Liquid phase hydrogenation of adiponitrile over directly reduced Ni/SiO2 catalyst

• A highly dispersed Ni/SiO2 was used to catalyze the hydrogenation of adiponitrile.
• The mechanism of side reactions was investigated.
• An excellent primary amine selectivity as well as catalytic activity was achieved.

Liquid phase hydrogenation of adiponitrile (ADN) to 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) was investigated on Ni/SiO2 catalysts prepared under different conditions. In this reaction, the highly reactive imine intermediate forms condensation byproducts by reacting with the primary amine products (ACN and HMD). A highly dispersed Ni/SiO2 catalyst prepared by the direct reduction of Ni(NO3)2/SiO2 was found to suppress the condensation reactions by promoting the hydrogenation of adsorbed imine, and it gave excellent hydrogenation activity and primary amine selectivity. Addition of NaOH increased the primary amine selectivity to 79% at the ADN conversion of 86%.

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