Investigating the effect of temperature, pressure, and reactor wall in non-catalytic ethylene oligomerization

The aviation industry contributes to greenhouse gas (GHG) emissions, driving interest in sustainable aviation fuel (SAF) production. A promising route is the bioethanol-to-jet process, where bioethylene undergoes non-catalytic (thermal) oligomerization to form longer-chain hydrocarbons. However, limited research exists on this process at high temperatures and pressures. This study examines the influence of temperature (200–650°C), pressure (5 and 15 bar), and reactor material (SS316 and Inconel) on ethylene conversion and product distribution. Higher temperature (600–650°C) and pressure (15 bar) significantly enhanced conversion, reaching 94% in both reactors, while at lower pressure (5 bar), conversion of 30–58% was reached. Increased temperature and pressure promoted C4 hydrocarbon formation, with heavier products appearing at a lower temperature in the Inconel reactor (450°C) compared to SS316 (500°C). Additionally, liquid product yield was higher in the Inconel reactor, producing up to 2 g of liquid, compared to 1.71 g in SS316, which showed a greater proportion of heavier hydrocarbon distribution. Liquid product analysis showed that C6-C8 hydrocarbons were predominant, while heavier fractions (C9-C12 and C12+) were more abundant at lower pressures. These results highlight Inconel’s potential for improving ethylene oligomerization efficiency, offering insights for optimizing SAF production.