Résumé
A new V2O5–MoO3–TiO2–SO42− nanostructured aerogel system, containing V and Mo loadings representative of the V2O5–MoO3/TiO2 commercial SCR catalyst, was developed via a one step sol–gel method combined with the supercritical drying approach for the low temperature selective catalytic reduction of NO by NH3, in excess O2. The new V2O5–MoO3–TiO2–SO42− catalyst was analysed via XRD, N2-physisorption, H2-TPR, NH3-TPD, Raman spectroscopy, XPS and DR UV-vis spectroscopy. The elaboration and characterization of TiO2, V2O5–TiO2, MoO3–TiO2, V2O5–MoO3–TiO2, TiO2–SO42−, V2O5–TiO2–SO42− and MoO3–TiO2–SO42− aerogel samples were also reported in this work. The results prove the successful synthesis of nanostructured aerogel materials with good crystallinity of the TiO2 anatase phase, a developed mesoporous texture and a nanometer size as new SCR catalysts. V, Mo and SO42− were found to be highly dispersed on the TiO2 surface, and their presence and the diverse interactions developed between them strongly affect the physicochemical properties and catalytic behaviour of the derived sol–gel powders. Among all the samples investigated, the new V2O5–MoO3–TiO2–SO42− aerogel was found to be the most efficient catalyst for the low temperature NO-SCR: compared to a V2O5–WO3/TiO2 commercial catalyst (EUROCAT), it demonstrates similar SCR activity in the 200–375 °C temperature range, but, at higher temperatures (375–500 °C), it exhibits superior catalytic performance. A complete conversion of NO into N2 (100%) was achieved in the 450–500 °C temperature range over the new V2O5–MoO3–TiO2–SO42− nanostructured aerogel catalyst, when the NH3-SCR reaction was realized using 1000 ppm NO and 1000 ppm NH3, in the presence of 3.5% H2O.