Issue 9, 2025

Methanolysis of polyethylene terephthalate (PET) using non-stoichiometric protic ionic liquids

Abstract

Methanolysis of polyethylene terephthalate (PET) to dimethyl terephthalate (DMT), carried out in a microwave reactor, was catalysed by an inexpensive and recyclable non-stoichiometric protic ionic liquid, formulated from sulfuric acid and triethylamine. The influence of the catalyst composition (excess of acid or base), reaction temperature and time, as well as methanol excess, on the conversion of PET and the yield of DMT, was investigated. Under optimised conditions (3 h, 180 °C), waste PET from milled plastic bottles was depolymerised, reaching 100% PET conversion and 98% isolated yield of DMT. Pure DMT was separated through recrystallisation directly from the reaction mixture. Preliminary experiments with carpet waste (dyed mixed polymer waste, without milling) gave results on par with those achieved for PET bottles, with 100% PET conversion and 97% of DMT (isolated yield).

Graphical abstract: Methanolysis of polyethylene terephthalate (PET) using non-stoichiometric protic ionic liquids

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Article information

Article type
Paper
Submitted
01 May 2025
Accepted
28 Jul 2025
First published
31 Jul 2025
This article is Open Access
Creative Commons BY license

RSC Sustainability, 2025,3, 3987-3996

Methanolysis of polyethylene terephthalate (PET) using non-stoichiometric protic ionic liquids

E. McCrea, P. Goodrich, J. D. Holbrey and M. Swadźba-Kwaśny, RSC Sustainability, 2025, 3, 3987 DOI: 10.1039/D5SU00316D

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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