The influence of La<inf>2</inf>O<inf>3</inf>-doping on structural, surface and catalytic properties of nano-sized cobalt–manganese mixed oxides

Abstract

Structural, textural and catalytic activity of CoO–Mn2O3 system as being influenced by La2O3-doping (0.75–3 mol%) and calcination temperatures (300–500 °C) were investigated. The techniques employed were XRD, N2-adsorption–desoprtion at −196 °C, EDX and catalysis of H2O2-decomposition in aqueous solution at 30–50 °C. The results revealed that the investigated system consisted of nano-sized Co2MnO4 as a major phase together with un-reacted portion of Co3O4 and γ-Mn3O4. Doping with the smallest amount of La2O3 greatly increased the surface molar ratio of Mn/Co (88 %) for the solid calcined at 500 °C with subsequent increase of the catalytic activity more than 12-fold for solids calcined at 500 °C. The increase of La2O3-dopant above 0.75 mol% decreased progressively the surface molar ratio of Mn/Co with subsequent decrease in the catalytic activity which still measured higher values than that measured for the un-doped catalyst.