Potential rare-earth modified CeO2 catalysts for soot oxidation

The physico-chemical properties of ceria (CeO2) and rare earth modified ceria (with La, Pr, Sm, Y) catalysts are studied and correlated with the soot oxidation activity with using O-2 and O-2 + NO. CeO2 modified with La and Pr shows superior soot oxidation activity with O-2 compared with the unmodified catalyst. The improved soot oxidation activity of rare earth doped CeO2 catalysts can be correlated to the increased meso/micro pore volume and the stabilisation of the external surface area. On the other hand, unreducible ions decrease the intrinsic soot oxidation activity of rare earth modified ceria with both O-2 and NO + O-2 due to the decreased amount of redox surface sites. The catalyst bulk oxygen storage capacity is not a critical parameter in determining the soot oxidation activity. The modification with Pr shows the best soot oxidation with both O-2 and O-2 + NO compared with all other catalysts.