C ₂ oligomerization over H‐ ZSM ‐5 to synthetic kerosene

Ethylene oligomerization is the second conversion step in alcohol‐to‐jet processes employing ethanol as the feed. Ethylene has a lower Brønsted acid catalyzed oligomerization rate compared to C 3 and heavier olefins, which can be overcome by making use of a two‐step process involving Ni catalysis in the first step. Single‐step ethylene oligomerization was investigated with emphasis on determining viability for use in an alcohol‐to‐jet process. Ethylene oligomerization was performed in a packed bed flow reactor (180 g H‐ZSM‐5) at 260°C and 2.0, 3.5, and 4.5 MPa pressure. The liquid product was distilled to recover the >140°C boiling kerosene‐rich fraction, which was further characterized. Single‐pass selectivity to the >140°C product was 74%–80% and was further increased to 85% by co‐feeding naphtha (as surrogate of a naphtha recycle). The high kerosene selectivity compared to the literature could be explained in terms of the lower temperature, but mostly the higher olefin partial pressure used for oligomerization. The olefinic kerosene‐rich product had < −80°C freezing point and >775 kg/m 3 density at 15°C. It indicated that substantial oligomerization, cracking, cyclization, and isomerization took place. Based on the kerosene selectivity and product characteristics, single‐step ethylene oligomerization is a promising alternative to a two‐step oligomerization for an alcohol‐to‐jet process.