Synthesis, characterization and physicochemical properties of nanosized Zn/Mn oxides system

A series of pure and doped Li2O-zinc/manganese mixed oxides was prepared by ceramic route at 400-1000 degrees C. The obtained solids have been characterized by the thermo-gravimetric analyzer (TGA), differential scanning calorimetry (DSC), X-ray powder diffractogram (XRD), infrared (IR), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) techniques. The catalytic behavior of pure and doped mixed solids was investigated using the decomposition reaction of H2O2 at 30-50 degrees C. The obtained results revealed that the solid state reaction between ZnO and Mn2O3 started at 500 degrees C yielding zinc manganite (ZnMn2O4) nanoparticles. The augmentation in the calcination temperature of the investigated solids up to 1000 degrees C for 4 h brought about complete conversion of unreacted oxides yielding ZnMn2O4 crystallites. By doping the system with Li2O at different calcination temperatures, an enhancement of the formation of zinc manganite was observed. The products obtained by doping with Li2O at different temperatures had less catalytic activity than the pure solids. The catalytic activity of pure and Li2O-doped Zn/Mn mixed oxides system decreased by increasing the calcination temperature. (c) 2010 Published by Elsevier B.V.