Low-temperature oxidation of particulate matter using ozone

Low-temperature oxidation of particulate matter (PM) was investigated using ozone, which has high oxidation ability. Granular carbon was first used as a model PM to investigate the influential factors for PM oxidation with ozone. The PM collected from diesel exhaust using a diesel particulate filter was then evaluated to determine the oxidation performance of ozone. Carbon was effectively oxidized by ozone at low temperatures less than 573 K and the oxidation rate was larger than ten times that for NO2 at 423 K; however, the oxidation rates were decreased by the thermal decomposition of ozone and reaction with NO as an exhaust gas component. The oxidation rate when using ozone could be calculated with inclusion of these factors using the Arrhenius equation. The PM oxidation characteristics were similar to those for granular carbon. The results indicate that oxidation with ozone is a promising method for low-temperature PM oxidation and optimized performance with ozone could be achieved.