Process for the recovery of terephthalic acid and ethylene glycol from poly(ethylene terephthalate)

A process for the recovery of ethylene glycol and terephthalic acid from a resin comprised of poly(ethylene terephthalate), wherein said process is a neutral hydrolysis, the process comprising the steps:

• (a) contacting the resin with water at a temperature range of about 200.degree. C. to 280.degree. C. in a reaction vessel at the vapor pressure of water at said temperature range to form a mixture comprised of about 1 to 40 weight percent of the resin;
• (b) cooling the mixture to about 70.degree. C. to 100.degree. C., filtering the solids, washing the solids and then drying the solids at a temperature from about 25.degree. C. to 100.degree. C. to provide a solid portion comprised of terephthalic acid and a liquid portion comprised of ethylene glycol;
• (c) recovering the ethylene glycol from the liquid portion of the mixture by a two-step distillation,
• wherein in a first step of the two-step distillation the water and low boiling components are removed at about 0.1 to 6 atmospheres pressure and temperatures of about 100.degree. C. to 170.degree. C., and
• wherein in a second step of the two-step distillation high boiling species are removed at about 1 mm Hg to 10 atmospheres pressure and at a temperature range of about 50.degree. C. to 300.degree. C.;
• (d) recovering the solid terephthalic acid by heating the solid portion above its dew point with a continuous stream of water vapor at a temperature of about 310.degree. C. to 370.degree. C. and a pressure of about 0.1 atmosphere to 1.2 atmosphere to produce a vapor comprised of water and terephthalic acid;
• (e) cooling the vapor containing the terephthalic acid and the water to a temperature below the dew point of the terephthalic acid;
• and
• (f) collecting solid polymer grade terephthalic acid formed therefrom.