generation step> 100 mL of pure water, 2 g of sodium chlorite (manufactured by Sigma-Aldrich, technical grade 80%), and 2 mL of hydrochloric acid (manufactured by Kishida Chemical, special grade, 37%) were placed in a light-shielding sealed container made of PFA (perfluoroalkoxyalkane) to prepare chlorine dioxide radicals. This light-shielding sealed container was used as a chlorine dioxide radical supply unit.

[0084] <Oxidation Reaction Step> 25 mL of perfluorohexane and 5 mL of water were placed in a 50 mL glass reaction vessel, and a silicone stopper with a gas injection tube was attached. The reaction vessel separated into two layers: a lower layer of perfluorohexane (organic phase) and an upper layer of water (aqueous phase). The tube was connected to a chlorine dioxide radical supply unit. 1. 850 mL of methane (an excess amount relative to the chlorine dioxide radicals) was bubbled into the perfluorohexane in the reaction vessel to dissolve it. 2. In parallel with the introduction of the methane, nitrogen was flowed into the chlorine dioxide radical supply unit at 25 mL / min, and nitrogen gas containing gaseous chlorine dioxide radicals (0.096 g) was bubbled into the perfluorohexane in the reaction vessel. 3. While introducing methane and chlorine dioxide radicals into perfluorohexane as described above, a single 365 nm focused LED lamp (Hololight HL5800 HLKK60UV365FM-V, manufactured by Pi Photonics Inc.) was turned on to irradiate the reaction vessel with light, and the stirrer was activated to stir the contents of the reaction vessel, allowing the reaction to proceed at room temperature and atmospheric pressure for 34 minutes. The LED lamp was then turned off, and the stirrer and the supply of nitrogen and methane were stopped. 4. The reaction vessel was allowed to stand for 10 minutes, allowing the liquid phase to separate into an aqueous phase and an organic phase. A 100 μL sample for quantification was taken from the aqueous phase. 5. A new aqueous phase containing chlorine dioxide radicals was prepared in a separate light-tight, sealed PFA container, similar to the radical generation process described above.

[0085] The steps 1 to 5 were repeated 11 times with the perfluorohexane and water in the reaction vessel. That is, the light-shielding sealed vessel used as the chlorine dioxide radical supply unit in step 2 was not reused, but a new one prepared in step 5 was used, and the reaction was carried out a total of 12 times. The required time was 12 hours. After the reaction was completed, the volume of the aqueous phase in the reaction vessel was 3.9 mL. １ Each product was quantified by H-NMR.

[0086] Comparative Example 1 Radical Generation Step 0.15 g of sodium chlorite and 0.15 mL of hydrochloric acid were placed in a container containing 5 mL of pure water, and the mixture was stirred for 3 minutes under light-shielded conditions using a stirrer. The mixture was then allowed to stand for 30 minutes to stabilize the amount of chlorine dioxide generated. This resulted in the preparation of an aqueous phase containing chlorine dioxide radicals. The aqueous phase containing chlorine dioxide radicals was yellow and transparent, and the amount of chlorine dioxide radicals contained in the aqueous phase under these conditions was quantified using an ultraviolet-visible spectrophotometer (UV-VIS, Agilent Cary 8454 manufactured by Agilent Technologies, Inc.) and found to be 0.096 g.

[0087] <Oxidation Reaction Step> 25 mL of perfluorohexane was placed in a 50 mL glass reaction vessel. 1. 850 mL of methane was dissolved in the perfluorohexane in the reaction vessel by bubbling. 2. The entire aqueous phase was then quickly placed in the reaction vessel and capped with a silicone stopper. 3. A single 365 nm concentrating LED lamp (Hololight HL5800 HLKK60UV365FM-V, manufactured by Pi Photonics Inc.) was turned on to irradiate the reaction vessel with light, and the stirrer was operated to stir the contents of the reaction vessel, allowing the reaction to proceed for 34 minutes at room temperature and atmospheric pressure. After confirming that the aqueous phase had changed from yellow and transparent to colorless and transparent, the LED lamp was turned off and the stirrer was stopped. Because the chlorine dioxide radical solution absorbs the light from the 365 nm LED lamp, the colorless and transparent aqueous phase indicates that chlorine dioxide radicals (yellow) had converted to chlorine radicals and oxygen (colorless). 4. The reaction vessel was allowed to stand for 10 minutes, allowing the liquid phase to separate into an aqueous phase and an organic phase. A 100 μL sample for quantification was taken from the aqueous phase. 5. The aqueous phase was recovered from the reaction vessel, and sodium chlorite and hydrochloric acid were added to the recovered aqueous phase in the same manner as in the radical generation step described above to prepare an aqueous phase containing chlorine dioxide radicals.

[0088] The 25 mL of perfluorohexane remaining in the reaction vessel was subjected to 11 cycles of steps 1 to 5. Specifically, the aqueous phase was recovered from the reaction vessel, replenished with the consumed sodium chlorite and hydrochloric acid, and then returned to the reaction vessel. This process was repeated (reusing the aqueous phase containing chlorine dioxide radicals) for a total of 12 reactions. The reaction took 12 hours.１ Each product was quantified by H-NMR. When the amount of formic acid produced per reaction was less than 10% of the maximum, it was determined that the amount of formic acid produced had saturated, and the test was terminated after 12 reactions. The volume of the aqueous phase in the reaction vessel after the reaction was completed was 3.9 mL. １ Each product was quantified by H-NMR.

[0089] Comparative Example 2 Radical Generation Step 0.6 mL of a 25% aqueous sodium chlorite solution and 0.15 mL of hydrochloric acid were added to a container containing 4.25 mL of pure water, and the mixture was stirred for 3 minutes under a light-shielded condition using a stirrer, and then allowed to stand for 30 minutes to prepare an aqueous phase containing chlorine dioxide radicals.

[0090] <Oxidation Reaction Step> 25 mL of perfluorohexane was placed in a 100 mL glass reaction vessel. 1. 850 mL of methane was dissolved in the perfluorohexane in the reaction vessel by bubbling. 2. The aqueous phase was then quickly placed in the reaction vessel and capped with a silicone stopper. 3. A single 365 nm concentrating LED lamp (Hololight HL5800 HLKK60UV365FM-V, manufactured by Pi Photonics Inc.) was turned on to irradiate the reaction vessel with light, and the stirrer was operated to stir the contents of the reaction vessel, allowing the reaction to proceed for 3 minutes at room temperature and atmospheric pressure. After confirming that the aqueous phase had changed from yellow and transparent to colorless and transparent, the LED lamp was turned off and the stirrer was stopped. 4. The reaction vessel was allowed to stand for 10 minutes, allowing the liquid phase to separate into an aqueous phase and an organic phase. 100 μL of a sample for quantification was collected from the aqueous phase. 5. In another light-shielding sealed PFA container, a new aqueous phase containing chlorine dioxide radicals was prepared in the same manner as in the radical generation step described above.

[0091] The steps 1 to 5 were repeated 11 times for the perfluorohexane / water mixed solution in the reaction vessel. In other words, the process of adding a freshly prepared aqueous phase to the reaction vessel was repeated 12 times in total. The reaction time was 12 hours. After the reaction was completed, the amount of aqueous phase in the reaction vessel was 58.9 mL. １ Each product was quantified by H-NMR.

[0092] Example 2 An experiment was carried out using an apparatus having the same configuration as the manufacturing apparatus 103 shown in FIG.

[0093] <Radical Generation Step> A 10% aqueous sodium chlorite solution was added dropwise at 0.2 mL / min to a light-tight, sealed PFA container containing 223.3 g of 1 M aqueous sulfuric acid solution to generate chlorine dioxide radical gas. The 1 M aqueous sulfuric acid solution was prepared by mixing 23.3 g of sulfuric acid (special grade, manufactured by Kishida Chemical Co., Ltd.) with 200 mL of water. The 10% aqueous sodium chlorite solution was prepared by diluting sodium chlorite (80% technical grade, manufactured by Sigma-Aldrich Co., Ltd.) 10 times with pure water.

[0094] <Oxidation Reaction Step> 700 mL of perfluorohexane (manufactured by Tokyo Chemical Industry Co., Ltd., purity 96% or higher) and 30 mL of water were placed in a cylindrical glass reaction vessel serving as a stationary separation tank 90. ​​The organic phase (perfluorohexane) was circulated at 200 mL / min by a liquid transfer pump 80.

[0095] Chlorine dioxide radical gas generated in the chlorine dioxide radical generator was introduced into the circulating organic phase using a carrier gas (nitrogen, flow rate 100 mL / min). Similarly, methane gas (high-purity methane 99.9%) was fed into the organic phase at a flow rate of 100 mL / min. Light was irradiated using three 365 nm LED lamps (Hololight HL5800 HLKK60UV365FM-V manufactured by Pi Photonics Co., Ltd.) as light source 40b, and the reaction was carried out at room temperature without pressure for 65 hours. In Example 2, the light source 40a and oxygen supply unit 50 shown in FIG. 3 were not used. After 65 hours, a sample was collected from the aqueous phase in the settling separation tank 90. １ The concentration (wt %) of each product in the aqueous phase was calculated by H-NMR.

[0096] Example 3 An experiment was carried out using an apparatus having the same configuration as the manufacturing apparatus 102 shown in FIG.

[0097] <Radical Generation Step> As the chlorine dioxide radical generating unit 31, 100 mL of pure water, 2 mL of hydrochloric acid, and 2 g of sodium chlorite were placed in a light-shielding sealed container made of PFA, and chlorine dioxide radical gas was generated.

[0098] <Oxidation Reaction Step> 5 mL of pure water and 25 mL of perfluoropolyether 1 (GALDEN SV-110, manufactured by Solvay Specialty Polymers, kinematic viscosity at 25°C: 0.77 mm) were added to a 50 mL glass reaction vessel serving as the liquid phase container 10. ２ / s) was placed in the flask, and a silicone stopper having a tube for injecting gas was attached.

[0099] Methane gas was introduced into the light-shielded sealed container in which chlorine dioxide radical gas had been generated at a rate of 25 mL / min, and the chlorine dioxide radical gas and methane gas were blown into the perfluoropolyether 1 in the glass reaction container. A single condensing LED lamp with a wavelength of 365 nm was turned on as the light source 40, and the glass reaction container was irradiated with light, allowing the reaction to proceed for 34 minutes at room temperature and atmospheric pressure. Thereafter, the supply of methane was stopped, and the LED lamp was extinguished. The reaction time was set to 34 minutes in order to achieve a total input amount of methane gas of 850 mL and a radical generation amount of 0.096 g. A sample was collected from the aqueous phase in the glass reaction container, １ The weight of each product was calculated by H-NMR.

[0100] Example 4: 25 mL of pure water was placed in a 50 mL glass reaction vessel. The reaction was carried out in the same manner as in Example 3, except that water was used as the reaction phase instead of perfluoropolyether 1. Then, a sample was taken. １ The weight of each product was calculated by H-NMR.

[0101] Comparative Example 3: A reaction was carried out in the same manner as in Example 3, except that a 50 mL glass reaction vessel was plugged with a silicone stopper equipped with a gas injection tube without adding any liquid (pure water and perfluoropolyether 1). The product in the glass reaction vessel was then washed out with 5 mL of pure water for product extraction and recovered. A sample was taken from the recovered aqueous solution. １ The weight of each product was calculated by H-NMR.

[0102] Example 5 An experiment was conducted using an apparatus having a similar configuration to the manufacturing apparatus 103 shown in Fig. 3, with light irradiation performed at the position of the light source 40b. In Example 5, the light source 40a and the oxygen supply unit 50 shown in Fig. 3 were not used. In Example 5, the same apparatus as in Example 2 was used, but the light source and circulation speed were different.

[0103] <Radical Generation Step> Chlorine dioxide radical gas was generated in the same manner as in Example 2.

[0104] <Oxidation Reaction Step> 850 mL of perfluorohexane and 30 mL of water were placed in a cylindrical glass reaction vessel serving as a static separation tank 90. ​​The organic phase (perfluorohexane) was circulated at 100 mL / min by a liquid transfer pump 80.

[0105] Chlorine dioxide radical gas generated in the chlorine dioxide radical generator was introduced into the circulating organic phase using a carrier gas (nitrogen, flow rate 100 mL / min). Similarly, methane gas was fed into the organic phase at a flow rate of 100 mL / min. Light was irradiated using two condenser LED lamps with a wavelength of 365 nm at the position of light source 40b, and the reaction was carried out at room temperature without pressure for 7 hours. The LED lamps used were Hololite HL5800 HLKK60UV365FM-V manufactured by Pi Photonics Co., Ltd. Samples were collected from the aqueous phase in the settling separation tank 90 every hour. １ The average production amount per hour (mg / h) of each product was calculated by H-NMR.

[0106] Example 6 Instead of perfluorohexane, perfluoropolyether 1 (GALDEN SV-110, manufactured by Solvay Specialty Polymers, kinematic viscosity at 25°C: 0.77 mm) was used. ２ The same procedure as in Example 5 was carried out except that a 100% aqueous solution of 1,000 sucrose was used. A sample was taken from the aqueous phase of the still separation tank 90, １ The average production amount per hour (mg / h) of each product was calculated by H-NMR.

[0107] Example 7 The same method as in Example 6 was carried out in the production apparatus of FIG. 3 , except that compressed air was introduced from the oxygen supply unit 50 at a flow rate of 60 mL / min. A sample was taken from the aqueous phase in the still separation tank 90, １The average production amount per hour (mg / h) of each product was calculated by H-NMR.

[0108] Example 8 An experiment was conducted using an apparatus having a similar configuration to the manufacturing apparatus 103 shown in Fig. 3, with light irradiation performed at the position of the light source 40a. In Example 8, the light source 40b and the oxygen supply unit 50 shown in Fig. 3 were not used. In Example 8, the same apparatus as in Example 6 was used, but the light source and light irradiation position were different.

[0109] The same procedure as in Example 6 was carried out, except that a high-intensity UV surface irradiator LMH240x214 FUV365-0161 48V LED lamp with a wavelength of 365 nm, manufactured by ITEC Systems Co., Ltd., was used instead of the Hololight HL5800 HLKK60UV365FM-V LED lamp, and light was irradiated at the position of light source 40a. A sample was collected from the aqueous phase of the settling separation tank 90, １ The average production amount per hour (mg / h) of each product was calculated using H-NMR. The use of a surface light source increases the irradiation area, allowing light to be irradiated evenly.

[0110] Example 9 An experiment was carried out using an apparatus having the same configuration as the manufacturing apparatus 104 shown in FIG.

[0111] <Radical Generation Step> A 10% aqueous sodium chlorite solution was added dropwise at a rate of 0.3 mL / min to a light-shielding sealed PFA container containing 223.3 g of 1 M aqueous sulfuric acid solution as the chlorine dioxide radical generator 31a, to generate chlorine dioxide radical gas. The 1 M aqueous sulfuric acid solution and the 10% aqueous sodium chlorite solution were prepared in the same manner as in Example 2.

[0112] <Oxidation Reaction Step> 750 mL of perfluoropolyether 2 (GALDEN SV-135, manufactured by Solvay Specialty Polymers) and 30 mL of water were placed in a cylindrical glass reaction vessel serving as a stationary separation tank 90. ​​The perfluoropolyether 2 was circulated at 300 mL / min by a liquid feed pump 80.

[0113] Chlorine dioxide radical gas generated in the chlorine dioxide radical generator was introduced into the circulating organic phase (perfluoropolyether 2) using carrier gases (nitrogen, flow rate 40 mL / min, high-purity methane (99.9%), flow rate 60 mL / min). Light was irradiated using an LED lamp (wavelength 365 nm, high-intensity UV surface irradiator LMH240x214 FUV365-0161 48V, manufactured by ITEC Systems Co., Ltd.) as the light source 40.

[0114] To reintroduce chlorine dioxide radicals during irradiation with the LED lamp, another chlorine dioxide radical generator 31b was prepared: a light-shielded PFA sealed container containing 223.3 g of 1 M aqueous sulfuric acid solution. Chlorine dioxide radical gas was generated by dripping 10% aqueous sodium chlorite solution into the sealed container at a rate of 0.2 mL / min, and introduced into the circulating organic phase (perfluoropolyether 2) using a carrier gas (nitrogen, flow rate 100 mL / min). The chlorine dioxide radical gas was introduced into the organic phase in the light-irradiated region and reacted at room temperature without pressure for 7 hours. A sample was collected from the aqueous phase in the static separation tank 90. １ The average production amount per hour (mg / h) of each product was calculated by H-NMR.

[0115] [Evaluation Results] The evaluation results are shown in Tables 1 to 4 below and FIG.

[0116] As shown in Table 1, Example 1, which used gaseous chlorine dioxide radicals, had a higher formic acid concentration in the aqueous phase after 12 runs and a larger amount of formic acid produced than Comparative Examples 1 and 2. Furthermore, Example 1 did not produce any residue, primarily composed of inorganic salts, which are produced as by-products during chlorine dioxide radical generation. Therefore, it was found that the production method and production apparatus using gaseous chlorine dioxide radicals as in Example 1 do not require a step for removing inorganic salts, and do not require extra steps such as residue disposal and recycling. Therefore, it can be determined that the production method and production apparatus as in Example 1 are suitable for mass production. Furthermore, as shown in Figure 6, the amount of formic acid produced in Example 1 increased in proportion to the reaction time (number of reactions). Therefore, it was found that the production method and production apparatus using gaseous chlorine dioxide radicals, which is one embodiment of the present invention, are suitable for mass production of oxidation reaction products, without a decrease in the production rate of the target product even when the reaction is repeated.

[0117] On the other hand, in Comparative Examples 1 and 2, an aqueous solution of chlorine dioxide radicals was used. In Comparative Example 1, the aqueous solution of chlorine dioxide radicals was repeatedly prepared by reusing the aqueous phase recovered from the reaction vessel. In Comparative Example 1, the amount of formic acid produced was lower than in Example 1, and the amount of residue containing inorganic salts was greater. Furthermore, as shown in FIG. 6 , the rate of formic acid production decreased with repeated reactions in Comparative Example 1. This is presumably because inorganic salts generated as by-products during the generation of chlorine dioxide radicals were present in the aqueous phase, inhibiting the oxidation reaction of the raw materials. Therefore, if a production method such as that of Comparative Example 1 is applied to mass production, it is believed that residues will accumulate and the production amount of the oxidation reaction product will decrease. Furthermore, in Comparative Example 2, an aqueous solution of chlorine dioxide radicals was prepared and added each time the reaction was repeated. In this case, the increased amount of aqueous phase made it difficult for chlorine dioxide radicals to be supplied to the organic phase, resulting in a lower amount of formic acid produced than in Example 1. Furthermore, even though formic acid was produced in Comparative Example 2, the increased amount of aqueous phase in which formic acid dissolved resulted in a low formic acid concentration in the aqueous phase. Therefore, when applying the production method of Comparative Example 2 to mass production, it is considered that the concentration of the reaction product is low and therefore formic acid must be concentrated.

[0118] As can be seen from Table 2, the formic acid concentration was relatively high even in Example 2, in which the organic phase was circulated. Furthermore, when the average production amount of the product per hour was confirmed in Example 2 in the same manner as in Example 5 described below, no significant decrease in the production rate was observed. It is believed that the production method of Example 2 is more suitable for mass production. In Table 2, "F solvent" means a fluorous solvent, and the same applies to the following tables.

[0119] As can be seen from Table 3, Examples 3 and 4, in which a liquid phase was used as the reaction phase, produced larger amounts of formic acid and methanol than Comparative Example 3, in which no liquid phase was used as the reaction phase. Therefore, it was found that it is preferable to use a liquid phase as the reaction phase. It was also found that an organic solvent is more preferable than water as the reaction phase.

[0120] In Example 5, the total amount and flow rate of perfluorohexane were changed compared to Example 2, but formic acid and methanol were still efficiently obtained. Example 6, in which perfluoropolyether was used instead of perfluorohexane, also produced formic acid and methanol. Furthermore, in Example 7, in which air was introduced, the amount of formic acid produced was increased by approximately two times, and the amount of methanol produced was increased by approximately eight times, compared to Example 6, in which air was not introduced. Furthermore, in Example 8, in which a surface-illumination LED light was used, formic acid and methanol were also obtained. Example 9, in which chlorine dioxide radicals were added during light irradiation, produced a higher amount of formic acid than Example 8.

[0121] It should be noted that the introduction of chlorine dioxide radicals into the liquid phase in a gaseous state is sufficient, and the form of introduction of chlorine dioxide radicals before the start of the reaction is not important. For example, before the start of the reaction, a liquid phase containing an aqueous phase and an organic phase may be prepared by mixing an aqueous solution of sodium chlorite and an acid, and then in the introduction step after the start of the reaction, chlorine dioxide radicals in a gaseous state may be introduced into the liquid phase. In this case, the amount of inorganic salt produced is small, so the influence of the inorganic salt can be substantially ignored.

[0122] One aspect of the present invention can be utilized in the production of oxidation reaction products of hydrocarbons or their derivatives.

[0123] 10 Liquid phase storage section 20, 20a, 20b, 21 Raw material supply section 30, 30a, 30b Chlorine dioxide radical supply section 31, 31a, 31b Chlorine dioxide radical generation section 40, 40a, 40b, 41a, 41b Light source 50 Oxygen supply section 60 Product recovery section 70, 70a, 70b, 71a, 71b Stirrer 101, 102, 103, 104, 105 Manufacturing apparatus 105a, 105b Module 110, 111 Flow path

Claims

1. A method for producing an oxidation reaction product, comprising: an introduction step of introducing a raw material, which is a hydrocarbon or its derivative, and gaseous chlorine dioxide radicals into a liquid phase; and a reaction step of obtaining an oxidation reaction product of the raw material by irradiating the liquid phase with light.

2. The method for producing an oxidation reaction product according to claim 1, wherein the liquid phase irradiated with light is circulated and reused as a liquid phase for introducing the raw material and chlorine dioxide radicals.

3. A method for producing the oxidation reaction product according to claim 1 or 2, comprising a step of generating chlorine dioxide radicals in a reaction system isolated from the reaction system generating the oxidation reaction product of the raw material.

4. A method for producing an oxidation reaction product according to claim 1 or 2, comprising the steps of separating the liquid phase irradiated with light into an aqueous phase and an organic phase, and recovering the target substance from the aqueous phase.

5. The method for producing an oxidation reaction product according to claim 1 or 2, wherein the liquid phase contains a fluorous solvent.

6. A method for producing an oxidation reaction product according to claim 1 or 2, wherein the reaction step includes a step of adding the chlorine dioxide radicals to the liquid phase while irradiating the light.

7. A method for producing an oxidation reaction product according to claim 1 or 2, comprising a step of introducing oxygen into the liquid phase prior to the reaction step.

8. An apparatus for producing an oxidation reaction product, comprising: a liquid phase storage section for storing a liquid phase; a raw material supply section for introducing a raw material which is a hydrocarbon or a derivative thereof into the liquid phase; a chlorine dioxide radical supply section for introducing chlorine dioxide radicals in a gaseous state into the liquid phase; and a reaction section having a light source for irradiating the liquid phase with light.

9. The apparatus for producing an oxidation reaction product according to claim 8, further comprising a flow path connecting the liquid phase storage section and the reaction section and for circulating the liquid phase.

10. An apparatus for producing an oxidation reaction product as described in claim 8 or 9, wherein the chlorine dioxide radical supply unit is provided with a chlorine dioxide radical generating unit for generating chlorine dioxide radicals, and the chlorine dioxide radicals are introduced into the liquid phase by gas supplied to the chlorine dioxide radical generating unit.

11. The apparatus for producing an oxidation reaction product according to claim 8 or 9, comprising two or more modules each including the raw material supply unit, the chlorine dioxide radical supply unit, and the light source.

12. The apparatus for producing an oxidation reaction product according to claim 8 or 9, further comprising an oxygen supply section for introducing oxygen into the liquid phase.

13. The apparatus for producing an oxidation reaction product according to claim 8 or 9, further comprising: a product recovery section that separates the liquid phase in the liquid phase storage section into an aqueous phase and an organic phase; and recovers the oxidation reaction product from the aqueous phase.

14. The apparatus for producing an oxidation reaction product according to claim 8 or 9, further comprising an agitator for agitating the liquid phase into which the raw material and the chlorine dioxide radicals have been introduced.

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