JPH0119629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air electrode used in air cells, fuel cells, etc., and more specifically to 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 sulfon 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 inventors have completed the present invention by paying attention to the fact that metal phthalocyanine into which an alkylaminomethyl group has been introduced is soluble in an aqueous solution of a volatile acid. The method involves dissolving a metal phthalocyanine having an alkylaminomethyl group in an aqueous solution of a volatile acid at a low concentration, impregnating a carbon body into this aqueous solution, drying it, and then heating it to 150°C to 200°C to dissolve the volatile acid. It is obtained by molecularly adsorbing metal phthalocyanine containing alkylaminomethyl groups which are dispersed and insoluble in water to the surface of a carbon body.

It is presumed that this adsorption is strong and uniform, resulting in good polarization characteristics of the air electrode.

The present invention will be explained in detail below.

A metal phthalocyanine having an alkylaminomethyl group is obtained by dissolving the metal phthalocyanine in an aluminum chloride-pyridine complex compound and chloromethylating it with dichlorodimethyl ether. Three to four chloromethyl groups may be introduced per molecule. Next, this chloromethylated metal phthalocyanine is heated in an aqueous alkylamine solution to obtain an alkylaminomethylated metal phthalocyanine.

Next, the obtained alkylaminomethylated metal phthalocyanine was dissolved in a 5% volatile acid aqueous solution,
Immerse the carbon body in this solution, dry it, and then heat it to 150℃~200℃.
By heating to a temperature of 0.degree. C., the volatile acid is scattered, and an air electrode in which water-insoluble alkylaminomethylated metal phthalocyanine is uniformly adhered to the carbon body can be obtained.

As metal phthalocyanine, ease of production,
Considering stability, iron, nickel, cobalt,
Phthalocyanines such as copper are preferably used.

Further, as the alkylaminomethyl group, groups such as monomethylaminomethyl, dimethylaminomethyl, monoethylaminomethyl, and diethylaminomethyl are preferable in consideration of the solubility of volatile acids in aqueous solutions.

Furthermore, volatile acids that dissolve metal phthalocyanine having an alkylaminomethyl group and scatter at 150°C to 200°C include inorganic acids such as hydrochloric acid, formic acid,
Organic acids such as acetic acid are preferably used.

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
10 parts of 0.5μ graphite and 5 parts of thermoplastic resin are mixed together, a round bar with a diameter of 10 mm is made by extrusion molding, and heated to 200°C to decompose the thermoplastic resin to form a carbon body.

When a 10% acetic acid aqueous solution of tetradimethylaminomethylated iron phthalocyanine is prepared, the above carbon body is immersed, and after vacuum drying at 50°C and heated at 150°C for 30 minutes, 0.5 of the tetramethylaminomethylated iron phthalocyanine is dissolved.
An air electrode using % by weight as a catalyst was obtained.

Comparative Example 1 The carbon body in Example 1 was immersed in a 5% aqueous solution of sulfonated iron phthalocyanine, and then dried in an air stream at room temperature. By heating the dried carbon body at 150°C for 10 minutes, an air electrode with iron phthalocyanine attached to the surface of the carbon body was obtained.

Example 2 The carbon body in Example 1 was immersed in a 5% aqueous hydrochloric acid solution of tridimethylaminomethyl copper phthalocyanine,
Treat with ultrasound for 30 minutes. Then take it out
After vacuum drying at 50°C, the mixture was heated at 200°C for 30 minutes to obtain an air electrode containing 0.3% by weight of tridimethylaminomethyl copper phthalocyanine as a catalyst.

The polarization curves of the air electrodes obtained in Examples 1 and 2 and Comparative Example 1 are shown in FIG.

As described above, in the air electrode obtained by the manufacturing method of the present invention, the metal phthalocyanine is uniformly distributed on the surface of the carbon body.
The air electrode has excellent polarization characteristics because it is firmly attached.

[Brief explanation of drawings]

Figure 1 shows the polarization curves of the air electrodes obtained in Examples 1 and 2 and Comparative Example 1, and ~ indicates the polarization curves obtained in Example 1, Example 2, and Comparative Example 1 in this order. The vertical axis shows the current density (mA/cm ² ), and the horizontal axis shows the potential (V/SCE).

Claims (1)

[Scope of Claims] 1. An air electrode in which a carbon body contains a metal phthalocyanine having an alkylaminomethyl group. 2. The air electrode according to claim 1, wherein the alkylaminomethyl group is methylaminomethyl, dimethylaminomethyl, ethylaminomethyl, or diethylaminothyl. 3. The air electrode according to claims 1 and 2, wherein the metal phthalocyanine contains iron, nickel, cobalt, and copper.