Process for the purification of caprolactam obtained from the depolymerization of polyamide-containing carpet

Abstract

The present invention provides a process for the preparation of purified caprolactam comprising the steps of: (a) depolymerizing polyamide-containing carpet in the presence of steam to obtain crude caprolactam and steam; (b) condensing or distilling said crude caprolactam and steam to form aqueous crude caprolactam comprising at least ten percent by weight water; (c) removing substantially all floating oil from the aqueous crude caprolactam so as to form a substantially floating oil-free aqueous crude caprolactam; (d) removing substantially all of said water from said substantially floating oil-free aqueous crude caprolactam; (e) distilling the resulting concentrated crude caprolactam at a pressure of less than about 8 mmHg and a temperature from about 110° C. to about 145° C. so as to form overheads and bottoms of the caprolactam; and (f) crystallizing the caprolactam overheads to obtain caprolactam crystals and mother liquor. The resulting purified caprolactam may then be used to make polycaprolactam which may then be used in engineered materials or spun into fiber.

Dependencies are inferred from the claim text.