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 degrees C and CO-oxidation by O-2 at 80-220 degrees 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 degrees C and Li2O-doping of CuO/Fe2O3 system enhanced CuFe2O4 formation. However, heating both pure and doped solids at 600 degrees 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 degrees C. This process led to a significant increase in the S-BET of the treated solids. Doping CuO/Fe2O3 system with either Li2O or CoO, followed by calcination at 400 and 600 degrees C decreased its catalytic activity in CO-oxidation by O-2. However, the activation energy of the catalyzed reaction was not much affected by doping. (C) 2007 Elsevier B.V. All rights reserved.