Upcycling of polyvinyl chloride to hydrocarbon waxes via dechlorination and catalytic hydrogenation

Abstract

Converting polymer waste to marketable products is a promising method to incentivize the development of competitive waste upcycling processes. Polyvinyl chloride (PVC) waste streams pose a unique challenge in this regard because of the presence of Cl atoms in the molecule. To address this issue, we report here a method to upcycle PVC plastics and produce a polyethylene wax in a mixed amine-water system, using hydrogen and a heterogeneous catalyst. We demonstrate that alkylamines as homogeneous catalysts and as Cl- sequestration media successfully dechlorinate PVC to a polyene, which is hydrogenated over a Pt/C heterogeneous catalyst. At optimal conditions, hydrocarbon wax yields greater than 70 % with melt temperatures above 80 °C were achieved. We use X-ray tomography to illustrate the PVC dissolution and reaction and quantify the product by differential scanning calorimetry (DSC). Characterization of the product reveals complete dechlorination and hydrogenation, as well as partial C-C bond scission, indicating a product similar to polyolefin adhesive waxes.