Hydrocarbon production from oleic acid via catalytic hydrogenation

The production of paraffinic hydrocarbons from renewable fatty acids is a promising route in HEFA (Hydroprocessed Esters and Fatty Acids) technology, contributing to the reduction of greenhouse gas emissions. In this work, the conversion of the model molecule, oleic acid, under catalytic hydrotreatment in continuous flow was evaluated using a bifunctional catalyst 2% Pd/NbOPO₄ diluted in SiO₂ (1:15, w/w), at 350 °C and 100 bar. The effect of the oleic acid:hydrogen molar ratio (1:10, 1:30, and 1:50) on the distribution of liquid products was investigated. The results showed that increasing the molar ratio raised the hydrocarbon fraction from approximately 78% to about 91% when going from 1:10 to 1:30, demonstrating the role of hydrogen in the saturation of C=C bonds and in the removal of oxygen. At a 1:10 ratio, n-C₁₈ predominated (38.61%), while at a 1:30 ratio there was greater formation of n-C₁₆ (56.42%) and n-C₁₇ (21.08%), indicating the combined action of the metallic and acidic functions of the catalyst. At 1:50, greater selectivity for n-C₁₈ (44.26%) was observed, associated with the hydrodeoxygenation pathway. Thus, the 1:30 molar ratio stood out as the best condition for these process conditions, promoting the formation of hydrocarbons and demonstrating the determining role of hydrogen availability in controlling the reaction pathways.