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

Abstract

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 /CeO 2 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 /CeO 2 exhibits high NO x removal efficiency, four times that of the As-poisoned V 2 O 5 /TiO 2 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 CeO 2 can provide both Lewis acid sites and active lattice oxygen species, enhancing the adsorption and activation of NH 3 to form key −NH 2 intermediates, thereby facilitating the NH 3 −SCR reaction. More surprisingly, a thin CeO 2 layer on the top of V 2 O 5 /TiO 2 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 V 2 O 5 /TiO 2 (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.