Direct synthesis, characterization and catalytic activity of titanium-substituted SBA-15 mesoporous molecular sieves

Titanium-substituted SBA-15 mesoporous molecular sieves have been successfully synthesized under conventional hydrothermal conditions by using titanium trichloride and tetraethyl orthosilicate as titanium and silica source, respectively. The synthesized materials were characterized by powder X-ray diffraction patterns (XRD), diffuse reflectance UV-visible spectroscopy (UV-vis), X-ray fluorescence spectroscopy (XRF), N-2 sorption isotherms and the reaction of catalytic oxidation of styrene. When the pH value of the gel solution was approximately 1.8 and titanium chloride was added after prehydrolysis of tetraethyl orthosilicate for a certain time, the titanium could be effectively incorporated into the framework of SBA-15. The Ti-SBA-15 so obtained was of high quality. With the present synthesis approach, the formation of anatase TiO2 in Ti-SBA-15 can be avoided. Moreover, the addition of H2O2 during the preparation process can improve the quality of Ti-SBA-15. The calcined Ti-SBA-15 materials showed high catalytic activity in the selective oxidation of styrene. (C) 2004 Elsevier B.V. All rights reserved.