Room-Temperature Upcycling of Mixed PVC and Polyolefin Waste

Polyolefins and polyvinyl chloride (PVC) stand out as the most ubiquitous plastic products.1,2 The physical separation and mechanical recycling of mixed waste face significant technical and economic challenges and is, hence, typically uncomplete.3,4 Traditional waste-to-energy methods like incineration and pyrolysis necessitate thorough PVC dechlorination to prevent the release of toxic chlorinated compounds such as dioxins and polychlorinated biphenyls.5 Moreover, PVC's flame-retardant properties hinder energy recovery efficiency,6 leading to a substantial portion of PVC ending up in landfills.7 Despite progress in chemical upcycling of PVC under mild conditions, effective dechlorination still demands temperatures ranging from 200 to 250 °C and a two-stage approach to prevent chlorine-derived compounds from deactivating metal active sites.8,9 We present here a strategy for upgrading discarded PVC into liquid iso-alkanes and HCl at room temperature in a single-stage process, catalyzed by (the cost-effective) anhydrous aluminum chloride (AlCl3) and AlCl3-based chloroaluminate ionic liquids. This approach effectively integrates the endothermic dechlorination and C-C bond cleavage with the exothermic alkylation of light isoparaffins (isobutane/isopentane) as co-reagent into a tandem process that ensures kinetic and thermodynamic efficiency. The iso-alkanes are available via refinery processes10 and can be partly recycled from the product stream. This approach presents a novel and cost-effective route to jointly upcycle PVC and isoparaffins, conserving the carbon atoms in both compounds in the final chlorine free isoalkanes. It is also applicable to real-world mixed and contaminated PVC and polyolefin waste streams, offering a superior option for decentralized conversion compatible with existing refinery infrastructure.