Lamellar perovskites MI (An−1BnO3n+1) catalysts for oxidative coupling of methane

Abstract

Abstract The aim of this work concerns the study of new lamellar perovskites M I (A n −1 B n O 3 n +1 ) as catalysts for the oxidative coupling of methane. The main results show that: Substitution in an octahedral site (B) strongly modifies both activity and selectivity. In this site niobium (an element of Group V) leads to a more selective catalyst. Substitution either of the A cation in the perovskite site or of the interlamellar cation (M I ) modifies the selectivity more than the activity. An increase in the thickness ( n ) of the layer decreases both activity and selectivity. It can be considered as a structural effect in the oxidative coupling of methane. Variations of catalytic properties can be correlated to the covalent character of the B-O bond. The reactional center can be described as a polaron created at a structural defect, the existence of very localized centers being less probable at such high temperatures.