Insight Into the Origins of N ₂ O Byproduct on Confinement Structure TiO ₂ /MnSm Catalyst Through Sulfation Pre‐Treatment for Low‐Temperature NH ₃ ‐SCR Reaction

ABSTRACT Mn‐based catalysts are the most promising catalysts for low‐temperature NH 3 ‐SCR, but improving N 2 selectivity still faces great challenges. Herein, the tubular structure TiO 2 –SO 4 2− /MnSm assembled from nanosheets was developed, which exhibited superior NO removal efficiency and outstanding N 2 selectivity over a wide operation temperature window in NH 3 ‐SCR. It was experimentally proven that sulfation treatment disturbs the lattice of TiO 2 to effectively promote the generation of oxygen vacancies and raise the proportion of weak acid sites. In addition, Sm modification greatly improved the dispersion of active species and enhanced the metal–support interaction, which promoted the interfacial electron transfer to modulate the activation capacity of NH 3 to reduce the generation of N 2 O. Importantly, DFT calculations and in situ DRIFTS revealed that the generation of N 2 O originated from the over‐oxidation of NH 3 and non‐selective catalytic reduction via E–R or L–H mechanism, which required higher Gibbs free energy on catalyst TiO 2 –SO 4 2− /MnSm. This work highlights a new insight into improving the N 2 selectivity of Mn‐based catalysts in NH 3 ‐SCR.