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

• Published in: Applied catalysis. B, Environmental Environmental, 2022-08, Vol.310, p.121331, Article 121331
• Main Authors: Mao, Xuezan, Liu, Shuran, Liu, Wei, Wu, Xiaodong, Liu, Shuang
• Format: Article
• Language: English
• Subjects: Catalysts; CeO2; Cerium oxides; Combustion; Lattice oxygen; Metal oxides; Oxidants; Oxidation; Oxidizing agents; Oxn- species; Oxygen; Pr6O11; Praseodymium oxide; Propane; Propane and soot combustion; Soot
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121331

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.