GB900451A - Improved fuel cell electrodes - Google Patents

Abstract

A fuel cell electrode comprises high density porous carbon impregnated with a catalyst, the carbon having a porosity of 10-35%, a maximum pore diameter of 4 x 105 , an internal surface area of 100-300 sq.m./gm., and a real density of 1,9-2,25 gm./c.c. The porous carbon may be produced by mixing graphite and lamp black or calcined coke with pitch or a cellulosic material, moulding at a pressure of 1-30 tons/sq. inch, heating over a period of several days to a temperature of 1000 DEG -2500 DEG C., to carbonize the binder, and heating in the presence of an oxidizing gas to increase the porosity to the desired extent. Oxidation may be effected by heating at 600 DEG -900 DEG F. for 1-10 hrs. in the presence of 2-80% of oxygen added as such of as air, or by heating at 1600 DEG -2000 DEG C. for 1-10 hrs. in the presence of carbon dioxide. 20-80% of the pore volume may be made up of pores having a diameter of 0,2 x 104 - 2 x 105 and 70-30% of the pore volume may be made up of pores having a diameter of 50-400 . Catalysts specified are gold, silver, copper, chromium, tungsten, molybdenum, cobalt, nickel, platinum, vanadium, palladium, rhodium, iridium, and manganese, and inorganic compounds containing oxygen and one or more of said metals, e.g. cobalt and manganese molybdate. 0,1-5% of gold or platinum and 1-30% of a metal of Group VI or VIII of the Periodic Table may be employed. The electrode may be cylindrical, flat, angular or curved. The electrolyte may be sulphuric, phosphoric, hydrochloric, nitric, or peracetic acid, potassium, sodium, or lithium hydroxide, or sodium or potassium carbonate-bicarbonate. The fuel may be a liquid or gaseous hydrocarbon, alcohol, aldehyde, ketone, carboxylic acid, carbon monoxide, or hydrogen.