Gaseous mercury removal by manganese-based compounds: A review

Developing cost-efficient sorbents or catalysts is a viable route to mitigate Hg0 emission. Recently, manganesebased composites, for instance, MnO2, MnOx, Mn spinels and perovskites, and Mn sulfides, have gained incremental research interests due to their good redox abilities and variety diversity. This work reviews the advances in Hg0 removal by Mn-based compounds in recent decade. MnO2 possesses a good Hg0 oxidation ability due to the abundant high-valence Mn4+ ions; however, the lower thermal stability disfavors its durability and reusability. MnOx is more popular than MnO2 due to its structure flexibility and good redox capacity via Mn4+/Mn3+ shift. Mn spinels and perovskites are prospective sorbents or catalysts for Hg0 removal due to their peculiar structural and physiochemical properties. Nevertheless, most Mn oxides can be readily deactivated by sulfur species due to the formation of inactive Mn sulfates. Thus, Mn sulfides show great promise for mercury capture due to their good resistance to sulfur oxide.