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

✍ Scribed by Stanislaw Dzwigaj; Masaya Matsuoka; Masakazu Anpo; Michel Che

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 288 KB
• Volume: 93
• Category: Article
• ISSN: 1387-1811
• DOI: 10.1016/j.micromeso.2006.03.003

✦ Synopsis

The presence of different V V species in VSiBEA zeolite prepared by impregnation in air of dealuminated BEA zeolite with aqueous V IV OSO 4 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 VSi-BEA 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 V V 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.