The combined removals of Hg-0 and NO over zeolite (HZ5M-5 was chosen to use) modified by copper (Cu/HZSM-5) catalysts were studied under different simulated flue gas conditions. Compared with HZSM-5, Cu/HZSM-5 showed higher activity and performed a synergetic effect for the Hg-0 and NO removal at 250 degrees C. But the excess of copper could cause destruction of the thin pore walls and blocking of internal porosity of the catalyst leading to decrease of the activity. A comparison between Cu/HZSM-5 of different silica to alumina ratios (SiO2/Al2O3 ratio) was also performed. The highest NO and Hg-0 conversions were observed over the lowest SiO2/Al2O3 ratio. In addition, the experimental results indicated that there was a synergetic effect between HZSM-5 and copper for the removal of NO and Hg-0 by accelerating the intermediate formation (NO2) and by strengthening the adsorption NO and Hg-0 on the catalyst surface under the reaction conditions. Moreover, the effects of individual flue gas components on the removals of Hg-0 and NO were examined. O-2 in the flue gas had a positive effect on both Hg-0 and NO removals. However, the presence of H2O and SO2 inhibited both Hg-0 and NO removals. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.