SO-Driven In Situ Formation of Superstable HgSeCl for Effective Flue Gas Mercury Removal.

Flue gas mercury removal is mandatory for decreasing global mercury background concentration and ecosystem protection, but it severely suffers from the instability of traditional demercury products (, HgCl, HgO, HgS, and HgSe). Herein, we demonstrate a superstable HgSeCl compound, which offers a promising next-generation flue gas mercury removal strategy. Theoretical calculations revealed a superstable Hg bonding structure in HgSeCl, with the highest mercury dissociation energy (4.71 eV) among all known mercury compounds. Experiments demonstrate its unprecedentedly high thermal stability (>400 °C) and strong acid resistance (5% HSO). The HgSeCl compound could be produced via the reduction of SeO to nascent active Se by the flue gas component SO and the subsequent combination of Se with Hg and Cl ions or HgCl. During a laboratory-simulated experiment, this HgSeCl-based strategy achieves >96% removal efficiencies of both Hg and HgCl enabling nearly zero Hg re-emission. As expected, real mercury removal efficiency under Se-rich industrial flue gas conditions is much more efficient than Se-poor counterparts, confirming the feasibility of this HgSeCl-based strategy for practical applications. This study sheds light on the importance of stable demercury products in flue gas mercury treatment and also provides a highly efficient and safe flue gas demercury strategy.