Influence of methane and carbon monoxide in the volumetric behaviour of the anthropogenic CO2: Experimental data and modelling in the critical region

Density measurements of the systems CO2 + CH4 at T = 304.21 K and CO2 + CO at T = 304.21 and 308.15 K were carried out at pressures and compositions of interest in the process of transport and storage of CO2 (CCS technology): P = 0.1 to 20 MPa, and xCO2≥0.97. From the experimental P-ρ-T-xCO2 data, we have studied the dependence of the isothermal compressibility, the excess molar volume, and the partial molar volume of the solute with composition, pressure and temperature within the critical region. We have modelled the volumetric behaviour of these systems with Peng-Robinson, PC-SAFT and GERG Equations of State, thus validating these equations under the conditions considered. Furthermore, we have confirmed the weakly attractive behaviour of these systems by performing a study of the interactions between solvent molecules, CO2, and those of the solute, CO or CH4, using the Krichevskii Function concept and the Kirkwood-Buff Theory. Finally, we have quantified the influence of small amounts of CH4 and CO in the transport of anthropogenic CO2 through several normalized parameters, related to the design and operation of the fluid transport process.