Product regulation mechanism in Joule flash pyrolysis of polyethylene for low carbon olefins and carbon nanospheres

Conventional pyrolysis of polyethylene (PE) yields low-value, hard-to-separate mixed components. To produce usable products, flash Joule heating (FJH) was employed to selectively convert PE into low-carbon olefins, with carbon nanospheres as a byproduct. In this process, molten PE was evenly spread on a graphite boat and heated to 1250°C, selectively producing low-carbon olefins (C 2 -C 4 ) with a selectivity of 72.05%. We examined the effects of chain length, branching structure, and the number of double bonds on reaction pathways and product distribution using three long-chain olefin model compounds (terminal olefin, internal olefin, and polyene hydrocarbon) as well as various polyolefins and their mixtures. We also studied the impact of rapid heating/cooling and peak temperature variations on product regulation. These insights provide a theoretical foundation for the highly selective production of low-carbon olefins and co-production of carbon materials from waste polyolefin plastics.