Catalytic oxidation of VOCs and CO by ozone over alumina supported cobalt oxide

Abstract

An alumina-supported cobalt oxide system with overstoichiometric oxygen (CoO x /Al 2O 3) was investigated with respect to heterogeneous catalytic decomposition of ozone, complete oxidation of volatile organic compounds (VOCs) and oxidation of CO. The experiments were performed in the temperature range of −45 to 250 °C in an isothermal plug-flow reactor. The characterization of the CoO x /Al 2O 3 catalyst was performed by chemical analysis, XPS, XRD, IR techniques, magnetic and adsorption measurements. A very high activity of the catalyst towards ozone decomposition was observed even at temperatures below −40 °C, the catalyst remaining active for a long time. The activity of the catalyst with respect to complete oxidation of VOCs and oxidation of carbon monoxide was studied in presence of different oxidizing agents (ozone or oxygen). A significant increase in the catalytic activity and decrease in the reaction temperature was observed using ozone as an oxidant. Two main reasons for this behaviour were found: (i) the high content of active and mobile oxygen obtained during the synthesis on the catalyst surface; (ii) the catalytically active complex of O −[Co 4+], formed during the reaction of ozone decomposition and able to oxidize VOCs at room temperature.