Yingjie Shi

Fe and Co modified vanadium–titanium steel slag as sorbents for elemental mercury adsorption

Iron and cobalt modified vanadium titanium steel slag (VTSS) adsorbents Fe(x)–Co(y)/VTSS (with different Fe/Co molar ratios of x/y) prepared by an impregnation method were employed to remove elemental mercury (Hg0) from simulated flue gas in a wide-temperature window (150–300 °C). The samples were characterized by XRD, BET, HRTEM, EDS and H2-TPR. The effects of iron to cobalt molar ratios of x/y, capture temperature, and flue gas components (such as O2, SO2 and H2O) on the Hg0 adsorption efficiency were evaluated. The Hg0 adsorption mechanisms were proposed by XPS, TG and the pseudo-second-order kinetic model. The results showed that the increase of cobalt amount and the cooperation of Fe and Co promoted Hg0 capture. The Fe(3)–Co(3)/VTSS adsorbent exhibited the highest Hg0 removal efficiencies of 77.4% within 600 min in 6 vol% O2 at 300 °C. The presence of O2 promoted Hg0 adsorption. The influence of SO2 on the Hg0 removal efficiency was weak, while the addition of 8 vol% H2O and 500 ppm SO2 was found to have a serious inhibition effect. The XPS and TG results showed that the HgO was the major species in the captured mercury, which illustrated that Hg0 removal over Fe(x)–Co(y)/VTSS was a catalytic oxidation process. The pseudo-second-order model was demonstrated to simulate the removal of Hg0 by Fe(x)–Co(y)/VTSS and the adsorption process is controlled by chemisorption.