Methane catalytic combustion on La-based perovskite catalysts

Two series of La-based perovskites oxides (La1-xSrxMO3-y with M = Fe or Co) have been used as methane total oxidation catalysts. The best catalytic performances, in isothermal, high temperature conditions (900 degreesC), in the presence of water and carbon dioxide, were obtained for both series when 20% of lanthanum cations are replaced by strontium. The catalytic behavior of the two series of catalysts is quite similar, although the cobalt-containing samples are easily reducible by H-2 or CH4, whereas the iron-containing ones are not reduced in the same conditions. It is proposed, to explain this apparent inconsistency, that the active sites reoxidation process occurs directly from the molecular oxygen of the gas phase, without participation of the bulk oxygen species mobility. (C) 2001 Editions scientifiques et medicales Elsevier SAS.