18O-isotope exchange behavior and oxidation activity of La1-xSrxMnO3+δ

Different preparation routes derived both from the usual high-temperature solid state synthesis and the sol-gel process were applied for the synthesis of crystalline La1-xSrxMnO3+δ phases with 0≤x≤ 0.2. They were investigated by means of temperature programmed isotope exchange (TPIE) under various conditions. The 18O isotope exchange experiments yielded information on the dependence of the oxygen mobility on temperature and the Mn4+/Mn3+ratio. Both are related to the defect structure of the solid. TPIE was applied for studying the interaction between 18O2 and CH4 under static conditions and was compared with results obtained from catalytic investigations, i.e. the behavior of La1-xSrxMnO3+δ (0≤x≤0.2) in both CO and CH4 oxidation with normal oxygen 16O2 under steady flow conditions.