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 pe
rformances, in isothermal, high temperature conditions (900 degreesC), in t
he 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-conta
ining samples are easily reducible by H-2 or CH4, whereas the iron-containi
ng ones are not reduced in the same conditions. It is proposed, to explain
this apparent inconsistency, that the active sites reoxidation process occu
rs directly from the molecular oxygen of the gas phase, without participati
on of the bulk oxygen species mobility. (C) 2001 Editions scientifiques et
medicales Elsevier SAS.