New CeO2–TiO2, WO3–TiO2 and WO3–CeO2–TiO2 mesoporous aerogel catalysts for the low temperature selective catalytic reduction of NO by NH3

New mesoporous and well-structured aerogel catalysts (CeO 2 –TiO 2 , WO 3 –TiO 2 and WO 3 –CeO 2 –TiO 2 ) were elaborated via the sol–gel method, characterized by means of various techniques (XRD; N 2 -Physisorption at 77 K; NH 3 -TPD; H 2 -TPR; DRUV–Vis spectroscopy) and evaluated in the selective catalytic reduction (SCR) of NO by NH 3 . The results reveal that all the aerogel catalysts develop essentially the diffraction peaks of TiO 2 anatase phase and are classified as mesoporous materials with a high surface area (70 < S BET < 106 m 2 g −1 ), large porosity (0.27 < V PT < 0.46 cm 3 g −1 ) and nanometer size of crystallites (8–15 nm). The addition of Ce and/or W influences differently the structure, texture, crystallites size, surface oxygen concentration, total acidity and redox ability of aerogel samples and clearly affects their NO-SCR activity which follows this order: TiO 2 < WO 3 –TiO 2 < CeO 2 –TiO 2 < WO 3 –CeO 2 –TiO 2 . It was also found that cerium species are more active in the low temperature NO-SCR reaction than tungsten ones (NO conversions obtained at 300 °C using CeO 2 –TiO 2 and WO 3 –TiO 2 were 75 and 0%, respectively). On the other hand, it was suggested that the interactions between Ce and W species play a key role in improving the reactivity of WO 3 –CeO 2 –TiO 2 catalyst in the SCR of NO by NH 3 . Interestingly, the NO conversion into N 2 reaches 85% at 300 °C and exceeds 90% between 320 and 400 °C over this novel meso-structured aerogel catalyst.