Hg-0 Removal by a Palygorskite and Fly Ash Supported MnO2-CeO2 Catalyst at Low Temperature

MnO2-CeO2/PG-FA catalysts were prepared by supporting MnO2-CeO2 to PG-FA and used to remove Hg-0 in simulated flue gas. The results show that MnO2-CeO2/PG-FA catalyst had excellent and stable Hg-0 removal activity, which was mainly due to the combination effect of the catalytic oxidation activity by MnO2-CeO2 and the adsorption ability by PG-FA. Mn8-Ce0.5/PG-FA (with 8.0% MnO2 and 0.5% CeO2 loading) catalyst showed the highest Hg-0 removal efficiency at 140 degrees C and Hg-0 removal efficiency could be maintained above 95% with the space velocity of 6000 h(-1) and Hg-0 concentration of 160 mu g/m(3). O-2 promoted Hg-0 removal by MnO2-CeO2/PG-FA catalyst, while SO2 and H2O had inhibitory effects. In the presence of O-2, the inhibitory effect of SO2 and H2O can be obviously weakened. MnO2-CeO2/PG-FA catalysts were characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption experiments (TPD). The results of SEM and XRD showed that the active components MnO2-CeO2 dispersed well on the surface of PG-FA support. The results of XPS and TPD show that the Hg-0 removal process over MnO2-CeO2/PG-FA catalyst included adsorption and oxidation, HgO and HgSO4 were generated and adsorbed on the catalyst. MnO2-CeO2/PG-FA catalyst also showed excellent regeneration performance after Hg-0 removal.