Photocatalytic oxidation of liquid propan-2-ol by titanium dioxide

Abstract

The photocatalytic oxidation of liquid propan-2-ol to propanone has been investigated using suspensions of TiO₂ irradiated with filtered u.v. radiation at temperatures in the range 277–313 K. The dependence of reaction rate on the square root of the intensity of the incident radiation, together with low quantum yields, reflect the dominance of photoelectron and photohole recombination within the TiO₂. The activation energy for reaction on pure rutile using 366 nm radiation, 27 kJ mol^–1, was independent of reaction conditions. For pure anatase, five doped rutiles and coated anatase and rutile pigments, the activation energy under standardized conditions ranged from 31 to 91 kJ mol^–1. These energies are considered to reflect the solid-state properties of the catalysts rather than the chemistry of propan-2-ol oxidation, which proceeds by a radical mechanism.