Low-Temperature Upcycling of Polypropylene Waste into H2 Fuel via a Novel Tandem Hydrothermal Process

Graphical Selective upcycling of polyolefin waste into H 2 fuel has been limited by the relatively high temperatures. Here, we report a novel tandem hydrothermal oxidation and reforming strategy that can convert polypropylene waste into H 2 in high yield at low temperature. The entire process operated in a mild and clean way with almost no solid residue remaining and equipment contamination. Plastic waste is a promising and abundant resource for H 2 production. However, upcycling plastic waste into H 2 fuel via conventional thermochemical routes requires relatively considerable energy input and severe reaction conditions, particularly for polyolefin waste. Here, we report a tandem strategy for the selective upcycling of polypropylene (PP) waste into H 2 fuel in a mild and clean manner. PP waste was first oxidized into small-molecule organic acids using pure O 2 as oxidant at 190 °C, followed by the catalytic reforming of oxidation aqueous products over ZnO-modified Ru/NiAl 2 O 4 catalysts to produce H 2 at 300 °C. A high H 2 yield of 44.5 mol/kg PP and a H 2 mole fraction of 60.5 % were obtained from this tandem process. The entire process operated with almost no solid residue remaining and equipment contamination, ensuring relative stability and cleanliness of the reaction system. This strategy provides a new route for low-temperature transforming PP and improving the sustainability of plastic waste disposal processes.