Vapor–liquid critical properties of multi-component mixtures containing carbon dioxide and n-alkanes

Vapor–liquid critical temperatures, pressures and densities of multi-component mixtures containing CO2 and n-alkanes (C4–C7) were measured in a high-pressure view cell by direct visual observations. The molar ratio of alkanes was fixed during the experiment while the composition of CO2 was varied over the whole range. The critical loci show type I fluid phase behavior if the n-alkanes mixture is treated as a pseudo-continuous component, while correspondingly, CO2 is a discrete component. The critical properties were calculated by Redlich–Kwong–Soave equation of state (SRK) combined with a renormalization group correction (RG). The predictions of critical properties by SRK + RG are in good agreement with the experimental results.