The influence of water on the dispersion of vanadia supported on silica SBA-15

X-ray photoelectron spectroscopy (XPS) is shown to be a sensitive tool to study the influence of water on the dispersion of silica SBA-15 supported vanadia model catalysts XPS characterization of the V 2p3/2 state reveals the presence of two V5+ states, which are assigned to vanadia with distinctly different cluster size. Upon dehydration a dramatic change in their intensity ratio is observed as a result of a substantial increase in the vanadia dispersion.