Impact of Sulfur Oxides on Mercury Capture by Activated Carbons

摘要

Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SO_x). In order to gain a more complete understanding of the impact of SO_x on ACI, we tested mercury capture under varying conditions of SO2 and SO3 concentration using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO2 concentration in the SFG, but the presence of SO3 inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury content decreases as the sulfur content of the activated carbons increases from 1–10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H2SO4 impregnation, shows almost no mercury capacity. The results indicate that mercury and SO_x are in competition for the same binding sites on the carbon surface.