Cleaner production of aviation oil from microwave-assisted pyrolysis of plastic wastes

Large amounts of plastic wastes are generated due to the wide applications. Microwave-assisted pyrolysis for the production of aviation oil is a cleaner method to achieve the recycle of plastic waste. The study focuses on microwave-assisted pyrolysis of five kinds of plastic wastes (polypropylene, polystyrene, high-density polyethylene, low-density polyethylene, and polycarbonate) for cleaner aviation oil production. In this study, the heating performance, product yield, product component, and pyrolysis mechanism of five kinds of plastic wastes through performing microwave-assisted pyrolysis were systematically explored and visually compared, so as to highlight the advantages and disadvantages about the conversion of different kinds of plastic wastes into aviation oil. It was concluded that polystyrene showed the lowest average heating rates of 60 °C/min and highest aviation oil yield of 98.78 wt% among the five plastic wastes, and the highest aviation oil yield was occurred at the microwave power of 650 W, microwave absorbent load of 60 g, and pyrolysis temperature of 460 °C. Polypropylene, high-density polyethylene, and low-density polyethylene preferred to aliphatic hydrocarbons (99.33 area%, 98.45 area%, and 100 area%, respectively) mainly through random chain scission, recombination, and addition. Polystyrene preferred to aromatic hydrocarbons (73.39 area%) through β-scission, random chain scission, and intermolecular hydrogen transfer, whereas polycarbonate preferred to phenols (87.73 area%) mainly through decarboxylation and dihydroxylation. The majority of C8-16 hydrocarbons in aviation oil from polypropylene, polystyrene, high-density polyethylene, and low-density polyethylene were 91.02 area%, 64.79 area%, 77.52 area%, and 59.73 area%, respectively. Microwave-assisted pyrolysis of plastic waste can not only effectively solve the environmental problem, but also contribute to value-added products, showing a very good cleaner production method.