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

Abstract

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.

Keggin‐type Heteropolyacids‐Catalyzed Selective Hydrothermal Oxidation of Microalgae for Low Nitrogen Biofuel Production

“…[6,23,24] In order to improve the catalytic properties of heterogeneous catalysts, researchers use porous materials such as activated carbons, zeolites, molecular sieves, metal organic frameworks (MOFs), and nanomaterials, as supporting materials of these transition metals to increase the surface area of the catalysts. [25][26][27] However, the bio-oil yield of heterogeneous catalyzed HTL of microalgae is greatly limited by the mass transfer resistance of the reactants, which is based on the adsorption-desorption of reactants on the surface of the catalysts. Also, the low catalytic selectivity of heterogeneous catalysts to the decompositions of the cellular compounds and the tandem reactions leads to the formation of the heteroatomic compounds, reducing the quality of bio-oil.…”

“…Accordingly, transition metals, such as Ni, Pd, Pt, Ru, and Mo, are extensively utilized as heterogeneous catalysts to catalyze the hydrothermal hydrolysis of microalgae [6,23, 24] . In order to improve the catalytic properties of heterogeneous catalysts, researchers use porous materials such as activated carbons, zeolites, molecular sieves, metal organic frameworks (MOFs), and nanomaterials, as supporting materials of these transition metals to increase the surface area of the catalysts [25–27] . However, the bio‐oil yield of heterogeneous catalyzed HTL of microalgae is greatly limited by the mass transfer resistance of the reactants, which is based on the adsorption‐desorption of reactants on the surface of the catalysts.…”

Highly selective production of bio-jet fuel grade alkanes over an Fe/SiO2–Al2O3 solid acid catalyst under solvent-free conditions

“…9 The two main factors for the catalytic activity are associated with metals and their support system. Usually, catalysts based on noble metals such as Pt, [10][11][12] Pd, 13 Ru, 14 and Rh 15 have been extensively utilized for the deoxygenation reactions of vegetable and nonedible oils due to facile substrate adsorption, leading to high catalytic hydrogenation activity. Still, their high cost and less abundance limit large-scale applications.…”

Effect of H-Bonding on Brønsted Acid Ionic Liquids Catalyzed In Situ Transesterification of Wet Algae

“…It avoids the energy-intensive dewatering and extraction processes in conventional in situ transesterification (IST) . Accordingly, there are many attempts made to improve the biodiesel yield of in situ transesterification of wet algae in recent years, such as catalyst-free IST under subcritical or supercritical methanol conditions, acid/base/biphasic catalyst/enzyme-catalyzed IST, and ultrasound/microwave irradiation assisted in situ transesterification of wet algae. − To further improve the biodiesel yield of IST of wet algae, cosolvents such as toluene and ethyl acetate have been added to enhance the extractive reaction. − Though sulfuric acid is a promising catalyst of IST of wet algae with high biodiesel yield; however, their unrecycled property subsequently leads to the high cost of IST of wet algae …”