PROPERTIES OF ASPHALTENES FROM A WAXY CRUDE

The asphaltenes from a waxy crude were isolated using several different n-paraffinic solvents at various temperatures. As the carbon number of the precipitant increased from C5 to C-8, the amount of solvent required to initiate precipitation (onset) increased, consistent with an increase in solvating power. The amount of asphaltene material recovered decreased with increase in carbon number. The average molecular weight of the asphaltenes generally increased with increase in carbon number and with temperature. It could be concluded that the higher molecular weight asphaltenes precipitate first upon addition of solvent and determine the onset value for a particular solvent. The lower molecular weight asphaltenes precipitate during the later stages of solvent addition and determine the overall asphaltene content. The solubility of these asphaltenes increases with temperature. Finally, higher n.m.r. aromaticities were generally observed for the higher molecular weight asphaltenes.