Catalytic oxidation and adsorption of Hg0 over low-temperature NH3-SCR LaMnO3 perovskite oxide from flue gas

To simultaneously remove elemental mercury (Hg-0) and NOx at low temperature from flue gas in coalfired power plants, an efficient NH3-SCR LaMnO3 perovskite oxide was chosen as the catalyst for Hg-0 removal. The physicochemical properties, surface reaction and mercury desorption were investigated using BET, XRD, XPS, H-2-TPR and Hg-0-TPD, to investigate the Hg-0 capture mechanism over LaMnO3 oxides. The results indicated that LaMnO3 exhibits a Hg-0 capacity that is as high as 6.22 mg/g (600 min),at 150 degrees C. O-2 enhanced the Hg-0 removal performance by re-oxidation of reduced Mn3+ to Mn4+ and providing additional adsorbed oxygen. NO enhanced the Hg-0 removal performance. However, NH3 exhibited negative effects on Hg-0 removal. The NH3 + O-2-TPD and NO + O-2-TPD results indicated that the ad-NH3 species prevent Hg-0 adsorption, but the ad-NO2 species were beneficial for Hg-0 oxidation. The effects of SO2 and H2O were also investigated, and the results indicated that they inhibited Hg-0 removal. Hg-0-TPD under different reaction atmospheres was employed to further investigate the combing state of Hg-0 on LaMnO3 surface, the results indicated that mercury primarily existed as Hg-0-O, and LaMnO3 can be regenerated using thermal desorption. (C) 2016 Elsevier B.V. All rights reserved.