Synergistic effect between ceria and tungsten oxide on WO3-CeO2-TiO2 catalysts for NH3-SCR reaction

WO3-CeO2-TiO2 catalysts for NO(nitrogen monoxide) reduction by ammonia were prepared by a sol-gel method. The catalysts were characterized by BET, XRD, Raman, NH3/NO adsorption and H-2-TPR to investigate the relationships among the catalyst composition, structure, redox property, acidity and deNO(x) activity. WO3-CeO2-TiO2 catalysts show a high activity in a broad temperature range of 200-480 degrees C. The low-temperature activity of catalysts is sensitive to the catalyst composition especially under low-O-2-content atmospheres. It may be related to the synergistic effect between CeOx and WOx in the catalysts. On one hand, the interaction between ceria and tungsten oxide promotes the activation of gaseous oxygen to compensate the lattice oxygen consumed in NH3-SCR(selective catalytic reduction) reaction at low temperatures. Meanwhile, the Bronsted acid sites mainly arise from tungsten oxides, Lewis acid sites mainly arise from ceria. Both of the Bronsted and Lewis acid sites facilitate the adsorption of NH3 on catalysts and improve the stability of the adsorbed ammonia species, which are beneficial to the NH3-SCR reaction. (C) 2012 Chinese Materials Research Society. Production and hosting by Elsevier Ltd. All rights reserved.