Suppressed lattice oxygen mobility on Ag/FeO catalyst enhances the sulfur selectivity of HS selective oxidation.

The regulation of lattice oxygen mobility on metal oxide-based catalysts holds great significance for balancing the conversion and selectivity in the selective catalytic oxidation of HS (HS-SCO). Herein, we successfully suppress the lattice oxygen mobility of iron oxide-based catalyst via Ag loading to realize the high HS removal effect and high sulfur selectivity simultaneously. The Ag-loaded FeO catalyst synthesized by simple precipitation and impregnation method exhibits an outstanding sulfur capacity of 3344.9 mgS g and a high sulfur selectivity of 93.0 % at 120 °C, which is superior to those of FeO catalyst (771.1 mgS g and 86.4 %). The X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS) and hydrogen temperature programmed reduction (H-TPR) characterization results reveal that the bond energy of Fe-O is enhanced via Ag loading, resulting in the reduced lattice oxygen mobility. Furthermore, oxygen temperature programmed desorption (O-TPD) result shows that the amount of lattice oxygen is decreased after Ag loading. These regulations of lattice oxygen prevent the over-oxidation of HS and improve sulfur selectivity, thereby delaying the catalyst poisoning and prolonging the lifespan of catalyst. Meanwhile, the Ag loading reduces the alkaline environment on the catalyst surface, which avoids the accumulation of sulfur. This work provides a new insight into designing desulfurizers with high conversion and selectivity for HS-SCO process.