Copper-containing hexagonal mesoporous silicas for styrene epoxidation using tert-butylhydroperoxide

Copper-containing hexagonal mesoporous silicas (Cu-HMS) with different Si/Cu atomic ratios were synthesized by one-pot sol–gel method using dodecylamine surfactant as templating agent. The structure was characterized by X-ray diffraction, N2 adsorption–desorption, infrared spectroscopy, transmission electron microscopy, ultraviolet and visible diffuse reflectance spectroscopy, electron spin resonance and H2 temperature-programmed reduction. The results show that the Cu-HMS material is an efficient catalyst for epoxidation of styrene with use of aqueous tert-butylhydroperoxide. The catalytic performance is dependent on Si/Cu atomic ratio and reaction solvent. A styrene conversion of 99% with epoxide selectivity up to 84% can be obtained over the Cu-HMS material with Si/Cu atomic ratio of 40 in the case of using a mixed solvent of acetonitrile and N,N-dimethylformamide. No significant loss in the catalytic performance is observed during catalyst reuse. The enhanced catalytic performance over Cu-HMS material may be attributed to the homogeneous dispersion and uniformity of active Cu2+ species.

Graphical abstractCopper-containing hexagonal mesoporous silicas with appropriate Si/Cu atomic ratios synthesized by one-pot sol–gel method could show excellent performance and stability in the styrene epoxidation using aqueous tert-butylhydroperoxide. A styrene conversion over 95% with epoxide selectivity up to 84% could be obtained over the Cu-HMS material with a Si/Cu atomic ratio of 40.Figure optionsDownload full-size imageDownload as PowerPoint slide