Control of NO and Hg0 emissions by SCR catalysts from coal-fired boiler

CuO/gamma-Al2O3 and CuO-MnO2-Fe2O3/gamma-Al2O3 catalysts were synthesized by impregnation method. Their performances for selective catalytic reduction (SCR) were explored in a 200 MW coal-fired power plant boiler tail flue. The effects of catalyst amounts, NH3/NO molar ratios, abrasion resistance, catalyst regeneration and the catalytic efficiencies for Hg-0 oxidation were also discussed here. The optimum temperature range for the SCR of NO over fresh catalysts was 300 similar to 400 degrees C. In the optimum temperature range, the efficiencies of the two catalysts were over 80%, with a maximum efficiency of nearly 90% obtained at 350 degrees C. Reducing the catalyst amounts to half did not change the efficiency dramatically. The highest SCR activity was obtained with NH3/NO molar ratios ranging from 1.0 to 1.2. Abrasion resistance test indicates that the mechanical strength of the catalysts can bear the industrial scale and long-term erosion of fly ash. The activities of the catalysts remained constant during a 200 h test. Meanwhile, the catalysts were able to maintain excellent NO reduction efficiency after three times recycling. CuO/gamma-Al2O3 and CuO-MnO2-Fe2O3/gamma-Al2O3 achieved 40% and 80% Hg-0 oxidation efficiency, respectively. The present study provides a promising catalyst for NO and Hg-0 removal for coal-fired power plants. (C) 2015 Elsevier B.V. All rights reserved.