Mechanical Activation of Perovskite-Type Oxides for Catalytic Combustion

The effect of grinding on the catalytic properties of La0.8Sr0.2MnO3±λ powders prepared via a ceramic or sol–gel process was studied with respect to the carbon black combustion temperature (TC). For the ceramic process, a milling time of 5 h led to a decrease of 77°C in the TC (from 615 to 538°C) in relation with increasing BET surface area. Regarding the sol–gel process, the TC decreased from 535 to 505°C after 1 h of grinding. Nevertheless, upon further milling (10 h), the benefit of the grinding effect disappeared due to a continuous decrease in the BET surface area. Finally, grinding (when well controlled) enabled one to obtain ceramic powders showing performances as good as sol–gel materials (TC≈540°C).