IMPROVED METHOD FOR PRODUCING HEXAMETHYLENE DIAMINE

摘要

The invention relates to a method for the catalytic hydrogenation of adipodinitrile to hexamethylene diamine at a high temperature and at high pressure in the presence of catalysts based on elementary iron as the catalytic component, and ammonia as a solvent. The method is characterised i n that a) adipodinitrile is hydrogenated at temperatures of 70 to 220 ~C and a t pressures of 100 to 400 bar in the presence of catalysts based on elementary iron as the catalytic component, and ammonia as a solvent to produce a mixtu re containing adipodinitrile, 6-aminocapronitrile, hexamethylene diamine and hi gh boilers, until the sum of the 6-aminocapronitrile and adipodinitrile concentration is 1 to 50 wt. % in relation to the ammonia-free hydrogenation mixture; b) ammonia is separated out of the hydrogenation discharge; c) hexamethylene diamine is separated out of the remaining mixture; d) 6- aminocapronitrile and adipodinitrile are separated from the high boilers together or separately and e) 6-aminocapronitrile, adipodinitrile or their mixtures are returned to step a).