Comparison of catalytic properties of vanadium centers introduced into bea zeolite and present on (010) v2 o5 surface–dft studies

Abstract

Vanadium-based catalysts, in which vanadium is present either as bulk V2 O5 or as isolated species, are active in numerous oxidation reactions. In the present study, vanadium speciation and the possibility of its introduction in various forms (V=O, V–OH, V(=O)(–OH)) into the structurally different crystallographic positions in BEA zeolite was considered by means of Density Functional Theory (DFT). Out of nine nonequivalent positions, T2 and T3 positions are the most preferred. The former may accommodate V=O or V–OH, the latter V–OH or V(=O)(–OH). The structural and electronic properties of all possible centers present in the BEA zeolite are then compared with the characteristics of the same species on the most abundant (010) V2 O5 surface. It is demonstrated that they exhibit higher nucleophilic character when introduced into the zeolite, and thus, may be more relevant for catalysis.