Photoreduction of nitrobenzene to aniline in ?hybrid? photocatalytic systems

Abstract

Irradiation of suspensions of CdS in water-ethanol mixtures containing nibrobenzene with light at λ > 320 run does not in practical terms lead to the reduction of the nitrobenzene to aniline. It has been shown that the formation of aniline occurs when solvato complexes of vanadium(III) (γPhNH2=18.1·10−3) and vanadium(IV) (γPhNH2= 2.84·10−3) are added to the system. The photocatalytic reduction of nitrobenzene is accompanied by oxidation of the alcohol to acetaldehyde and acetal. The proposed process mechanism includes stages and acceptance of an electron photogenerated in the semiconductor by vanadium compounds and of a hole by molecules of the alcohol and subsequent stages of reaction of the reduced forms of vanadium, and also of the ethoxy radicals with nitrobenzene, which leads to its reduction.