Hydrotalcite-Supported Cobalt Phosphide Nanorods as a Highly Active and Reusable Heterogeneous Catalyst for Ammonia-Free Selective Hydrogenation of Nitriles to Primary Amines

Traditional non-noble-metal catalysts for the hydrogenation of carboxylic acid derivatives have suffered from air instability and inadequate activity, requiring delicate catalyst handling and harsh reaction conditions. Thus, the development of non-noble-metal-based catalysts with both air stability and high activity has recently received much attention. We herein report hydrotalcite-supported cobalt phosphide nanorods (Co2P NR/HT) acting as an air-stable, active, and reusable non-noble-metalbased heterogeneous catalyst for the selective hydrogenation of nitriles to the corresponding primary amines. Co2P NR/HT exhibits a broad substrate generality, including sulfur-containing nitriles as well as aromatic, heteroaromatic, aliphatic, and dinitriles, under mild conditions, typically merely 1 bar of H-2 atmosphere. Moreover, the high activity of Co2P NR/HT enabled nitrile hydrogenation under ammonia-free conditions, affording primary amines in high yields. The used Co2P NR/HT catalyst was recoverable and reusable without any significant loss in activity or selectivity, thus demonstrating the high performance of the Co2P NR/HT catalyst. Density functional theory (DFT) calculation results indicate that Co2P NR activates a nitrile at the surface through the back donation of d-electrons in Co2P NR to C.N moiety, facilitating the nitrile hydrogenation to the primary amine.

Automated summary

An air-stable, active, and reusable non-noble-metal-based heterogeneous catalyst, hydrotalcite-supported cobalt phosphide nanorods (Co2P NR/HT), has been developed for the selective hydrogenation of nitriles to primary amines. The catalyst shows broad substrate generality and high activity under mild conditions, enabling nitrile hydrogenation with high yields without the need for ammonia.