Cost-Effective Manganese Ore Sorbent for Elemental Mercury Removal from Flue Gas.

Abstract

Mercury capture from flue gas remains a challenge for environmental protection due to the lack of cost-effective sorbents. Natural manganese ore (NMO) was developed as a cost-effective sorbent for elemental mercury removal from flue gas. NMO sorbent showed excellent Hg0 removal efficiency (>90%) in a wide temperature window (100-250 °C) under the conditions of simulated flue gas. O2, NO, and HCl promoted Hg0 removal due to the surface reactions of Hg0 with these species. SO2 and H2O slightly inhibited Hg0 removal under the conditions of simulated flue gas. O2 addition could also weaken the inhibitory effect of SO2. NMO sorbent exhibited superior regeneration performance for Hg0 removal during ten-cycle experiments. Quantum chemistry calculations were used to identify the active components of NMO sorbent and to understand the atomic-level interaction between Hg0 and sorbent surface. Theoretical results indicated that Mn3O4 is the most active component of NMO sorbent for Hg0 removal. The atomic orbital hybridization and electrons sharing led to the stronger interaction between Hg0 and Mn3O4 surface. Finally, a chemical looping process based on NMO sorbent was proposed for the green recovery of Hg0 from flue gas. The low cost, excellent performance, superior regenerable properties suggest that the natural manganese ore is a promising sorbent for mercury removal from flue gas.