Promoting effect of Co-doped CeO2 nanorods activity and SO2 resistance for Hg0 removal

A simple hydrothermal method for doping cobalt species into CeO2 nanorods to prevent deactivation of ceria and provide additional active sites for Hg0 removal. The materials were extensively characterized by XRD, SEM, HRTEM, H2-TPR, Raman, XPS, and Hg-TPD techniques. The introduction of Co improves the reduction properties and greatly enhances the activity of CeO2 for Hg0 removal. On the basis of the prepared materials, 0.2Co/Ce nanorods with a well-defined (1 1 0) surface display excellent performance with more than 95% Hg0 removal efficiency at 19099 h−1 gas hourly space velocity (GHSV) from 100 to 200 °C, as well as good resistance to SO2 and H2O. According to the Hg-TPD results, HgO was the major product over Co doped CeO2 nanorods. DFT studies have shown that Co doping can increase the adsorption energy of Hg0 and promote the formation of oxygen vacancies, which all contribute to the enhanced activity of Hg0 removal. The oxidation of Hg0 over Co-doped CeO2 nanorods through a Mars-van Krevelen mechanism, where Hg0 react with surface oxygen to form HgO. Moreover, the synergistic effect between Ce4+ and Co2+ inhibits the oxidation of SO2 to surface sulfate, preventing the CeO2 from being deactivated.