Catalytic reductive amination of furfural to furfurylamine on robust ultra-small Ni nanoparticles

The synthesis of primary amines via reductive amination in the presence of NH₃ and H₂, as a green and sustainable process, has attracted much attention. In this paper, we prepared series of Ni/SiO₂ catalysts with deposition-precipitation and impregnation methods, and their catalytic performances on the reductive amination of a biomass derived compound of furfural to produce furfurylamine were studied. The catalytic activity and the yield were correlated to the structure and the surface properties of catalysts largely. The Ni/SiO₂ is of high Lewis acidity and small Ni particle with numerous large Ni flat step surface showed high activity and selectivity, it afforded a reaction rate of 12.8 h⁻¹ and a high yield to furfurylamine around 98%. These results are superior to the most non-noble metal catalysts reported so far. Moreover, the reaction route was examined with the unit control reactions of the intermediate. To produce furfurylamine selectively, the most suitable catalyst should have the moderate but not the highest activity in activation of hydrogen and hydrogenation in the reductive amination of furfural. This work provides some useful information for the catalytic reductive amination of aldehydes both in the design of catalyst and the reaction route.