Thermal behaviour and catalytic properties towards propene combustion of zirconia modified by different first row transition metals

Zirconium oxyhydroxide was synthesized in the presence of different transition metals from the first row (Cr, Mn, Fe, Co, Ni, Cu) and calcined at two different temperatures 450 °C and 700 °C. Differential Thermal Analysis exhibits a delay in zirconia crystallization with high specific surface areas when the transition metal is associated with zirconium. Transition metals improved zirconia catalytic activity and selectivity in propene deep oxidation to CO2 and H2O. Catalytic activity enhancement was explained by the stabilization (total or partial) of zirconia tetragonal phase (evidenced by ambient and temperature programmed XRD studies) which leads to higher amount of anionic vacancies. The existence of reduction peaks (Temperature Programmed Reduction with hydrogen) in the temperature range of catalytic activity explained the better catalytic performances of Cr, Mn, Co and Cu samples compared to Fe- and Ni-based ones.