Abstract
Co-Ce mixed oxides were loaded on commercial cylindrical activated coke granules (CoCe/AC) by an impregnation method to remove gaseous elemental mercury (Hg-0) from simulated coal combustion flue gas at low temperature (110-230 degrees C). Effects of the Co/Ce molar ratio in Co-Ce mixed oxides, mixed oxides loading value, reaction temperature, and flue gas components (O-2, NO, SO2, H2O) on Hg-0 removal efficiency were investigated, respectively. Brunauer-Emmett-Teller analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) analysis were employed to analyze the characteristics of the samples. Results showed that up to 92.5% of Hg-0 removal efficiency could be obtained over Co4.5Ce6/AC at 170 degrees C. The remarkably high Hg-0 removal ability of Co4.5Ce6/AC mainly depended on the synergetic effect between cobalt oxide and ceria. Additionally, different with the pure N2 condition, the existence of O-2 and NO could increase He removal efficiency. SO2 exhibited an inhibitive effect on Hg-0 removal in the absence of O-2. H2O(g) could slightly hinder Hg-0 removal. The characterization results exhibited that addition of cobalt oxide led to the excellent dispersity of CeO2 on AC. TGA and XPS analysis results revealed that the captured mercury species on the used Co4.5Ce6/AC mainly existed as Hg-0, and both lattice oxygen and chemisorption oxygen contributed to Hg-0 oxidation. Furthermore, the mechanisms involved in Hg-0 removal were identified.