Electrochemical hydrogenation of soybean oil by filling H2 in supercritical CO2

Electrochemical hydrogenation under a mixed gas environment of CO2 and H-2 was studied. It was found that in supercritical CO2 (SC-CO2), the mole fraction of H-2 in both the CO2 and electrolytes increased as H-2 pressure increased. CO2 was dissolved in the electrolyte to form unstable carbonic acid, which was easily decomposed into HCO3- and H+. Meanwhile, H-2 was electrolyzed to form H+ at the anode, so that the conductivity increased, the hydrogen consumption of the reaction increased, and then tended to be stable at a total pressure of 9.0MPa. Herein, the electrochemical hydrogenation of soybean oil was accomplished at a current of 120mA, a temperature of 50 degrees C, and an agitation speed of 300rpm. The iodine value (IV) of the hydrogenated soybean oil was 90.6g I-2/100g oil at 7hr and the trans fatty acid (TFA) content in the oil was 3.32%. Practical applicationsIn the present study, H-2 was added to the electrochemical hydrogenation reactor and soybean oil was electrochemically hydrogenated by filling H-2 in supercritical CO2. By filling H-2, the TFAs of the hydrogenated soybean oil were reduced, and the TFA content was only 3.32%. The reaction rate of the hydrogenation was faster and the hydrogenation time decreased by 5hr compared with the hydrogenation of soybean oil at a normal pressure. Moreover, the electrochemical hydrogenation reactor used a moderate pressure and a large reaction volume, which is beneficial to industrialization. The electrochemical hydrogenation by filling H-2 in SC-CO2 decreased the hydrogenation time and reduced the industrial production costs. This method can be further applied for industrial purposes.