Development of Chemical Recycling Process for Post-Consumer PET Bottles by Methanolysis in Supercritical Methanol

摘要

In recent years, Chemical Recycling from PET Bottle to PET Bottle (B to B) by depolymerizing polyethylene terephthalate (PET) to yield monomers as its raw materials, has been gaining greater interest as ideal means of recycling. Mitsubishi heavy industries LTD (MHI) has been developing "Chemical Recycling Process for Post-Consumer PET Bottles by Methanolysis in Supercritical Methanol". Based on results of the fundamental study and laboratory test, we have constructed the Bench Test Plant. This plant consists of Depolymerization in Supercritical Methanol section with a continuous reactor and Monomer purification section. We have operated this plant stably for roughly total 400 hours, We recovered diethyl terephthalate (DMT) and ethylene glycol (EG) as monomer from Post-Consumer PET Bottles in this Plant. The qualities of those recycled monomers that were produced in the laboratory test were equivalent to those of virgin monomers that are produced from petroleum. The recycled DMT produced on laboratory test was converted into pure terephthalic acid (PTA) by Hydrolysis with batch type reactor. The purity of this recycled PTA was equivalent to that of virgin PTA. The results suggested that our process would make The Bottle-to-Bottle Chemical Recycling Process to come in practical. Further, the results of our feasibility studies have also shown that our PET recycling process could be economically feasible.