Concentration of wax derivatives with supercritical fluids: 1. A feasibility study
Currently alcohol ethoxylates produced contain a wide distribution of the number of ethylene oxide units added. One possible method to reduce the wide distribution is with the use of supercritical fluids. From their phase behavior in supercritical propane, it can be seen that a significant difference in solubilization exists between an n-alkane (starting material), an n-alcohol (intermediate), and alcohol ethoxylates, thus, in combination with the concept of group contribution, indicating that propane may be able to fractionate a wide-distribution alcohol ethoxylate according to the number of ethylene oxide units. An analysis of the relative solubility was used to further show the large solubility difference and to assist in determining suitable operational parameters. An experimental countercurrent pilot plant test at 393 K and 130 bar showed that, although these conditions are not optimal, supercritical propane has the ability to fractionate alcohol ethoxylates according to the number of ethylene oxide units. Optimization of the experimental conditions is required before the process can be used commercially. © 2007 American Chemical Society.