Synthesis of hierarchical porous carbon loaded with chlorine and its mercury removal performance

Chlorine-loaded hierarchical porous bio-char was prepared by co-pyrolysis using nano-CaCO₃ as template and rice straw as carbon precursor. The removal of mercury (Hg⁰) from flue gas by porous materials was studied on a fixed bed test bench with simulated flue gas. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption (BET), temperature programmed desorption (Hg-TPD) and X-ray photoelectron spectroscopy (XPS). The results show that HCl impregnation not only removes the products on the template to form porous structures but also effectively loads chlorine onto the surface of the material. The specific surface area and total pore volume of B1C1-Cl2 are 398.1 m²/g and 0.4923 cm³/g, respectively. When the GHSV is 225000 h^-1 at 120 ℃, the removal efficiency of Hg⁰ by chemical adsorption is up to 95%. The porous structure is beneficial to gas diffusion and the high specific surface area can provide more active sites. The covalent groups (C-Cl) participating in the Hg⁰ removal process are the dominant chemical adsorption sites on the inner micro-mesopore surface.