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

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. [Display omitted] •Pr6O11 with higher lattice oxygen mobility oxidized propane faster than did CeO2.•The defects-induced Oxn- worked as the key soot oxidizer over CeO2.•Pr6O11 deactivated with the draining of its lattice oxygen by soot.•The catalytic combustion of propane followed a typical Mars-van Krevelen mechanism.•Soot ignition followed a Mars-van Krevelen-like mechanism with open redox cycles.