文摘
As promising functional materials, ionic liquids have been widely used in flue gas purification and separation. Previous studies reported that ionic liquid based mixtures can be used for mercury removal due to their high economic efficiency and environmental friendliness. In comparison with ionic liquid based mixtures, a supported ionic liquid phase (SILP) adsorbent shows significantly improved mercury removal performance because of its greatly enhanced gas/liquid interfacial area. In this study, a novel supported task-specific ionic liquid phase adsorbent [C4mim][FeCl4]–SiO2 was prepared for high efficiency elemental mercury capture from flue gas. The Hg0 removal performance was investigated in a bench-scale fixed bed reactor, and the reaction mechanism was proposed based on the temperature programmed desorption (TPD) test. The results showed that Hg0 removal was mainly due to the oxidation by [C4mim][FeCl4]. The addition of [C4mim][FeCl4] on SiO2 in a certain composition range enhanced the Hg0 removal performance, and the optimized ionic liquid loading is 30%. The Hg0 removal by the adsorbent was favored at higher temperatures. TPD results showed that the mercury compound formed on the adsorbent was HgCl2. The Hg0 removal mechanism involves combined physisorption and chemisorption, which consists of Hg0 oxidation to HgCl2 by the ionic liquid and physical adsorption of HgCl2 on the porous adsorbent.