Identifying Top Zr-MOFs for HgCl 2 Removal through Computational Screening under Humid and SO 2 -Containing Conditions

Mercuric chloride (HgCl 2 ) is a volatile and highly toxic mercury compound commonly encountered in industrial emissions, demanding effective capture strategies to limit environmental and health impacts. This work presents a high-throughput computational screening of 181 zirconium-based metal–organic frameworks (Zr-MOFs) to evaluate their selective adsorption of HgCl 2 under conditions simulating flue gas (393 K) in the presence of SO 2 and water vapor. HgCl 2 uptake was found to be strongly influenced by pore structure and chemical environment, with optimal adsorption observed in frameworks featuring cavity diameters between 7.5 and 20 Å, void fractions from 0.55 to 0.75, and surface areas below 3000 m 2 /g. Among the top-performing MOFs, Zr-L5 and MOF-806 exhibited the high HgCl 2 capacity of 16 and 12 mol·kg –1, respectively, even under the presence of SO 2 and H 2 O molecules. Competitive adsorption caused some capacity loss, but unique adsorption sites within tetrahedral and octahedral cages preserved selectivity, as supported by density and radial distribution analyses. Free-energy calculations further confirmed the thermodynamic favorability of HgCl 2 binding. These insights highlight promising Zr-MOF candidates and offer design principles for developing selective, moisture- and acid-resistant adsorbents suitable for practical HgCl 2 removal from flue gas.