Ce-Al Mixed Oxide with High Thermal Stability for Diesel Soot Combustion

A series of Al-doped CeO(2) catalysts (n-AlCeO(2), where n represents the molar ratio of Cc to Al in the samples) were prepared by a citric acid complexation-combustion method and used for soot combustion. There is a strong interaction between CeO(2) and Al(2)O(3) in the mixed oxide, and some aluminum can be incorporated into the CeO(2) lattice forming a solid solution. The existence of gamma-Al(2)O(3) in the mixed oxide obviously improved the thermal stability of CeO(2) as a "diffusion barrier", which induced a higher catalytic activity of the mixed oxides compared with the pure CeO(2). For the Al-containing samples, the mobility of surface lattice oxygen seems to play an important role in soot combustion. The 30-AlCeO(2) sample exhibited the highest soot combustion activity with the temperature corresponding to the CO(2) + CO peak of 356 degrees C