Development of High Performance Catalyzed DPF with New Soot Burning Mechanism

We developed ZrO₂-based new catalysts that exhibit high carbon-burning performance and superior thermal stability for catalyzed diesel particulate filter (CDPF). Characterizations indicated that the developed ZrO₂-based catalysts function by a new soot burning mechanism different from the conventional CeO₂-based catalysts. Based on the results of evaluations using isotopic oxygen, we supposed that the ZrO₂-based catalysts released active oxygen derived from the lattice of the oxides effectively as well as in the vicinity of the surface, while the conventional CeO₂-based catalysts utilized active oxygen mainly from the vicinity of the surface. By amperometry of the inside of the catalysts applied during the carbon burning electric current was detected only for the ZrO₂-based catalysts. Presumably, ZrO₂-based catalysts promoted the carbon burning by a mechanism that oxygen ion in the lattice of the oxides is transferred to the active site with oxygen-ion conduction. An experiment to examine the carbon burning performance which simulated DPF regeneration showed that regeneration duration of the developed ZrO₂-based catalysts was shortened by 33% compared with the shortest value for the conventional CeO₂-based catalysts. The catalyst was also superior to the CeO₂-based catalyst for the soot burning under the engine exhaust gas conditions. The new high-performance soot-burning catalyst developed in this study was introduced to the market in the end of 2008.