|SC -reaction recovers pure monomers||Bookmark|
Publication :CE Date :November, 1999 file=CE-106-12 Copyright :Copyright 1999 Chemical Week Publishing, LLC Volume :106 Issue :12 Page :21 Section :CHEMENTATOR
Supercritical reaction recovers pure monomers from waste PET
Developed by Shin-Nippon Air Technologies Co. (Tokyo; 740), in cooperation with the National Institute of Materials and Chemical Research (Tsukuba), the process reacts ground PET (polyethylene terephthalate) with supercritical methanol. The reaction takes about 20 min., at about 330 degrees C and 81 bars, to obtain dimethyl terephthalate and ethylene glycol. Shin-Nippon says the yield is 95%, with 5% recycle.
Following methanolysis, the two monomers are separated and recovered by crystallization, centrifugation and distillation. The methanol is recycled. Shin-Nippon has tested the process in a 5-L autoclave and says the monomers can be used for high-purity PET production without any special cleanup.
Next, the company plans to confirm the results at a larger scale. Shin-Nippon estimates that a commercial plant will need a capacity of at least 20,000 m.t./yr to be economically viable.
Edited by Gerald Parkinson