Oxidation of ethanol in gas phase via heterogeneous photocatalysis

TiO2 (anatase) powder irradiated by near-UV light was used for carrying out the ethanol oxidation in gas phase. The reactivity experiments, performed at atmospheric pressure and low temperature, were carried out in a continuous annular photoreactor of Pyrex glass whose internal surfaces were covered by a thin layer of photocatalyst. The influence on the photoreactivity of the following operative parameters: gas flow rate, amount of catalyst, ethanol concentration, oxygen concentration, and presence of water in the reacting mixture was investigated. A Langmuir-Hinshelwood kinetics well expresses the dependence of the ethanol degradation rate on the ethanol and oxygen concentration. The presence of water does not affect the photoreactivity. The absence of catalyst deactivation during the photoprocess was also checked. The main product of ethanol photooxidation was acetaldehyde; the mass balance of reacted ethanol was closed by small amounts of formaldehyde and carbon dioxide.