Henry's Law Constants and Vapor-Liquid Distribution Coefficients of Noncondensable Gases Dissolved in Carbon Dioxide

The accurate determination of the solubilities of the typical impurity gases present in captured CO2 in the carbon capture, utilization, and storage chain is an essential prerequisite for the successful modeling of the CO2 stream thermodynamic properties. In this paper, Henry's law constants and the vapor-liquid distribution coefficients of six noncondensable gases, namely, N-2, O-2, H-2, CH4, Ar, and CO, at infinite dilution in liquid CO2 are derived based on published vapor-liquid equilibrium data at temperatures ranging from the triple point (216.59 K) to the critical point (304.13 K) of CO2. The temperature dependence of Henry's law constants of the six gases is correlated using approximating functions previously proposed for aqueous solutions. A correlation that provides the best fit for the Henry constants data for all the six gases, with the accuracy (absolute average deviation %) of 4.2%, is recommended. For N-2, O-2, H-2, Ar, and CO, the combined standard uncertainty in the derived Henry constants is less than 6%, whereas for CH4, due to a larger deviation between the utilized data, the uncertainty is less than 18%. Analysis of the temperature variation of the vapor-liquid distribution coefficient at infinite dilution shows that when all the six gases are present in the CO2 stream, separation of N-2, O-2, Ar, and CO from CO2 can be problematic due to their similar volatilities, while the distinct volatilities of H-2 and CH4 at lower temperatures make their separation from CO2 easier.