Effects of HCl and SO2 Concentration on Mercury Removal by Activated Carbon Sorbents in Coal-Derived Flue Gas†

The effect of the presence of HCl and SO2 in the simulated coal combustion flue gas on the Hg0 removal by a commercial activated carbon (coconut shell AC) was investigated in a laboratory-scale fixed-bed reactor in a temperature range of 80−200 °C. The characteristics (thermal stability) of the mercury species formed on the sorbents under various adsorption conditions were investigated by the temperature-programmed decomposition desorption (TPDD) technique. It was found that the presence of HCl and SO2 in the flue gas affected the mercury removal efficiency of the sorbents as well as the characteristics of the mercury adsorption species. The mercury removal rate of AC increased with the HCl concentration in the flue gas. In the presence of HCl and the absence of SO2 during Hg0 adsorption by AC, a single Hg0 desorption peak at around 300 °C was observed in the TPDD spectra and intensity of this peak increased with the HCl concentration during mercury adsorption. The peak at around 300 °C may be derived fro...