Continuous Deoxygenation of Palmitic Acid, Methyl Palmitate, and Licuri Biodiesel over Granular Pd/C Catalysts in a Trickle-Bed Reactor

Biofuels offer potential to mitigate climate change, increase energy security, and economically support farmers around the world. Licuri (Syagrus coronata) could be an important biofuel feedstock because its kernel (edible seed) has high energy content. This research investigates the optimal reaction conditions to convert fatty acids (FAs) and fatty acid methyl esters (FAMEs) (including licuri biodiesel) to hydrocarbons via deoxygenation in a trickle-bed reactor over granular Pd/C catalysts. Our results indicate that a 20 wt.% palmitic acid (PA) feed is optimum for continuous deoxygenation at 300 °C and 15 bar in 5% H2/He because of decarboxylation inhibition at higher concentrations. Deoxygenation rates are higher for PA than for methyl palmitate (MP) because of the slow initial hydrogenolysis of the methoxy bond over Pd/C. The hydrocarbon product distributions from deoxygenation of licuri biodiesel were fully consistent with FA decarboxylation and decarbonylation. A lab-prepared 5 wt.% Pd/C catalyst with higher metal dispersion provided modestly higher hydrocarbon yields from licuri biodiesel than a commercial 1 wt.% Pd/C catalyst.