Calculation of Interfacial Properties of Binary Mixtures Containing Polar and Non-polar Components

摘要

Carbon dioxide (CO_2) is a component that has become a central role for the industry nowadays. Not only is this compound of wide use for certain applications (i.e. supercritical extraction processes) but also plays an important role in global warming. Therefore, the understanding of the phenomena related with this molecule is of great importance. Furthermore, the accurate modelling of its mixtures may not only have a positive effect on technical modelling, but also on economical revenue in several applications. This paper focuses on the understanding of phase and interfacial behaviour of CO_2 mixtures. These mixtures may appear in petrochemical processes like the enhanced oil recovery or in carbon capture and storage systems [1]. Recently [2, 3, 4,], a method was suggested to predict the surface tension of non-polar mixtures with help of the density gradient theory [5] in very good agreement with experimental data. The proposed methodology uses a suited equation of state (EOS), namely the polar perturbed chain statistical association fluid theory (PCP-SAFT EOS) [6], for calculation or prediction of the phase behaviour and interfacial properties of a given mixture. This model allows to take into account the quadrupole moment of CO_2, resulting in improvements for the modelling of properties of pure CO_2 and its mixtures [2, 3, 4]. With help of this theoretical background it is possible to make use of the density gradient theory for prediction of interfacial tension of CO_2 in mixtures. Some examples (CO_2 + methane, CO_2 + benzene and CO_2 + toluene) of these mixtures will then be presented and compared with experimental data from the literature, if available.