Catalytic performance of surface-silylated and Phenyl-bridged Ti-containing mesoporous silica for epoxidation of propylene

Titanium-doped phenyl-bridged ordered mesoporous organosilicon (Ti-PMO) was initially prepared by a one-step hydrothermal synthesis method under acidic conditions. Following silanization modification, a Ti-PMO-S sample was obtained with an improved surface hydrophobic characteristic. The environment of titanium within the samples was analyzed by Fourier-transform infrared spectroscopy (FT-IR), diffuse reflectance ultraviolet visible spectroscopy (UV-Vis-DR), ammonia temperature programmed desorption (NH3-TPD), and Raman spectroscopy. Furthermore, the textural and structural properties of corresponding materials were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms and transmission electron microscopy (TEM). The results showed that Ti-PMO-S has more active Ti centers than Ti-SBA-15 and Ti-PMO on the basis of maintaining the mesoporous structure of ordered channels, despite the presence of few TiO2 species. The catalytic performance of the synthesized samples was assessed in the epoxidation of propylene with tert-butyl hydroperoxide (TBHP) as an oxidant. The prepared Ti-PMO-S materials showed the best epoxidation performance under optimized conditions, with conversion of TBHP up to 95.8% and selectivity of propylene epoxide and tart butyl alcohol reaching 78.8% and 95.9%, respectively.