Enhancement of CeO2 modified commercial SCR catalyst for synergistic mercury removal from coal combustion flue gas

CeO2 modified commercial SCR (selective catalytic reduction) catalysts with different CeO2 content were prepared and researched for synergistic mercury removal from coal combustion flue gas in this study. The characterization analyses on the catalysts indicated that the introduction of CeO2 increased the surface area, the dispersity of the metal oxides on the TiO2 support and the redox behavior of the catalyst, which was beneficial to the catalytic activity. The experimental results confirmed that the CeO2 loading improved the catalytic efficiencies over the commercial SCR catalyst. The catalyst with a CeO2 content of 4% displayed the optimal performance for NO and synergistic Hg-0 removal, of which the NO conversion and Hg-0 removal efficiency reached 90.5% and 78.2%, respectively, at 300 degrees C in simulated coal-fired flue gas. The Hg-0 removal activity, the independence of Hg-0 removal from HCl concentration and the effects of SO2, NO and NH3 on Hg-0 removal efficiency all became positive over the modified catalyst compared to over the raw one, which was mainly due to the sufficient chemisorbed oxygen derived from the synergy of V2O5 and CeO2 and the redox transformation between Ce3+ and Ce4+ on the catalyst surface. The CeO2 modification generated a significant enhancement on the catalytic performance and made the commercial SCR catalyst more suitable to be employed for NO and synergistic mercury removal in a coal combustion power plant.