Photocatalytic oxidation of benzyl alcohol using pure and sensitized anatase

The photocatalytic oxidation of liquid benzyl alcohol by suspension of titanium dioxide (anatase) and sensitized anatase has been investigated under an oxygen atmosphere. Measurements were made over the temperature range 278–303 K, using low pressure mercury lamp. Spectrophotometer measurements have been used to determine the concentration of benzaldehyde by following the formation of 2,4-dinitrophenyl hydrazone derivatives at a wavelength 480 nm. Activation energies for benzaldehyde formation were effectively identical on naked and sensitized anatase (21 ± 1 kJ mol−1), however, the activity of sensitized anatase was higher than that of naked anatase. The identical activation energy for the photoreaction of benzyl alcohol over sensitized and naked TiO2 in the presence of oxygen is believed to be associated with the transport of photoelectrons through the catalyst to the adsorbed oxygen on the surface.