Adsorption, thermal decomposition, and photoreactions of ethylene oxide (EO) on powdered TiO2 have been studied by Fourier-transformed infrared spectroscopy. Most of the adsorbed EO molecules at the saturated coverage on 35 °C TiO2 remain intact. As the temperature is increased (> 100 °C), the surface EO molecules dissociate into ethylene glycol-like species (-OCH2CH2OH or -OCH2CH 2O-) by ring rupture and crotonaldehyde (CH3CH=CHCHO) possibly via acetaldehyde from EO isomerization. The ring-opening process is enhanced in the presence of coadsorbed H2O molecules. EO with the highly strained three-membered ring is thermally more reactive than 1,4-dioxane on TiO2. EO molecules adsorbed on TiO2 readily undergo photodegradation in O2, forming surface H2O, CO 2, HCO3, CO3, and HCOO. The comparative studies of 16O2 and 18O2 indicate that both O2 and lattice oxygen take part in the EO photodecomposition. The reaction pathways involving the two oxygen species are discussed.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films