Continuous production of aminobenzenes by hydrogenation of nitrobenzenes over a TiO2 photocatalyst in a spiral flow reactor

Abstract

To overcome the disadvantage associated with a photocatalytic suspension reaction system, it is essential to fabricate a flow-type reactor that can eliminate the need for mixing and separation, thereby enabling continuous photocatalytic reactions. We developed a novel flow reactor that consists of a narrow and long perfluoroalkoxy alkane (PFA) tube containing small TiO₂-zircon bead composites (TiO₂-ZB). The reactor was encircled by a spiral configuration around a fluorescent lamp, facilitating the reduction of nitrobenzene (NB) to aniline (AN). The merits of this novel reactor include the capacity to accommodate a greater quantity of TiO₂, the efficacy of light supply to TiO₂, and the utilization of a long fluorescent lamp, i.e., black light, as the light source. A comprehensive investigation was conducted to determine the effects of various parameters, including zircon bead size, tube length and flow rate, on photocatalytic performance. Under optimized conditions, various nitrobenzenes having reducible groups can be reduced chemoselectively to the corresponding anilines with high yields. The results presented in this paper provide a new approach to the design of a flow-type reactor for continuous photocatalytic production.