Effect of cobalt ion dispersion on H 2D 2 equilibration and other simple reactions catalyzed by CoOMgO solid solutions

Abstract

Solid solutions of CoOMgO, with Co Mg ratios from 1 to 50, have been studied as catalysts for the H 2D 2 equilibration reaction. This paper presents data in the temperature range above 300 K (high temperature range, HTR). The catalytic activity per cobalt ion increases with cobalt content. A statistical analysis of the surface configurations shows that the turnover number (molecules per second per site) is a constant if the active site is a cluster containing at least a pair of cobalt ions. The mechanism of the HTR reaction is then discussed. Comparison of the concentration dependence for the N 2O decomposition reaction, and for the CO oxidation, shows that the former shows a decrease of activity per site with increasing Co 2+ content (“dilution effect”), which cannot be explained on the basis of configuration requirements only, while the second reaction shows a constant turnover number, implying a configuration-insensitive reaction. The data suggest details on the mechanisms.