Self-propagating high-temperature synthesis with post-heat treatment of La1−xSrxFeO3 (x=0–1) perovskite as catalyst for soot combustion

Abstract

Abstract La1−xSrxFeO3 (x = 0–1) perovskite, Sr-substituted LaFeO3, was prepared by Self-propagating high-temperature synthesis (SHS) and its catalytic activity for soot combustion was experimentally examined in comparison with that of a conventional Pt/Al2O3 catalyst. The products were also characterized by XRD, FE-SEM, and BET specific surface area. The XRD analysis revealed that all the products had a perovskite phase as the major compound, together with intermediate phases with higher x values (x = 0.7–1). The BET specific surface area of the products increased with x. Moreover, the catalytic activity for soot combustion also increased with x, wherein the BET specific surface area appeared an appropriate index for explaining the observed activity. The sample with x = 0.8 exhibited the highest activity for soot combustion among all the SHS products. The soot combustion temperature of this product was as much as 100 °C lower than that of non-catalytic soot combustion. In other words, it had the same activity as that at only 20 °C higher, in comparison to conventional Pt/Al2O3 catalyst. More significantly, average apparent activation energy of sample with x = 0.8 calculated by Friedman method using TG/DTA was approximately 15 kJ/mol lower than that of Pt/Al2O3 catalyst. This result suggested that La1−xSrxFeO3 has the possibility to be an alternative catalyst to Pt/Al2O3 catalyst.