Highly selective epoxidation of styrene over mesoporous carbon support with titanium dioxide under ambient photocatalytic condition

The main purpose of this paper was to design a novel structure mesoporous carbon composite materials and develop economic and green photocatalytic oxidation process for common chemical reaction intermediates of styrene oxide under ambient condition based on the basic principle of environmentally friendly chemistry. Order mesoporous silica was prepared by conventional hydrothermal method using triblock copolymer as template agent, and then order mesoporous carbon materials were synthesized via a simple template method by adding sucrose to the sulfuric-acid-treated mesoporous silica and followed by carbonization and removal template of mesoporous silica on account of inverse replica effects. The composite mesoporous carbon materials assembled in situ anatase TiO₂ of different contents were obtained through impregnation and sintering at 700℃ for 2h in nitrogen atmosphere for both removal of unhydrolyzed tetrabutyl titanate and crystallization of titanium dioxide. All the composite catalysts had been unambiguously characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscoscopy, scanning electron microscopy, and high-resolution transmission electron microscopy, etc. Structural and morphological of prepared carbon materials showed that the typical ordered mesoporous structure was maintained after TiO₂ insertion and active component of TiO₂ was uniformly distributed in mesoporous carbon channels. A variety of reaction parameters such as molar ration of H₂O₂ to the styrene, reaction time, solvent, the amount of catalyst and so on were optimized at length for epoxidation of styrene with H₂O₂ as the oxidant over prepared composite catalysts under photo-irradiation. The results indicated that reaction conversion reached over 30% with 90% selectivity under the photocatalytic condition for room temperature, 0.50g of styrene, 2.00g of H₂O₂(30%wt%), 0.200g of catalyst and 3h reaction time. This process strategy for green photocatalytic oxidation under ambient condition was expected to be applied to other organic synthesis processes as a general environmentally benign chemical means.