Comparative study of La1–xCexMnO3+δ perovskites and Mn–Ce mixed oxides for NO catalytic oxidation

A series of La 1– x Ce x MnO 3+ δ ( x  = 0, 0.05, 0.1, 0.2, and 0.3) perovskites and Mn–Ce mixed oxides were prepared. Their physico-chemical properties were systematically characterized and the NO oxidation activities of the catalysts were investigated. The La 0.9 Ce 0.1 MnO 3+ δ has the best activity among all of the catalysts, with a maximum NO conversion of 85% at 300 °C. The characterization results indicate that the doping of Ce improves the properties of the perovskites in terms of the specific surface area, the average valence state of Mn ions, the number of reactive oxygen species and the NO x desorption behaviors. The Mn–Ce mixed oxide calcined at 500 °C shows a similar NO oxidation activity with La 0.9 Ce 0.1 MnO 3+ δ . However, the activity of the mixed oxide obtained at 750 °C decreases a lot, which results from the loss of active sites and active oxygen species.