Epoxidation of alkenes and their derivatives over Ti-YNU-1

The catalytic properties of Ti-YNU-1 for the epoxidation of various alkenes and their derivatives have been investigated in detail, and further were made a comparison with those of Ti-Beta. The much higher efficiency of Ti-YNU-1 than Ti-Beta was observed in catalyzing the epoxidation of alkenes and their electron-rich analogues. Although it was less active in the epoxidation of α,β-unsaturated ketones, it showed much higher stability. In contrast, Ti leaching from the framework sites occurred to Ti-Beta, and the leaching degree increased with the carbon number of ketones. It was also shown that the catalytic conditions, including the Ti content in samples, H ₂O₂/substrate ratio, reaction temperature and time, acid washing and catalyst amount, significantly influenced the activity, selectivity and H₂O₂ efficiency. Co-oxidation of different alkenes led to the activity and epoxide selectivity being different from those obtained in the oxidation of single olefin as a result of the differences in adsorption properties of substrates over various titanosilicates, which affected the diffusion of substrate molecules and accounted for the unique shape-selectivity of Ti-YNU-1.