Effect of ZrO2-doping of nanosized Fe2O3/MgO system on its structural, surface and catalytic properties

Abstract

Fe2O3/MgO system was prepared by wet impregnation method followed by treatment with different amounts of Zr-dopant salt then heating at 500 and 700°C. The dopant concentrations were 0.48, 0.95 and 1.4mol% ZrO2. Pure and variously doped solids were characterized using XRD, N2-adsorption isotherms carried out at −196°C and catalytic decomposition of H2O2 in aqueous solution at 25–35°C. The results revealed that the nanosized MgO phase was only detected in the diffractograms of pure and doped solids calcined at 500°C. Heating pure and doped solids at 700°C produced nanosized MgFe2O4 phase together with MgO phase. Pure and ZrO2-doped solids calcined at 500 and 700°C are mesoporous adsorbents. The doping process brought about a measurable decrease in the SBET of Fe2O3/MgO system with subsequent increase in its catalytic activity. The catalytic activity of the investigated system toward H2O2 decomposition, expressed as reaction rate constant per unit surface area was found to increase as a function of dopant concentration. The maximum increase in the reaction rate constant per unit surface area measured for the reaction carried out at 30°C attained 125% for the heavily doped samples. This significant increase was based on the catalytic activity of pure catalyst sample measured under the same conditions.