Transforming polystyrene wastes to aromatic products near ambient temperature with aluminium chloride

Abstract

Against global resource scarcity and environmental crises, recycling large quantities of discarded polyolefin waste presents an urgent challenge for humanity. However, the thermal degradation of polyolefin, which typically requires high temperatures to cleave the carbon-carbon (C–C) bonds, has been hindered by energy limitations. We present a simple approach that uses inexpensive AlCl3 and dichloromethane to convert the polystyrene into aromatics at 40 °C within 3 hours, achieving a polystyrene conversion of over 70 wt.%. The Lewis acid catalysts interact with benzene under acidic conditions, promoting the elimination of the C-C backbone to generate carbocations, which subsequently undergo β-scission. The dissolution of polystyrene in dichloromethane increases the reaction interface, thereby enhancing the reaction rate. This study provides a cost-effective approach for the high-value utilization of aromatic rings in polystyrene.