Surface properties and catalytic performance of La 1− xSr xCrO 3 perovskite-type oxides for CO and C 3H 6 combustion

Abstract

Catalytic CO oxidation and C 3H 6 combustion have been studied over La 1− x Sr x CrO 3 ( x = 0.0–0.3) oxides prepared by solid-state reaction and characterised by X-ray diffraction (XRD), nitrogen adsorption (BET analysis) and X-ray photoelectron spectroscopy (XPS). The expected orthorhombic perovskite structure of the chromite is observed for all levels of substitution. However, surface segregation of strontium along with a chromium oxidation process, leading to formation of Cr 6+-containing phases, is produced upon increasing x and shown to be detrimental to the catalytic activity. Maximum activity is achieved for the catalyst with x = 0.1 in which mixed oxide formation upon substitution of lanthanum by strontium in the chromite becomes maximised.