Process for making nylon 6,6

A continuous process for the manufacture of nylon 6,6 from adiponitrile (AND) comprising the steps of:

• a) providing a vertical countercurrent multistage reactor having a top and a bottom, and having upper stages and lower stages, said reactor being equipped with internal perforated barrier means for establishing a plurality of stages and for effecting contact of an AND-containing stream and a countercurrently-flowing steam stream;
• b) introducing into said reactor an AND-containing reactant stream at an AND introduction point near the top of said reactor;
• c) introducing into said reactor a steam-containing stream at least one point near the bottom of said reactor;
• d) introducing into said reactor a hexamethylenediamine-containing stream at least one point below the AND introduction point;
• e) maintaining a pressure within said reactor between 100 and 800 psig (0.69 and 5.52 MPa) and a temperature at the top of said reactor between 190 and 250 degrees C and a temperature at the bottom of said reactor between 260 and 290 degrees C;
• f) withdrawing a steam and ammonia-containing stream overhead of said reactor;
• g) recovering a nylon 6,6-containing product stream from the bottom of said reactor;
• wherein in said process the introducing of the AND-containing reactant stream and the introducing of the HMD-containing stream are adapted to provide a nylon 6,6-containing product stream in which the nylon 6,6 is characterized by balanced amine and acid ends.