Supercritical fluid extraction of BAL 150 crude oil asphaltenes

Supercritical fluid extractions (SFE) from BAL 150 asphaltenes were achieve d with carbon dioxide as solvent under various experimental conditions (pre ssure, temperature, extraction time, and presence of cosolvent). SFE yields were between 5 and 12% of total asphaltenes. Extracts contained mainly lin ear alkanes (with chain lengths ranging from C-14 to C-30), various branche d alkanes, and a multitude of complex branched and cyclic alkanes as shown by the GC/MS chromatograms. Many aromatic hydrocarbons, heteroaromatic comp ounds and their methyl derivatives, and polar compounds were also extracted . The best balance between rapid and efficient extraction was obtained for an extraction time of 60 min. Within the range of the study (40-50 degrees C), the temperature did not show a marked influence upon the extraction eff iciency. Pressure and presence of cosolvent appeared to be the major parame ters. Increasing pressure (from 130 to 300 bar) yielded to preferential ext raction of heavy n-alkanes, more branched and cyclic alkanes, and aromatics . The comparison of extractions performed with or without cosolvent (toluen e and dichloromethane) under the same conditions of time and temperature sh owed that heavier n-alkanes, more highly branched alkanes, and complex cycl ic alkanes (biomarkers) were recovered with modifiers.