Application of transient response method to the study of heterogeneous catalysis: II. Mechanism of catalytic oxidation of carbon monoxide on manganese dioxide

Abstract

The mechanism of the oxidation of carbon monoxide over manganese dioxide was studied by a transient response method. To follow the transient behavior, measurements were made on the time dependencies of the reaction gas composition and of the electrical conductivity of the catalyst. The analyses of the response curves showed that the gaseous carbon monoxide reacts directly with the surface oxygen species, which is negatively charged, to form some intermediates, which successively decompose to form carbon dioxide. It was found that the amount of carbon dioxide existing on the surface during the reaction under steady states was larger than the equilibrium amount, which was calculated from the adsorption isotherm specified by the Langmuir equation, and it was suggested that the desorption step of carbon dioxide is one of the slower steps in the overall reaction.