Upcycling Single-Use Polyethylene into High-Quality Liquid Products.

Our civilization relies on synthetic polymers for all aspects of modern life; yet, inefficient recycling and extremely slow environmental degradation of plastics are causing increasing concern about their widespread use. After a single use, many of these materials are currently treated as waste, underutilizing their inherent chemical and energy value. In this study, energy-rich polyethylene (PE) macromolecules are catalytically transformed into value-added products by hydrogenolysis using well-dispersed Pt nanoparticles (NPs) supported on SrTiO ₃ perovskite nanocuboids by atomic layer deposition. Pt/SrTiO ₃ completely converts PE ( M _n = 8000-158,000 Da) or a single-use plastic bag ( M _n = 31,000 Da) into high-quality liquid products, such as lubricants and waxes, characterized by a narrow distribution of oligomeric chains, at 170 psi H ₂ and 300 °C under solvent-free conditions for reaction durations up to 96 h. The binding of PE onto the catalyst surface contributes to the number averaged molecular weight ( M _n ) and the narrow polydispersity ( Đ ) of the final liquid product. Solid-state nuclear magnetic resonance of ¹³ C-enriched PE adsorption studies and density functional theory computations suggest that PE adsorption is more favorable on Pt sites than that on the SrTiO ₃ support. Smaller Pt NPs with higher concentrations of undercoordinated Pt sites over-hydrogenolyzed PE to undesired light hydrocarbons.
Competing Interests: The authors declare the following competing financial interest(s): Two patent applications partially based on this work have been filed (US Patent Applications 62/796,482 and 62/892,347).
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