Catalytic diesel soot elimination over potassium promoted transition metal oxide (Co/Mn/Fe) nanosheets monolithic catalysts

Abstract

A series of potassium promoted transition metal oxide crossed nanosheets (KTMO-NS: KCo-NS, KMn-NS and KFe-NS) on the monolithic three-dimensional macroporous (3-DM) nickel foam substrate was prepared through the facile hydrothermal and wet impregnation methods, and utilized to evaluate for catalytic soot oxidation. The KTMO-NS catalysts display higher activity than that potassium-free catalysts (TMO-NS) for soot elimination. The results of XPS O1s, Soot-TPR and the amount of active oxygen species indicate that the interaction between potassium and transition metal oxides can generate more oxygen vacancies, so that the catalysts have more active oxygen species, especially for KCo-NS and KFe-NS. Under O2/N2 atmosphere, the KCo-NS and KFe-NS display the higher catalytic activity because of the more surface oxygen species and the stronger interaction between potassium and cobalt/ferric oxide. After introducing NO in the O2/N2 ambient, the KMn-NS possesses the similar catalytic activity with the KFe-NS owing to the higher oxidation ability of NO. Among these catalysts, the KCo-NS shows the highest catalytic soot performance with the lowest T10 (229 °C) and T50 (333 °C), which is higher than the Pt promoted transition metal oxide catalysts.