Elemental mercury removal from syngas by nano-ZnO sorbent

Nano-ZnO sorbents synthesized by a homogeneous precipitation method were characterized by BET (Brunauer-Emmett-Teller), XRD (X-ray diffraction) as well as XPS (X-ray photoelectron spectroscopy) analysis. The adsorption of elemental mercury by nano-ZnO under nitrogen and simulated gas atmosphere was studied on a bench-scale fixed-bed apparatus. The effect of various gases on Hg⁰ removal performance by nano-ZnO was analyzed. The results show that the mercury removal efficiency of the nano-ZnO is relatively poor in nitrogen atmosphere. The presence of H₂S promotes the Hg⁰ removal by nano-ZnO observably and the mercury removal efficiency can be maintained for a long time even after stopping pass into H₂S. The presence of CO and H₂ promotes the Hg⁰ removal because of desulfurization effect of nano-ZnO. As the temperature increases, the formation of elemental sulfur in the surface of the nano-ZnO decreases, which can suppress the removal of Hg⁰ by sorbent.