Catalytic Oxidation and Stabilized Adsorption of Elemental Mercury from Coal-Derived Fuel Gas

The aim of this study is to develop an efficient process for the stabilized removal of elemental mercury (Hg-0) from coal-derived fuel gas by the aid of the catalytic oxidation of Hg-0 over activated carbon (AC). The experiments were performed in the temperature range of 120-240 degrees C with simulated coal-derived gases containing varying concentrations of CO, H-2, CO2, H2O, and H2S. O-2 was introduced to promote the oxidation reaction between H2S and He over the AC sorbent to form mercury sulfide (HgS). The results indicated that the Hg removal capacity of AC could be dramatically improved in the presence of both H2S and O-2. The presence of O-2 was indispensable for the efficient and stable removal of Hg-0 from H2S-containing fuel gas. The high temperature and high content of reducing gases, such as CO and H-2, may inhibit the oxidation reaction and decrease the Hg removal efficiency, whereas the high content of H2O can promote Hg-0 removal. On the basis of thermodynamic analysis, as well as the temperature-programmed decomposition (TPD) and X-ray photoelectron spectroscopy (XPS) characterization of the sorbents, it is suggested that the partial oxidation, of H2S with O-2 to active sulfur may contribute to the stabilized removal of Hg-0 by the reaction of active sulfur with Hg-0 to form HgS.