JPS6051125A - Oxidation and reduction of organic compound - Google Patents

Abstract

PURPOSE:To carry out the oxidation reduction of an organic compound, by using a laminated sheet composed of an internally short-circuited cell catalyst layer and a porous polyethylene fluoride membrane, and contacting the organic compound to the catalyst layer and an oxidizing or reducing gas to the porous membrane. CONSTITUTION:An organic compound is supplied to the reactor containing a bonded catalyst 2 through the organic compound inlet 3, and is made to react with air supplied through the air inlet 4. The bonded catalyst is composed of the internally short-circuited cell catalyst layer 7, the porous polytetrafluoroethylene membrane 9, the sprayed layer 8 of tetrafluoroethylene-hexafluoropropylene copolymer for bonding the catalyst layer and the porous membrane, and the porous Ni plate 6 acting as a reinforcing material. The internally short-circuited cell catalyst layer 7 is composed of (a) an electrically conductive powder effective for the electrolytic reduction of oxidized material, (b) an electrically conductive powder effective for the electrolytic oxidation of the reduced material, (c) powder or short fibers of an ion exchange resin and (d) a fluororesin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for redoxing organic compounds, and its purpose is to more efficiently redox organic compounds by using internal short-circuit battery type catalysis. There are a number of ways to do this.

Many chemical reactions are redox reactions. However,
A reaction in which a reductant is oxidized is an oxidation reaction, and a reaction in which an oxidant is reduced is a reduction reaction.

On the other hand, electrochemical reactions in electrochemical devices such as batteries are also redox reactions. That is, an electrochemical device always includes a cathode, an anode, and an electrolyte, and all cathode reactions are reduction reactions, and all anode reactions are oxidation reactions.

The difference between a normal chemical reaction and an electrochemical reaction is that in the front right, no exchange of electrons occurs, at least in appearance, whereas in the latter, exchange of electrons occurs and current flows through an external circuit. At the point. However, even if a normal chemical reaction is viewed microscopically, it is actually an electrochemical reaction, or the reaction mechanism can often be better understood if it is explained as an electrochemical reaction. For example, when sulfur dioxide and oxygen are reacted in the presence of water using activated carbon as a catalyst, RA acid is produced.This reaction appears to be a normal catalytic chemical reaction, but when viewed microscopically, , at the oxygen adsorption site of activated carbon, the following electrolytic reduction reaction of oxygen occurs: 1/202 +28" +2e--+1-120 (
1) Activated carbon adsorption night of sulfur dioxide is 802 +
2H20 1+SO4'-+41-1++2e-(2) An electrolytic oxidation reaction occurs, and the total is 1/202 +SO2+
It is explained that the reaction H20 → t-12SO4 (3>) occurs.In other words, an oxygen-sulfur dioxide battery is formed on the activated carbon, and this can be considered to be internally short-circuited by the electronically conductive activated carbon. In this case,
At the beginning of the reaction, sulfur dioxide, which is produced by dissolving sulfur dioxide in water, acts as a supporting electrolyte, and after the reaction of equation (2) has progressed to a certain extent, sulfuric acid can be considered to act as a supporting electrolyte.

In addition, for example, Japanese Patent Publication No. 50-40395 states that when an aqueous solution of j-1-lium sulfide is made to react with air using water-repellent activated carbon as a catalyst, sodium hydroxide is produced as a single substance. This reaction (equation 6) is expressed as the following (4
It is explained that it is a combination of the electrolytic oxidation reaction of equation () and the electrolytic reduction reaction of equation (5).

52-->30 +2e-(4) 21-120+02 +4e--+ 40H-(5)2
Na2S −+−21−120+02→230+4
-〇11(13) Although there is no explanation in the above cited example,
In this reaction, in the early stage of the reaction, Ni128 is used, and after the reaction [+5 in equation (5)] has progressed to a certain extent, an oxygen-sulfide ∆ cell with 1-lium hydroxide as the supporting electrolyte is used with activated carbon. This can be explained as a reaction caused by an internal short circuit.

In this way, an example of a reaction using activated carbon with electron conductivity as a heterogeneous catalyst, which appears to be a simple chemical reaction, but is actually an electrochemical reaction when viewed microscopically. Publication No. 52-38982 lists the following:

(b) Oxidation of sodium thioate to sodium sulfate by air, (b) Oxidation of ferrous sulfate or ferrous ammonium sulfate to ferric sulfate by air, (c) Oxidation of hydroquinone to quinhydrone by air. oxidation, (d) oxidation of phenol by air, (e) oxidation of benzaldehyde to benzoic acid by air, and (v) reduction of silver nitrate to silver by hydrogen gas.

In any case, in order for the chemical reaction to proceed through the microscopic internal short-circuit phenomenon of the battery, it is essential that the catalyst be a solid with electronic conductivity and that a supporting electrolyte coexist. It is.

Conventionally, supporting electrolytes have been either inorganic salts, acids, or alkali hydroxides, which are the starting materials before the reaction, or reaction products produced as the reaction progresses, depending on each individual reaction. There was no idea of actively adding electrolytes. On the other hand, in organic chemical reactions, neither the reaction starting material nor the reaction product generally exhibits ionic conductivity and does not function as an electrolyte, so it is necessary to separately mix an inorganic supporting electrolyte.

However, when an inorganic supporting electrolyte is added (), after the reaction is complete, the desired reaction product and the inorganic supporting electrolyte are separated into 1 part.
13Il becomes a major challenge. J, the above-mentioned Special Publication No. 50-40395 and Special Publication No. 52-38982
In this issue, activated carbon () is used as a catalyst, and this activated carbon has both the function of electrolytically reducing the oxidant and the function of electrolytically oxidizing the reductant, but depending on the reaction system. is activated carbon.There are actually many cases where things don't work out like this.

On the other hand, conventionally, when performing a redox reaction using a catalyst that utilizes the internal short-circuit phenomenon of a battery, oxidizing gas i3 or reducing gas is blown into the liquid reaction starting material in the form of bubbles. However, in such a method, it is difficult to bring the catalyst, starting reactant, and oxidizing gas or reducing residue into contact efficiently.

The present invention seeks to eliminate the above-mentioned drawbacks. In other words, the present invention provides an electronic conductive powder effective for electrolytic reduction of an oxidant, an electronic conductive powder effective for electrolytic oxidation of a reductant, and an ion exchange resin powder or wl fiber as an ion conductor. An organic compound is placed on the side of the internally shorted battery type catalyst layer of a sheet-like assembly in which an internally shorted battery type catalyst layer composed of a mixture with a fluororesin and a porous polytetrafluoroethylene membrane are integrally bonded. By contacting an aqueous solution or an aqueous suspension of an organic compound and also contacting an oxidizing gas or a humidified oxidizing gas with the porous polytetrafluoroethylene side, the organic compound is oxidized, or a reducing gas or The present invention provides a method for redoxing an organic compound, which is characterized in that the organic compound is reduced by contacting it with a humidified reducing gas.

When such a method is adopted, first, the ion exchange resin of the internally shorted battery type catalyst layer becomes a solid electrolyte, which facilitates the separation of reaction products. In addition, in the internally shorted battery type catalyst layer, electrolytic reduction of the oxidant occurs at the contact point between the ion conductor powder and the ion exchange resin, which is effective for the electrolytic reduction of the oxidant, and electron conductivity is effective for the electrolytic oxidation of the reductant. Electrolytic oxidation of the reductant occurs at the contact point between the powder and the ion exchange resin. In other words, a battery is constructed in which an electronically conductive powder effective for electrolytic reduction of an oxidant is used as a positive electrode, an electronically conductive powder effective for electrolytic FIv oxidation of a reductant is used as an h electrode, and an ion exchange resin is used as an electrolyte. An internal short-circuit current flows at the contact point between the electronically conductive powder effective for the electrolytic Flv reduction of the oxidant and the electronically conductive powder effective for the electrolytic oxidation of the reductant, and the electrolytic redox reaction occurs due to their unity. Ru.

The phrase "internally shorted battery type catalyst" was coined by the inventors of the present invention, and such a clear idea of the catalyst membrane 51 has not existed before.

The target organic compound may be a reduced form or an oxidized form. When an organic compound has a reduced form,
When this organic compound is placed on the side of the internally shorted battery-type catalyst layer and an oxidizing gas, such as oxygen or air, is supplied from the side of the porous polytetrafluoroethylene membrane, the oxidizing gas is transferred to the porous polytetrafluoroethylene membrane. It passes through the pores of the membrane and reaches the surface of the electronically conductive powder, which is effective for the electrolytic reduction of oxidants in the internal short-circuited battery type catalyst - soot layer, where it undergoes electrolytic reduction and, at the same time, organic compounds are electrolytically oxidized. . On the other hand, if the organic compound is an oxidant, a reducing gas such as hydrogen may be supplied from the side of the porous polytetrafluoroethylene.
This organic compound is electrolytically reduced.

The ion exchange resin of this internally shorted battery type catalyst layer functions as an electrolyte only when it contains water, so the organic compound to be redoxed must be in the form of an aqueous solution or suspension, or else, It is necessary to add oxidizing gas or reducing gas. This point is also one of the features of the present invention.

Next, the porous polytetrafluoroethylene membrane has the function of preventing the leakage of an aqueous solution or suspension of an organic compound, and at the same time prevents organic compounds and oxidizing gas from leaking within the pores of the internally shorted battery-type catalyst layer. Alternatively, it has the function of increasing the number of points of contact with reducing gas and allowing the oxidation or reduction reaction of organic compounds to proceed more efficiently.

The electronically conductive powder used for this H-section short-circuited battery type Wc layer varies depending on the reaction system, but generally metal, carbon, or carbon with 111 metals is suitable, but some spinel powders are suitable. Metal oxides, such as type oxides or perovskite-type oxides, and compounds exhibiting some degree of electronic conductivity, such as metal borides, may also be used.

Alternatively, carriers that do not themselves have electronic conductivity, such as alumina or silica, can be used to carry the metal. In addition, it may be effective to mix these powders exhibiting catalytic activity with materials that do not exhibit catalytic activity but contribute to improving electronic conductivity.

Furthermore, powders that have electronic conductivity and exhibit catalytic activity can be made into a mixture of different types that have selectivity for the reduction reaction of oxidants and the oxidation reaction of reduction and oxidation. Although it is effective, in some cases it may not be possible to use the same powder.

The anion exchange resin, which is another component of the internally shorted battery type catalyst, includes cation exchange type and anion exchange type. As a cation exchange resin, styrene-
Suitable materials are those based on fluorine-containing polymers such as divinylbenzene copolymers or perfluorocarbons, into which sulfonic acid groups, carboxylic acid groups, or both are introduced, but the present invention is not limited to these. . The ions that move in this cation exchange resin are hydrogen ions.

As an anion exchange resin, one in which an ammonium salt type amine or an amine such as diethylene triamine is introduced as an exchange JAW into a boris dylene mother nucleus and treated with an alkali to form a hydroxyl ion transfer type may be used. .

These ion exchange resins are available in powder form for short Sli$
A 4i-shaped one is suitable. If it is in powder form, it should have a particle size of several tens of microns or less. The short fibers preferably have a diameter of several microns and a length of several mm or less.

Whether to use a cation exchange resin or an anion exchange resin must be appropriately selected depending on the target reaction system.

Internal short circuit The fluororesin binder, which is another constituent material of the battery type catalyst layer, has electronic conductivity and functions to bind powder and ion exchange resin that exhibit catalytic activity. It also has the function of imparting water repellency to the battery type catalyst layer.

In other words, the internally shorted cell type catalyst layer is suitable for reactions using liquid reactants and gaseous reactants as starting materials;
If the internal short-circuit cell type catalyst is completely hydrophilic, it will be covered with the liquid reactant and the adsorption 1 noid for the C1 gaseous reactant will disappear, whereas it has partial water repellency. Since both adsorption sites for the gaseous reactant and adsorption sites for the liquid reactant are secured, the reaction tends to proceed more smoothly.

As a fluororesin binder, polytetrafluoroethylene is particularly used because it is not easily attacked by the starting reactants, has good heat resistance, and does not cover the other constituent materials of the battery catalyst. Although suitable, it is not limited to this material.

The suitable method for joining the internally shorted battery type catalyst layer and the porous polytetrafluoroethylene membrane is pressure bonding at room temperature or hot pressing. It is also effective to use a powder of a fluororesin having a melting point lower than that of polytetrafluoroethylene, such as propylene copolymer or tetrafluoroethylene-ethylene copolymer.

In addition, in order to reinforce the joint between the internally shorted battery type catalyst layer and the porous polytetrafluoroethylene membrane, a porous nickel plate is crimped onto the side of the internally shorted battery type catalyst layer 1, or a porous polyethylene Tetrafluoroethylene side or internal short circuit battery type Ml! It is also very effective to place a porous nickel plate treated with water repellent with fluororesin between the Hj and the polytetrafluoroethylene membrane.

Hereinafter, positional embodiments of the present invention will be described in detail.

Example: 2 g of activated carbon powder, 10 g of platinum black powder, and styrene.
Distilled water was added to a well mixed mixture of 5 g of ion exchange resin powder made by introducing sulfonic acid groups into divinylbenzene copolymer. Add 61 ml of an aqueous suspension of ethylene tetrafluoride, stir vigorously to agglomerate it, and apply it to one side of a porous ↑11 nickel plate with a thickness of 1 mm and a porosity of 80%. This coating layer becomes an internally shorted battery type catalyst layer. Next, on top of this internal %t7-circuit cell type catalyst layer,
An aqueous suspension of tetrafluoroethylene-hexafluoropropylene copolymer is sprayed and once dried in vacuum. Next, a porous polytetrafluoroethylene membrane with a porosity of 35% is placed on the layer onto which the tetrafluoroethylene-〇fluoropropylene copolymer has been sprayed, and the porosity is increased to 4,100! ] / cnt Press with pressure. Finally, heat treatment is performed at 100°C in a nitrogen stream.1. The catalyst assembly is thus completed.

Next, this catalyst assembly was assembled into a reaction vessel as shown in Figure 1, and one portion of methanol was placed on the side of the porous nickel plate.
A 0% aqueous solution was added, and air was supplied from the side of the porous polytetrafluoroethylene membrane.

In Figure 1, (1) is a reaction vessel, (2) is a catalyst conjugate, (3) is an organic compound supply port, (4) is an air supply port,
(5> is an air outlet. The catalyst assembly (dan) consists of a porous nickel plate (6) as a reinforcing agent, an internally shorted battery type catalyst layer (7), and a tetrafluoroethylene-hexafluoropropylene The 1-pyrene copolymer spray consists of a layer (8) and a porous polytetrafluoroethylene membrane (9).

One hour after methanol and air were supplied to the upper reaction vessel, formaldehyde was analyzed.
The oxidation rate of methanol to formaldehyde was 60%.

In this oxidation reaction from methanol to formaldehyde, activated carbon serves as the positive electrode, platinum black serves as the negative electrode, an electrolytic reduction reaction of oxygen in the air occurs at the positive electrode, and an electrolytic oxidation reaction of methanol occurs at the negative electrode. it is conceivable that.

Comparative Example 1 An experiment was conducted in exactly the same manner as in the above example except that the ion exchange resin was not mixed, and the oxidation rate of methanol to formaldehyde was 8%. Comparative Example 2 In the above example, Catalyst conjugate at 10xlO+nn
When a piece cut into + dimensions was placed in a 10% methanol aqueous solution and air was blown into it in the form of bubbles, the oxidation rate of methanol to formaldehyde was 37%.

The following can be understood from the above examples and comparative examples. In other words, as seen in Comparative Example 1, if an ion exchange resin is not included, the internally shorted battery-type catalyst will not become an internally shorted battery-type catalyst, and since it is a mere catalytic reaction, even if an internally shorted battery-type catalyst is used, air will not be bubbled. When carbon is supplied in the form of carbon, the oxidation of methanol is relatively slow compared to the case where air is supplied through a polytetrafluoroethylene membrane as in the present invention, because there are fewer reaction points. Recognize.

As detailed above, the present invention provides a method for efficiently redoxing organic compounds, and has extremely great commercial value.

[Brief explanation of drawings]

FIG. 1 shows a schematic cross-sectional structure of a reaction vessel according to an embodiment of the present invention.

Claims (1)

[Claims] It consists of an electronically conductive powder effective for the electrolytic reduction of an oxidant, an electronically conductive powder effective for the electrolytic oxidation of an element, an ion exchange resin powder or short fibers as an ion conductor, and a fluororesin. Internally shorted battery-type catalyst layer and porous polyester
An organic compound, an aqueous solution of an organic compound, or an aqueous suspension of an organic compound is brought into contact with the side of the internal short-circuited battery type catalyst layer of a sheet-like assembly formed by integrally joining a tetrafluoroethylene membrane, and a porous The organic compound is oxidized by bringing an oxidizing gas or a humidified oxidizing gas into contact with the polytetrafluoroethylene film, or i
A method for redoxing an organic compound, characterized in that the organic compound is reduced by contacting with a U-based gas or a humidified reducing gas.