Synergistic effect of HCl, SO2 and O2 on mercury removal by Mn0.5Cu0.5Fe2O4 adsorbent

Abstract

Ferrite-structured adsorbents have demonstrated high potential for adsorbing zero-valent mercury (Hg0), but their performance in complex flue gas is not well understood. This study investigated the effects of HCl, O2, and SO2 on Hg0 oxidation capacity using Mn0.5Cu0.5Fe2O4 adsorbent. The morphology and microstructure of Mn0.5Cu0.5Fe2O4 were examined, and mass transfer theoretical analysis and X-ray photoelectron spectroscopy experiments were conducted to explore the synergistic effect of HCl, SO2, and O2 on mercury removal. The results indicated that the adsorbent achieved a high Hg0 removal efficiency of approximately 98% when HCl, SO2, and O2 coexisted in the flue gas at 120 °C. The reaction can be separated into three steps. In the first step, HCl dominates the reaction, resulting in the formation of HgCl2 and H2O. In the second step, oxygen defect sites accelerate the breakdown of O2 into chemisorbed oxygen. In the third step, the chemisorbed oxygen combines with Hg0 and SO2 to generate HgO and HgSO4. This study has important implications for the development of ferrite-structured adsorbents in complex flue gas.