Transformation of Arsenic from Poison into Active Site by Construction of Unique AsO_x/CeO₂ Interface for Stable NO_x Removal

Arsenic in the flue gas has been widely reported as a common poison for SCR catalysts; however, an appropriate coping strategy is still lacking to improve the arsenic resistance performance. Herein, a unique AsO_x/CeO₂ interface is constructed to transform arsenic from poison into active site with balanced acid-redox property, successfully achieving efficient NO_x removal. The optimized AsO_x/CeO₂ exhibits high NO_x removal efficiency, four times that of the As-poisoned V₂O₅/TiO₂ catalyst, and even comparable to the state-of-the-art SCR catalysts. It was found that the As-O-Ce interfacial sites in oxygen-bridged As dimers on CeO₂ can provide both Lewis acid sites and active lattice oxygen species, enhancing the adsorption and activation of NH₃ to form key -NH₂ intermediates, thereby facilitating the NH₃-SCR reaction. More surprisingly, a thin CeO₂ layer on the top of V₂O₅/TiO₂ can capture arsenic to protect catalysts from arsenic attacking, which improves the catalytic activity to 2.8 × 10^-7 mol g^-1 s^-1, even higher than that of fresh V₂O₅/TiO₂ (2.0 × 10^-7 mol g^-1 s^-1). Therefore, this strategy provides new ideas not only for designing antipoisoning SCR catalysts but also a feasible solution for the stable operation of commercial SCR catalysts in arsenic-containing flue gas.