Kohlenstoffe als Katalysatoren für die Oxydation von schwefliger Säure / Carbons as Catalysts for the Oxidation of Sulfurous Acid

Abstract

Conductometric measurements of the catalytic oxydation of dilute aqueous sulfurous acid were used in the comparison of various carbon catalysts, e.g. active charcoals and carbon blacks. The oxidation rate is proportional to (Po₂) 1/2 and to the amount of adsorbed HSO₃- ions. Basic surface oxides are responsible for the HSO₃ -adsorption. The catalytic activity of a carbon is influenced also by other factors than the concentration of basic surface oxides. It is changed by heat treatment of the carbon as well as by chemical treatment of its surface. Treatment with ammonia at 600 °C increases its activity dramatically, absolutely inactive carbon blacks were rendered highly active.