Recoverable macroporous polyanion bead catalysts for scalable continuous chemical depolymerization of polyethylene terephthalate

초록

The glycolysis of polyethylene terephthalate (PET) offers a promising closed-loop recycling method, converting PET waste into a single monomer bis(hydroxyethyl) terephthalate (BHET). However, traditional metal-based catalysts leave hazardous residues, while alternatives are costly and energy-intensive to recover, limiting the economic feasibility of glycolysis. Herein, we present polyanion-based macroporous bead catalysts that enable efficient PET depolymerization, easy separation, and excellent reusability. These macroporous bead catalysts can be recovered through simple filtration and reused over 30 times, maintaining a BHET yield of 90.7 +/- 2.7%, and further enable continuous PET depolymerization in a continuous stirred-tank reactor (CSTR) operation with a 79.7 +/- 2.6% conversion rate for over 4 h. A techno-economic analysis (TEA) and life-cycle assessment (LCA) of the proposed process estimate a minimum selling price of $1.02/kg BHET, making it economically competitive with virgin BHET, along with a global warming impact of 1.90 kg CO2-eq/kg recycled PET-substantially lower than virgin PET production.

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