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

A series of Al-doped CeO2 catalyst (n-AlCeO2, where n represents the molar ratio of Ce 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 CeO2 and Al2O3 in the mixed oxide, and some aluminum can be incorporated into the CeO2 lattice forming a solid solution. The existence of J-Al2O3 in the mixed oxide obviously improved the thermal stability of CeO2 as a “diffusion barrier”, which induced a higher catalytic activity of the mixed oxides compared with the pure CeO2. For the Al-containing samples, the mobility of surface lattice oxygen seems to play an important role in soot combustion. The 30-AlCeO2 sample exhibited the highest soot combustion activity with the temperature corresponding to the CO2 + CO peak of 356 °C.