Process for converting pet scrap to diamine monomers.

摘要

Scrap poly(ethyleneterephthalate) is converted to useful amine and diamine monomers such as para-xylylenediamine, 1,4-bis(aminomethyl)cyclohexane and 4-aminomethyl benzoic acid for the production of various polyamides. The conversion of poly(ethyleneterephthalate) to diamine monomers is achieved by a three step process involving (a) ammonolysis of the poly(ethyleneterephthalate) to produce terephthalamide and ethylene glycol; (b) pyrolytic dehydration of the terephthalamide to produce terephthalonitrile; and (c) hydrogenation of the terephthalonitrile to produce the para-xylylene diamine and/or 1,4-bis(aminomethyl)cyclohexane. The conversion of poly(ethyleneterephthalate) to 4-aminomethyl benzoic acid involves the steps of (a) ammonolysis of the poly(ethyleneterephthalate) to produce terephthalamide; (b) partial pyrolytic dehydration of said terephthalamide to produce 4-cyanobenzoic acid; and (c) hydrogenation of said 4-cyanobenzoic acid to produce 4-aminomethylbenzoic acid. The process of the present invention permits the conversion of low value PET scrap such as beverage bottles, fibers and film to relatively high value and relatively pure diamine monomers and ethylene glycol.