Effect of catalytic reactions on soot feature evolutions in oxidation process

In order to improve fuel economy and soot abatement efficiency of internal combustion engine vehicles, particulate filters are regenerated periodically. Catalyst coating on filter substrate is effective technology promoting regeneration, possessing the merits of high regeneration efficiency and low energy consumption. Filter regeneration depends on soot oxidation activity which is determined by catalyst and physicochemical properties. In this paper, oxidation activity of soot substitute at both with and without catalyst conditions is tested; moreover, soot feature evolutions during oxidation are analyzed. The results showed that thermogravimetric analysis (TGA) profiles of Printex-U and Printex-V were slightly shifted to low temperature directions by CeO₂. The drop of Printex-U start oxidation temperature by CeO₂ and Al₂O₃ was approximately 13.3 °C and 2 °C, respectively. Activation energy of Printex-U and Printex-V was increased significantly by CeO₂ at the end of oxidation, with the maximum values reaching 500 kJ/mole and 400 kJ/mole, respectively. Oxygen-containing functional groups of Printex-U and Printex-V changed slightly in the first stage of oxidation process. Surface oxidation of Printex-U and Printex-V was enhanced by mixing catalyst, which facilitated soot particles to oxidize into small sizes.