Comparative study of oxygen cathodes loaded with Ag and Pt catalysts in chlor-alkali membrane cells

Basic electrocatalytic properties as well as the lifetime of the oxygen cat hodes loaded with platinum and silver catalyst were studied under the pract ical conditions of chlor-alkali electrolysis as a function of the catalyst loading. In general, catalytic activity of the cathode loaded with platinum catalyst is superior to that loaded with silver catalyst. Long-term lifeti me tests have shown, however, that the cathode loaded with 2.63 mg/cm(2) Ag catalyst has lifetime longer than 3 years under the practical chlor-alkali electrolysis conditions, while the cathode loaded with 0.56 mg/cm(2) Pt ca talyst has shown potentiality to have lifetime over 2 years. The lifetime o f the oxygen cathodes could be extended further by optimizing the catalyst loading. From these results wt: could anticipate practical applications of the oxygen cathodes loaded with Ag catalyst instead of the cathodes with Pt catalyst. Application of the oxygen cathodes to the practical chlor-alkali electrolysis would contribute greatly to reduction of the power requiremen t in the industry. (C) 2000 Elsevier Science Ltd. All rights reserved.