FRACTIONATION OF POLYUNSATURATED FATTY-ACIDS BY UREA ADDUCT FORMATION USING SUPERCRITICAL CO2 AS SOLVENT

Urea adduct separation methods usually require several urea precipitation steps along with filtration, washing, and recovery of fractions enriched in polyunsaturated fatty acids. These complicated operations can be simplified by using supercritical fluid as a solvent. In the present work a series of the formation and decomposition reactions of urea adduct were performed, using supercritical CO2 gas as solvent and their applicability to an industrial process was examined. Experimental results showed that urea adduct formation could not attain thermodynamic equilibrium and that final conversion of urea to the urea adduct was affected by several kinetic factors such as the existence of an activator like methanol and the amount of solid urea. Although an agitation vessel and a packed bed were employed as reactors, the conversion of adduct formation was almost independent of contacting method. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.