Simultaneous oxidation of NO, CO, and CH4 from exhaust gas in LNG combined cycle power plant over MnCuCeOx/Al2O3 catalyst.

Nitrogen oxides (NOx), carbon monoxide (CO), and methane (CH₄) are co-emitted at the start-up of LNG combined-cycle power plants. Simultaneous oxidation using mixed metal oxide catalysts is applied to remove these pollutants. Mn, Cu, Ce, MnCu, MnCe, and MnCuCe oxides supported on Al₂O₃ catalysts were prepared, and their catalytic activities were investigated. Among them, the MnCuCe/Al₂O₃ catalyst exhibited the highest conversions: 38% for NO at 250 °C, 95% for CO at 200 °C, and 35% for CH₄ at 500 °C. These superior catalytic performances were attributed to its amorphous structure, strong electronic interactions among metal ions, and an abundance of surface-active oxygen species. Catalytic activity tests showed that NO promoted the oxidation of CO and CH₄. Furthermore, temperature-programmed oxidation reactions indicated that NO, CO, and CH₄ oxidation are competitive reactions on the active sites. However, it was suggested that some of the NO₂ produced from NO oxidation acts as oxidants for CO and CH₄ to promote their oxidation. The findings of this study provide novel insights into the simultaneous removal of exhaust gases emitted from industrial combustion.