Support effect of Mn-based catalysts for gaseous elemental mercury oxidation and adsorption. Issue 1 (30th November 2017) - Wu, Yinghong
Abstract : Mn-Based catalysts with a Mn loading of 4 wt% were prepared using an impregnation method. Abstract : Mn-Based catalysts with a Mn loading of 4 wt% were prepared using an impregnation method. Their Hg 0 removal efficiencies were in the following order: 4% Mn/MK10 (montmorillonite K 10) > 4% Mn/SiO2 > 4% Mn/TiO2 > 4% Mn/Al2 O3 . Results from various characterization techniques, such as BET, XRD, STEM, H2 -TPR, Hg 0 -TPD and XPS, suggested that the species, morphologies, and distributions of MnO x led to the different performances in Hg 0 removal. The support effect on Hg 0 adsorption and oxidation was studied. For 4% Mn/Al2 O3 and 4% Mn/SiO2, physical adsorption dominates Hg 0 removal at low temperature (150 °C), while chemical adsorption is more important at high temperature (350 °C). At both low and high temperatures, chemical adsorption and oxidation play leading roles in 4% Mn/TiO2 and 4% Mn/MK10, respectively. The effect of MnO x species and their morphologies on Hg 0 oxidation was investigated. Amorphous MnO2 benefits Hg 0 oxidation at both low and high temperatures, while amorphous Mn2 O3 only facilitates Hg 0 oxidation at high temperature. Hg 0 oxidation on Mn-based catalysts follows a Mars–Maessen mechanism where the lattice oxygen of MnO x reacts with the absorbed Hg 0 .