Recycling of Polyolefins Using Recycled PVC under Sunlight

The recycling of polyolefin plastics is often hindered by high energy consumption and low economic efficiency. In particular, the recycling of poly(vinyl chloride) (PVC) is especially challenging. Here, we present an innovative protocol to recycle discarded PVC into a photothermal catalyst for the depolymerization of polyolefins under sunlight. By dechlorinating the PVC, we harness its unique ability to converts sunlight into the energy required to break C-C bonds in polyolefins. This protocol allows for the transformation of low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) into waxes enriched with terminal olefins, which can be further utilized for the synthesis of surfactant. Furthermore, this protocol enables the conversion of polystyrene, poly(methyl methacrylate), poly(α-methyl styrene), styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene (ABS) into their respective monomers. This broad applicability makes our protocol suitable for the recycling of a wide range of real-life plastic products and their mixtures under ambient environment. Notably, with the aid of just 0.1 wt% catalyst, a successful depolymerization of kilogram-scale PS waste, such as plastic cups, using solar energy has been achieved. Additionally, the catalysts derived from PVC can be reused, thereby enhancing the sustainability and cost-effectiveness of the depolymerization of polyolefins. Our study presents a promising solution to the recycling of PVC and polyolefin plastics, leveraging solar energy to create a sustainable and efficient recycling process.