Reversal Effect of Phosphorus on Catalytic Performances of Supported Nickel Catalysts in Reductive Amination of 1,6-Hexanediol

Abstract

The reductive amination of 1,6-hexanediol with ammonia is one of the most promising green routes for synthesis of 1,6-hexanediamine. Herein, we developed a phosphorous modified Ni catalyst of Ni-P/Al₂O₃. It presented satisfactory improved selectivity to 1,6-hexanediamine in the reductive amination of 1,6-hexanediol compared to the Ni/Al₂O₃ catalyst. The phosphorous tended to interact with Al₂O₃ to form AlPO_x species, induced Ni nanoparticle to be flatter, and the decrease of strong acid sites, the new-formed Ni-AlPO_x-Al₂O₃ interface and the flatter Ni nanoparticle were the key to switch the dominating product from hexamethyleneimine to 1,6-hexanediamine. This work develops an efficient catalyst for production of 1,6-hexanediamine from the reductive amination of 1,6-hexanediol, and provides a point of view about designing selective non-noble metal catalysts for producing primary diamines via reductive amination of diols.

Keywords: 1,6-hexamethylenediamine; 1,6-hexanediol; Ni/Al2O3; reductive amination; triphenylphosphine.