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

Abstract

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 per-formed. NOx-assisted soot oxidation activities showed the large difference between the catalysts. Especially, Ag/2MnO(x)-1CeO(2) catalysts showed remarkably improved T-20 at 349 degrees C compared with T-20 of Ag/CeO2 at 464 degrees C (each T-50 is 391 degrees C and 400 degrees C, and each T-max is 514 degrees C and 509 degrees 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/2MnO(x)-1CeO(2) 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/2MnO(x)-1CeO(2) catalysts were proposed as optimal catalysts.