The Effect of Sr Addition in Cu- and Fe-Modified CeO2 and ZrO2 Soot Combustion Catalysts

This study investigates the activity of transition and alkaline-earth metal-doped catalysts supported on ceria or zirconia for the NOx-assisted oxidation of diesel particulate. A series of Cuand Fe-impregnated catalysts over CeO2 and ZrO2 supports were prepared by incipient wetness impregnation and characterized by BET, X-ray diffraction (XRD), and temperature-programmed reduction (TPR) experiments while their catalytic activity was investigated in NOx-assisted reaction by means of temperature programmed oxidation experiments (TPO). Higher activity was achieved by copper modified catalysts; the addition of Sr positively affected the performance of the materials, suggesting a synergic effect between transition metals and alkaline-earth metal. The role of copper is correlated to the oxidation of NO to NO2, while strontium seems to be mainly involved in the storage of NOx species.