Selective photooxidation of light alkanes to oxygenates using supported molybdenum oxide catalysts

Abstract

Photo-assisted catalytic partial oxidation of methane, ethane and propane has been performed in the presence of supported molybdenum oxide catalysts at around 500 K by the use of a fluidized bed flow-type reactor under UV irradiation. Temperatures as high as 500 K were indispensable for the selective formation of methanal from methane (ca. 19 µmol h^–1), corresponding to 5.5% of the photons irradiated into the catalyst bed ( <300 nm). The yields were greatly affected by the loding levels of molybdenum species, the preparation methods of the catalysts and the light flux into the catalyst bed. Photooxidation of ethane and propane also selectively gave the corresponding aldehydes and ketones in high yields (ca. 80 µmol h^–1) at elevated temperature. The reaction seemed to proceed via charge-transfer complexes formed by photo-activation of terminal coordinatively unsaturated MO groups in multilayers of molybdenum species.