Removal of elemental mercury from simulated flue gas by ZSM-5 modified with Mn-Fe mixed oxides

Zeolite (ZSM-5), as a kind of carbon-free sorbent or catalyst, has been widely applied in many fields due to its big surface area, good chemical and thermal stability, and excellent adsorption performance. In this study, Mn-Fe modified ZSM-5 are synthesized via sol-gel approach and employed for elemental mercury (Hg 0 ) removal from simulated flue gas at low temperature. The results show that pure ZSM-5 shows poor mercury capture ability with Hg 0 removal efficiency of ~8.5–18.8% at 100–300 °C. Mn or Fe modification can both efficiently enhance the Hg 0 removal efficiency of the ZSM-5. The sorbent with Mn/Fe molar ratio of 1:2 exhibits the optimal mercury capture ability with the highest Hg 0 removal efficiency near 100% at temperatures of 200 and 250 °C due to the significant synergy effect between Mn 2 O 3 and Fe 2 O 3 . The presence of NO has a negligible effect on the Hg 0 removal performance of Mn/ZSM-5 and Mn1Fe2/ZSM-5, while the existence of SO 2 considerably degrades the Hg 0 capture performance of Mn/ZSM-5 owing to competing adsorption and side reactions. Fe addition can protect Mn active sites from SO 2 poisoning and thereby enhancing the SO 2 resistance of Mn/ZSM-5 to some extent.