Effect of Li 2O and CoO-doping of CuO/Fe 2O 3 system on its surface and catalytic properties

Abstract

Physicochemical, surface and catalytic properties of pure and doped CuO/Fe 2O 3 system were investigated using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), nitrogen adsorption at −196 °C and CO-oxidation by O 2 at 80–220 °C using a static method. The dopants were Li 2O (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 Li 2O-doping of CuO/Fe 2O 3 system enhanced CuFe 2O 4 formation. However, heating both pure and doped solids at 600 °C did not lead to complete conversion of reacting oxides into CuFe 2O 4. The promotion effect of Li 2O dopant was attributed to dissolution of some of dopant ions in the lattices of CuO and Fe 2O 3 with subsequent increase in the mobility of reacting cations. CoO-doping led also to the formation of mixed ferrite Co x Cu 1− x Fe 2O 4. The doping process of the system investigated decreased to a large extent the crystallite size of unreacted portion of Fe 2O 3 in mixed solids calcined at 600 °C. This process led to a significant increase in the S BET of the treated solids. Doping CuO/Fe 2O 3 system with either Li 2O or CoO, followed by calcination at 400 and 600 °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.