Studies of the Structure of Vanadium Species in VAPO-5 Molecular Sieves via Density Functional Theory Computation and Raman Spectroscopy

Based on the density functional theory calculation using B3LYP hybrid method, a distorted square pyramidal (V4+O)(Of)4 unit in a reduced and dehydrated VAPO-5 is formed by the vanadium (IV) oxide ion anchored to two neighboring 12-membered TO4 rings of the aluminophosphate-5 lattice. By breaking two V−O−T bonds on one twelve-membered-ring to form another VO bond, V4+ can be oxidized to a tetrahedral di-oxo V5+O4 unit. The computed structures of vanadium oxide species have been confirmed by Raman spectroscopy.