Nanostructured VOx/VO(PO4)n Using Solid-State Vanadium Containing Phosphazene Precursors: A Useful Potential Bi-Catalyst System

Abstract

Pyrolysis of molecular precursors containing vanadium organometallic and cyclic phosphazene affords mixtures of nanostructured vanadium oxides and pyrophosphates. The products from the molecular precursor [N3P3(OC6H5)5OC5H4N·Cp2VCl][PF6], and of the mixtures Cp2VCl2/N3P3(OC6H4CHO)6 and Cp2VCl2/[NP(O2C12H8)]3 in several relationships 1:1, 1:3, 1:5 and 1:10, pyrolyzed under air and at 400 °C and 600 °C, give mixtures mainly V2O5 and VO(PO3)2. Varied morphologies depending on the molecular or mixture precursors and of the temperature used were observed. Nanowires with diameters of approximate 40 nm were observed for the 1:5 Cp2VCl2/[NP(O2C12H8)]3 mixture pyrolyzed at 400 °C, while the same mixture pyrolyzed at 600 °C, affords xerogels of V2O5. The products were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), infra-red (IR) spectroscopy and X-ray diffraction (XRD). The preparation method constitutes a novel one-pot solid-state way to nanostructured materials with potential applications both in oxidative dehydrogenation of light hydrocarbons with V2O5, as well as alkenes oxidations with VO(PO3)2.