Design of O2/SO2 dual-doped porous carbon as superior sorbent for elemental mercury removal from flue gas

A porous carbon was synthesized via hydrothermal carbonization and CO2 activation. O-2 and SO2 were successfully co-doped onto carbon surface by applying non-thermal plasma technique. Porous carbon possessing excellent textural properties is effective to adsorb the radicals generated by plasma. Plasma promotes the adsorption of O(2)and SO2 on carbon surface with the formation of abundant C=O, C-S and C-SO,, (x = 1-3) groups. The O-2/SO2 dual-doped porous carbon was utilized to adsorb elemental mercury (Hg) from the flue gas of coal combustion. The Hg-0 adsorption ability of the O-2/SO2 dual-doped porous carbon is closely related with the concentrations of O-2 and SO2 for plasma treatment and the treatment time. The optimal O-2/SO2 dual-doped porous carbon exhibited far greater He adsorption capacity than a commercial brominated activated carbon. Density functional theory was employed to understand the He adsorption mechanism at the molecular level. C-S and C-SOx (x = 1-3) groups enhanced the interaction of He with surface carbon atom. The activity of them for enhancing Hg-0 adsorption is in the order of C-SO2 > C=O > C-S > C-SO > C-SO3. Porous carbon can be activated by plasma in flue gas containing O-2 and SO2, and used as superior sorbent for He removal.