Research of mercury removal from sintering flue gas of iron and steel by the open metal site of Mil-101(Cr)

Metal-organic frameworks (MOFs) adsorbent Mil-101(Cr) was introduced for the removal of elemental mercury from sintering flue gas. Physical and chemical characterization of the adsorbents showed that MIL-101(Cr) had the largest BET surface area, high thermal stability and oxidation capacity. Hg0 removal performance analysis indicated that the Hg0 removal efficiency of MIL-101(Cr) increased with the increasing temperature and oxygen content. Besides, MIL-101(Cr) had the highest Hg0 removal performance compared with Cu-BTC, UiO-66 and activated carbon, which can reach about 88% at 250 °C. The XPS and Hg-TPD methods were used to analyze the Hg0 removal mechanism; the results show that Hg0 was first adsorbed on the surface of Mil-101(Cr), and then oxidized by the open metal site Cr3+. The generated Hg2+ was then combined surface adsorbed oxygen of adsorbent to form HgO, and the open metal site Cr2+ was oxidized to Cr3+ by surface active oxygen again. Furthermore, MIL-101(Cr) had good chemical and thermal stability.