Methane is one of the main components of automobile exhaust and has 25 times higher greenhouse effect than CO2. Methane is difficult to be purified by three-way catalyst (TWC) because of its stable chemical property. However lean / rich lambda oscillation improves methane purification rate. In this study we clarified CO, NO, and H2O in the exhaust and CeZr oxide in catalyst play a crucial role in improving the methane purification rate under lambda oscillation.
