Epoxidation of Styrene on a Novel Titanium–Silica Catalyst Prepared by Ion Beam Implantation

A Ti–SiO2catalyst with highly isolated titanium ions was prepared by ion beam implantation. The catalyst was tested for the epoxidation of styrene using dilute H2O2(30%) as the oxidizing agent. Two kinds of product were formed: epoxide and benzaldehyde. The selectivity for epoxide approaches 100% at 298 K and decreases at elevated reaction temperatures. A turnover frequency for styrene up to 11.7 h−1was observed. The activity and selectivity for epoxide decreased when the catalyst was calcined at higher temperatures. It is proposed that there are at least two types of active sites on the catalyst: Ti(α) (isolated Ti3+and Ti4+) for the selective formation of epoxide and Ti(β) (TiO2clusters) for the formation of benzaldehyde.