Ordered mesoporous chromium–zirconium oxophosphate composites with homogeneously dispersed chromium oxide: synthesis, characterization and application in liquid phase oxidation of benzyl alcohol and ethylbenzene

Abstract

In this paper, a sequence of ordered mesoporous chromium–zirconium oxophosphate (M–Cr–ZrPO) composites with controllable chromium contents (0–15 mol%) were projected and successfully synthesized through a modified one-pot evaporation-induced self-assembly method. Characterized by N2 adsorption–desorption isotherms and TEM techniques, the resultant M–Cr–ZrPO composites owned ordered mesoporous structure and the textural properties [specific surface areas (160–210 m2 g−1), pore volumes (0.25–0.28 cm3 g−1) and pore sizes (5.6–6.6 nm)] of materials were improved by the introduced chromium species. In addition, the dispersion, existing states and contents of introduced chromium species in the materials were researched in detail by elemental mapping images, XRD, UV–vis, FT-IR, XPS and H2-TPR techniques. All the characterizations implied that the chromium oxides were introduced as expected and homogeneously dispersed in the skeleton of mesoporous materials. Owing to the outstanding structural properties and chromium species with homogeneous dispersion, the M–Cr–ZrPO materials exhibited superior catalytic activity for liquid phase oxidation of benzyl alcohol and ethylbenzene.