VLE properties of CO2 – Based binary systems containing N2, O2 and Ar: Experimental measurements and modelling results with advanced cubic equations of state

Mainly due to the complex thermodynamic modelling of high-pressure CO2-based mixtures containing supercritical components, none of the thermodynamic models present in the literature shows a sufficient accuracy level in describing both their low and high-pressure saturation properties. One of the most challenging thermodynamic tasks is, in fact, the representation of the critical region of high-pressure binary systems at the basis of the optimization of thermodynamic models for multicomponent systems treated by CO2 Capture and Storage (CCS) applications and Enhanced Oil Recovery (EOR) processes. The limited number of experimental data, on the one side, and the absence of a sufficiently accurate equation of state, on the other, pose doubts on the reliability and predictive capability of models especially when applied to complex multicomponent systems. The uncertainty about such capability drives engineers towards the oversizing of equipment and, thus, of the related costs. With the aim of filling some of the mentioned thermodynamic gaps, this work presents new experimental vapor-liquid equilibrium data for the systems CO2-N2, CO2-Ar and CO2-O2 and modelling results obtained from the successful application of the Peng-Robinson equation of state with an advanced class of mixing rules, that highly improve the representation of the critical region of these fluids.