JPH0143984B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing an air electrode used in air cells, fuel cells, etc., and more particularly to a method for manufacturing an air electrode having excellent polarization characteristics. Conventionally, air electrodes such as air cells and fuel cells have used catalysts such as metal phthalocyanine in activated carbon to increase oxygen reduction ability.However, metal phthalocyanine is insoluble in water, so it cannot be saturated with organic solvents such as quinoline. Activated carbon was immersed in this solution, pulled up and dried, and the organic solvent was scattered to cause metal phthalocyanine to adhere to the activated carbon surface as a catalyst. It was necessary to repeat the operation many times. Furthermore, since a special organic solvent is used, it is necessary to use expensive equipment for drying, and furthermore, the vapor of the organic solvent that evaporates and scatters poses a safety problem. Therefore, some attempts have been made to solve the above problem by attaching a water-soluble group such as a sulfone group to metal phthalocyanine to make it soluble in water, but the amount of metal phthalocyanine attached to carbon bodies is still insufficient. It wasn't. The present invention has been made in view of the above-mentioned problems. Namely, the present invention provides for impregnating a carbon body with a water-soluble metal phthalocyanine represented by the following general formula () and/or (). The gist of the present invention is a method for producing an air electrode, which is characterized in that the metal phthalocyanine is insolubilized by reacting with a polyvalent metal. (In the formula, X: iron, nickel, cobalt, chromium, copper, Pc: talocyanine residue, m: represents an integer from 1 to 4.) (In the formula, Y: iron, nickel, cobalt, chromium, copper Pc: phthalocyanine residue R: hydrogen or an alkyl group having 1 to 4 carbon atoms; n: represents an integer of 1 to 4.) A stable air electrode with an excellent polarization curve can be obtained by reacting the water-soluble metal phthalocyanine with a polyvalent metal in the carbon body and making it insolubilized. The present invention will be explained in detail below. An example of a method for producing a water-soluble metal phthalocyanine represented by the general formula of the present invention is shown below. A solution of metal phthalocyanines such as iron, copper, nickel, cobalt, and chromium dissolved in 10 times the amount of chlorosulfonic acid was stirred at 138 to 140°C for 3 hours, and then the solution was heated to 79 to 80°C. Add the same amount of thionyl chloride, stir for 1 hour at the same temperature, pour into ice water, and wash with water to obtain the corresponding tetrasulfochloride of metal phthalocyanine. This metal phthalocyanine tetrasulfochloride is dispersed in water and condensed with aminosalicylic acid while adding sodium carbonate to adjust the pH to 6.5 to 7.5. Examples of aminosalicylic acid include 3-aminosalicylic acid and 4-aminosalicylic acid.
-aminosalicylic acid, 5-aminosalicylic acid, 6
-Aminosalicylic acid and the like can be used. The obtained aminosalicylic acid condensed metal phthalocyanine (general formula ()) is made insolubilized by reacting with a polyvalent metal, but in order to make it more easily insolubilized, the metal phthalocyanine condensed with 5-aminosalicylic acid or 6-aminosalicylic acid is alkaline. By diazotizing and coupling orthoaminophenol, metal phthalocyanine (general formula ()), which is more easily insolubilized, can be obtained. Taking copper phthalocyanine as an example, a flow sheet for synthesizing water-soluble copper phthalocyanine is shown below. Both A and B thus obtained react easily with polyvalent metals and become insoluble. Polyvalent metals include magnesium, aluminum, calcium, titanium, vanadium, chromium,
Manganese, iron, cobalt, nickel, copper, zinc,
Strontium, zirconium, molybdenum, cadmium, tin, antimony, barium, tungsten, lead, etc. are used as their chlorides, bromides, iodides, sulfates, and acetates. In order to impregnate a carbon body with a water-soluble metal phthalocyanine, the carbon body is immersed in an alkaline aqueous solution of the metal phthalocyanine and dried. By immersing this carbon body in a water-soluble salt of a polyvalent metal, the water-soluble metal phthalocyanine represented by the general formula becomes insolubilized, and the desired air electrode is obtained. The carbon bodies used in the present invention include commonly used carbon blacks such as furnace black, channel black, and thermal black, as well as wood, charcoal, coconut shell charcoal, palm kernel charcoal, coal,
Examples include one or a mixture of two or more of activated carbon and graphite made using petroleum residue, synthetic resin, organic waste, etc., and extrusion molding, as necessary.
It is made into a certain shape by injection molding, pressure molding, etc. Hereinafter, it will be explained in more detail according to examples,
In the examples, "parts" indicate "parts by weight." Example 1 10 parts of coconut shell activated carbon with a particle size of 0.1 to 1μ, particle size of 0.1 to 1μ
Mix 10 parts of 0.5 μ graphite and 5 parts of thermoplastic resin (polyvinyl chloride), make a round bar with a diameter of 10 mm by extrusion molding, and heat treat to a final temperature of 1000°C to decompose the thermoplastic resin. and make it into a carbon body. This carbon body An air electrode in which the carbon body was impregnated with a chelate compound was obtained by immersing the carbon body in a 10% alkaline aqueous solution, pulling it up and drying it, and heating it in a 2% ferric chloride aqueous solution. Comparative Example 1 The carbon body used in Example 1 is immersed in a 10% aqueous solution of copper phthalocyanine and tetrasulfonic acid (hydrolyzate of copper phthalocyanine/tetrasulfochloride) and dried. Next, an air electrode was obtained by heating this carbon body to 400°C in a nitrogen stream. The polarization characteristics of the air electrodes obtained in Example 1 and Comparative Example 1 are shown in FIG. Furthermore, when both air electrodes were immersed in a 5% caustic soda aqueous solution, no change was observed in the air electrode of Example 1, but in the air electrode of Comparative Example 1, the attached copper phthalocyanine/tetrasulfonic acid or some sulfonic groups Copper phthalocyanine released from
Sulfonic acid was observed to elute. Example 2 The carbon body of Example 1

[Formula] (Obtained by trisulfonating iron phthalocyanine, then converting it to iron phthalocyanine trisulfochloride with phosphorus pentachloride, and condensing it with 4-aminosalicylic acid.)
The carbon body is immersed in a 10% alkaline aqueous solution, pulled up and dried, and then immersed in a manganese chloride aqueous solution to make it insolubilized. This operation was repeated five times to obtain the desired air electrode. Comparative Example 2 The carbon body of Example 1 was immersed in a 1% by weight quinoline solution of iron phthalocyanine, and then quinoline was removed by reducing pressure and heating. An air electrode was obtained by repeating this operation 10 times. FIG. 2 shows the polarization curves of the air electrodes obtained in Example 2 and Comparative Example 2. Example 3 The carbon body in Example 1 The material was immersed in a 10% alkaline aqueous solution of 1, pulled up and dried, and then immersed in an aqueous solution of chromic chloride to make it insolubilized to obtain the desired air electrode. Example 4 The carbon body of Example 1

It was immersed in a 10% alkaline aqueous solution of [Formula] and insolubilized with an aqueous nickel acetate solution to obtain the desired air electrode. The polarization characteristics of the air electrodes obtained in Examples 3 and 4 are shown in FIG. The air electrode obtained by the manufacturing method of the present invention exhibits excellent polarization characteristics as shown in the drawings, and is also stable even in alkaline electrolytes.

[Brief explanation of drawings]

Figure 1 shows the polarization curve of the air electrode obtained in Example 1 and Comparative Example 1, Figure 2 shows the polarization curve of the air electrode obtained in Example 2 and Comparative Example 2, and Figure 3 shows the polarization curve of the air electrode obtained in Example 2 and Comparative Example 2. are the polarization curves of the air electrodes obtained in Examples 3 and 4, and 1 to 6 are the polarization curves of the air electrodes obtained in Example 1, Comparative Example 1, Example 2, Comparative Example 2, Examples 3 and 4, respectively. The polarization curve is shown, and the vertical axis is the current density (mA/cm ² ),
The horizontal axis shows the potential (V/SCE).

Claims (1)

[Claims] 1. A carbon body is impregnated with a water-soluble metal phthalocyanine represented by the following general formula () and/or (), and then reacted with a polyvalent metal to insolubilize the metal phthalocyanine. A method for manufacturing an air electrode. (In the formula, X: iron, nickel, cobalt, chromium, copper, Pc: phthalocyanine residue, m: represents an integer from 1 to 4.) (In the formula, Y: iron, nickel, cobalt, chromium, copper Pc: phthalocyanine residue R: hydrogen or an alkyl group having 1 to 4 carbon atoms n: represents an integer of 1 to 4.)