Catalytic Deoxygenation of Fatty Acids and their Derivatives for the Production of Renewable Diesel

Abstract

Production of diesel-like hydrocarbons from renewable resources through catalytic deoxygenation is summarized. As a feedstock, fatty acids (C9 - C23) and their derivatives (esters, triglycerides) can be used, as well as tall oil fatty acids (TOFA). The catalytic deoxygenation of fatty acids and their derivatives was typically performed over Pd and Pt catalysts supported on micro- and mesoporous carbon in the temperature and pressure ranges of 270°C – 360°C and 6 – 17 bar, respectively, under inert conditions or in the presence of small amounts of hydrogen. The main liquid phase products were hydrocarbons having one less carbon than in the original fatty acid, whereas CO and CO2 were obtained as major products in the gas phase. n-Heptadecane, with a yield of greater than 90%, was the main product in stearic acid deoxygenation. The feasibility of deoxygenation was demonstrated in both semi-batch and continuous modes. Although no sintering of Pd occurred, which was confirmed by TEM particle size analysis, catalyst deactivation was noticeable due to coking. Overall, deoxygenation can be a viable technology for the upgrading of vegetable oils.