FTIR study of interactions of ethyl iodide with powdered TiO2

Abstract

The adsorption, thermal reactions, and photochemistry of C₂H₅I have been studied on TiO₂ by Fourier-transformed infrared spectroscopy. C₂H₅I is adsorbed on TiO₂ and remains intact at 35°C. However, it decomposes to form C₂H₅O(a) at temperatures below 200°C in vacuum. It is found that this decomposition process is enhanced by the presence of isolated surface hydroxy groups. In the study of the thermal reaction of C₂H₅I on TiO₂ in a closed IR cell without O₂, ethylene is the only gas product detected. However in the presence of O₂, in addition to ethylene, H₂O, CO and CO₂ are generated together with surface species probably derived from the adsorption of another product of acetaldehyde. In the photochemistry of C₂H₅I on TiO₂ in forming surface formate and acetate, which are probably produced ia acetaldehyde intermediate, O₂ plays an essential role. It is likely that the photoreaction is initiated by O₂⁻, generated from photoelectron capture by adsorbed O₂.