Textural–structural properties and soot oxidation activity of MnOx-CeO2 mixed oxides

A series of MnOx-CeO2 mixed oxides were prepared using a sol-gel method followed by calcinations at various temperatures. The soot oxidation activities were measured in different NO concentrations under loose contact conditions. A quasi-parabolic curve is observed for the apparent dependency of activity on the catalyst surface area. As the surface area is below 8 m2/g, the soot oxidation is limited by the availability of NO2 due to the separation and sintering of the mixed oxides. The rate-determining step turns to be NO2 reaction with soot for the high-surface-area catalysts.

Graphical AbstractFigure optionsDownload as PowerPoint slideDependency of soot oxidation and NO2 production on the BET surface area of MnOx-CeO2 mixed oxides.Research Highlights
► A threshold of the surface area of MnOx-CeO2 is 8 m2/g.
► Soot oxidation is limited by NO oxidation for the low-surface-area catalysts.
► It is restricted by NO2–soot reaction for the high-surface-area catalysts.
► NO2 production capacity is determined by both textural and structural properties.