The Liguid-Phase Hydrogenation of Isophthalonitrile over Nickel Catalysts

Abstract

The kinetics of liquid-phase hydrogenation of isophthalonitrile in methanol-ammonia (1:1) in the presence of a reduced nickel catalyst and a Raney nickel catalyst were studied at temperatures ranging from 90 to 110°C.In the presence of a reduced nickel catalyst, the reactions proceeded in a stepwise manner, m-cyanobenzylamine being the intermediate. Under given conditions, the absorption rate of hydrogen was first order in catalyst concentration and agreed with the Langmuir-type rate equation for the partial pressure of hydrogen. At a partial pressure of hydrogen above 70 kg/cm2, the absorption rate was not affected by the partial pressure. The effects of isophthalonitrile concentration also agreed with the Langmuir-type rate equations. The adsorption of isophthalonitrile and m-cyanobenzylamine was relatively strong and their adsorption equilibrium constants almost comparable with each other. The specific rate constant for isophthalonitrile was almost three times as much as that for m-cyanobenzylamine. The activation energy for the reaction was calculated to be 12.8 kcal/mol.Similar reaction mechanisms can also be applied for the hydrogenation in the presence of a Raney nickel catalyst.