Insight into the sulfur resistance of OMS-2 modified with iron for mercury oxidation

To improve the sulfur resistance of manganese oxide octahedral molecular sieve (OMS-2) for Hg0 oxidation, OMS-2 modified by iron (Fex-OMS-2) is prepared through hydrothermal synthesis method in this study, and their Hg0 removal performance and sulfur resistance were tested in simulate flue gas. Hg0 removal efficiency of Fe0.05OMS-2 can reach 98 % at 150 degrees C. Its mercury removal efficiency remains 89.2 % even in the presence of 1500 ppm SO2, while the value of OMS-2 under the same condition is only 54 %. Characterization results show that Fe0.05-OMS-2 has spinel structure with Fe2O3 wrapped on the catalyst surface which is (Mn0.983Fe0.017)2O3. Its active components both contain iron oxide and manganese oxide, which forms a double active center. Iron oxide on the catalyst surface can compete with manganese oxide for SO2 adsorption and further forms FeSO4, thus, inhibiting the sulfation of active manganese oxide and improving its sulfur resistance. Additionally, Fe0.05-OMS-2 exhibit strong water resistance, and Hg0 removal efficiency is nearly no change after the addition of 8 % H2O in the simulated flue gas.