A simple model catalyst study to distinguish the roles of different oxygen species in propane and soot combustion

Abstract

It is important yet difficult to distinguish the specific roles of superficial Oxn- and interfacial lattice oxygen in catalytic combustion, especially over catalysts consisting of reducible metal oxides. In this study, based on the comparison of two natural counterparts with similar structure — CeO2 (an Oxn- generator) and Pr6O11 (a lattice oxygen contributor), it is suggested that the catalytic combustion of propane under lean-burn conditions followed a typical Mars-van Krevelen mechanism, in which catalyst lattice oxygen represented the dominant reactive phases while superficial Oxn- played negligible roles. As for soot combustion, adsorbed Oxn- represented more sustainable oxidants than lattice oxygen (drained easily at the beginning of the reactions). Such a comparison is readily achieved and widely applicable, which may shed light on the identification of dominant reactive phases for various oxidation reactions over oxide-based catalysts.