Synthesis, characterization and catalytic performance of titanium-grafted mesoporous Ti-HMS molecular sieve

A series of Ti-HMS samples with different Ti amounts were prepared by a grafting method using organometallic titanocene dichloride as the Ti source and HMS as the support. The template of HMS was removed by calcination at 600 degrees C or by ethanol-extraction followed by calcination at 400 degrees C. The Ti-HMS samples were characterized by thermogravimetric and differential thermal analysis, powder X-ray diffraction, N-2 adsorption-desorption isotherm, diffuse reflectance UV-visible spectroscopy, and Fourier transform infrared spectroscopy. The catalytic performance of the Ti-HMS samples for oxidation of 4-tert-butyltoluene with aqueous H2O2 was tested under the mild conditions. Pretreatment of HMS by ethanol-extraction followed by low temperature calcination made OH groups available for grafting. The isolated framework Ti( IV) decreased with the increase in Ti loading. The four-coordinated Ti state displayed catalytic activity for oxidation of 4-tert-butyltoluene. Non-framework Ti species were responsible for low catalytic activity. A conversion of 4-tert-butyltoluene up to 9.3% and a complete selectivity for 4-tert-butylbenzaldehyde were achieved.