Influence of grinding on the catalytic properties of oxides

The influence of grinding on the structure and catalytic performances of two families of oxides, namely the perovskite-type La0.8Sr0.2MnO3±λ and the spinel-type Li–Mn–O, was investigated. Ball-milling of the well-known La0.8Sr0.2MnO3±λ prepared either by a solid state reaction or by a sol-gel method led to (i) a decrease in carbon black combustion temperature of 100 °C (TC=540 °C) and of 40 °C (TC=505 °C) for ceramic and sol-gel ground 5-h samples, respectively, and (ii) to faster kinetics and higher rates of toluene conversion. A greater enhancement of the catalytic performances was obtained by using mechanical milled lithiated manganese oxides that are reported as promising catalyst candidates for the first time. Li–Mn–O catalysts were synthesized by room temperature mechanochemistry of a stoichiometric mixture of Li2O and MnO2 using various milling times (0