Ultrafine Ru nanoparticles integrated on ordered mesoporous carbon for solvent-free hydrogenation of nitroarenes

Abstract

The hydrogenation of nitroarenes to aromatic amines with H₂ under solvent-free conditions in place of organic solvents is a crucial process for the synthesis of fine chemicals. However, the catalysts that have been identified so far are relatively inactive with primary nitroarenes under solvent-free conditions. Herein, ordered mesoporous carbon (OMC)-supported highly dispersed Ru nanoparticles (Ru NPs) were easily prepared by using a coordination-assisted solvent evaporation induced co-assembly method, where 8-hydroxyquinoline exerts a significant influence on the mesostructure ordering and specific surface area of the Ru/OMC composites. The ultrasmall-sized Ru NPs (∼2.0 nm) supported on ordered mesoporous carbon were then applied in the hydrogenation of nitroarenes, exhibiting high activity and selectivity for numerous structurally diverse nitroarenes under solvent-free conditions. Compared with Ru/OMC-imp and Ru/AC-imp, Ru/OMC-800 exhibited a much higher activity and selectivity for hydrogenation of nitroarenes, suggesting its overwhelmingly better performance than OMC or AC supporting noble NPs by simple impregnation method. The strong metal–support interaction is capable of stabilizing the Ru NPs and achieving good recyclability as well as high selectivity.