Preparation methods and thermal stability of Ba-Mn-Ce oxide catalyst for NOx-assisted soot oxidation

Manganese oxide-loaded and -doped ceria as well as the corresponding barium-modified oxide catalysts were prepared for soot oxidation in the presence of NOx,and were characterized by using X-ray diffraction,Brunauer-Emmett-Teller and NO temperatureprogrammed oxidation measurements.The activity of catalyst depended strongly on the NO2 production capacity,and the importance of surface nitrates was weakened without heat transfer limitations.The formation of perovskite-type oxides after the high-temperature calcination caused the loss of NOx storage capacity for the Ba-modified catalysts,but did not seem to affect the NO oxidation activity obviously.The addition of barium did not prevent the phase separation of MnOx-CeO2 solid solutions,whereas it inhibited the sintering of oxide crystallites effectively.This,as well as the relatively high surface area,resulted in a small increase in soot oxidation temperature for the thermally aged Ba/Mn-Ce catalyst.