Current Progress in Thermochemical Conversion of Plastics into Jet-fuel Hydrocarbons and Recommendations for COVID-19 Waste Management

ABSTRACT

A vast amount of plastics are produced globally to comply with human needs. Additionally, the COVID-19 pandemic enabled an extreme rise in single-use plastic, creating an extra burden on plastic waste handling and promoting environmental pollution. Thermochemical conversion of plastic wastes into liquid hydrocarbons would be promising in this context. Numerous literature showed plastic-to-liquid hydrocarbon fuel formation;however, jet-fuel grade hydrocarbons generation from plastics is rarely assembled and hence become the focus of the current review. Reportedly, 200 – 600 °C reaction temperature, 10bar hydrogen pressure, 12 hrs retention time, and 0.13 catalyst-to-feed ratio produced jet fuel from plastics;albeit, it remained system-specific, including batch and continuous processes. Critical evaluation of several plastics to jet-fuel techniques suggested research attention in (i) complete plastic conversion into the plastic-derived oil, (ii) catalyst selection and new design enabling aliphatic/aromatics selectivity within the product mixture, (iii) mechanistic understanding of plastic to jet-fuel processes (with and without catalyst), and (iv) catalyst recyclability studies. Thermal degradation under microwave, hydrothermal liquefaction, pyrolysis, methanolysis/hydrogenation, thermal cracking/co‑hydrogenation, and aqueous phase hydrodeoxygenation are possible routes for plastic to jet-fuel conversion. Catalytic pyrolysis could be a promising for plastic/COVID-19 thermochemical conversion into jet fuel, and biomass-derived catalysts may replace the expensive metal-based catalysts.