Removal of elemental mercury in flue gas at lower temperatures over Mn-Ce based materials prepared by co-precipitation

A series of Mn-Ce based materials were synthesized by co-precipitation method and were examined for mercury removal at lower temperatures (50-250 degrees C) in the absence of HCl. The effect of preparation conditions (metal oxides and calcination temperature) and reaction conditions (reaction temperature and gas constituents) was investigated. Results showed that Mn0.1Ce0.2Al-400 was found to be the most active catalyst for mercury removal, achieving around 96% Hg-0 removal efficiency in the presence of 6% O-2 at 150 degrees C. Higher calcination temperature could result in the grain growth and particle agglomeration, thus decreasing the activity. The optimum reaction temperature for mercury removal over Mn0.1Ce0.2Al-400 was about 150 degrees C. NO was observed to promote mercury removal over Mn0.1Ce0.2-400 catalyst but SO2 generally suppressed it. Various techniques (BET, XRD, TEM, H-2-TPR and XPS) were used to characterize the samples. The results substantiated the formation of a composite material consisted of high concentration of amorphous MnOX and nano-crystalline CeO2 supported by Al2O3, which might lead to an enhanced interaction of Ce with Mn. Moreover, the adsorbed Hg-0 mainly interacted with the lattice oxygen in MnO2 to form HgO which was replenished by gas-phase O-2. CeOx could facilitate the activation and transfer of oxygen and consequently improve the activity for oxidation removal of Hg-0 over manganese oxides further. (C) 2017 Elsevier Ltd. All rights reserved.