Heterogeneous-catalyzed methanolysis for efficient chemical recycling of bio-based PEF

Abstract

The promising bio-based polymer, poly(ethylene 2,5-furandicarboxylate) (PEF), is expected to be produced on a large scale worldwide to meet demands across various market segments due to its superior properties and performance, despite its end-of-life still remains challenging due to the non-(bio)degradable nature. In this work, two different heterogeneous catalysts, Amberlyst 70 and zeolite H-Y, were studied for the first time in the methanolysis of PEF. The depolymerization conditions, such as time, temperature, and catalyst loading, were optimized to maximize depolymerization of PEF, resulting in high selectivity to dimethyl 2,5-furandicarboxylate (DMFDC), as confirmed by 1H NMR and GC-MS. A complete PEF conversion and 100% DMFDC yield were achieved during a 1-hour reaction at 175°C with 5 wt% zeolite. The potential to reuse the most effective catalyst (zeolite H-Y) across multiple depolymerization cycles while maintaining its catalytic activity comparable to that of virgin zeolite was also demonstrated, enhancing process greenness as assessed by its E-Factor. Additionally, the closure of the PEF whole-value chain is confirmed by reusing the recovered monomers to produce PEF polyester with identical physical and thermal properties, as verified by 1H and 13C NMR, GPC, DSC, and TGA.