The equilibrium solubility of carbon dioxide in aqueous solutions of morpholine: Experimental data and thermodynamic modeling

Experimental carbon dioxide solubility data in aqueous 34.8 wt % (6.14 m) and 43.5 wt % (8.85 m) morpholine solutions at 40, 60, 100, and 120 °C are presented. The solubility measurements were done in a static vapor liquid equilibrium cell by measuring total pressure. Furthermore, selected data points were confirmed using gas phase GC methodology. The obtained combined solubility data was integrated with speciation data extracted using an established titration method, for thermodynamic modeling of the system. In regression of the model parameters, the liquid phase activity coefficients were determined using the electrolyte-NRTL equations. In addition to binary and pair interaction adjustable parameters included in the electrolyte-NRTL model, the temperature dependent carbamate stability and Henry's law constants for CO₂ in pure morpholine were also calculated. The determined CO₂ equilibrium properties are in good agreement with most of the experimental data.