Characteristic of SO2 Adsorption on Activated Carbon for Simulated Flue Gas and its Thermal Regeneration

In the presence of O2 and H2O, SO2 is oxidized to H2SO4 on the surface of activated carbon. Activated carbon, which adsorbs certain amounts of H2SO4, is regenerated and recycled. However, the SO2 adsorption capacity decreases gradually as the adsorption and regeneration are repeated. In this study, the effect of surface oxide on SO2 adsorption capacity of activated carbon was investigated. It was found that the amount of surface oxide not decomposed at the regeneration temperature (723 K) increased as the SO2 adsorption capacity decreased, and this made the surface of activated carbon hydrophilic. By decomposing the surface oxide at higher temperatures than the regeneration temperature, the SO2 adsorption capacity was found to increase. It is concluded that the increase of amount of surface oxide and hydrophilic properties cause a decrease in active sites for SO2 adsorption.