Low-temperature NO reduction via NH3-SCR over a P-modified MnCe/Ti catalyst in sintering exhaust: N2 selectivity and catalytic pathways elucidated by in situ DRIFTS

P-modified MnCe/Ti catalysts were developed to facilitate NO reduction via NH 3 -SCR from sintering flue gas. Catalytic tests showed that the optimal MnCeP2/Ti sample achieved NO ₓ conversion above 87% with an average N 2 selectivity of 89% over 150–300 °C. This behavior was associated with stronger surface acidity, an increased abundance of acid sites, alongside a weakened reducibility after P incorporation, which was , linked to a reduced Mn 4+ fraction and the emergence of phosphate complexes. Furthermore, characterization results and DFT calculations confirm that phosphate ions are more likely to combine with the Ce sites to form Ce-O-P bond. Under CO-containing conditions, the development of reactive bidentate nitrate species was fully suppressed, indicating that NH 3 -SCR over MnCeP2/Ti proceeded only via an Eley-Rideal route, wherein gaseous NO directly interacts with surface-bound NH 3 /NH 4 + species. Furthermore, upon MnCeP2/Ti no adsorbed carbonate species and chemisorbed CO were detected, which explains the strong CO tolerance of MnCeP2/Ti. Accordingly, CO oxidation over MnCeP2/Ti follows a Mars-van Krevelen pathway involving the reaction between gas-phase CO and surface active oxygen.