Solvent deasphalting effects on whole cold lake bitumen

Cold Lake bitumen was separated using light hydrocarbon solvents (n-pentane, n-butane, isobutane, and propane) into deasphalted oil (DAO) and asphaltene fractions. The resulting range of deasphalting was from 20 to 50 wt % of the whole bitumen. An extensive study of the fractions, as a function of yield, has shown how and to what extent volatiles, aromatics, sulfur, and metals are distributed between the fractions. A study of how the asphaltenes affect viscosity and overall molecular weight revealed that the heaviest-end fractions of asphaltenes have the most impact on the viscous nature of such heavy oils, suggesting that even low levels of deasphalting can have a dramatic impact in reducing viscosity. In addition, thiophenic sulfur was found to be more concentrated in the asphaltenes. It is also suggested that sulfides acting as cross-links between large structures may be responsible for the largest molecular weight fractions of the asphaltenes.