NOx-assisted soot oxidation based on Ag/MnOx-CeO2 mixed oxides

In previous studies, Ag/CeO2 catalyst showed the high activity on NOx-free soot oxidation. For additional improvement of oxidation activity, Mn was introduced in Ag/CeO2 and NOx-assisted soot oxidation was performed. NOx-assisted soot oxidation activities showed the large difference between the catalysts. Especially, Ag/2MnOx-1CeO2 catalysts showed remarkably improved T20 at 349 °C compared with T20 of Ag/CeO2 at 464 °C (each T50 is 391 °C and 400 °C, and each Tmax is 514 °C and 509 °C). NO oxidation activity was increased as the mole ratio of Mn increased, while amount of NO adsorption was increased in Ag/MnOx-CeO2 mixed oxide compared to other catalysts. Especially, Ag/2MnOx-1CeO2 catalysts showed NO oxidation activity at low-temperature and NO desorption at appropriate temperature. As a result, it was confirmed that not only the NO oxidation activity but also the NOx adsorption characteristics are the most important factors in NOx-assisted soot oxidation. Accordingly, Ag/2MnOx-1CeO2 catalysts were proposed as optimal catalysts. [Display omitted] •Ag/MnOx-CeO2 catalysts were synthesized according to the mole ratio of Ce/Mn.•Ag/2MnOx-1CeO2 catalysts showed highest NOx-assisted soot oxidation activity compared to other catalysts.•NOx adsorbed on the catalyst was main factor in low-temperature soot oxidation.•NO was oxidized to NO2 by the Mn active site and the oxidized NO2 was adsorbed on the Ce surface site.