Effect of metal content and calcination–hydration on the environment of V in zeolites prepared by impregnation of SiBEA with VIVOSO4 solution

The presence of different VV species in VSiBEA zeolite prepared by impregnation in air of dealuminated BEA zeolite with aqueous VIVOSO4 solution is evidenced by diffuse reflectance UV–Visible and photoluminescence spectroscopies. The former technique shows that in as prepared VSiBEA with 0.26 and 0.68 wt%, V is present as lattice mononuclear tetrahedral species. In calcined-hydrated VSiBEA whatever the V content (0.26 and 0.68 wt%) and in as prepared VSiBEA with 1.36 V wt%, V is present both as lattice mononuclear tetrahedral and extra-lattice octahedral species. However, only photoluminescence spectroscopy is able to clearly distinguish three kinds of distorted lattice mononuclear tetrahedral VV species, whose relative amounts depend on V content and calcination–hydration treatments. Moreover, FT-IR demonstrates that the presence of V in dealuminated BEA zeolite generates Brønsted and Lewis acidic sites whose amounts increase with V content.