Improvement in the Hg0 removal performance of CeO2 by modifying with CuO

In this study, a CuO-modified CeO2 material was synthesized using the combination of sol–gel and wet-impregnation methods to remove Hg0 from simulated flue gas. It was found that the Hg0 removal efficiency almost tripled upon the addition of 10% CuO and a satisfactory recyclability was also presented. The doped CuO functioned as a chemical promoter, which introduced extra surface acid sites and active chemical adsorbed oxygen species, enabling CuO/CeO2 with an improved Hg0 removal performance. The presence of NO facilitated the removal of Hg0, whereas the addition of SO2 exerted an inhibitory effect on Hg0 abatement. During the Hg0 removal process, CeO2 functioned as a catalyst-like substance and Ce4+ was the main active site; while CuO/CeO2 sometimes played the role of an adsorbent to capture Hg0 with Cu2+ involved in the direct oxidation of Hg0 and Ce4+ accelerating the regeneration of Cu2+ through the electron transfer between Ce4+ and Cu+. Combined with the activity and characterization results, it seemed that both the oxidability and acidity determined the Hg0 removal performance of the materials at lower temperatures, while the acidity might dominate in the Hg0 adsorption cycles at a high-temperature region.