In situ spectroscopic characterization of some LaNi1-xCoxO3 perovskite catalysts active for CH4 reforming reactions

Abstract

ABSTRACTLanthana-supported Ni and Co catalysts were investigated by “operando” techniques (XAS and APPES) for methane reforming reactions. The samples were prepared by the “solid phase crystallization” method (spc), where the precursors La(Ni1-xCox)O3 contains homogeneously distributed metals (Ni, Co) in the crystal structure (perovskite), which, on further reduction, result in the formation of catalytic system Ni1-xCox/La2O3. The monometallic samples (NiLaO3, CoLaO3) have been compared with a bimetallic system of an intermediate composition Ni0.5Co0.5LaO3. This “operando” study has allowed us to obtain important conclusions about the bimetallic particles and the metal-support interactions. The data revealed the formation of bimetallic particles (NiCo); on these ones, the Ni avoids the Co oxidation during the reaction. However, this protection does not induce an improvement in the activity, which presents an intermediate behaviour between Ni/La2O3 and Co/La2O3. These bimetallic particles form a pseudo-alloy with the surface enriched in cobalt (under reduced conditions), resulting nearly in a core-shell structure (Ni@Co).