Enhanced Nitrous Oxide Decomposition on Zirconium-Supported Rhodium Catalysts by Iridium Augmentation

The effective elimination of N₂O from automobile exhaust at low temperatures poses significant challenges. Compared to other materials, supported RhO_x catalysts exhibit high N₂O decomposition activities, even in the presence of O₂, CO₂, and H₂O. Metal additives can enhance the low-temperature N₂O decomposition activities over supported RhO_x catalysts; however, the enhancement mechanism and active sites require further investigation. In this study, we demonstrate the significant enhancement of the low-temperature N₂O decomposition activity of a monoclinic ZrO₂-supported Rh catalyst [Rh(1)/ZrO₂] with Ir addition in the presence of N₂O + O₂ + CO₂ + H₂O. The promotional effect of Ir and the active sites on N₂O decomposition in Rh(1)-Ir(1)/ZrO₂ (Rh = 1 wt % and Ir = 1 wt %) were investigated by kinetic studies and in situ spectroscopic methods, including X-ray absorption spectroscopy, ambient-pressure X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy. These results indicate that both surface Rh and Ir species in Rh(1)-Ir(1)/ZrO₂ were active sites for N₂O catalytic decomposition at low temperatures, and Ir augmentation promoted the desorption of gaseous O₂, which are regarded as key steps in N₂O decomposition.