Production of jet fuel from cracked fractions of waste polypropylene and polyethylene

Abstract

Because of increasing consumption and the environmental impacts, the search for alternatives to fossil-fuel-based kerosene is crucial. Plastic waste cracking and subsequent co‑hydrogenation can be a promising way to produce jet fuels. The aim of this study was to investigate the feasibility of production of standard jet fuel from mixtures of cracked fractions of polyethylene (PE) or polypropylene (PP) and straight-run kerosene on commercial NiMo/Al2O3/P catalyst (10–30% cracked fraction content). The effects of process parameters (T = 200–300 °C, P = 40 bar, Liquid Hourly Space velocity (LHSV) = 1.0–3.0 h−1, H2/hydrocarbon ratio = 400 Nm3/m3) and the feedstock composition on the hydrodesulphurisation and hydrodearomatisation efficiencies and the main product properties were investigated. It was found that, olefins affect the hydrodesulphurisation and the hydrodearomatisation reactions until 220 °C and 240 °C, respectively. At the most favourable process parameters (T = 300 °C, LHSV = 1.0–3.0 h−1) practically sulphur and olefin-free jet products with reduced aromatic contents (7.2–11.2%) were produced. The freezing points of the jet fuel (−60.3 to −56.4 °C) produced from the 10–30% cracked PP fraction containing feedstocks were significantly lower than the required −47 °C, but in the case of the products containing the cracked PE fraction one further step (hydroisomerisation) is needed before the application.