Liquid–liquid equilibrium studies of <i>n</i> ‐butane–bitumen system with application to solvent‐aided in situ bitumen recovery

Abstract Solvent‐assisted recovery methods have gained attention as an alternative to conventional thermal methods which have significant environmental drawbacks and high greenhouse gas emissions. Solvent‐assisted recovery methods can lead to various phase equilibria, such as vapour–liquid equilibrium (VLE) and liquid–liquid equilibrium (LLE), under specific thermodynamic conditions. A thorough understanding of this phenomenon is essential for effectively designing and optimizing these processes. Despite the availability of both VLE and LLE for mixtures of solvent‐bitumen systems, LLE data is scarcer, particularly at conditions close to the solvent's saturation pressure. This study reports on LLE measurements of n ‐butane–bitumen mixtures at temperatures ranging from 295 to 372 K. The pressures were set just above the solvent's saturation pressure at each temperature to maintain LLE conditions. We examined both the phase behaviour and thermophysical properties of the mixture. The thermophysical properties of the light phase, including density and viscosity, were recorded. The bubble point pressure, n ‐butane content in the light phase, heavy phase onset, and detailed characterization of both the light and heavy cuts were also conducted. The experimental thermophysical data were then modelled using the Peng–Robinson equation of state (PR‐EoS) and modified Pederson model. In conclusion, these findings enhance our understanding of the LLE behaviour of n ‐butane–bitumen systems under conditions near the solvent's saturation pressure and find plications in solvent‐aided in situ bitumen recovery processes.