PREPARATION AND PHOTOCATALYTIC REACTIONS OF TITANIUM DIOXIDE ULTRAFINE PARTICLES IN REVERSE MICELLAR SYSTEMS

摘要

Photocatalytic oxidation of cyclohexane forming the organic phase of reverse micellar systems on in situ prepared TiO2 ultrafine particles has been investigated. The cyclohexane was photo-oxidized on the TiO2 ultrafine particles to form cyclohexanone and cyclohexanol under air-saturated conditions. In the absence of O-2, H-2 was generated via reduction of water in the micellar waterpools. CO was also generated in the absence of O-2 probably via a photocatalytic side reaction of I-butanol which was added as a solvent of the precursor of TiO2 (titanium tetrabutoxide: TTB) to prepare the particles, 1-butoxyl groups of TTB or l-butanol formed via hydrolysis of TTB. The molar ratio of water to TTB, W-t (=[H2O]/[TTB]) was a major factor in controlling the photocatalytic reaction behavior of the system. When the irradiation was carried out under air-saturated conditions for 18 h, the consumption rate of O-2 increased monotonously as the value of the parameter W-t decreased, while the quantities of cyclohexanone and cyclohexanol formed decreased at W-t<10. This can be attributed to a side reaction of 1-butoxyl groups of TTB molecules which is oxidized more easily than cyclohexane. This reaction becomes prominent in the extremely low W-t range owing to incomplete hydrolysis of TTB molecules. [References: 25]