A Review on Adsorption Technologies for Mercury Emission Control
This study summarized existing adsorption technologies for the removal of elemental mercury in the flue gas. Both carriers (e.g., active carbon (AC), pyrolyzed char, inorganic adsorbents and fly ash) and various modification methods (pore structure improvement, oxygen-containing functional groups addition and new active reagents impregnation) were compared to shed light on the development of future adsorption technology. AC and char possibly performed more mercury adsorption capacity (MAC) compared with fly ash and inorganic adsorbents since carbon atom existence was easier to form the active halogen groups (C–X) and oxygen containing groups. Though both pore structure improvement and chemical group formation improved the MAC of adsorbents, the chemical modification methods (oxygen-containing functional groups addition and new active reagents impregnation) were more effective. The impregnation of halogen, sulfur and metal chloride could distinctly form lots of active sites on the adsorbents and developed high effective mercury adsorbents. In the future, the adsorption researches possibly focus on SO2 and H2O resistance of adsorbents, separable adsorbents, low-cost chemical modification methods, and utilization potential of fly ash.