Effect of the properties of MnOx/activated carbon and flue gas components on Hg0 removal at low temperature

Manganese oxide loaded on activated carbon (Mn/AC) was synthesized using an impregnation method, and its capacity for Hg0 removal in simulated flue gas was investigated at 120 °C. The Hg0 removal performance was significantly enhanced by manganese oxide. The effects of the Mn loading on Hg0 removal were evaluated. X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) were employed to characterize the samples. In addition, the effects of individual flue gas components, including SO2, NO and HCl, on the Hg0 removal performance over the Mn/AC sorbent were investigated. The results indicated that 10% Mn/AC was the optimal sorbent under the simulated flue gas conditions. The XRD and BET analyses indicated that the Mn3O4 crystal particles and surface area were the primary factors that contributed to Hg0 removal. The competitive adsorption and formation of Mn(SO4)x were the primary reasons that SO2 inhibits Hg0 removal. In a pure N2 atmosphere, a low concentration of NO decreased the Hg0 removal due to consumption of active oxygen species. However, a high concentration of NO promoted Hg0 removal due to the formation of N-containing active species that were generated on the sample surface. The Mn/AC sample remained highly active toward Hg0 removal in the presence of HCl due to reaction with active chlorine species.