(242b) Asphaltene Precipitation in Bitumen-Diluent Blends

In this talk we will discuss experiments that explore the effect of diluent composition on asphaltene precipitation in bitumen blends. Naphtha is commonly used as a diluent in the bitumen extraction process, and a laboratory analog consisting of known solvent blends (e.g., heptol) will aid in the design of process modification and testing procedures. Furthermore, characterizing the influence of deviations in naphtha composition will aid in the control of varying feedstock and open opportunities for specialty or designer bitumen diluents. In this study, heptane-toluene blends (heptol) and naphtha-solvent blends were used as diluents to change the solvency power in diluted bitumen. Our goal was to measure the influence of the solvent blend on the solubility of asphaltenes to better understand their phase behavior and precipitation rate. Testing was predominantly performed at ambient conditions, but the influence of elevated temperature on the diluent solvency power was also explored. Because solvent blends and naphtha have different critical points and chemical properties, a heptol blend that represents naphtha at ambient condition may not be an appropriate analogy at elevated temperature. The results of this investigation provide an improved understanding of asphaltene phase behavior in diluent bitumen under the process conditions and will aid in design of novel bitumen extraction procedures.