Gas-phase Photocatalytic Oxidation of 1-Hexene Using Heterogeneous Semiconductor Materials

Abstract

Photo-catalytic reactions have been carried out and proved to be conducted under mild conditions in contrast to several conventional industrial chemical processes, which involve the use of high amounts of temperature and pressure. In this work, an investigation of the photo-catalytic oxidation of 1-hexene was carried out using UVA-activated TiO2, and coupled TiO2/WO3 to drive organic reactions. Different mol % of WO3 ranging from 1-7mol% were used to monitor effect of coupling amount. The chosen photocatalyst was immobilized on glass beads using an innovative in-house procedure. The immobilized catalyst was then used in a vapour-phase flow reactor designed for alkene photo-oxidation studies. It was possible to establish oxidation rates of 0.14+-0.02 mmol/h for 1-hexene with TiO2/WO3 (1mol %). 1,2-epoxyhexane was successfully synthesized from 1-hexene achieving 15.9% conversion and 41% and 54% selectivity for the 1-hexene, 1,2-epoxyhexane and CO2 respectively when H2O/O2 was used as oxidant. Selectivity of 96% and 97% for CO2 were achieved with N2 and O2 respectively. No epoxide was formed with either N2 or O2 alone.

Keywords

• alkene, photo-catalysis, flow reactor, titanium dioxide, glass beads