Recovery of Arenes from Polyethylene Terephthalate (PET) over a Co/TiO₂ Catalyst

Abstract

Upcycling of spent plastics has become a more emergent topic than ever before due to the rapid generation of plastic waste associated with the change of lifestyles of the human society. Polyethylene terephthalate (PET) is a major aromatic plastic and herein, the conversion of PET back into arenes was demonstrated in a one-pot reaction combining depolymerization and hydrodeoxygenation (HDO) over a Co/TiO 2 catalyst. The effectiveness of the Co/TiO 2 catalyst in HDO and the underlining reaction pathway were established using the PET monomer terephthalic acid (TPA) as the substrate. Quantitative TPA conversion together with 75.2 mol% xylene and toluene selectivity under 30 bar initial H 2 pressure at 340°C was achieved after 4 h reaction. More encouragingly, the catalyst induced both depolymerization and HDO reaction via CÀ O bond cleavage when PET was used as a substrate. 78.9 mol% arenes (toluene and xylene) was obtained under optimized conditions.

Converting waste PET plastics into automobile fuels and antifreeze components

“…However, the use of Ru increased the cost of the catalyst, and these catalytic systems led to an arene mixture product with a low selectivity to PX. Similarly, Yan et al 14 demonstrated the conversion of PET into 70% yield of arenes in octane over a Co/TiO 2 catalyst at 340 °C and 3 MPa H 2 . Li and Zhang et al 15 converted PET to C 7 –C 8 cycloalkanes and aromatics by a three-step reaction.…”

Converting waste PET plastics into automobile fuel and antifreeze components

“…However, the use of Ru as the metal active center increased the cost of the catalyst, resulting in a complex mixture of products. Similarly, Yan et al 14 demonstrated the conversion of PET into arenes via depolymerization and hydrodeoxygenation over a Co/TiO 2 catalyst with 75.2 mol% p-xylene and toluene selectivity under 30 bar initial H 2 pressure at 340 °C. Tang et al 15 selectively synthesized gasoline and jet fuel range C 7 -C 8 cycloalkanes and aromatics by a three-step reaction.…”

Enabling the Circular Economy through Chemical Recycling and Upcycling of End-of-Use Plastics

“…For the hydroconversion of waste plastics, both the Pt group (Ru, Rh, Pd, Os, Ir, and Pt) and earth-abundant (Fe, Co, Ni, and Cu) metals have been used. 5,[21][22][23][24] Among these catalysts, Pt, Zr, and Ru were found to be the most effective. Ab initio density functional theory (DFT) calculations have reported these metals to have smaller energy barriers in model alkane C-C bond cleavage.…”