Studies on Mercury Adsorption Species and Desorption Activation Energy on Activated Carbon under Oxy Combustion

Mercury ought to be removed to near zero in O 2 /CO 2 due to safety issues. The mercury adsorption species can influence the efficiency of the mercury adsorbent. The mercury adsorption species on the activated carbon determined the mercury adsorption efficiency by the activated carbon. To elucidate the mechanism of the mercury adsorption with SO 2 under the O 2 /N 2 and O 2 /CO 2 atmosphere, mercury adsorption species on the samples of adsorbed activated carbon (AC–Hg) were investigated by the mercury temperature-programmed desorption (TPD) method, and the mercury desorption activation energy was also calculated. It could be found that Hg–OH, HgS, HgO (yellow), Hg≡O, and HgSO 4 were the major forms under O 2 /CO 2 atmosphere. Furthermore, it also indicated that the chemical adsorption with strong Hg≡O bond and high mercury desorption activation energy was the dominant form under O 2 /CO 2 atmosphere. The results of the present work implied that temperature-programmed desorption could identify mercury species on the AC–Hg clearly. The sorbate–sorbate bond was stronger than the sorbate–surface bond.