Simultaneous catalytic oxidation of elemental mercury and arsine over CeO(111) surface: a density functional theory study.

Ceria (CeO)-based materials are potential catalysts for the removal of the Hg and AsH present in reducing atmospheres. However, theoretical studies investigating the Hg and AsH removal capacity of ceria remain limited. In this study, the adsorption behavior and mechanistic pathways for the catalytic oxidation of Hg and AsH on the CeO(111) surface, including the calculation of optimized adsorption configurations and energies, were investigated using density functional theory calculations. The results suggest that Hg and AsH are favorably adsorbed on the CeO(111) surface, whereas CO is not, which is crucial for selective removal when CO is a desirable gas component. Furthermore, AsH is adsorbed more favorably than Hg. In addition, the calculations revealed that the Hg atom is initially adsorbed on the surface and then oxidized by lattice oxygen to form HgO. Concerning AsH decomposition, the stepwise dehydrogenation of AsH followed by bonding with lattice O atoms to form the As-O bond seems the most plausible. Finally, the adsorbed As-O bond is further forms elemental As and AsO. Therefore, CeO can adsorb and remove Hg and AsH, making it a promising catalyst for the simultaneous catalytic oxidation of Hg and AsH in strongly reducing off-gas.