Synergistic effect between H2O and SO2 on mercury removal by activated carbon in O2/CO2 conditions

Abstract

AbstractBACKGROUNDThis work evaluated the mechanism of H2O on mercury oxidation and adsorption by activated carbon in simulated flue gas in a fixed‐bed reactor. The effect of the addition of SO2 on the mercury removal was also discussed. Mercury desorption tests were conducted in a setup for classifying mercury forms adsorbed on activated carbon by the temperature‐programmed desorption (TPD) method.RESULTSThe results indicated that H2O could inhibit Hg0 removal through blocking the microporous channels of activated carbon. Additionally, the enriched H2O could provide the electrons to inhibit Hg0 oxidation. While medium H2O concentrations around 15% could dominate the competitive adsorption in O2/CO2, high and low H2O concentrations of 23% and 8%, respectivly, could not dominate the competition.CONCLUSIONWith the addition of SO2 in O2/CO2, Hg0 removal efficiency decreased with H2O increased from 8% to 23%. Furthermore, Hg0 adsorption proportion were all larger than 87% with the addition of SO2 with H2O in O2/CO2, which indicated that Hg0 adsorption was the main contributor to Hg0 removal performance. These results are useful for the control of mercury in O2/CO2 combustion technology. © 2018 Society of Chemical Industry