Immobilization of Cu(II) in KIT-6 supported Co3O4 and catalytic performance for epoxidation of styrene

KIT-6 is a cage type three dimensional cubic mesoporous silicate with Ia3d type structure, which shows scintillating promise in nanocasting, surface functionality, metal incorporation, and pharmaceutics. Nevertheless, little attention was paid to its application as support in heterogeneous catalysts. Cu-containing cobaltosic oxide spinel composite supported by mesoporous silica KIT-6 was synthesized via impregnation method and subsequent calcination under different temperatures. The prepared ordered materials were characterized by X-ray diffraction, N-2 adsorption-desorption, transmission electron microscopy, atomic adsorption spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The results showed that Cu2+ was successfully embedded in spinel structure when calcined at 550 degrees C, in contrast, the samples through thermal treatment at 250 degrees C remained hybrid composition of CuO and Co3O4. Catalytic performance of mesoporous materials was evaluated for epoxidation of styrene in the presence of tert-butylhydroperoxide as oxidant. Among a range of prepared materials, a significant enhancement in styrene conversion and selectivity of styrene oxide was obtained for Cu-spinel catalysts, in comparison with hybrid oxide. A dramatic decrease in catalytic activities was found while KIT-6 support was removed, due to the partial destruction of ordered structure of Cu-Co oxide. Consequently, the catalytic behaviors were chiefly ascribed to copper species and their textural properties. (C) 2015 Elsevier B.V. All rights reserved.