Solubility Parameters of Bitumen-Derived Narrow Vacuum Resid Fractions

Narrow fractions of Athabasca vacuum topped bitumen (VTB) were prepared by supercritical fluid extraction and fractionation (SFEF) and characterized. Phase equilibria of various narrow fractions in the propane system were determined using a high-pressure PVT unit, operating at 30−50 °C, 4−6 MPa, and solvent/oil (S/O) ratio of 1.5 to 5 (wt/wt). Solubility parameters were determined using the activity coefficient equation from Scathard−Hildebrand’s regular solution theory. The value of the solubility parameter of the VTB fraction was obtained by extrapolation of the Gaussian function at the S/O ratio approaching zero. It was found that the solubility parameter of the VTB fraction was not constant, varying from 14 to 16 MPa1/2. The solubility parameter exhibited a Gaussian distribution as a function of the S/O ratio, with a maximum at the S/O ratio of 3.25, and a parabolic function of pressure, with a maximum at 5 MPa. It decreased with temperature. As the VTB fraction becomes heavier, the solubility paramet...