Methane catalytic combustion on La-basedperovskite type catalysts in high temperature isothermal conditions

摘要

The rate constants in isothermal conditions at 900°C have been measured for a series of Lal-xSrxFeO3 unsupported oxide (O~x~0.5) with the perovskite structure. The best catalytic performances were obtained, in terms of catalytic activity per weight of catalyst for x=0.2, and in terms of catalytic activity per unit surface area for 0.3=>:x<=:0.5. A deactivation, mainly due to the sintering of the catalysts, was observed with the time on stream at 900°C. This deactivation can be lowered by supporting the perovskite phase on BaA112019, but unfortunately, an important CO formation occurred, increasing with the time on stream.From pulses experiments, two oxidation sites behaving differently have been revealed: a very reactive one leading to a fast and selective CO2 formation and a less reactive one, selective for the CO+H2 formation which could arise from the partial reduction of the very reactive site.