Liquid composition, process for its production, and process for producing membrane-electrode assembly for polymer electrolyte fuel cells
View Patent ↗An electrolyte membrane is prepared from a liquid composition comprising at least one member selected from the group consisting of trivalent cerium, tetravalent cerium, bivalent manganese and trivalent manganese; and a polymer with a cation-exchange group. The liquid composition is preferably one containing water, a carbonate of cerium or manganese, and a polymer with a cation-exchange group, and a cast film thereof is used as an electrolyte membrane to prepare a membrane-electrode assembly. The present invention successfully provides a membrane-electrode assembly for polymer electrolyte fuel cells being capable of generating the electric power in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas, and being capable of stably generating the electric power over a long period of time.
1. A process for producing a liquid composition comprising at least one member selected from the group consisting of trivalent cerium, tetravalent cerium, bivalent manganese and trivalent manganese; and a polymer having a cation-exchange group,
which comprises dissolving or dispersing the polymer having the cation-exchange group in a liquid containing water and then dissolving therein at least one member selected from the group consisting of a cerium carbonate and a manganese carbonate.
2. The process for producing a liquid composition according to claim 1 , wherein the cation-exchange group is sulfonic acid group.
3. The process for producing a liquid composition according to claim 2 , wherein the cerium ion is contained in an amount of from 0.3 to 30 mol% relative to the molarity of —SO 3 − in the polymer, in the liquid composition.
4. The process for producing a liquid composition according to claim 2 , wherein the manganese ion is contained in an amount of from 0.5 to 45 mol% relative to the molarity of —SO 3 − in the polymer, in the liquid composition.
5. A process for producing a liquid composition comprising at least one member selected from the group consisting of trivalent cerium, tetravalent cerium, bivalent manganese and trivalent manganese; and a polymer having a cation-exchange group,
which comprises dissolving or dispersing the polymer having the cation-exchange group in a liquid containing water and then dissolving therein at least one member selected from the group consisting of a water-soluble cerium salt and a water-soluble manganese salt.
6. The process for producing a liquid composition according to claim 5 , wherein the cation-exchange group is sulfonic acid group.
7. The process for producing a liquid composition according to claim 6 , wherein the cerium ion is contained in an amount of from 0.3 to 30 mol% relative to the molarity of —SO 3 − in the polymer, in the liquid composition.
8. The process for producing a liquid composition according to claim 6 , wherein the manganese ion is contained in an amount of from 0.5 to 45 mol% relative to the molarity of —SO 3 − in the polymer, in the liquid composition.