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

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.