An efficient sorbent based on CuCl2 loaded CeO2-ZrO2 for elemental mercury removal from chlorine-free flue gas

To remove elemental mercury (Hg0) in chlorine-free coal combustion flue gas efficiently, CuCl2 loaded CeO2-ZrO2 sorbents (denoted as CC/CZ) were developed. In this way, the abundant Cl and affluent active chemical adsorbed oxygen (O∗) on the surface of the sorbent would be combined and made full use for Hg0 removal. XRD, XPS, SEM, Raman, TG, and N2 adsorption/desorption were employed to characterize the sorbents. Hg0 removal behaviors over CC/CZ were studied using a lab-scale fixed-bed reactor. The sorbent with optimal loading 6% CuCl2 exhibited superior and stable performances (89.6-97.1%) within a much wider applicable temperature range (100-300 °C) in the absence of HCl. The results also indicated that 6%CC/CZ exhibit very good performance at lower temperature (100-200 °C). The interaction between Cl and chemical adsorbed oxygen was observed and probably responsible for its superior Hg0 removal performance. XPS results of the fresh, thermal-treated, and spent 6% CuCl2/CZ may explain the Hg0 oxidation process. Hg0 was mainly oxidized by the generated active chlorine species and the main reaction product was HgCl2. The active chlorine species were formed due to the interaction between chlorine and chemical adsorbed oxygen species.