Direct Synthesis of Bifunctionalized Hexagonal Mesoporous Silicas and Its Catalytic Performance for Aerobic Oxidation of Cyclohexane

According to the characteristics of the cyclohexane oxidation reaction a series of bifunctionalized hexagonal mesoporous silicas, CoPh-HMS, were designed and successfully synthesized by a one-step co-condensation route. The results of small-angle XRD, TEM, and N-2 adsorption-desorption measurements showed that the resultant materials had well-ordered mesoscopic structures. Co2+ ions were incorporated into the frameworks in tetrahedral coordination along with phenyl groups immobilized on the surface, confirmed by a careful spectroscopic (FT-IR, UV-visible, and Si-29 MAS NMR) study. The surfaces of the materials were proved to be more hydrophobic with higher Ph loading, and the largest water droplet contact angle is tip to 110.50 degrees. These materials were applied in the liquid-phase oxidation of cyclohexane with molecular oxygen as oxidant and tert-butyl hydroperoxide as initiator Linder solvent-free conditions. High activity could be obtained with these bifunctionalized catalysts being used. The modification effect of phenyl groups played an important role in the activity enhancement.