Highly Selective Hydrogenation of Halogenated Nitroarenes over Ru/CN Nanocomposites by in situ Pyrolysis Route

A highly chemoselective and recyclable ruthenium catalyst for the hydrogenation of halogenated nitroarenes has been prepared by a simple in situ calcination of mixed melamine, glucose and ruthenium trichloride. The superfine Ru particles (2.3 ± 0.3 nm) were obtained and highly dispersed in the nitrogen-doped carbon matrix. The Ru/CN catalyst could smoothly transform a variety of halogenated nitroarenes to the corresponding haloanilines with high intrinsic activity (e.g. TOF = 1333 h–1 for p-chloronitrobenzene) and selectivity of more than 99.6%. Furthermore, through the analysis of the products in the reaction process, it was concluded that there were two parallel reaction pathways (direct pathway and indirect pathway) for the hydrogenation of aromatic nitro compounds over the Ru/CN catalyst, and the direct pathway was proved to be dominated by catalyzing the intermediates.