Effect of Different Aging Conditions on the Soot Oxidation by Thermogravimetric Analysis

Diesel particulate filter is an effective device to reduce diesel particulate emission. The particles in diesel particulate filter are usually affected by the aging of high-temperature exhaust gas before the regeneration process. In order to investigate the effect of aging conditions on the soot oxidation process, the effect of aging temperature and aging time on the oxidation process of carbon black (Printex-U, PU) and the PU/catalyst/ash mixture are studied by thermogravimetric analysis. The aging PU particles have lower starting temperature, peaking temperature, ending temperature, and activation energy. Compared with the particles without aging, the PU particles with a 400 °C aging temperature and 20 h aging time are able to reduce the activation energy from 191.2 to 158 kJ/mol. Low aging temperatures (200-300 °C) and the catalyst have a certain synergistic effect on the improvement of PU oxidation activity. The PU/CeO₂ mixture with a 300 °C aging temperature and 20 h aging time decreases the activation energy from 178.4 to the lowest 113.6 kJ/mol. The addition of CaSO₄ in PU particles cannot stop the improvement of its oxidation activity by aging, but it reduces the effect of aging. This work is helpful to reveal the mechanism of aging on PU and the PU/catalyst/ash mixture in air environment.