Effect of Temperature and Acid Gases on Elemental Mercury Removal by a Ce–Bi-Doped Cobalt-Based Adsorbent under Simulated Flue Gas Conditions

The complex conditions of coal-fired flue gas, particularly temperature fluctuations and the presence of acid gases, pose significant challenges to elemental mercury (Hg 0 ) removal. To address these issues, a Ce-Bi-doped cobalt-based (Ce–Bi–Co) adsorbent was synthesized and evaluated for Hg 0 removal from simulated coal-fired flue gas. The adsorbent exhibited favorable Hg 0 removal performance in the low-temperature range of 50–150 °C. The effects of typical flue-gas components, including O 2, HCl, and SO 2, were further examined in the fixed-bed reaction system. O 2 promoted Hg 0 oxidation by continuously replenishing surface active oxygen, while HCl enhanced Hg 0 removal through the formation of reactive chlorine species. Notably, low concentrations of SO 2 promoted Hg 0 removal, whereas relatively high SO 2 concentrations inhibited the performance due to competitive adsorption and the accumulation of sulfur-containing species. Comprehensive characterizations indicated that the doping of Ce and Bi modifies the surface structure and significantly enriches the chemisorbed oxygen, which directly facilitates the catalytic oxidation of Hg 0 . XPS analysis showed that chemisorbed oxygen directly participated in Hg 0 oxidation, while Co 3+ and the Ce 4+ /Ce 3+ contributed to the surface redox reactions. This study provides practical insights for the application of modified Co-based materials for mercury emission control under coal-fired flue gas.