Solvent-free selective photocatalytic oxidation of benzyl alcohol over modified TiO2

Abstract

Heterogeneous photocatalysis offers a promising route to realize green oxidation processes in organic synthesis. In this research, the solvent-free selective photocatalytic oxidation of benzyl alcohol to benzaldehyde in the presence molecular oxygen was studied by using TiO₂ and modified TiO₂ as photocatalysts. The surface modification of TiO₂ by transition metal clusters dramatically enhanced the photocatalytic oxidation activity. Ir/TiO₂ prepared by photodeposition showed a remarkably high activity for the photocatalytic oxidation of benzyl alcohol, and an average reaction rate of 14538 μmol h⁻¹ g_cat⁻¹ could be obtained. The effect of preparation method, iridium loading and reaction conditions on the catalytic performance of Ir/TiO₂ is investigated in detail. Based on the catalytic and characterization results, the problem of product selectivity and the reaction mechanism of the photocatalytic oxidation of benzyl alcohol over Ir/TiO₂ are discussed.