Influence of gold and manganese as promoters on surface and catalytic performance of Fe2O3/Al2O3 system Original Research Article

The physicochemical, surface and catalytic properties of pure and doped Fe2O3/Al2O3 solid catalysts with Au and Mn2O3 calcined at 300, 500 and 700 °C were investigated. The dopant concentration of Au was varied between 0.4 and 1.6 mol%, while Mn2O3 concentration was varied between 1.0 and 8.0 mol%. The techniques employed were DTA, XRD, TPR, EDX, nitrogen adsorption at −196 °C, CO oxidation by O2 at 225–275 °C and H2O2 decomposition in aqueous solution at 30–50 °C.The results obtained revealed that the doping of Fe2O3/Al2O3 solids with different amounts of Au and Mn2O3 changed the degree of crystallinity of Al2O3 and Fe2O3 phases. The doping process led to a progressive increase in the specific surface area of the treated solid catalysts to an extent proportional to the amount of Au and Mn2O3 added. This process led also to a progressive increase in the catalytic activities of the investigated solid catalysts towards CO oxidation by O2 and H2O2 decomposition. The doping of solid catalysts with Au calcined at 300, 500 and 700 °C exhibited catalytic activity in CO oxidation by O2 higher than those measured for solid catalysts doped with Mn2O3 calcined at the same temperatures. Opposite results have been observed in case of H2O2 decomposition. These findings indicate that the active sites taking part in CO oxidation by O2 are different from those involved in H2O2 decomposition.