Ozone-assisted diesel soot combustion over Mn2O3 catalysts: A tandem work of different reactive phases

Abstract

Catalytic diesel particulate filtration (CDPF) assisted by ozone is a promising strategy for soot elimination at exhaust temperatures. It is important yet challenging to utilize the strongly oxidizing ozone while prevent its escape. In this study, rod-like Mn2O3 catalysts with high ozone decomposition ability were proved as an ideal tool for such a task. With thorough characterizations and temperature-programmed oxidation tests in selected atmospheres, triple low-temperature incubation effects were ascribed to the (catalytic) decomposition of ozone, including oxidizing NO to NO2, breeding surface oxygen complexes on soot and surface manganese species on the catalyst. Superior soot elimination efficiency (T10 = 267 °C, T50 = 392 °C, TOFMn = 1.0 × 10−2 s−1) was achieved by the tandem work of NO2 (at ∼200–500 °C), NO2-induced nitrates/nitrites (at ∼200–300 °C), surface manganese oxides (at ∼300–400 °C) and O2 (at ∼400–500 °C), indicating the coupling of ozone and transition metal oxides may lead to reliable and cost-effective CDPF systems.