Generic Biphasic Catalytic Approach for Producing Renewable Diesel from Fatty Acids and Vegetable Oils

• Published in: ACS catalysis 2019-04, Vol.9 (4), p.3753-3763
• Main Authors: Xie, Shaoqu, Jia, Chuhua, Prakash, Arushi, Palafox, Mackenzie Irene, Pfaendtner, Jim, Lin, Hongfei
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.9b00215

Conversion of fatty acids to diesel-range hydrocarbons suffers from elevated reaction temperature or low selectivity in single liquid-phase processes. Herein the biphasic interfacial catalytic process was developed for the decarboxylation of fatty acids to produce alkane hydrocarbons using Pd/C catalyst at the water-organic solvent interface. An exceptionally high carbon yield of 91.7 ± 2.3% (theoretical maximum 94.4%) and a high selectivity of ∼99% to n-heptadecane were obtained from the conversion of stearic acid in the cycloalkane/water biphasic solvent system at a relatively low temperature (260 °C). The kinetic study of the conversion of stearic acid and oleic acid in the biphasic catalytic process was investigated and the activation barriers of both reactions were determined and compared to those of the monophasic catalytic processes. Both the experimental studies and MD simulations were performed to elucidate the synergistic effects of water and various organic solvents, which stabilize the carboxylate group and the hydrophobic hydrocarbon tail in a fatty acid molecule, respectively, and improve the kinetic rates and the selectivity. The application of the biphasic tandem catalytic process (biTCP) approach was further extended to the decarboxylation of a wide selection of saturated and unsaturated fatty acids, triglycerides (e.g., glyceryl trioleate), and oilseed biocrude oil (e.g., canola oil) to produce high-quality diesel fuels.