JP3398413B2 - Method for producing partial oxide of aromatic compound - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention produces a partial oxide such as a phenol or a quinone from an aromatic compound and oxygen by a fuel cell system using an ionic conductor provided with a catalyst electrode and, if necessary, an electric power. Regarding how to take out. Partial oxides of aromatic compounds such as phenol are raw materials for resins and the like, and are extremely important intermediate raw materials in the field of organic industry.

[0002]

2. Description of the Related Art Various methods for producing monovalent or polyvalent phenols and quinones such as benzoquinone from aromatic compounds are known. For example, phenols have been conventionally produced mainly by methods such as the cumene method, the benzoic acid method, the chlorobenzene method, and the sulfonic acid method (see, for example, Journal of Organic Synthetic Chemistry, Vol. 35, No. 2, Item 138). All of these methods require complicated reaction operations involving several steps. In addition, it has drawbacks such as consumption of expensive auxiliary materials. From an industrial point of view, it is desirable to develop a production process that directly oxidizes aromatic compounds with oxygen and produces phenol by a one-step reaction operation, does not consume expensive by-products and does not involve co-products. Although various proposals have been made, none of them has been industrially implemented because of low yield, and severe reaction conditions or complicated reaction methods. .

In recent years, various attempts have been made to produce electric power at the same time as producing various useful compounds under mild conditions using a fuel cell system. The method of synthesizing organic compounds by the fuel cell system is very economical because the reaction is carried out under relatively mild conditions, the selectivity of the products is high, and electric power can be taken out of the reaction system as needed. It is a high manufacturing method. However, the present inventors have previously proposed a method for producing a partial oxide of an aromatic compound by a fuel cell system (Japanese Patent Application No. 1-349970, Japanese Patent Application No. 1-261493, Japanese Patent Application No. No. 105924,
There is only a patent.

[0004]

The object of the present invention is required to carry out the production of aromatic partial oxides such as phenol and hydroquinone under mild conditions, with high selectivity, in an efficient and economical manner, and at the same time. In order to overcome the problems of the conventional method for producing a partial oxide of an aromatic compound, an electric power is generated according to the above.

[0005]

The present inventor has focused on the excellent advantages of the method for producing an aromatic partial oxide by a fuel cell system, and has solved various problems in the method for producing a partial oxide of an aromatic compound. The inventors have made earnest studies to solve the problems and arrived at the present invention. That is, the present invention is a fuel cell system using a proton conductor, wherein one of the catalyst electrodes, an anode, is a hydrogen donor, the other catalyst electrode containing copper and / or a copper compound is a cathode, and the cathode is an aromatic compound. Contact the compound and oxygen, and from -0.01V to the anode side-
A method for producing a partial oxide of an aromatic compound, which comprises applying a negative voltage of 1.0 V and / or extracting electric power from this system. A conceptual diagram of a fuel cell reactor used for carrying out the method of the present invention is shown in FIG.

An anode chamber 3 having an anode 1 made of a catalyst electrode and a cathode chamber 4 having a cathode 2 are separated by a proton conductor 5, and the anode and the cathode are connected by a lead wire 6. The catalyst electrode is preferably porous or sheet-shaped, but is not limited thereto. 7 is a stirrer. Reference numeral 8 is a direct current voltage applying device (for applying a negative voltage to the anode) connected in series to the lead wire 6, and 9 is a variable external resistance, which may be used alone or both may be connected and used at the same time.

Although various materials can be used as the anode, which is one of the catalyst electrodes used in the method of the present invention, at least one or more of various metals or compounds thereof can be used in the method of the present invention.
Preferably, a catalyst electrode used in a conventional fuel cell containing platinum and graphite is recommended as a readily available catalyst electrode. However, the method of the present invention is not limited to these catalyst electrodes. A material containing copper and / or a copper compound is used as the cathode, which is the other catalyst electrode. Further, it is also possible to mix or support copper and / or a copper compound in an electrically conductive substance, preferably a conductive polymer material for use. The copper compound used in the method of the present invention is not particularly limited, an inorganic copper compound,
Various copper compounds such as organic copper metal compounds are used. Preferably copper halide, oxide, hydroxide, nitrate,
Examples of easily available metal compounds include sulfates and acetates.

As the conductive polymer material used in the present invention, generally, a conductive carbonaceous material such as graphite is used because of its low cost, availability and good electric conductivity. Is preferred. The conductive carbonaceous substance may be any carbonaceous substance having electrical conductivity, and may be a carbonaceous substance exhibiting electrical conductivity by oxidation treatment. Specific examples include graphite, activated carbon, carbon black, carbon whiskers, etc., which are easily available. Next, the oxidation treatment of the carbonaceous material will be described. The oxidation treatment can be carried out by various methods such as ordinary heat treatment using an oxygen-containing gas and reagent oxidation treatment using an oxidizing reagent. Examples of the reagent oxidation treatment include treatment with an aqueous solution of permanganate or a salt thereof, heat treatment with nitric acid, treatment with an aqueous solution of dichromic acid or a salt thereof, heat treatment with sulfuric acid, and treatment with hydrogen peroxide. Preferably, the oxidation treatment is carried out by heating or contacting or leaving the carbonaceous substance at room temperature in at least one solution selected from the group consisting of a permanganate solution, a nitric acid solution and a dichromate solution. However, the method of the present invention is not limited to these treatments. Further, in order to make the method of the present invention easier to carry out, it is preferable to use those molded by using a binder in addition to these constituent components of the anode and cathode electrodes. At this time, it is possible to use various binders as the binder used in molding the electrode, but from the viewpoint of ease of molding, etc., hot pressing may be performed using Teflon resin powder. preferable. However, the method of the present invention is not limited to only these materials and methods.

As the proton conductor used in the method of the present invention, a protonic acid such as phosphoric acid, sulfuric acid, hydrochloric acid or nitric acid, a solid electrolyte known as a proton conductor such as heteropolyacid, H-montmorillonite or zirconium phosphate, S
A perovskite type solid solution having rCeO ₃ as a matrix can be used. Further, a fluoropolymer such as perfluorocarbon is used as a base, and one or more cation exchange groups such as sulfonic acid groups or carboxylic acid groups are introduced into the base, for example, Nafion (registered trademark of DuPont) is also used. it can. A liquid such as phosphoric acid can be used by impregnating it with silica wool or the like, or can be sandwiched between ion-permeable filters or membranes.

The hydrogen donor used in the present invention generally means a substance which can be oxidized by an anode which is one of the catalyst electrodes to generate a proton (hydrogen cation). Specific examples include hydrogen molecules, alcohols, hydroquinones, and saturated hydrocarbons. Hydrogen molecules are preferably used. The hydrogen donor to be supplied is usually supplied as a gas or a liquid, but if necessary, it may be dissolved in an inert medium or water and brought into contact with the electrode in a liquid phase, and further nitrogen, helium, As a mixed gas with an inert gas such as argon, the gas may be brought into contact with the electrodes. The supply method is also not particularly limited, and may be a continuous method or a batch method,
For example, when supplying in a gas phase, a continuous system is preferable. The oxygen used in the method of the present invention does not necessarily have to be pure, and may be air or a mixture with an inert gas such as nitrogen, helium or argon. The aromatic compound used for the partial oxidation in the method of the present invention is a substituted or unsubstituted aromatic hydrocarbon. For example, benzene, toluene, xylene, naphthalene, anthracene and their derivatives, and the substituents which they may have include an alkyl group, an aryl group, an aryloxy group, a sulfone group, an alkoxy group, a halogen atom and the like. To be The aromatic compound supplied to the cathode chamber is also supplied as a gas or liquid,
Further, the oxygen or oxygen-containing substance may be used in a gas state or diluted with a suitable solvent or gas. The supply system may be either a continuous system or a batch system. When performing in liquid phase,
It is preferable to vigorously stir in order to effectively make contact with the catalyst electrode.

In the method of the present invention, a catalyst electrode containing copper and / or a copper compound is used as a cathode, and power is supplied by a constant voltage generator or the like and / or by connecting a load such as a resistor in an external circuit. The yield of the partial oxide of the aromatic compound is remarkably increased by increasing the cathode potential as compared with that at the time of short-circuit by a method such as taking out.

According to the method of the present invention, the method of applying a negative voltage to the anode is not particularly limited, and any method may be used as long as a negative voltage is applied to the anode. It is recommended that a method such as putting the above in a circuit is applied as an easy method. The value of the voltage applied to the anode is usually -0.01V to -1.0V.
The range is more preferable, and the range of −0.1V to −0.5V is more preferable. To extract electric power from the fuel cell system in the method of the present invention is to connect the catalyst electrode of the fuel cell, install a resistor or the like in the connection, and generate electric energy. The method of extracting the electric power is not particularly limited, but generally, it can also be implemented by inserting a variable external resistance and raising the potential on the cathode side. The potential increase value at that time is not particularly limited, but is preferably in the range of 0.01 V to 1.0 V,
More preferably, it is in the range of 0.1V to 1.0V. The reaction temperature is not particularly limited, but is usually from -20 ° C to 200
The temperature is preferably in the range of 0 ° C to 0 ° C to 100 ° C.
Is more preferable. Furthermore, according to the method of the present invention, the reaction is generally carried out at atmospheric pressure, but it can be carried out under pressure or under reduced pressure if necessary. Partial oxides such as phenols and quinones, which are reaction products, are usually distilled from a reaction product liquid or reaction product gas, distillation after concentration,
The target product can be obtained by separation and purification by a method such as distillation and extraction after gas-liquid separation.

[0013]

EXAMPLES The method of the present invention will be described in more detail based on the following examples. However, these are exemplary and the method of the present invention is not limited by the examples.

(A) Introduction of Hydrogen Donor into Anode Chamber All the hydrogen donors used were argon: hydrogen = 50: 50 volume ratio gas, which was fed to the anode chamber at a flow rate of 20 ml / min. (B) Oxygen introduced into the cathode chamber is pure oxygen at a flow rate of 5 ml / min and 50 ml of benzene.
Was charged and introduced into the stirred cathode chamber. (C) Oxidation treatment of carbonaceous substance A carbonaceous substance was immersed in an 8N nitric acid aqueous solution, heated and boiled for 2 hours, washed sufficiently with pure water, and dried. (D) Preparation of Anode A well-mixed mixture of 20 mg of platinum black powder, 70 mg of graphite powder and 5 mg of Teflon powder was formed into a circular sheet by a hot pressing method, which was used as an anode. In the symbols shown in this example, mF is millifaradaic, V is volt, μmol is micromol, PhOH.
Represents phenol and HQ represents hydroquinone. The reaction temperature and reaction time were 30 ° C. and 3 in all examples.
The analysis of the products was carried out by gas chromatography.

Examples 1 to 6 Two pieces of disk-shaped glass wool (thickness 1.0 mm, diameters 21 mm and 26 mm) impregnated with a 1 M aqueous solution of phosphoric acid were used as ion conductor membranes, and the above-mentioned anode and pre-oxidized were prepared. The treated carbon whiskers 65 mg, cupric oxide 5 mg, and Teflon powder 5 mg were formed into a sheet by the hot press method as the anode, and the sheet was used as the cathode.
They were attached to the anode chamber and cathode chamber, respectively. Hydrogen and argon were introduced into the anode chamber and oxygen gas was introduced into benzene in the cathode chamber at the above composition and inflow rate, and a closed circuit was formed by connecting the anode, the cathode, and a DC voltage power source in series with a lead wire, and the anode was -0. 1, -0.2, -0.2
The reaction was performed by applying negative voltages of 5, -0.3, -0.35, and -0.4V, respectively. The results are as shown in Table 1.
Phenol and hydroquinone were produced in good yield.

COMPARATIVE EXAMPLE 1 No voltage was applied to the anode, and all other than that in Example 1
The partial oxidation reaction of benzene was carried out under the same conditions as above. The results are shown in Table 1.

[0017]

[Table 1] ────────────────────────────────────                Applied voltage Charge amount Generated amount (μmol)                 (V) (mF) PhOH HQ ────────────────────────────────────  Example 1-0.1 1.5 74.9 8.1  Example 2-0.2 2.1 79.6 4.0  Example 3-0.25 2.2 97.7 7.4  Example 4-0.3 1.6 102.5 7.3  Example 5-0.35 0.9 90.1 7.1  Example 6-0.4 0.4 59.1 6.0  Comparative Example 1 0 0.9 55.5 8.0 ────────────────────────────────────

Example 7 As a cathode, a carbon whisker pre-oxidized and impregnated with copper sulfate in an amount of 1.0 mol% to make a total amount of 70 mg, and 5 mg of Teflon powder were prepared into a sheet form by a hot pressing method similarly to the anode. Example 1 was used except that a negative voltage of -0.3 V was applied to the anode.
The partial oxidation reaction of benzene was carried out under the same conditions as above. The results are shown in Table 2.

Comparative Example 2 No voltage was applied to the anode, and all other than that in Example 7
The partial oxidation reaction of benzene was carried out under the same conditions as above. The results are shown in Table 2.

Example 8 As a cathode, a carbon whisker pre-oxidized and impregnated with 1.0 mol% of copper nitrate to carry a total amount of 70 mg, and 5 mg of Teflon powder were prepared into a sheet form by a hot pressing method like the anode, Example 1 was used except that a negative voltage of -0.3 V was applied to the anode.
The partial oxidation reaction of benzene was carried out under the same conditions as above. The results are shown in Table 2.

Comparative Example 3 No voltage was applied to the anode, and all other than Example 8
The partial oxidation reaction of benzene was carried out under the same conditions as above. The results are shown in Table 2.

Example 9 As a cathode, a carbon whisker pre-oxidized and impregnated with 1.0 mol% of copper acetate to carry a total amount of 70 mg, and 5 mg of Teflon powder were prepared into a sheet form by a hot pressing method similarly to the anode. Example 1 was used except that a negative voltage of -0.3 V was applied to the anode.
The partial oxidation reaction of benzene was carried out under the same conditions as above. The results are shown in Table 2.

COMPARATIVE EXAMPLE 4 No voltage was applied to the anode, and all other than that in Example 9
The partial oxidation reaction of benzene was carried out under the same conditions as above. The results are shown in Table 2.

Example 10 As a cathode, 1.0 mol% cupric chloride was impregnated and supported on carbon whiskers which had been previously subjected to an oxidation treatment, and the total amount was 70 mg.
And 5 mg of Teflon powder were prepared into a sheet by a hot pressing method similarly to the anode, and were used under the same conditions as in Example 1 except that a negative voltage of −0.3 V was applied to the anode. A partial oxidation reaction of benzene was performed.
The results are shown in Table 2.

Comparative Example 5 No voltage was applied to the anode, and all other than Example 1
The partial oxidation reaction of benzene was performed under the same conditions as 0. The results are shown in Table 2.

[0026]

[Table 2] ────────────────────────────────────                Applied voltage Charge amount Generated amount (μmol)                 (V) (mF) PhOH HQ ────────────────────────────────────  Example 7-0.3 1.4 114.9 8.1  Example 8-0.3 1.3 102.9 7.1  Example 9-0.3 1.3 101.6 6.7  Example 10-0.3 1.7 54.3 5.7  Example 11-0.3 1.6 92.0 8.6  Comparative Example 2 0 0.9 47.9 7.8  Comparative Example 3 0 1.0 49.5 6.7  Comparative Example 4 0 0.8 43.4 5.8  Comparative Example 5 0 0.7 18.4 3.2  Comparative Example 6 0 0.8 32.8 6.1 ────────────────────────────────────

Example 11 As a cathode, 1.0 mol% of cuprous chloride was impregnated and supported on a carbon whisker which had been previously subjected to an oxidation treatment, and the total amount was 70 mg.
And 5 mg of Teflon powder were prepared into a sheet by a hot pressing method similarly to the anode, and were used under the same conditions as in Example 1 except that a negative voltage of −0.3 V was applied to the anode. A partial oxidation reaction of benzene was performed.
The results are shown in Table 2.

Comparative Example 6 No voltage was applied to the anode, and all other than Example 1
The partial oxidation reaction of benzene was performed under the same conditions as in 1. The results are shown in Table 2.

Comparative Example 7 Carbon whiskers 6 previously oxidized as a cathode
5 mg, ferric oxide 5 mg, and Teflon powder 5 mg were prepared into a sheet form by a hot pressing method like the anode,
The partial oxidation reaction of benzene was carried out under the same conditions as in Comparative Example 1 except that this was used. As a result, phenol is 5
1.7 μmol and 10.5 μmol of hydroquinone were produced, and the amount of charge flowing during this was 0.8 mF.

Comparative Example 8 The partial oxidation reaction of benzene was carried out under the same conditions as in Comparative Example 7 except that a voltage of -0.3 V was applied to the cathode electrode. As a result, the amount of phenol produced decreased to 16.1 μmol. The cathode electrode in the method of the present invention contains copper and / or
It can also be seen that the amount of phenol produced was extremely increased by applying a negative voltage to the anode using a copper compound.

[0031]

According to the present invention, a fuel cell system capable of producing a partial oxide of a corresponding aromatic compound by a one-step reaction operation from an aromatic compound and oxygen as compared with a conventional complicated method such as the cumene method. In the method for producing an aromatic partial oxide, a copper and / or copper compound is used as a cathode electrode, and electric energy is taken out of the reaction system to produce a partial oxide of an aromatic compound in a high yield. This is a very economical method for producing a partial oxide of an aromatic compound.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a fuel cell reactor.

[Explanation of symbols]

1 Catalytic electrode (anode) 2 Catalyst electrode (cathode) 3 Anode chamber 4 Cathode chamber 5 Ionic conductor 6 lead wire 7 Stirrer 8 DC voltage application device 9 Variable external resistance

Claims (7)

(57) [Claims] 1. In a fuel cell system using a proton conductor, one of the catalyst electrodes, an anode, is a hydrogen donor, the other catalyst electrode containing copper and / or a copper compound is a cathode, and the cathode is an aromatic compound. And a method for producing a partial oxide of an aromatic compound, which comprises contacting oxygen and applying a negative voltage of −0.01 V to −1.0 V to the anode side and / or extracting electric power from this system. . 2. The method according to claim 1, wherein the cathode, which is the other catalyst electrode, contains copper and / or a copper compound and a conductive polymer material. 3. The method according to claim 2, wherein the conductive polymer material is a conductive carbonaceous material. 4. The method according to claim 3, wherein the conductive carbonaceous material is an oxidized carbonaceous material. 5. The method according to claim 1, wherein the hydrogen donor is a molecular hydrogen. 6. The method according to claim 4, wherein the oxidation treatment is heat treatment of the carbonaceous material in the presence of an oxygen-containing gas. 7. The carbonaceous material is heated or contacted or left at room temperature in at least one solution selected from the group consisting of a permanganate solution, a nitric acid solution and a dichromate solution, for the oxidation treatment. 5. The method of claim 4, wherein: