Transformation of Arsenic from Poison into Active Site by Construction of Unique AsO/CeO Interface for Stable NO 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/CeO interface is constructed to transform arsenic from poison into active site with balanced acid-redox property, successfully achieving efficient NO removal. The optimized AsO/CeO exhibits high NO removal efficiency, four times that of the As-poisoned VO/TiO 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 can provide both Lewis acid sites and active lattice oxygen species, enhancing the adsorption and activation of NH to form key -NH intermediates, thereby facilitating the NH-SCR reaction. More surprisingly, a thin CeO layer on the top of VO/TiO can capture arsenic to protect catalysts from arsenic attacking, which improves the catalytic activity to 2.8 × 10 mol g s, even higher than that of fresh VO/TiO (2.0 × 10 mol g s). 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.