Polymer upcycling converts plastic waste to high-value chemicals, representing a highly attractive approach to addressing the urgent environmental crisis. Existing upcycling methods are mediated by sophisticated catalysts and challenged by the low selectivity and economic value of the products, undercutting their practicality. This report reveals a highly efficient and resilient approach of degradation-upcycling (Deg-Up) to upcycling plastic wastes, by utilizing judiciously selected cascade reactions rather than complicated, sophisticated, and expensive catalysts. We find that the degradation-upcycling approach effectively upcycles polystyrene to high-value products, including diphenylmethane, benzophenone, 1,2-diphenylethane, or 4-oxo-4-phenyl-butyric acid. Techno-economic analysis shows high profitability and minor sensitivity to market fluctuation.<\/p>\n\n\n\n
Plastic waste represents one of the most urgent environmental challenges facing humankind. Upcycling has been proposed to solve the low profitability and high market sensitivity of known recycling methods. Existing upcycling methods operate under energy-intense conditions and use precious-metal catalysts, but produce low-value oligomers, monomers, and common aromatics. Herein, we report a tandem degradation-upcycling strategy to exploit high-value chemicals from polystyrene (PS) waste with high selectivity. We first degrade PS waste to aromatics using ultraviolet (UV) light and then valorize the intermediate to diphenylmethane. Low-cost AlCl3<\/sub> catalyzes both the reactions of degradation and upcycling at ambient temperatures under atmospheric pressure. The degraded intermediates can advantageously serve as solvents for processing the solid plastic wastes, forming a self-sustainable circuitry. The low-value-input and high-value-output approach is thus substantially more sustainable and economically viable than conventional thermal processes, which operate at high-temperature, high-pressure conditions and use precious-metal catalysts, but produce low-value oligomers, monomers, and common aromatics. The cascade strategy is resilient to impurities from plastic waste streams and is generalizable to other high-value chemicals (e.g., benzophenone, 1,2-diphenylethane, and 4-phenyl-4-oxo butyric acid). The upcycling to diphenylmethane was tested at 1-kg laboratory scale and attested by industrial-scale techno-economic analysis, demonstrating sustainability and economic viability without government subsidies or tax credits.<\/p>\n\n\n\n