Carbon dioxide (CO2) transformation into added-value
products through non-thermal plasma (NTP) represents a novel technology
of interest. The process involves, apart from CO2, mixtures
of different gases such as carbon monoxide (CO), oxygen (O2), nitrogen (N2), argon (Ar), and hydrogen (H2) for subsequent CO2 methanation. In this work, a preliminary
study of the thermodynamic representation of the mixtures relevant
in the context of carbon capture, utilization, and storage (CCUS)
processes, but focused on the NTP conversion, is presented. The thermodynamic
characterization is achieved through the application of the polar
soft-statistical associating fluid theory (SAFT) equation of state
(EoS), which allows molecular parameterization of pure compounds and
the description of mixtures at different conditions of temperature
and pressure. An accurate parametrization of all gases is carried
out by explicitly considering the quadrupolar nature of CO2, CO, and N2. The characterization is then used to describe
several single-phase densities, derivative properties, second virial
coefficients, and the vapor–liquid equilibrium (VLE) of CO2 binary mixtures with Ar, O2, CO, N2, and H2, as well as combinations between some of these
gases. A parametric analysis of the impact of the binary parameters
on the equilibria description is carried out to assess the temperature
dependency. The results have overall shown good agreement to experimental
data in most conditions using one or two binary parameters. Finally,
ternary systems involving CO2, O2, Ar, and N2 have been predicted in good agreement with the experimental
data, demonstrating the capacity of the model to evaluate the behavior
of multicomponent gas mixtures.