in-situ DRIFTs study on different exposed facets of VO_x-MnO_x/CeO₂ catalysts for low-temperature NH₃-SCR

In order to achieve the low-temperature (200-250℃) NH₃-SCR, highly dispersed VO_x-MnO_x/CeO₂ catalysts with different exposed facets were produced. The NH₃-SCR performance results indicate that the NO conversion over VO_x-MnO_x/CeO₂-R with preferentially exposed 110 facets can achieve NO conversion >95% over a wide temperature span of 220-330℃. From the in-situ DRIFTs, gaseous NH₃ and NO are favorable to be absorbed on the surface of the VO_x-MnO_x/CeO₂-R catalyst with preferentially exposed 110 facets, which improves the efficiency of NO conversion. The mechanism study via in situ DRIFTs demonstrates that the well dispersed vanadium species on CeO₂ 110 absorb NH₃ to generate NH₃(L) and NH₄⁺(B) species, which in turn become highly reactive toward bridging nitrate and bidentate nitrate species to form N₂ and H₂O according to the Langmuir-Hinshelwood mechanism.