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

摘要

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.