Alumina-supported nickel oxide for ozone decomposition and catalytic ozonation of CO and VOCs

An alumina-supported nickel oxide system with overstoichiometric oxygen (NiOx/Al2O3) was investigated with respect to heterogeneous catalytic decomposition of ozone, complete oxidation of volatile organic compounds (VOCs) and oxidation of CO. The catalyst was prepared by a deposition oxidation–precipitation method and was characterized by chemical analysis, XPS, XRD, IR techniques, magnetic and adsorption measurements.The experiments were performed in the temperature range of −50 to 250 °C in an isothermal plug-flow reactor. A very high activity of the catalyst towards ozone decomposition was observed even at temperatures below −45 °C and at the same time the catalyst remained 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 catalytic activity and decrease in reaction temperature were 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, and (ii) the catalytically active complex of Ni4+O(OH)2, formed during the reaction of ozone decomposition and able to oxidize VOCs at room temperature.