Catalytic soot combustion over CeO2-based oxides

The catalytic soot combustion, surface area, and reducibility for the CeO2-based oxides were investigated. The carbon black (CB), which was used as a model of soot particle, was combusted over 700 °C, while the CeO2-based catalysts reduced the CB oxidation temperature by more than 150 °C. Although the addition of rare-earth metal oxides to CeO2 increased the surface area, no remarkable improvement of catalytic activity was confirmed. The transition metal oxide added to CeO2 significantly promoted the oxidation reaction, and the CuO–CeO2 catalyst exhibited the highest activity despite the lowest surface area of all composite oxides investigated. The reduction behavior of catalysts was closely related with the activity of CB oxidation. It was indicated that the oxygen species available for the oxidation reaction was increased by the addition of transition metal components. When the Cu content was varied for the CuO–CeO2 catalyst, the optimal amount existed for the CB oxidation.