Design of MnO2/CeO2-MnO2 hierarchical binary oxides for elemental mercury removal from coal-fired flue gas.

MnO2/CeO2-MnO2 hierarchical binary oxide was synthesized for elemental mercury (Hg0) removal from coal-fired flue gas. CeO2 in-situ grow on the surface of carbon spheres, and that CeO2@CSs acted as precursor for porous MnO2/CeO2-MnO2. XRD, Raman, XPS, FT-IR, and H2-TPR were selected for the physical structural and chemical surface analysis. The results indicated that the composite has sufficient surface oxygen and hierarchical porous structure. The Hg0 removal experiments results indicated that MnO2/CeO2-MnO2 exhibited excellent Hg0 removal performance, with an 89% removal efficiency of total 300min at 150°C under 4% O2. MnO2 was the primary active site for Hg0 catalytic oxidation. The porous structure was beneficial for gaseous mercury physically adsorption. In addition, CeO2 enhanced the oxygen capture performance of the composite and the oxidation performance for MnO2. Moreover, the effects of O2, SO2 and H2O were also tested in this study. O2 promoted the Hg0 removal reaction. While SO2 and H2O can poison the MnO2 active site, resulted in a low Hg0 removal efficiency.