Elemental mercury oxidation over manganese-based perovskite-type catalyst at low temperature

La1-xSrxMnO3 (LSx, x = 0/0.2/0.4/0.6) perovskite-type oxides catalysts were synthesized for elemental mercury (Hg-0) oxidation in simulated coal-fired flue gas at low temperature. LS0.4 exhibited superior catalytic behavior for Hg-0 oxidation at 100-200 degrees C. The superior performance was mainly due to the surface adsorbed oxygen species in the catalysts. Effects of different components in the flue gas including HCI, O-3, SO2, H2O, NO and NH3 on Hg-0 oxidation efficiencies were studied. The results suggested that HCI significantly enhanced Hg-0 oxidation efficiency in the presence of O-2 and 10 ppmv HCI was sufficient for enhancing the oxidation process. As the catalyst had strong oxygen storage capacity, the Hg-0 oxidation activity was less dependent on O-2 concentration. As a result, the catalyst could be applied in the power plants burning low-chlorine coals. SO2, H2O and NH3 had inhibitory effect on Hg-0 oxidation, while NO enhanced it. SO2 could deactivate the catalyst and the deactivation was irreversible. In terms of mechanism, Hg-0 oxidation with LSx could be explained by the suprafacial process (Langmuir-Hinshelwood mechanism) whereby reactive species from adsorbed flue gas components reacted with adsorbed Hg-0. The catalyst also had potential for selective catalytic reduction (SCR) of NO with NH3 at low temperature, and the simultaneous removal of NO and Hg-0 over LS0.4 was investigated. The NO and Hg-0 conversion were higher than 50% and 85% when the space velocity was 40,000 h(-1), respectively. The results indicated that the catalyst might be used to remove NO and Hg-0 simultaneously after the cold-side electrostatic precipitators in flue gas with low concentration of ash. (C) 2015 Elsevier B.V. All rights reserved.