Synthesis of carbonylic derivatives from alkylaromatics by a photocatalytic oxidation using Fe/Ti-pillared clays.

A pillared montmorillonite containing iron doped titania (Fe/Ti-PILC) has been prepared from a natural clay. This material has been characterized by X-ray diffraction, nitrogen adsorption, temperature programmed desorption of ammonia, inductively coupled plasma atomic emission spectroscopy, atomic absorption and diffuse reflectance UV-VIS spectroscopy. The doped material was a robust photocatalyst able to oxidize liquid alkylaromatics to the corresponding carbonylic derivatives, using O-2 as the oxidizing species, at mild pressure and temperature conditions. Accumulation of valuable carbonylic derivatives was possible since their over-oxidation to carbon dioxide was negligible. Fe/Ti-PILC was able to discriminate between toluene and cyclohexane in favour of the aromatic compound with an efficiency that is about three times higher than that of titanium pillared clays (Ti-PILC). It is likely that the addition of iron favoured the formation of new acid sites able to interact with the aromatic substrate. Iron doping caused a significant TiO2 visible light induced activity (lambda > 400 nm) with only minor negative effects on its performance under UV-light irradiation (lambda > 290 nm).