Promotional Effect of Ag on the Catalytic Decomposition of N₂O in the Presence of O₂ over the Al₂O₃-Supported Rh Catalyst

Catalytic decomposition of N₂O into N₂ and O₂ is one of the most important techniques for removing N₂O from the atmosphere to curb global warming. Supported RhO_x catalysts are known to show high efficiency for N₂O decomposition, even in the presence of O₂, compared with other materials, such as supported metal oxides and Fe-based zeolite catalysts. In this study, the addition of Ag was found to enhance the efficiency of an Al₂O₃-supported RhO_x catalyst (RhO_x/Al₂O₃) for N₂O decomposition. The promotional effect of Ag was investigated using various operando spectroscopic methods, including X-ray absorption spectroscopy, diffuse reflectance UV-vis spectroscopy (DR UV-vis), ambient-pressure X-ray photoelectron spectroscopy, and kinetic studies. The results demonstrated that the addition of Ag enhanced the catalytic efficiency of the supported RhO_x catalysts by enhancing the thermal reduction of Rh oxide, which was identified as the rate-determining step, especially at low temperatures.