Conversion of diverse post-consumer PVC waste materials to PE dual catalytic tandem dehydrochlorination-hydrogenation

Chemical recycling of polyvinyl chloride (PVC) waste poses challenges due to its high chloride content and varied additive formulations. We present a dual catalytic system enabling full conversion of post-consumer PVC waste via tandem dehydrochlorination-hydrogenation. Using a ZnCl 2 catalyst (0.1-0.2 eq.) for dehydrochlorination and a Ru catalyst (1.0 mol%) for hydrogenation, it directly converts PVC into a lower molecular weight polyethylene (PE)-like polymer. It prevents the problematic formation of polyenes and aromatic char during thermal processing. The system tolerates common additives ( e.g. plasticisers and Pb-, Zn- and Ca/Zn-based stabilisers) and effectively dechlorinates materials with high inorganic filler content. The method can process PVC materials with a wide range of M n values (29 000-120 000 g mol −1 ). Methyl cyclohexanecarboxylate emerges as a suitable solvent for the tandem reaction, thereby producing 100% dechlorinated products with low molar mass averages ( M n ∼ 2400 g mol −1 and M w ∼ 5000 g mol −1 ) and allows additive removal. X-ray absorption spectroscopy (XAS) and a study of the reactivity of a model compound elucidate the Ru-catalyst structure and the chain splitting mechanism. This tandem process yields soluble short-chained polymer fragments, facilitating industrial processing and additive removal from chlorinated plastic waste. Chemical recycling of PVC waste materials using ZnCl 2 as a benign catalyst for solvent-based tandem dehydrochlorination-hydrogenation.