Hg⁰ Capture over CoMoS/γ-Al₂O₃ with MoS₂ Nanosheets at Low Temperatures

CoMoS/γ-Al₂O₃ sorbent was prepared via incipient wetness impregnation (IWI) and sulfur-chemical vapor reaction (S-CVR) methods and tested in terms of its potential for Hg⁰ capture. It was observed that the CoMoO/γ-Al₂O₃ showed a Hg⁰ capture efficiency around 75% at a temperature between 175 and 325 °C while CoMoS/γ-Al₂O₃ achieved almost 100% Hg⁰ removal efficiency at 50 °C. The high removal efficiency for CoMoS/γ-Al₂O₃ remained unchanged for 2000 min in the test. Its theoretical capacity for Hg⁰ capture was found to be 18.95 mg/g based on the Elovich model. The ability of this material for Hg⁰ capture is atributed to the MoS₂ nanosheets coated on surface of the maro- and meso-pores of γ-Al₂O₃. These MoS₂ are two-dimensional transition-metal dichalcogenide (2D TMDC) assembled with unsulfided cobalt atoms at the edges. It is believed that these MoS₂ nanosheets provided dense active sites for Hg⁰ capture. The removal of Hg⁰ at low temperatures was achieved via the combination of Hg⁰ with the chalcogen (S) atoms on the entire basal plane of the MoS₂ nanosheets with coordinative unsaturated sites (CUS) to form a stable compound, HgS.