Elemental mercury removal from syngas by porous carbon-supported CuCl2 sorbents

A series of sorbents based on biomass-derived porous carbon-supported CuCl2 (CuCl2-PC) were synthesized and employed for elemental mercury (Hg-0) removal from the syngas. The CuCl2-PC sorbent with a Cu mass content of 5.6 wt% exhibited superior Hg-0 adsorption ability (98.5%) at 200 degrees C. The meso-/micropores structure of porous carbon is favorable for the well-dispersing of CuCl2 in the inner pores with the formations of abundant Cu and Cl active sites, and beneficial for Hg-0 fast transfer among pores, thereby enhancing the effective collision of Hg-0 with active sites. Hg-Cu compound and mercury chlorides could be formed by the reactions of Hg-0 with Cu and Cl species. The effects of syngas components on Hg(0 )adsorption ability of sorbent were investigated. HCl improved Hg-0 adsorption by increasing the Cl concentration on sorbent surface. CO, H2S and H2O did not exhibit notable effects on Hg-0 adsorption. Although H-2 could not affect the surface chemistry of sorbent, it could occupy the inner pores of sorbent, thereby making the interactions of Hg-0 with active sites difficult. The amount of Cu2+ on sorbent surface decreased after Hg-0 adsorption, indicating that the oxidation state of copper changed from Cu2+ to Cu+ under syngas atmosphere.