Acidic properties of vanadium oxide on titania

Abstract

The adsorption of pyridine on V–Ti oxide prepared by the gas-phase method (1.4–5.6 wt%) has been studied by i.r. spectroscopy. V–Ti oxide exhibits both Brønsted- and Lewis-acid sites. The Lewis-acid sites are converted to Brønsted sites on the introduction of water vapour. From the absorption coefficients of the 1530 cm^–1 band (Brønsted site) and 1440 cm^–1(Lewis site), the number of both sites has been estimated. The acidic sites in two-dimensional or monolayer vanadia species are stronger Brønsted acids than those formed from crystalline vanadia.