A novel method for production of diesel-like hydrocarbons via catalytic deoxygenation of fatty acid is discussed. The model compound stearic acid is deoxygenated to heptadecane, originating from the stearic acid alkyl chain. The deoxygenation reaction is carried out in a semibatch reactor under constant temperature and pressure, 300 °C and 6 bar, respectively. A thorough catalyst screening was performed to obtain the most promising metal and support combination. The catalysts were characterized by N2-physisorption, CO-chemisorption, and temperature-programmed desorption of hydrogen. A highly active and selective in the deoxygenation reaction of stearic acid carbon supported palladium catalyst converted stearic acid completely with >98% selectivity toward deoxygenated C17 products.

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.

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The metal-support interactions on a series of catalysts of different acidities, including platinum-modified zeolites and H-MCM-41, are investigated by means of XPS, CO and pyridine adsorption, and a model reaction (ring opening of decalin). The electronic properties of Pt are influenced by the acidity of the support, and the alteration of Pt properties increases with increasing acidity of the support, as can be seen from the changes in the Pt binding energy and stretching frequency of adsorbed CO. At the same time, the presence of platinum affects the acidic properties of the supports by reducing the strength of the acid sites. This is observed directly as the changes in desorption of pyridine from the acid sites and indirectly as the suppression of cracking reactions during the ring opening of decalin on the Pt-modified catalysts. The observed results are discussed in terms of the interatomic potential model.