KCl Supported by γ‐Al₂O₃ for Selective Adsorption of Gaseous Oxidized Mercury: Flue Gas Influence and Application

ABSTRACT The KCl supported by γ‐Al 2 O 3 for selective adsorption of gaseous HgCl 2 has demonstrated high selectivity and adsorption capacity, which is crucial for mercury speciation partitioning from flue gas. However, its influence and stability in complex flue gas remains uncertain. Therefore, this paper explores the impact of common flue gas components (HCl, SO 2 , H 2 O, CO 2 , NO, O 2 ) on the adsorption process and elucidates the underlying mechanisms from experiment and DFT view. The experimental results demonstrate that the HgCl 2 breakthrough rate increases significantly from 2.119% to 17.921% as the concentration of HCl rises from 0 to 200 ppm. Comparatively, the HgCl 2 breakthrough rate affected by SO 2 and H 2 O is less than 8%, weakly reducing the adsorption efficiency of HgCl 2 , and that by CO 2 , NO, and O 2 is less than 5%, showing negligible effects on the HgCl 2 adsorption efficiency. The DFT indicates that HCl competes with HgCl 2 at the Top‐Cl site in KCl, thereby reducing the adsorption efficiency of HgCl 2 , with the adsorption energy decreasing from −87.11 to −43.39 kJ/mol. In contrast, SO 2 and H 2 O exhibit relatively weak interactions with Top‐Cl site of KCl, which exerts little influence on HgCl 2 adsorption. The 100‐h running in low‐concentration simulated flue gas test in laboratory and on‐site test in coal‐fired flue gas demonstrate that the KCl/γ‐Al 2 O 3 achieves a very low HgCl 2 breakthrough rate of less than 10%, highlighting its superior interference immunity for the complex flue gas components and strong suitability and stability for industrial applications. This study provides solid evidence to support the industrial application of KCl/γ‐Al 2 O 3 for highly selective adsorption of gaseous HgCl 2 in coal‐fired power plant.