Photocatalytic degradation of toluene by platinized titanium dioxide photocatalysts.

A photoreactor has been set up to study the photodegradation of volatile organic compound (VOC) in situ. In the reactor, TiO2 and Pt/TiO2 photocatalysts were immobilized on to UV-transparent quartz support. Scanning electron microscope (SEM) studies and Brunauer-Emmett-Teller (BET) surface area measurements revealed that the quartz fiber support was mostly coated with catalyst with a total surface area of 4.0 +/- 0.3 m2/g. The photocatalytic activity of the photocatalysts was evaluated for the photodegradation of 160 ppm toluene-laden air. It was found that 50-70% of toluene was degraded within the first 5 min of UV illumination. Both TiO2 and Pt/TiO2 photocatalysts suffered from deactivation after 18 hours of continuous operation, and the photocatalysts' activity was significantly reduced. However, platinization doubled the photocatalyst life and delayed the onset of de-activation. The presence of moisture was found to shift the onset of catalyst de-activation to an earlier time. It is concluded that the de-activation of the photocatalyst was due to the accumulation of intermediates on the photocatalysts surface preventing the toluene being adsorbed on the photocatalyst surface for degradation.