A general model for prediction of the CO2 equilibrium solubility in aqueous tertiary amine systems

We have developed a general model to predict CO2 equilibrium solubility in aqueous tertiary amine solutions by relating the equilibrium constant (K-1) to all relevant parameters in a logical function form. Testing our model, we measured CO2 equilibrium solubility data for N-methylmorpholine (NMM) and N-ethylmorpholine (NEM) across various conditions. Comparison with six existing models reveals our general model's superior predictive performance not only for NMM and NEM but also for an additional 10 tertiary amine solutions from literature, indicating its universality. Comprehensively considering the CO2 equilibrium solubility, amine dissociation constant (pKa) and the CO2 absorption heat, it is found that NMM and NEM may be promising desorption promoters enabling to reduce the energy cost. In short, it is expected the general model can be applied to more other tertiary amine systems.