Ordered mesoporous V2O5/WO3 composite catalysts for efficient oxidation of aryl alcohols

Abstract

Multicomponent mesoporous metal oxides show promise in the area of heterogeneous catalysis due to the synergetic interactions between the framework components and the high internal surface area. In this study, we present the synthesis of ordered mesoporous tungsten(VI) oxide–vanadium oxide (V₂O₅) nanocomposite frameworks via a two-step wet chemical deposition and nanocasting process and demonstrate that they exhibit high catalytic activity and stability for the oxidation of aryl alcohols, using tert-butyl hydroperoxide (t-BuOOH) as oxidant. X-ray diffraction, transmission electron microscopy and nitrogen porosimetry results indicate that the template-free materials possess a 3D mesoscopic structure of discernible domains of parallel-arranged nanorods and have an internal pore surface with narrow mesopores. The chemical composition and molecular structure of the mesoporous matrix were determined with elemental X-ray microanalysis (EDS), diffuse reflectance ultraviolet-visible (UV-vis) and Raman spectroscopy. Our catalytic results indicate that a small addition of V₂O₅ into the lattice of WO₃ has a beneficial effect on the catalytic performance. Thus, the 4% V₂O₅-loaded WO₃ catalyst shows a large improvement in the oxidation of various para-substituted aryl alcohols with respect to the pure mesoporous WO₃, giving good-to-high yields (ca. 80–100%) of the target products within 1–4 h reaction time.