Optimizing Olefin Production in Microwave Slurry Catalytic Pyrolysis of Low-Density Polyethylene

Pyrolysis can mitigate the accumulation of plastics in landfills and the environment. However, its high energy demand at high operating temperatures (400–800 °C) produces significant CO2 emissions. Here, we optimize a microwave slurry reactor operated at moderate temperatures (350–400 °C) to deconstruct low-density polyethylene to olefins with a selectivity of 93% and a selectivity of light olefins (C2–C4) of 43%. We demonstrate that the Brønsted and Lewis acid sites, along with the mesopore size of Al-SBA-15, influence the cracking activity, selectivity, and catalyst deactivation. Lewis acid sites promote side reactions that accelerate catalyst deactivation and should, therefore, be minimized, whereas increasing the mesopore size decreases the amount of coke at the expense of lower light olefin yield.