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ARS Home » Research » Publications at this Location » Publication #62023


item King, Jerry
item Jackson, Michael

Submitted to: European Symposium on Supercritical Fluid Chromatography and Extraction
Publication Type: Proceedings
Publication Acceptance Date: 9/5/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Traditional chemical manufacturing processes have often times had a negative influence on the environment, producing waste products that contaminate surrounding areas. In this study, we have combined the environmentally benign properties of high pressure carbon dioxide extraction into several reaction processes to yield methods which permit sequential extraction and reaction without contaminating the environment. High pressure carbon dioxide extraction, i.e., supercritical fluid extraction, is known to produce solvent-free products and to avoid the use of harsh conditions which result in product alteration. We have combined selective extraction of seed oils by carbon dioxide with a chemical catalyst to produce compound mixtures called esters which have value as fuels and as intermediates in other synthetic reactions. Alternatively, we have used carbon dioxide itself to initiate a reaction designed to produce an oil-derived product called a monoglyceride, which has utility in many food compounding applications. In this latter reaction, the use of CO2 under pressure facilitates a reaction that is normally catalyzed with solid catalysts; materials that are difficult to remove from the finished product. In the case of a carbon dioxide-initiated reaction, the gas is simply removed by a release of pressure. This tandem technology offers many advantages, including the integration of these reactions for analysis purposes.

Technical Abstract: It has been previously demonstrated that several types of chemical reactions can be carried out in supercritical fluid media, including those catalyzed by enzymes and active solids. The research reported in this study has focused on the development of industrially-useful processes, conducted in high pressure CO2, to convert agriculturally-derived substrates (seed oils) into methyl esters and monoglycerides. An enzyme catalyzed synthesis has been developed using a novel bench-top extraction/reaction system for the methanolysis of soybean and corn oils. Quantitative conversions in excess of 95% have been achieved with this system and fatty acid methyl ester (FAMES) compositions are equivalent to those utilized in biodiesel-based fuels. A variation of this reaction system has also proven useful in the formation of FAMES for nutritional labeling analysis. High pressure glycerolysis has also been studied in SC-CO2 with the intent of producing monoglycerides from seed oils and glycerol. The equilibrium-controlled reaction was conducted in a modified high-pressure, stirred, autoclave over the pressure range of 5-62 MPa and temperatures as high as 250 deg C. Yields of 45% monoglycerides have been achieved to date in the resultant product mixture.