MECHANISTIC STUDY OF DIESEL SOOT COMBUSTION OVER AN AgMnOx CATALYST

摘要

Various transition metal oxides can catalyze the oxidation of solid carbon, either through a redox mechanism involving lattice oxygen, or using adsorbed oxygen species. Carbon oxidation over ceria-based catalysts is generally considered to proceed through a redox mechanism (1), whereas for perovskite oxides such as lanthanum chromites, weakly chemisorbed oxygen species have been proposed to be responsible for soot combustion (2). Mul et al. (3) used 18O2 to study the mechanism of carbon black oxidation catalyzed by several simple transition metal oxides (Cr2O3, Co3O4, Fe2O3, MoO3, V2O5 and K2MoO4). They proposed three different possible mechanisms depending on the catalyst: (i) a surface redox mechanism for Co3O4 and Fe2O3, (ii) a dual surface redox and spillover mechanism also involving adsorbed oxygen species for Cr2O3, and (iii) a redox mechanism involving lattice oxygen for MoO3, V2O5 and K2MoO4.