Interactional effect of cerium and manganese on NO catalytic oxidation.

To preferably catalyze the oxidation of NO to NO2 in diesel after-treatment system, a series of CeO2-MnO x composite oxides was supported on silica-alumina material by the co-impregnation method. The maximum conversion of NO of the catalyst with a Ce/Mn weight ratio of 5:5 was improved by around 40%, compared to the supported manganese-only or cerium-only sample. And its maximum reaction rate was 0.056 μmol g-1 s-1 at 250 °C at the gas hourly space velocity of 30,000 h-1. The experimental results suggested that Ce-Mn solid solution was formed, which could modulate the valence state of cerium and manganese and exhibit great redox properties. Moreover, the strong interaction between ceria and manganese resulted in the largest desorption amount of strong chemical oxygen and oxygen vacancies, leading to the maximum O α area ratio of 62.26% from the O 1s result. These effective oxygen species could be continually transferred to the surface, leading to the best NO catalytic activity of 5Ce5Mn/SA catalyst. Graphical abstract.