Effect of Li2O and CoO-doping of CuO/Fe2O3 system on its surface and catalytic properties

Physicochemical, surface and catalytic properties of pure and doped CuO/Fe2O3 system were investigated using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), nitrogen adsorption at −196 °C and CO-oxidation by O2 at 80-220 °C using a static method. The dopants were Li2O (2.5 mol%) and CoO (2.5 and 5 mol%). The results revealed that the increase in precalcination temperature from 400 to 600 °C and Li2O-doping of CuO/Fe2O3 system enhanced CuFe2O4 formation. However, heating both pure and doped solids at 600 °C did not lead to complete conversion of reacting oxides into CuFe2O4. The promotion effect of Li2O dopant was attributed to dissolution of some of dopant ions in the lattices of CuO and Fe2O3 with subsequent increase in the mobility of reacting cations. CoO-doping led also to the formation of mixed ferrite CoxCu1−xFe2O4. The doping process of the system investigated decreased to a large extent the crystallite size of unreacted portion of Fe2O3 in mixed solids calcined at 600 °C. This process led to a significant increase in the SBET of the treated solids. Doping CuO/Fe2O3 system with either Li2O or CoO, followed by calcination at 400 and 600 °C decreased its catalytic activity in CO-oxidation by O2. However, the activation energy of the catalyzed reaction was not much affected by doping.