Highly efficient non-noble metallic NiCu nanoalloy catalysts for hydrogenation of nitroarenes

Highly dispersed NiCu alloy nanoparticles supported on carbon-doped silica (NiCu/C@SiO2) were first prepared through one-step impregnation with a mixed solution of nickel nitrate, cupric nitrate and glucose, followed by in situ carbothermal reduction. The addition of Cu to the NiCu/C@SiO2 materials not only improved the dispersion of metallic Ni particles, but also significantly enhanced the anti-oxidation ability of the catalyst. The effects of catalyst calcination temperatures and Cu element on the catalytic properties of the NiCu/C@SiO2 materials were investigated for nitrobenzene hydrogenation as a model reaction. The results indicated that the NiCu/C@SiO2-800 catalyst carbonized at 800 °C exhibited the highest activity for the hydrogenation of nitrobenzene with a turnover frequency (TOF) of as high as 46.5 s−1, and the superior catalytic activity of NiCu/C@SiO2 to Ni/C@SiO2 could be attributed to both the smaller Ni particles and the higher TOFs of metallic Ni due to the electronic interaction between the Ni and Cu atoms. The NiCu/C@SiO2-800 catalyst could be recycled at least 10 times without noticeable loss of catalytic performance in the hydrogenation of nitrobenzene, exhibiting better stability compared with the Ni/C@SiO2-800 catalyst. Moreover, the NiCu/C@SiO2-800 catalyst could smoothly transform various substituted nitro aromatics to the corresponding aromatic amines with high selectivities.