Conversion of Polystyrene Plastic into Aviation Fuel through Microwave-Assisted Pyrolysis as Affected by Iron-Based Microwave Absorbents

As recycling plastics through microwave-assisted pyrolysis becomes gradually popular, the selection of microwave absorbents is therefore of great importance because plastics generally have low microwave absorption capacities, and microwave absorbents are then required to improve the heating and pyrolysis processes. In this study, conversion of polystyrene plastic into aviation fuel through microwave-assisted pyrolysis as affected by iron-based microwave absorbents (Fe, Fe₃O₄, and FeS₂) was studied and reported for the first time. The heating performance, product yields, oil higher heating values, and aviation oil compositions with different microwave absorbents, microwave powers, and microwave absorbent loads were detailed. The results showed that Fe₃O₄ exhibited the highest average heating rate of 119.23 °C/min, and Fe had good selectivity for cycloalkenes, while FeS₂ had good selectivity for olefins. The highest oil yield (97.67 wt %) was obtained at a pyrolysis temperature of 460 °C, microwave power of 650 W, and Fe load of 90 g, and the oil compositions were mainly monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, olefins, and cycloalkenes with abundant C8-C16 hydrocarbons of 52.041-77.880 area%. The results indicated that polystyrene can be well converted into aviation fuel through microwave-assisted pyrolysis by screening the iron-based microwave absorbents.