Direct Synthesis of Titanium-Substituted Mesoporous SBA-15 Molecular Sieve under Microwave−Hydrothermal Conditions

Titanium-substituted mesoporous SBA-15 molecular sieve has been successfully prepared at 373 K by direct synthesis under microwave−hydrothermal conditions within about 2 h. By means of X-ray diffraction, nitrogen adsorption, infrared, UV−vis diffuse reflectance, and Raman spectroscopies, a successful isomorphous substitution of titanium in the silica framework of SBA-15 samples with Si/Ti ratios of 20, 30, and 40 has been reported. The substitution of Ti for Si did not change the textural properties. The higher titanium loading leads to the formation of extraframework titanium species. These results show that microwave-assisted synthesis is an ideal approach to prepare Ti-substituted SBA-15, which is expected to be useful as a selective oxidation catalyst for reactions involving large molecules.