Modifying the reactivity of a solid Lewis acid: niobium and antimony doped nanoscopic aluminum fluoride

Abstract

A series of acid catalysts were prepared, using niobium and antimony as dopants in the fluorolytic sol–gel synthesis of high surface aluminium fluoride. These new catalysts exhibit remarkable reactivity: they are able to isomerize compounds containing carbon–halogen bonds at room temperature by C–F, C–Cl and C–Br activation and perform the isomerization of double bonds and Friedel–Crafts-like reactions that are required for the cyclization of citronellal, for which the conversions increase by doping with Nb up to 99%. Furthermore, the characterization of the catalysts by means of MAS NMR, NH₃-TPD, py-PAS and N₂ adsorption is presented.