ARS | Publication request: HYDROLYSIS OF SOYBEAN OIL IN A SUBCRITICAL WATER FLOW REACTOR

Submitted to: Green Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1999
Publication Date: N/A

Interpretive Summary: The use of high pressure gases and liquids under pressure can provide a more effective way of extracting desired materials from many agriculturally and naturally propagated plants. When these gases and liquids are carefully selected, they can be made compatible with the environment and the consumer's desire to have naturally processed foods and related materials. In this study, the use of hot water under pressure has been used for converting vegetable oils, such as soybean oil, to their constituent fatty acids. These fatty acids find widespread use in a variety of industrial applications and as intermediates in the conversion to other chemicals. The described process offers a greater conversion level than currently available in industry as well as saving processing time. The process can be coupled with other natural processing agents such as carbon dioxide to yield a totally "green" conversion process.

Technical Abstract: Subcritical water has been recently demonstrated to be a viable medium for conducting hydrolysis reactions on a variety of organic compounds. In this study, the hydrolysis of triglycerides in soybean oil to their respective free fatty acids has been affected using a flow reactor. The flow reactor permits hydrolysis to be accomplished without the need of a catalyst but requires higher temperatures than previously used in a static system to attain >97% product conversion. Using a high pressure view cell as a diagnostic aid, it was found that the oil miscibility with water is crucial to attaining a high conversion to the free fatty acids. Water to oil ratios of 2.5:1.0-5.0:1.0 were found to optimal for high conversions as well as residence time between 10-15 minutes in the open tubular reactor. Although conversion of the all natural cis form of the fatty acids to some trans form occurred, the isolated products were clear and free of degradation products, unlike previous results reported for the reaction ru in a closed vessel under static conditions at these elevated temperatures (>300 deg C).