Preparation of molybdenum sulfoselenide composites adsorbent and capture mechanism of elemental mercury from smelting flue gas

In order to achieve efficient purification of gaseous elemental mercury in smelting flue gas, a series of molybdenum sulfoselenide composite adsorbents(MoSxSey) were prepared by selenium-sulfur anion composite strategy. Firstly, the microstructure and elemental composition of MoSxSey were determined by SEM, TEM and EDS. Secondly, the phase composition of MoSxSey was analyzed by XRD and Raman. Thirdly, the valence state of elements on the surface of MoSxSey was determined by XPS technique. Finally, the influence of MoSxSey on the adsorption efficiency of Hg0 was studied, and its adsorption performance was evaluated. The results show that the prepared MoS0.5Se2.1 adsorbent has the best Hg0 adsorption performance, and maintains good Hg0 adsorption performance in the temperature range of 50 – 150 ℃ . The optimal adsorption efficiency and adsorption rate can reach 97.86% and 7.05 μg/(g·min), respectively. O2 and H2O in flue gas will inhibit the adsorption of MoS0.5Se2.1 adsorbent, but SO2 can promote the adsorption of Hg0 to a certain extent. When the breakthrough threshold is 25%, the Hg0 adsorption capacity of MoS0.5Se2.1 is as high as 47.1 mg/g, which is much higher than that of other conventional adsorbents. At low temperature (2n- and Se – S2n- are the main adsorption sites, which chemically adsorb Hg0 to form stable HgS and HgSe. At high temperature (>150 ℃), only Se – S2n- is the adsorption site, and HgSe is the main adsorption product. The selenium doping strategy can not only increase the number of adsorption sites, but also improve the thermal stability of the adsorption sites, thereby achieving efficient removal of Hg0 over a wide temperature window. © 2024 Central South University of Technology. All rights reserved.