| 摘要 |
The depolymerisation comprises (a) charging nylon-6 to a depolymerisation reactor contg. 5-50 wt.% unpolymerised catalyst; (b) melting the nylon-6 and steam superheating the obtd. melt to obtain a steam distillate; (c) sepg. caprolactam monomer from other volatiles in the distillate; (d) when conversion to caprolactam is 40-90% complete, recharging nylon-6 to the depolymerisation reactor; and (e) repeating steps (a) - (d) until a pref. amt. of nylon-6 is converted to caprolactam. The nylon-6 is pref. melted at at least 270 deg.C. The catalyst is orthophosphoric or p-toluenesulphonic acid. When orthophosphoric acid is used, the reactor is recharged with nylon-6 after 40-85% conversion to caprolactam. When p-toluenesulphonic acid is used, the reactor is recharged with nylon-6 after 70-90% conversion to caprolactam. |
