Catalytic deoxygenation of fatty acids and their derivatives

Catalytic deoxygenation including decarboxylation/decarbonylation of fatty acids and their esters has been investigated over Pd supported on active carbons in a semibatch reactor. The main studied parameters were catalyst acidity, type of feed, effect of solvent, and gas atmosphere. High yields of the desired product, n-heptadecane, were achieved in the decarboxylation of stearic acid at 300 °C under helium. The results demonstrate that the catalytic transformation of fatty acids proceeded mainly via decarboxylation, whereas decarbonylation was the main route for esters, according to gas-phase analysis. The gas atmosphere and the acidity of the catalyst were important factors for determining product selectivity. Over alkaline catalysts as well as under a hydrogen atmosphere, higher yields of n-heptadecane were obtained. The decarboxylation of unsaturated fatty acids leads to hydrogenated products, which reacted further to hydrocarbons.