Effect of Ca-substitution in La1 − xCaxFeO3 perovskites on the catalytic activity for soot combustion

La1 − xCaxFeO3 (x = 0.1, 0.2, 0.3 and 0.4) perovskites, prepared by the citrate method and characterized by AAS, XRD, TPR-H2 and TPD-O2, were assayed, and its catalytic activity evaluated for soot combustion, using carbon black as a model compound for soot. The catalytic activity was determined by non-isothermal thermogravimetric analysis. A significant enhancement of the catalytic activity was found by increasing the degree of La3+ substitution by Ca2+ in the perovskites, which coincided with an increase of the α-oxygen concentration and thus, a probable enrichment of the CB surface with these oxygenated species, at the start of the combustion.