Direct Production of Aviation Fuel Range Hydrocarbons and Aromatics from Oleic Acid without an Added Hydrogen Donor

We herein report an atom-economic approach to produce aviation fuel range hydrocarbons and aromatics from oleic acid without an added hydrogen donor. The effects of catalyst loading, reactant loading, and reaction temperature on the conversion of oleic acid and the yields of hydrocarbons and aromatics were investigated. The conversion of oleic acid was 100%, and the yield of heptadecane (the main product) can reach 71% after 80 min at 350 °C. Moreover, an aromatics yield of 19% was determined, which is the critical composition of the aviation fuels due to their ability to maintain the swelling of fuel system elastomers, indicating that it is a complicated reaction system including in situ hydrogen transfer, aromatization, decarboxylation, and cracking. To probe the mechanism of the conversion of oleic acid without an added hydrogen donor, variations of the reactant and products as time elapsed at different temperatures and the reaction behavior of 1-heptadecene and stearic acid at 350 °C in the catalysis system were investigated. The main mechanism proposed was that oleic acid was decarboxylated to 8-heptadecene, followed by the dehydrogenation of 8-heptadecene to polyenes. Then, polyenes were cyclized to aromatics by an intramolecular Diels–Alder reaction, which provided hydrogen to hydrogenate the unreacted oleic acid to stearic acid. Finally, stearic acid was decarboxylated to heptadecane.