(160h) MEG Reclamation in the Chemical Recycling of PET Plastics

Polyethylene terephthalate (PET) is abundantly used in beverage and food packaging and textiles (in the form of polyester). The two building blocks of PET are terephthalic acid (TA) and monoethylene glycol (MEG), both of which are produced from fossil fuel feedstock.

Recently, several advanced chemical recycling technologies have been developed that depolymerize post-consumer PET plastic into its building blocks and use them to remake virgin-quality PET plastic without the need for fresh, new fossil fuel resources. In such multistage depolymerization processes, enzymes and/or chemicals are introduced that break down the PET and form a mixture of TA, MEG, water, and dissolved salts, each of which requires separation and purification before remaking PET. TA, which is precipitated and separated upstream of this entire separation process, is not the focus of this work. The last stage of the process, however, is a stream of MEG, water, and dissolved salts. It is in this stage where MEG reclamation technology, which has been successfully used in the oil and gas industry, can be successfully applied to recover high-purity MEG content.

Here, we focus on this last stage and present the results from experimental tests that were successfully conducted for several feeds containing varying compositions of MEG, water, dissolved salts, contaminants, and dyes, confirming the viability and suitability of flash vaporization and crystallization technology for this growing industry.