(385am) Continuous Catalytic Upcycling of Multilayered Plastic Packaging in a Biphasic System

Multilayered plastic packaging films often contain materials such as blends of polyethylene (PE) with oxygen barrier polymers such as poly(vinyl alcohol-co-ethylene) (EVOH). These materials when layered provide excellent barrier performance as well as stability, leading to their wide application in food and pharmaceutical industries. However, its barrier performance and the inherent immisciblity of the two polymers makes recycling challenging, resulting in waste in landfills. Melting or mechanical recycling produces low value of mixed plastics, while chemical reactions in single solvents are often unfavorable due to solubility issues with the various phases. In this work, we use a γ-Valerolactone – Decalin biphasic solvent system that allows the Pd supported on TiO₂ nanotubes to selectively deoxygenate polar layers without cracking the hydrocarbon backbone in one phase while isolating the nonpolar products in another phase. We show how the active metal-support interface selectively cleaves C-O bonds to convert waste EVOH impurities in multicomponent films into a compatible PE stream. Further, the GVL solvent remains in the same reaction mixture allowing for continuous separation and removal of the pure resulting polyolefin stream. The biphasic solvent system shows significant potential for selective upgrading and separation of complex plastic waste streams in a single pot. Conversion levels achieved in a biphasic system are far superior to those observed in a monophasic solvent system due to challenges associated with dissolving multilayered plastic packaging, prolonging reactions, and separating products in the latter. Furthermore, the reaction kinetics over the catalysts were studied supporting further studies. Through deoxygenation and continuous removal of products through in a single reaction vessel, this work addresses one of the important limitations of multilayered plastic packaging conversion.