I recently had the opportunity to present at the 23rd European Conference on Thermophysical Properties (ECTP2026), held June 21–24, 2026, at the Serge Kampf Les Fontaines campus in Gouvieux, near Paris.
My talk covered the high-pressure thermophysical properties of the CO₂ + cyclohexanol + toluene ternary system, a work carried out as part of the CO₂ES Industrial Chair (TotalEnergies / UPPA / CNRS). This mixture is used in our laboratory to study convective dissolution of CO₂ in transparent porous media, a process central to long-term geological CO₂ storage. Remarkably, no thermophysical data existed for this ternary system before our study.
We presented phase equilibrium data showing liquid–liquid immiscibility above a CO₂ mole fraction of 0.6, classifying the system as a Type III fluid with an upper critical end point between 8 and 13 MPa. Density measurements and molecular simulations agreed within 2–3%. The Fick diffusion matrix revealed significant, asymmetric cross-diffusion coupling that increases with CO₂ concentration and temperature, a phenomenon that cannot be ignored in mass transfer modelling.
The ongoing work is moving into non-equilibrium thermodynamics. We have already measured the Soret coefficient and diffusion coefficient of the binary cyclohexanol–toluene mixture at ambient pressure. The next step is to extend these measurements to the ternary CO₂-containing system at high pressure using a new thermodiffusion cell currently being commissioned in our laboratory.
The all-inclusive format at Les Fontaines created a relaxed scientific atmosphere where real conversations happen. I came away with sharper thinking about the work, new connections in the thermophysical properties community, and some wonderful collaborations for the future.
This work is part of the CO₂ES Industrial Chair and was carried out at the LFCR laboratory (UMR 5150, CNRS/UPPA) in collaboration with the Thermodynamics group at the Technical University of Berlin. I am grateful to my co-authors for their support and to the ECTP2026 organising committee for an excellent conference.
Interested in CO₂ storage thermodynamics or high-pressure fluid mixtures? Reach out at h.imuetinyan@univ-pau.fr