Selective Upcycling of Aromatic Polymer Waste into Light C₆C₉ Aromatics Over Ru-Supported Catalysts

The valorization of plastic waste and biomass has gained significant attention in the twenty first century. Despite structural similarities and the potential to yield similar products, an integrated approach to converting both feedstocks using the same catalyst has not been realized. This study demonstrates the catalytic upcycling of plastic waste and lignin biomass into selective C₆C₉ aromatics through CO and/or CC bond cleavage using Ru-supported catalysts. The Ru/TiO₂ exhibits remarkable performance, achieving 75%-90% yield from single, mixed plastic polymers and lignin. The exceptional activity of Ru/TiO₂ stems from its unique structural and electronic properties. H₂ spillover at the Ru-TiO₂ interface transfers in the form of H⁺/e^-, where the e^- reduces TiO₂ to TiO_x, generating surface oxygen vacancies and inducing strong metal support interactions, while H⁺ migrates to the adjacent oxygen sites, forming new Brønsted acid sites. Oxygen vacancies at TiO_x sites promote the activation and cleavage of CO bonds, while Brønsted acid sites assist in the cleavage of CC bonds. Additionally, ultrasmall, highly dispersed Ru suppresses the hydrogenation of aromatics. These synergistic properties enable Ru/TiO₂ to selectively produce aromatics, offering a promising strategy for catalytic upcycling of aromatic polymer waste into sustainable chemicals, aligning with the circular economy.