Enhancement of CeO 2 modified commercial SCR catalyst for synergistic mercury removal from coal combustion flue gas.

CeO 2 modified commercial SCR (selective catalytic reduction) catalysts with different CeO 2 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 CeO 2 increased the surface area, the dispersity of the metal oxides on the TiO 2 support and the redox behavior of the catalyst, which was beneficial to the catalytic activity. The experimental results confirmed that the CeO 2 loading improved the catalytic efficiencies over the commercial SCR catalyst. The catalyst with a CeO 2 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 °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 SO 2 , NO and NH 3 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 V 2 O 5 and CeO 2 and the redox transformation between Ce 3+ and Ce 4+ on the catalyst surface. The CeO 2 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.