(385k) Upcycling Plastic Wastes to Fuels and Monomers Via Electrified Spatiotemporal Heating

Nearly 9 billion metric tons of plastic have been produced in the human history, among which approximately 2/3 have become waste that can result in long-term negative environmental and ecological impacts. With the continuing heavy demand for plastics, it is urgent to develop efficient plastic recycling and upcycling strategies to ensure a sustainable future. While thermochemical plastic upcycling can generate more useful chemicals such as fuels and monomers compared to other methods, conventional thermochemical approaches generally suffer from low product selectivity and yield, large energy consumption, heavy carbon emission, poor catalyst stability, and limited scalability. In this talk, I will first demonstrate a catalyst-free depolymerization method via the pyrolysis reaction that can convert model polyolefin and polyester plastics to their monomers with high yield (Nature 2023, 616, 488-494). This pyrolysis process is realized by electrified heating, which helps create a spatial temperature gradient as well as a temporal heating profile. The spatial temperature gradient promotes continuous melting, wicking, vaporization and reaction of the plastics, meanwhile the temporal heating profile by pulsed Joule heating can reduce unwanted side products and keep the reaction under far-from-equilibrium conditions. With this process and setup, we converted polypropylene and polyethylene terephthalate to their monomers via the pyrolysis reaction at record high yields of ~40%. In the second half of the talk, I will then discuss another approach to convert polyolefin plastic wastes to jet fuel and diesel precursors, also through electrified spatiotemporal heating. We demonstrate using structural effect to control the reaction progress which can allow us to achieve record-high yield to C8-C18 hydrocarbons without using any catalysts. Our preliminary TEA and LCA results indicate excellent economic potential and significant greenhouse gas emission reduction for the manufacturing process.