Soot Oxidation Characteristics of SiC Nanoparticle Membrane Filters

A diesel particulate membrane filter (DPMF) has good trapping efficiency of soot and reduces the pressure loss through the soot accumulation process on the diesel particulate filter wall. The activation energy reduction effect of the soot oxidation reaction by DPMF was clarified. The membrane consists of SiC nanoparticles with a diameter of 10-100 nm. A thin oxide layer is formed on the SiC particle surface, and nanoscale noble metal particles are distributed on the surface. The reduction mechanism for the activation energy was investigated in detail.

Nanoscale soot was accumulated on DPMF from a diesel lamp. Furthermore, the soot oxidation in the regeneration process was observed using an optical microscope. An Arrhenius plot was made from the change of the concentration of the product gases CO and CO₂ with respect to time. The performance and the temperature dependence of oxygen desorption on the oxide layer was measured by thermal desorption spectroscopy (TDS).

Pt-CeO₂/ZrO₂-based materials are commonly used as oxygen storage capacity (OSC) materials and the TDS chart shows two peaks of oxygen desorption. However, the examined SiC exhibited only one peak. It is expected that the oxygen-supply mechanism of this material differs from the conventional reaction mechanism in OSC materials.