A Study on Improving Methane Purification Performance of a Three-Way Catalyst by Lean / Rich Lambda Oscillation

Abstract

Methane (CH₄) is one of the main constituents of the exhaust gas emitted by compressed natural gas (CNG) vehicles. CH4 has 25 times higher greenhouse effect than CO₂. Furthermore, it is difficult to be purified by a three-way catalyst (TWC) because of its chemical stability. In this study we clarified that lean / rich lambda oscillation improves CH₄ purification by contribution of oxygen storage capacity (OSC) of TWC. In addition, we investigated the mechanism of CH4 purification improvement by in situ FT-IR analysis.