| abstract |
Disclosed is a method for hydrogenating a dinitrile, such as adiponitrile, in the presence of ammonia to form a diamine, such as hexamethylenediamine. Also disclosed is a method for preparing a catalyst for this hydrogenation reaction by reducing iron oxide with hydrogen. Anhydrous ammonia is separated from a liquid mixture of ammonia and diamine in three distillation steps. The pressure of the liquid is reduced from, for example, 500 psig (3,549 kPa) to, for example, 2 psig (115 kPa), over the course of these three distillation steps. The anhydrous ammonia, which is separated from liquid mixture of ammonia and diamine is recovered and may be recycled to the hydrogenation reaction. |