Simultaneous Removal of Elemental Mercury and NO from Simulated Flue Gas at Low Temperatures over Mn–V–W/TiO2 Catalysts

A series of Mn–V–W/TiO2 (Mn–VWT) catalysts were synthesized by the impregnation method and calcinated at different temperatures (300–600 °C). To explore the effects of the reaction temperature, SO2, and H2O on the simultaneous removal performance of elemental mercury (Hg0) and NO, Mn–VWT were investigated by a fixed-bed reaction system. Various techniques (scanning electron microscopy, Brunauer–Emmett–Teller, X-ray diffraction, H2-temperature-programmed reduction, NH3-temperature-programmed desorption, and X-ray photoelectron spectroscopy) were utilized to characterize the samples. The results showed that the catalytic activity of Mn–VWT first increased and then decreased with the increasing calcination temperature. The removal efficiency of Hg0 and NO still had good performance even in low reaction temperature (200 °C), achieving 100 and 82%, respectively. Mn–VWT-400 had the best simultaneous removal performance because of the highest content of the Mn4+, V4+, and chemisorbed oxygen Oα and the best reductive activity at low temperature. Furthermore, SO2 irreversibly inhibited Hg0 and NO removal ability due to the sulfate and sulfite generation on the surface of Mn–VWT-400. Especially, the inhibition effect was more serious if SO2 and H2O coexisted because the rate of sulfate/sulfite was higher than that of the former. In addition, with the increase in reaction temperature, the effect of SO2 and H2O on the removal of Hg0 and NO over Mn–VWT was gradually reduced.