Photooxidation of trichloroethylene on Pt/TiO2

The gas-phase photooxidation of trichloroethylene (TCE) on Pt/TiO(2) has been investigated. The wavelength dependence of this reaction on Pt/TiO(2) shows that the addition of small amounts of platinum (less than or equal to 2%) to TiO(2) can enhance the photooxidation of TCE to much longer wavelengths. This result correlates with Maxwell-Garnett calculations and experimental absorption curves for Pt/TiO(2) samples. Although the spectral response of Pt/TiO(2) extends to longer wavelengths, Pt/TiO(2) is found to be less effective in the photooxidation of gas-phase TCE upon broad-band irradiation (lambda > 300 nm) compared to TiO(2). It is proposed that site blocking by the Pt particles of the most active sites, Ti(3+) sites, is the cause of the decreased photoactivity. In addition, it has also been determined that the photoproduct distribution changes as a function of platinum lending. Mechanisms to explain the observed effects of Pt loading on the photooxidation of TCE on Pt/TiO(2) are discussed.