Phenolic compounds are widely recognized because of their antioxidant capacity. In the present work, caffeic acid was shown to minimize the formation of oxidative radicals in soybean biodiesel, according to the induction period (IP) obtained by the Rancimat method. Its efficiency was much higher than usual antioxidants, such as butylated hydroxytoluene (BHT) and tertbutylhydroquinone (TBHQ). With a decomposition temperature of 170 °C, caffeic acid retained its properties, showing excellent antioxidant activity even when subjected to accelerated oxidation tests. While contamination with metals led to a meaningful decrease of the oxidative stability of soybean biodiesel, when small amounts of caffeic acid (500 mg L À1 ) were also present in the fuel, IP values higher than 6 h were obtained, reaching the limit specified by EN 14214.

Aviation industry has the challenge of halving CO2 emissions by 2050, as compared to 2005. An alternative are drop-in biofuels, which are sustainable and fully compatible with aircraft engines and also can be mixed with fossil jet fuel. Among the feedstock for biojet fuel production, licuri (Syagrus coronata) can be highlighted as most of its fatty acids are in the jet fuel range. Thereby, this work investigated the composition and physicochemical characterization of licuri oil and licuri biodiesel, both with satisfactory results according to international standards, with the purpose of obtaining hydrocarbons in the range of jet fuel from these feedstock, by catalytic deoxygenation. The semi-batch reaction, using a 5% Pd/C catalyst at 300 °C and 207 psi, produced n-alkanes with a conversion of up to 39.2%. The n-alkane selectivity was 80.7%, in addition to CO2 selectivity of 83.4% for biodiesel, indicating the preference for the decarboxylation pathway and also confirming licuri as a potential raw material for biojet fuel.

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