Depolymerization mechanisms and closed-loop assessment in polyester waste recycling.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39048542.
- Also identified by DOI 10.1038/s41467-024-50702-5 and PMC identifier 11269573.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Alcoholysis of poly(ethylene terephthalate) (PET) waste to produce monomers, including methanolysis to yield dimethyl terephthalate (DMT) and glycolysis to generate bis-2-hydroxyethyl terephthalate (BHET), is a promising strategy in PET waste management. Here, we introduce an efficient PET-alcoholysis approach utilizing an oxygen-vacancy (V<sub>o</sub>)-rich catalyst under air, achieving space time yield (STY) of 505.2 g<sub>DMT</sub>·g<sub>cat</sub><sup>-1</sup>·h<sup>-1</sup> and 957.1 g<sub>BHET</sub>·g<sub>cat</sub><sup>-1</sup>·h<sup>-1</sup>, these results represent 51-fold and 28-fold performance enhancements compared to reactions conducted under N<sub>2</sub>. In situ spectroscopy, in combination with density functional theory calculations, elucidates the reaction pathways of PET depolymerization. The process involves O<sub>2</sub>-assisted activation of CH<sub>3</sub>OH to form CH<sub>3</sub>OH<sup>*</sup> and OOH<sup>*</sup> species at V<sub>o</sub>-Zn<sup>2+</sup>-O-Fe<sup>3+</sup> sites, highlighting the critical role of V<sub>o</sub>-Zn<sup>2+</sup>-O-Fe<sup>3+</sup> sites in ester bond activation and C-O bond cleavage. Moreover, a life cycle assessment demonstrates the viability of our approach in closed-loop recycling, achieving 56.0% energy savings and 44.5% reduction in greenhouse-gas emissions. Notably, utilizing PET textile scrap further leads to 58.4% reduction in initial total operating costs. This research offers a sustainable solution to the challenge of PET waste accumulation.