Low-temperature upcycling of PET waste into high-purity H2 fuel in a one-pot hydrothermal system with in situ CO2 capture.

Abstract

The accumulation and improper disposal of a large amount of plastic waste have exacerbated the deterioration of the global ecosystem and environment. To simplify the complex management system and alleviate the environmental impact of plastic wastes, this study reports a novel one-pot hydrothermal conversion strategy for polyethylene terephthalate (PET), integrating three steps, namely depolymerization, subsequent in-situ aqueous phase reforming, and in-situ CO2 capture. Here, the PET waste was converted directly into the clean high-purity H2 fuel and the disodium terephthalate (Na2-TPA). A high yield of H2 at 23.7mol/kgPET with ca. 99 % of H2 concentration was obtained at a temperature as low as 240°C. The feasibility of this strategy in handling real-world PET plastic wastes was demonstrated through a series of tests on beverage bottles, food packaging, and polyester fabric waste. The Na2-TPA crystals produced from the proposed PET conversion system exhibited purity close to that of the standard sample, and thus had the potential to be directly used as an electrode material. Overall, this strategy provides an efficient way to transform PET waste into high-value products and improves the sustainability of the PET waste disposal process.