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.