Tandem Catalysis to Mitigate Coke Formation in the Upcycling of Mixed Polyolefin Wastes.

Postconsumer plastic waste is commonly made up of various types of polymers, and the compositional heterogeneity complicates their recycling. A notable example is polyethylene/ethylene vinyl acetate (PE/EVA) blends, which are widely used as multilayer packaging materials, films, and cable coatings. Chemical recycling of PE/EVA blends often yields low-value short-chain alkanes, especially methane, and suffers from coke formation. Here, we demonstrate a tandem hydrodeoxygenation-hydrogenolysis process for the valorization of PE/EVA waste into long-chain hydrocarbons using Ru-MoOx/CeO2. Mechanistic investigations reveal that the introduction of MoOx into the Ru catalyst facilitates the hydrodeoxygenation of the acetate group in EVA, thereby abating coke formation, while Ru subsequently catalyzes the hydrogenolysis of the carbon backbone. The system achieves near-complete conversion for mixed PE/EVA, yielding over 65% fuels and waxes with an exceptional high specific activity of 782 gPE/EVA gRu-1 h-1. Moreover, Ru-MoOx/CeO2 displays high efficiencies across various PE/EVA products and over a wide range of hydrogen pressures (0.5-2.0 MPa). This versatility underscores the potential of this tandem process for the upcycling of mixed polyolefin wastes.