Magnetic iron-manganese binary oxide supported on carbon nanofiber (Fe3-xMnxO4/CNF) for efficient removal of Hg-0 from coal combustion flue gas

Samples of magnetic iron-manganese binary oxide supported on activated carbon fiber (Fe3-xMnxO4/CNF) were prepared for Hg-0 removal from flue gas. The results showed that the Hg0 removal performance of Fe(3-x)MnxO(4)/CNF was significantly promoted with the increase of Mn incorporating content into Fe3O4 spinel structure. The optimal sample of Fe2MnO4/CNF, at the optimal reaction temperature of 150-200 degrees C, attained above 90% of Hg-0 removal efficiency (Ea). CNF played an important role in Hg0 removal by Fe(3-x)MnxO(4)/CNF due to the disperation of Fe(3-x)MnxO(4) particles and the enhancement for electron transfer process. O-2 enhanced the Hg-0 removal via the Mars-Maessen mechanism, and NO improved the Hg-0 removal performance slightly because of the formation of NO2. SO2 and H2O played an inhibitive role in Hg-0 removal due to the competition of active sites for Hg0 adsorption. A mechanism of Hg-0 removal over Fe(3-x)MnxO(4)/CNF is proposed, in which both Mn cations and lattice/chemisorbed oxygen were thought to the active sites for Hg-0 adsorption/oxidation. Further, the spent Fe3-xMnxO4/CNF could be regenerated with no obvious decrease of Hg-0 removal performance by water washing followed by thermal treatment at 450 degrees C in N-2 and calcination at 200 degrees C in air.