Synthesis, characterization and testing of a new V2O5/Al2O3–MgO catalyst for butane dehydrogenation and limonene oxidation

Abstract

We report the synthesis and characterization of new V₂O₅/Al₂O₃–MgO catalysts and their application in oxidative dehydrogenation and epoxidation reactions. The materials were prepared by wet impregnation under excess acid conditions. Anchoring of the desired species on the support occurs via an exchange reaction between the vanadium complex and surface hydroxyl groups. The IR and UV-Vis spectra of these catalysts indicate the presence of monomeric vanadium species at 5 wt% V₂O₅ loading, along with small amounts of polymeric species at 5 and 10 wt% V₂O₅ loadings. Electron paramagnetic resonance (EPR) spectroscopy reveals the presence of ferromagnetic VO²⁺ dimers following calcination at 773 K. The catalysts were then tested in two reactions, namely the gas phase oxidative dehydrogenation of n-butane under flow conditions at 773 K and the liquid phase epoxidation of limonene with H₂O₂. The dehydrogenation reaction gave butenes and 1,3-butadiene in moderate selectivity at 8–10% conversion. The epoxidation of limonene was less successful, giving 50–70% selectivity to the 1,2-epoxide at 10–20% conversion.