Abstract
Selective catalytic reduction (SCR) of nitrogen oxide (NO) by ammonia (NH 3) was studied in this work over new sulfate (SO 4 2-) or tungsta (WO 3) modified CeO 2-TiO 2 aerogel catalysts. The catalytic systems were elaborated via sol gel method then characterized by: XRD, N 2-Physisorption at 77 K, DRUV-vis, NH 3-TPD and H 2-TPR. It was revealed that the nature of acidic components influences differently the texture, surface oxygen concentration, acidity, reducibility and NH 3-SCR activity of new Ce-based catalysts. Hence, the incorporation of sulfate modifies the nature of Ce species, improves their dispersion through the Ce-SO 4 2interactions and, particularly, generates new strong acid sites which display superior catalytic performance at high temperature NO reduction (NO conversion into N 2 > 90 % between 450 and 500 °C over CeO 2-TiO 2-SO 4 2catalyst). However, the addition of tungsta affects slightly the surface acidity of CeO 2-TiO 2 catalyst but it induces the creation of more reactive surface oxygen and new redox sites at its surface (mainly due to the existence of W-Ce interactions) leading to highly active WO 3-CeO 2-TiO 2 system for the low temperature NH 3-SCR reaction with above 90 % NO conversion into N 2 between 320 and 400 °C.