Comparative Catalytic Hydrogenation Reactions of Aliphatic Dinitriles over Raney Nickel Catalysts

Abstract

Heterogeneous catalytic hydrogenation reactions of aliphatic dinitriles are of importance for industrial diamines production. 1,6-Diaminohexane (hexamethylenediamine, HMDA) is mainly used in nylon 66 manufacture and up to 2 MT is produced yearly. Heterogeneous catalytic hydrogenation of adiponitrile is by far the most used industrial route to produce this aliphatic diamine. The dinitrile was charged in a dropping funnel, then the autoclave was closed and purged repeatedly with nitrogen first and then with hydrogen. TThe rate of the reaction was followed by measuring the hydrogen consumption in the hydrogen supply. Samples were withdrawn at regular time intervals in the course of the hydrogenation reaction and were analyzed by gas chromatography. Even if hydrogenation rate constants of aminonitriles 2 are greater than those of secondary imines, the rate of reaction is controlled by adsorption of these species at the catalyst surface.