The Ultra-high Hg0 Adsorption Capacity Modified by Selenium

Abstract Activated carbon was one of the main adsorptions utilized in elemental mercury (Hg0) removal from coal combustion flue gas. However, the high cost and low physical adsorption efficiency of activated carbon injection (ACI) limited its application. In this study, an ultra-high efficiency catalyst sorbent-Sex/Activated carbon (Sex/AC) was synthesized and applied to remove Hg0 in the simulated flue gas, which exhibited 120 times outstanding adsorption performance versus the conventional activated carbon. The Sex/AC reached 17.98 mg/g Hg0 adsorption capacity at 160 °C in a pure nitrogen atmosphere. Moreover, it maintained an excellent mercury adsorption tolerance at the NO and SO2 conditions in a bench-scale fixed-bed reactor. Characterized by the multiple methods, including BET, XRD, XPS, and the DFT calculation, we demonstrated that the ultrahigh mercury removal performance was driven from the activated Se species in Sex/AC. Chemical adsorption was the main reason for Hg0 removal: Selenium on the surface of AC would capture Hg0 in the flue gas to form an extremely stable substance-HgSe, avoiding subsequent Hg0 released. Additionally, the oxygen-containing functional groups in AC and the higher BET areas promote the conversion of Hg0 to HgO. This work provided a novel and highly efficient carbon-based sorbent -Sex/AC to capture the mercury in coal combustion flue gas.