In-situ synthesis and characterization of V-MCM-41 for oxidative dehydrogenation of n-butane

Abstract

A series of MCM-41 catalysts with different vanadium content were prepared via prehydrolysis hydrothermal method with ammonia metavanadate as precursors. The prepared samples were characterized by Powder X-ray diffraction (XRD), N2 adsorption–desorption, X-ray photoelectron spectra (XPS), H2 temperature-programmed reduction (TPR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results showed that V-MCM-41 could still maintain hexagonal mesoporous structure and large specific surface area when the vanadium content was low, whereas the mesoporous structure collapsed in the high V-containing samples. Two vanadium species (V5+/VSiOx and V5+/V2O5) were identified in the catalysts and the highly dispersed vanadium species decreased with the increasing vanadium content. The activity of the catalysts were tested for the oxidative dehydrogenation (ODH) of n-butane with O2 as oxidant, the results showed that V5+/VSiOx was more active than V5+/V2O5.