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

CeO modified commercial SCR (selective catalytic reduction) catalysts with different CeO 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 increased the surface area, the dispersity of the metal oxides on the TiO support and the redox behavior of the catalyst, which was beneficial to the catalytic activity. The experimental results confirmed that the CeO loading improved the catalytic efficiencies over the commercial SCR catalyst. The catalyst with a CeO content of 4% displayed the optimal performance for NO and synergistic Hg removal, of which the NO conversion and Hg removal efficiency reached 90.5% and 78.2%, respectively, at 300 °C in simulated coal-fired flue gas. The Hg removal activity, the independence of Hg removal from HCl concentration and the effects of SO, NO and NH on Hg 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 VO and CeO and the redox transformation between Ce and Ce on the catalyst surface. The CeO 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.