A new model for correlation and prediction of equilibrium CO2 solubility in N-methyl-4-piperidinol solvent

In this work, the equilibrium CO 2 solubility in the aqueous tertiary amine, N-methyl-4-piperidinol (MPDL) was measured over a range of temperatures, CO 2 partial pressures and amine concentrations. The dissociation constant of the MPDL solution was determined as well. A new thermodynamic model was developed to predict the equilibrium CO 2 solubility in the MPDL-H 2 O-CO 2 system. This model, equipped with the correction factor (C f ), can give reasonable prediction with an average absolute deviation of 2.0%, and performs better than other models (i.e., KE model, Li-Shen model, and Hu-Chakma). The second-order reaction rate constant (k 2 ) of MPDL and the heat of CO 2 absorption (–ΔH abs ) into aqueous MPDL solutions were evaluated as well. Based on the comparison with some conventional amines, MPDL revealed a high-equilibrium CO 2 loading, reasonably fast absorption rate when compared with other tertiary amines, and a low energy requirement for regeneration. It may, therefore, be considered to be an alternative solvent for CO 2 capture. © 2017 American Institute of Chemical Engineers AIChE J , 63: 3395–3403, 2017