FTIR study of interactions of ethyl iodide with powdered TiO2

The adsorption, thermal reactions, and photochemistry of C2H5I have been st udied on TiO2 by Fourier-transformed infrared spectroscopy. C2H5I is adsorb ed on TiO2 and remains intact at 35 degrees C. However, it decomposes to fo rm C2H5O(a) at temperatures below 200 degrees 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 O-2, ethylene is the only gas product detected. How ever in the presence of O-2, in addition to ethylene, H2O, CO and CO2 are g enerated 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 via ac etaldehyde intermediate, O-2 plays an essential role. It is likely that the photoreaction is initiated by O-2(-), generated from photoelectron capture by adsorbed O-2.