摘要
First-principles calculanons were performed to investigate the mechamsm of Hg0 adsorpnon and oxidation on CeO2（111）. Surface oxygen acnvated by the reducnon of Ce to Ce a vlta to Hg~ adsorption and oxidation processes. Hg0 was fully oxidized by the surface lattice oxygen on CeO2（111）, without using any other oxidizing agents. HCI could dissociate and react with the Hg adatom on CeO2（111） to form adsorbed Hg CI or CI-Hg-Cl groups, which promoted the desorption of oxidized Hg and prevented CeO2 catalyst deactivation. In contrast, O-H and H-O-H groups formed during HC1 adsorption consumed the active surface oxygen and prohibited Hg oxidation. The consumed surface oxygen was replenished by adding O2 into the flue gas. We proposed that oxidized Hg desorption and maintenance of sufficient active surface oxygen were the rate-determining steps of Hg0 removal on CeO2-based catalysts. We believe that our thorough understanding and new insights into the mechanism of the Hg0 removal process will help provide guidelines for developing novel CeO2-based catalysts and enhance the Hg removal efficiency.
First-principles calculanons were performed to investigate the mechamsm of Hg0 adsorpnon and oxidation on CeO2（111）. Surface oxygen acnvated by the reducnon of Ce to Ce a vlta to Hg~ adsorption and oxidation processes. Hg0 was fully oxidized by the surface lattice oxygen on CeO2（111）, without using any other oxidizing agents. HCI could dissociate and react with the Hg adatom on CeO2（111） to form adsorbed Hg CI or CI-Hg-Cl groups, which promoted the desorption of oxidized Hg and prevented CeO2 catalyst deactivation. In contrast, O-H and H-O-H groups formed during HC1 adsorption consumed the active surface oxygen and prohibited Hg oxidation. The consumed surface oxygen was replenished by adding O2 into the flue gas. We proposed that oxidized Hg desorption and maintenance of sufficient active surface oxygen were the rate-determining steps of Hg0 removal on CeO2-based catalysts. We believe that our thorough understanding and new insights into the mechanism of the Hg0 removal process will help provide guidelines for developing novel CeO2-based catalysts and enhance the Hg removal efficiency.
