Near-ambient temperature ozone decomposition kinetics on manganese oxide-based catalysts

Abstract

Catalytic ozone decomposition on various manganese oxide-based catalysts was investigated at 40 °C for ozone concentrations in the range 2–20 ppm in dry and humid conditions. Ozone conversion efficiency shows a slight dependence with ozone concentration, slightly decreasing when ozone concentration increases. A strong but reversible inhibiting effect was observed when water is present in the gas phase likely due to the reversible adsorption of water on ozone reaction sites. Whatever the catalyst used, the same behavior was observed which is characterized by a transient decrease in efficiency at the beginning of the reaction until reaching the steady-state. A kinetic model was developed, based on the mechanism of ozone decomposition proposed by Oyama and co-workers, allowing us to properly describe the reaction behavior of ozone on manganese oxide catalysts for variable initial reactant concentrations. Additionally, the transient behavior of the MnO2 catalysts experimentally observed at the beginning of the ozone decomposition reaction was kinetically described for the first time, as well as the steady-state.