Highly ordered mesoporous zirconia-polyoxometalate nanocomposite materials for catalytic oxidation of alkenes

Abstract

A series of well-ordered mesoporous ZrO2-based heteropoly acid nanocomposite frameworks has been prepared through a surfactant-assisted sol–gel copolymerization route. The pore walls of these materials consist of nanocrystalline tetragonal ZrO2 and Keggin-type 12-phosphomolybdic acid (PMA) components with different PMA loadings, i.e. 12, 22 and 37 wt%. Small angle X-ray scattering, high-resolution TEM and N2 physisorption measurements indicated mesoporous property in hexagonal p6mm symmetry with large internal BET surface areas and narrow-sized pores. The incorporated PMA clusters preserve intact their Keggin structure into the mesoporous frameworks according to EDX, FT-IR and diffuse-reflectance UV/vis/NIR spectroscopy. The obtained ZrO2–PMA nanocomposites demonstrated great application potential in oxidative catalysis, exhibiting exceptional stability and catalytic activity in oxidation of alkenes using hydrogen peroxide as oxidant.