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 cathodes loaded with platinum and silver catalyst were studied under the practical 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 lifetime 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 catalyst has shown potentiality to have lifetime over 2 years. The lifetime of 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 requirement in the industry. (C) 2000 Elsevier Science Ltd. All rights reserved.