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Keywords:

  • Fractionation;
  • Pilot scale;
  • Supercritical fluids;
  • Waxes

Abstract

The virtual insolubility of synthetic wax can be improved by ethoxylating the wax with a polyethylene glycol segment to form an alcohol ethoxylate. Current methods lead to a wide ethylene oxide distribution. This work shows that supercritical propane can fractionate alcohol ethoxylates according to the ethylene oxide content. Solubility measurements in propane at 408 K show total solubility of an alcohol mixture (average 40 carbon atoms) below 140 bar and a region of immiscibility between 0.975 and 0.5 at pressures below 275 bar for the alcohol ethoxylate mixture (average 40 carbon atoms, 50 % ethoxylation). This large solubility difference shows that fractionation of the alcohol ethoxylate with propane is possible. Countercurrent pilot plant runs proved that separation is possible and with energy integration and selection of the correct decompression process the technology is both technically and economically viable.