Catalyst and process for the synthesis of hexamethylenediamine via catalytic amination from 6‑hydroxyhexanenitrile

ABSTRACT Hexamethylenediamine (HMDA), which is a crucial intermediate for the production of polyamides and other chemical products, was synthesized from the reductive amination of 6-hydroxycapronitrile (6-HHN) derived from ε‑caprolactone (ε‑CPL) with aqueous ammonia as the ammonia source. A bimetallic catalyst Co 10 Ru 1 /MgO-γ-Al 2 O 3(0.3:1) -500 was found to be effective in the reaction. Over this catalyst the conversion of 6-HHN reached up to 100 %, with a HMDA selectivity of 38.14 %, corresponding to a yield of 38.14 %, and the total selectivity of HMDA, 6-amino-1-hexanol (AHO) and hexamethyleneimine (HMI) of 86.92 %. Characterization results disclosed that Co and Ru uniformly disperse on the surface of the MgO-Al 2 O 3 mixed-oxide support, and respectively acts as the dehydrogenation-hydrogenation active species in the reaction with seldom agglomeration either in catalytic run or regeneration process. It was also found that some nonvolatile carbonaceous substances deposited on the surfaces of the catalyst during a catalytic run, leading to the deactivation of the catalyst. The catalysis of the catalyst could be largely recovered by high temperature calcination to remove the carbon deposits, followed by reduction with H 2 .