Synergistic effect between H 2 O and SO 2 on mercury removal by activated carbon in O 2 /CO 2 conditions

BACKGROUND This work evaluated the mechanism of H 2 O on mercury oxidation and adsorption by activated carbon in simulated flue gas in a fixed‐bed reactor. The effect of the addition of SO 2 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. RESULTS The results indicated that H 2 O could inhibit Hg 0 removal through blocking the microporous channels of activated carbon. Additionally, the enriched H 2 O could provide the electrons to inhibit Hg 0 oxidation. While medium H 2 O concentrations around 15% could dominate the competitive adsorption in O 2 /CO 2, high and low H 2 O concentrations of 23% and 8%, respectivly, could not dominate the competition. CONCLUSION With the addition of SO 2 in O 2 /CO 2 , Hg 0 removal efficiency decreased with H 2 O increased from 8% to 23%. Furthermore, Hg 0 adsorption proportion were all larger than 87% with the addition of SO 2 with H 2 O in O 2 /CO 2 , which indicated that Hg 0 adsorption was the main contributor to Hg 0 removal performance. These results are useful for the control of mercury in O 2 /CO 2 combustion technology. © 2018 Society of Chemical Industry