Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2012
Publication Date: 8/1/2012
Citation: Cheng, H.N., Dowd, M.K., Easson, M.W., Condon, B.D. 2012. Hydrogenation of cottonseed oil with nickel, palladium and platinum catalysts. Journal of the American Oil Chemists' Society. 89(8):1557-1566.
Interpretive Summary: A major process used in oil processing is hydrogenation. This process decreases the olefinic content of oils, increases the melting characteristics, and improves oxidative stability. However, hydrogenation is known to increase the levels of saturated and trans fatty acids (TFAs), both undesirable in view of health implications. There has been a lot of recent interest in decreasing TFA content in oils, with most of the efforts devoted to soybean oil. In view of the excellent physical properties of cottonseed oil and its low level of linolenic acid, we have reexamined the hydrogenation of cottonseed oil under low-pressure high-mixing conditions. Eleven catalysts from commercial sources (including those based on nickel, palladium, and platinum) have been gathered and studied with different process parameters. The results have shown interesting trends and have been fitted to kinetic models. It seems that under the experimental conditions studied, hydrogenated cottonseed oil is beneficial relative to other hydrogenated oils as far as TFA and stearic acid contents are concerned.
Technical Abstract: A number of commercial catalysts have been used to study hydrogenation of cottonseed oil, with the goal of minimizing trans fatty acid (TFA) content. Despite the different temperatures used, catalyst levels, and reaction times, the data from each catalyst type fall on the same curve when the TFA level is plotted against iodine value (IV). Under the low-pressure high-mixing hydrogenation conditions used, all three catalyst types produce less than 5% TFA and less than 5% stearic acid with IV 95. However, with IV 70, only Pt catalysts produce 9% TFA and about 17% stearic acid. Kinetic modeling provides a better understanding of the relative rates of the reactions involved in hydrogenation. It appears that Pt catalysts convert linoleic and oleic acid more slowly to TFA and also hydrogenate TFA quickly, thereby leading to the lowest TFA levels. In comparison to other hydrogenated oils reported in the literature, we observe equivalent or lower TFA and stearic acid levels with hydrogenated cottonseed oil.