Abstract: A Co(III)-modified mesoporous material (SBA-15-Co(III)) was prepared by supporting an in situ formed Co(III) complex on o-dicarboxylic acid modified SBA-15 (SBA-15-(COOH)₂) that was synthesized by first the Diels-Alder reaction between maleic anhydride and cyclopentadienyl-modified SBA-15 (SBA-15-Cp) and then the hydrolysis of resulting anhydride. Fourier transform infrared spectroscopy, elemental analysis (ICP-AES), and X-ray photoelectron spectroscopy confirmed the successful incorporation of carboxyl and Co(III) in the mesopores. The results of X-ray powder diffraction, N₂-sorption, and high resolution transmission electron microscopy showed that SBA-15-Co(III) well maintained the mesostructure of SBA-15. In the presence of isobutylaldehyde, SBA-15-Co(III) showed moderate activity and stability in the epoxidation of cyclohexene when the flow rate of O₂ was 5 ml/min, the solvent was acetonitrile, the reaction temperature was 40 °C, and time was 6 h. The yield and selectivity of cyclohexene oxide could reach 58% and 63.7%, respectively. The yield and selectivity of cyclohexene oxide could still maintained 51.6% and 56.5% after six catalytic cycles.

Key words: Diels-Alder reaction, o-dicarboxylic acid, SBA-15, mesoporous material, trivalent cobalt, cyclohexene epoxidation