Noble metal catalysts dedicated to the methane emission control for lean-burn mobile sources: A review

Natural gas serves as a crucial bridge fuel in the green transition of the energy and transportation sectors and is expected to remain pivotal for their long-term sustainable operation. However, uncontrolled emissions of methane—its principal component—intensify the greenhouse effect. Since mobile sources represent a key focus in air pollution control and noble metals have demonstrated decades of proven effectiveness in exhaust gas purification, this paper systematically reviews representative studies on eight noble metals (Pd, Pt, Rh, Ir, Ru, Os, Ag, and Au) for the catalytic abatement of methane emissions. It discusses the potential impact of exhaust gas composition on methane catalytic oxidation activity, explains factors influencing the activity and deactivation of noble metal catalysts, and emphasizes efforts to mitigate catalyst deactivation caused by two key poisons: water and sulfur. By offering an in-depth understanding of the challenges in designing and fabricating high-efficiency methane combustion catalysts, this review aims to facilitate the advancement of methane emission control technologies for lean-burn mobile sources.