Efficient MnFeW/Ti catalyst for simultaneous removal of NO and Hg0 in flue gas at low temperature: Effect of NO on Hg0 oxidation and reaction mechanism

• The MnFeW/Ti catalyst exhibited high activity for simultaneous removal of NO and Hg 0 . • NO significantly enhanced the catalytic activity for Hg 0 oxidation in the presence of O 2 . • NH 3 did not affect the Hg 0 removal over MnFeW/Ti catalyst. • HgO, resulted from the reaction of NO 2 and Hg 0 , is liable to desorb. The MnFeW/Ti catalyst was synthesized and used for simultaneously removing NO and Hg 0 from flue gas at low temperature and its catalytic performance has been tested. The MnFeW/Ti catalyst showed over 80% NO x conversion and 88% Hg 0 removal between 180 and 300 °C at a high GHSV of 100000 h −1 . NO obviously enhanced the catalytic capability for Hg 0 removal and NH 3 had almost no effect on Hg 0 removal because NH 3 did not affect the adsorption of NO and Hg 0 . Hg balance results revealed that Hg 0 removal over MnFeW/Ti catalyst proceeded via both chemisorption and catalytic oxidation, which is attributed to the different bonding strength between Hg 0 and active sites. The Hg 0 oxidation process was also investigated through transient reaction experiments along with Hg-TPD and XPS characterization. Hg 0 oxidation over MnFeW/Ti catalyst obeys both Mars–Maessen mechanism in which active oxygen reacts with adsorbed Hg 0 and Langmuir − Hinshelwood mechanism comprising the reaction of formed NO 2 with adsorbed Hg 0 . HgO, resulted from the reaction between NO 2 as an active intermediate and adsorbed Hg 0 , is liable to desorb from MnFeW/Ti catalyst.