Mercury capture from natural gas by carbon supported ionic liquids: Synthesis, evaluation and molecular mechanism
Abstract Superiority of silica supported ionic liquids over other adsorbents in capturing elemental mercury (Hg 0 from flue gases has been recently reported. In this study, activated carbon, which is more economical than silica, was experimented as a solid support for ionic liquids (ILs) for gaseous Hg 0 removal. Four ILs were successfully coated on activated carbon. The carbon supported ionic liquids (CSILs) were characterized by Fourier transform infrared spectroscopy, Brunauer Emmett Teller surface area analysis, field emission scanning electron microscopy, energy dispersive X ray, X ray photoelectron spectroscopy and nuclear magnetic resonance. A continuous fixed bed flow reactor was used to examine the performance of CSILs in treating 20 35 ppm Hg 0 vapor at a gas flow rate of 60 mL/min. 1 Butyl 3 methylimidazolium chloride [Bmim]Cl coated activated carbon was the most reactive among CSILs studied and a powdered form of [Bmim]Cl coated activated carbon was able to uptake Hg 0 up to 23 mg/g and 60 mg/g with N 2 and CH 4 as carrier gas, respectively. A molecular simulation was performed to investigate the molecular level interaction between the Hg 0 and the ILs to understand the effect of structural variations of the ILs on Hg 0 adsorption. The simulation reveals that the anion part of IL plays a major role in Hg 0 adsorption. Based on experimental results, a possible mechanism of Hg IL interaction was elucidated; the imidazolium cation can form a complex with HgCl 2 through the C2 hydrogen.