Researchers at the Karlsruhe Institute of Technology (KIT) have produced kerosene-range fuels from C_2-4 olefins and mixtures thereof via (co–)oligomerization. An open-access paper on their study is published in the journal Fuel.

A very promising pathway [for the production of SAF] is the methanol- or dimethyl ether (DME)-based ATJ process. This pathway comprises several conversion steps and allows for a targeted synthesis of jet fuel with selectivities of more than 70 %. At first, methanol or DME made from green hydrogen and CO₂ is converted to olefins and water in a Methanol/DME-to-Olefins process (MtO/DtO). The current state of the art is the conversion in fluidized bed reactors with continuous catalyst regeneration by burning off the coke. The main hydrocarbon products are light olefins in the range of C_2-4. Recently, the production of higher olefins in the range of C_5-9 by modified MtO/DtO processes was shown by Niethammer et al.

The subsequent olefin oligomerization is the crucial step for the production of jet fuel. The oligomerization reaction can be understood as a polymerization reaction, which terminates after the coupling of a few monomers. The product spectrum covers the entire carbon chain length range from gasoline to kerosene and diesel fuel. By varying the process parameters, the desired fuel fraction can be produced in a targeted manner. If olefin mixtures are used as feed, the reaction is referred to as co-oligomerization. After (co–)oligomerization, the liquid oligomers need to be hydrogenated leading to a purely paraffinic hydrocarbon mixture usable as gasoline, jet fuel and diesel fuel after separation of the fractions by distillation.

… Since the co-oligomerization of olefins has not been systematically developed for decades, this study focuses on the production of kerosene from C_2-4 olefins and mixtures thereof. The employed catalysts are not within the focus as they have been selected and described in previous studies. The main objective is to disclose the influence of feed compositions, e.g. by comparison of homo- and co-oligomerization, and to estimate the obtainable product spectra and their properties.

—Fuchs et al.

In the study, high olefin conversions and kerosene selectivities of up to 85% were reached.

Resources

• Constantin Fuchs, Ulrich Arnold, Jörg Sauer, Synthesis of sustainable aviation fuels via (co–)oligomerization of light olefins, Fuel, Volume 382, Part B, 2025, doi: 10.1016/j.fuel.2024.133680