Synthesis and functional verification of the unsupported active phase of VxOy catalysts for partial oxidation of n-butane

We studied unsupported VxOy nanoparticles prepared by a novel non-aqueous route in the selective oxidation of n-butane to maleic anhydride. The evolution of the electronic and geometric structure of the material was characterized by X-ray photoemission spectroscopy, electron energyloss spectroscopy, transmission electron microscopy and electron diffraction before and after the reaction at different temperatures. A change from a water mediated C-C bond cracking functionality of the catalyst forming acetic acid to an oxidizing functionality resulting in maleic anhydride was observed. It was found that the particles did undergo a radical modification of the geometric and electronic structure that finally resulted in V2O5 crystals. Experimentally derived conclusions will be related to some conceptual claims from the literature.