Asphaltene Precipitation Through Partial Dissolution Using C-Si-SARA Method

Abstract

Asphaltene is one of the key chemical species of bitumen and generally dictates its stiffness building behavior. Separation of asphaltene from bitumen and its gravimetric as well as chemometric analysis paves the way for a better understanding of bitumen behavior. Asphaltene is generally precipitated from a solution of asphalt in a non-polar solvent (such as n-heptane) where more polar asphaltene precipitates from solution. This study investigates the effectiveness of different solvent ratios of n-heptane/toluene solution, in separating asphaltene from bitumen due to changes in Hansen/Hildebrand Solubility Parameters. The experiment involved gradually varying ratios of n-heptane and toluene solvents such as 90:10, 80:20, and so on. A 50:50 solvent ratio was also examined to compare its effectiveness against using 100% of either solvent. Hansen Solubility Parameters were utilized to see the changes in different parameters due to the mixing of different solvents. The findings revealed that the solvent ratios influenced the asphaltene’s gravimetric yield percentage. Remarkably, the 50:50 solvent ratio demonstrated comparable results to those achieved using 100% of a single solvent of n-heptane. This outcome highlights the potential for cost optimization as well as redundancy by reducing the amount of solvent required while maintaining the asphaltene separation efficiency. The gradual changes of asphaltene yield also indicates that asphaltene is not a single chemical element, but a distribution of molecules of varying polarity.