Outstanding Resistance of H2S-Modified Cu/TiO2 to SO2 for Capturing Gaseous Hg0 from Nonferrous Metal Smelting Flue Gas: Performance and Reaction Mechanism

Abstract

The utilization of H2SO4, produced using SO2 from non-ferrous metal smelting flue gas as a source of S, is extremely restricted due to Hg contamination; therefore, there is great demand to remove Hg0 from smelting flue gas. Although the ability of Cu/TiO2 to capture Hg0 is excellent, its resistance to H2O and SO2 is very poor. In this study, Cu/TiO2 was treated with H2S to improve its resistance to H2O and SO2 for capturing Hg0. The chemical adsorption of Hg0 on Cu/TiO2 was primarily through the HgO route, which was almost suppressed by H2O and SO2 due to the transformation of CuO into CuSO4. Besides the HgO route, the HgS route also contributed to the chemical adsorption of Hg0 on modified Cu/TiO2. As the CuS on modified Cu/TiO2 was inert to H2O and SO2, the chemical adsorption of Hg0 on modified Cu/TiO2 through the HgS route was barely inhibited. Meanwhile, the HgS route was predominant in the chemical adsorption of Hg0 on modified Cu/TiO2. Therefore, modified Cu/TiO2 exhibited an excellent resistance to H2O and SO2, and its Hg0 capture capacity from simulated flue gas was up to 12.7 mg g-1 at 100 °C.