Heterogeneously Catalyzed Oxidation of Poly(Ethylene-co-Vinyl Alcohol) to Facilitate Multilayer Plastic Film Recycling.

The catalytic oxidation of poly(ethylene-co-vinyl alcohol) (EVOH) into oxygenated organic compounds such as carboxylic acids and aldehydes offers a promising approach to enhance the recyclability of multilayer plastic films. While EVOH provides oxygen barrier properties, its immiscibility with polyolefins in the melt phase limits physical recycling routes. A potentially low-cost option to increase multilayer plastic recycling is to selectively remove the more labile EVOH layer via oxidation while preserving the polyolefin content, which typically constitutes the majority of the film. In this study, we investigate the oxidation of EVOH using metal oxide catalysts under mild thermal conditions. Among catalyst candidates, CeO2 exhibited the highest activity, consistent with its low oxygen vacancy formation energy, high oxygen storage capacity, and redox-active Ce3+/Ce4+ pairs. Product analysis revealed the formation of a broad range of oxygenated compounds, including carboxylic acids, aldehydes, and ketones, demonstrating oxidative C─C bond cleavage. While EVOH conversion was limited by incomplete mixing and catalyst deactivation, the results demonstrate the potential of CeO2-catalyzed oxidation for selective removal of EVOH as a recycling approach, which is aligned with circular economy principles.