Cycloparaffin-rich high density sustainable aviation fuel: pathways from terpenes, terpenoids, and plant oils.

Air transportation is essential for global trade, travel, and military aircraft. Sustainable aviation fuels (SAF) derived from renewable biomass are vital to achieving net-zero carbon-emission goals. Cycloparaffins offer superior aviation fuel properties, such as high density and improved volumetric heat of combustion. Production of cycloparaffin-rich high-density SAF from cineole-based plant oils is a promising approach to produce 100% renewable aviation fuels after blending with synthetic paraffinic kerosene. This review provides an overview of aviation fuels, their key properties, and ASTM-approved SAF technologies with their limitations. The article then focuses on the recent trends in catalytic conversion of terpenes, terpenoids, and plant oils into high-quality SAF. The conversion of terpenoids involves dehydration, hydrodeoxygenation, isomerization, and oligomerization. Conversely, terpenes are processed via hydrogenation, dimerization, and cyclopropanation. The review examines the types of catalysts employed in various processes, along with their activity, selectivity, and product yields. It also compares the properties of resulting isomers, dimers, and their mixtures with aviation fuels to assess their suitability as drop-in replacements. Overall, this review presents the manufacturing of high-quality SAF from terpenes and terpenoids as renewable, scalable feedstocks, offering a sustainable solution in reducing greenhouse gas emissions from the aviation sector.