(411a) Hydrodeoxygenation of Palmitic Acid Using Mo2 C

The hydrolysis of triglycerides yields fatty acids that can be upgraded to remove the oxygen thereby creating hydrocarbons that used as a drop-in replacement for petroleum derived liquid fuels.  In this paper we report results for the hydrodeoxygenation (HDO) of palmitic acid in high temperature water using nanostructured Mo₂C. Previous studies have shown that Pt/C and Pd/C catalysts are highly active in aqueous environments; however, early transition metal carbides are an attractive alternative due to their significantly lower cost. For some reactions, these materials possess catalytic properties similar to those of platinum group metals. Compared to noble metals, the Mo₂C catalyst promoted HDO of fatty acids in aqueous conditions, versus decarboxylation of the carboxylic acids. HDO retains an extra carbon on the hydrocarbon chain, removing the oxygen as H₂O versus CO₂ in decarboxylation. Effects of temperature (370– 400 °C), time (0.5 – 6h), and water density at supercritical conditions (0.17 – 0.52mL/cm³) were studied. Liquid products were analyzed using GC/MS and GC/FID. Characterization of Mo₂C was done using N₂ physisorption (BET surface area analysis) and x-ray diffraction (XRD). Higher temperatures and longer times resulting in higher conversions of palmitic acid and a higher yield of hexadecane. Increased water density (higher reactor pressure) caused decreases in both conversion of the fatty acid and yield of hexadecane. Other products from the reaction included C₇- C₁₅ hydrocarbons and C₁₆ alcohols, aldehydes and ketones. The XRD patterns of the spent catalyst showed formation of an oxide phase, indicating that the catalyst oxidized and potential instabilities at reaction conditions in water in the absence of H₂. HDO of palmitic acid was also studied in organic solvents and in the presence of H₂ at variable partial pressures to determine the stability of the Mo₂C at reaction conditions