Density and viscosity correlations of aqueous solvents for amine-based CO2 capture

Abstract

Density and viscosity data are essential in designing process equipment and process simulations in the amine-based CO₂ capture process. In literature, semi-empirical and empirical correlations for density and viscosity were fitted to measured data available in the literature and the goodness of fit by calculating Average Absolute Relative Deviations (AARDs %) were examined. The correlations based on excess properties give insights on intermolecular interactions and packing efficiency in multicomponent liquid mixtures.

In this study, correlations for density, excess density (ρ^E, ln(ρ^E)) viscosity and excess viscosity (η^E, ln(η^E)) were examined for binary aqueous mixtures (Monoethylethanolamine) EMEA (1) + H₂O (2) and (Monoethylethanolamine) EMEA (1) + (Diethylethanol amine) DEEA (2) to represent the measured density and viscosity. The Redlich and Kister type polynomials were used to fit the excess properties and the goodness of fit was determined by calculating AARD%. The fitted experimental data at different mole fractions and temperatures were able to acquire a good accuracy. Highest deviation for density correlations of EMEA + DEEA mixtures was observed with AARD 0.135 % and AMD 2.98 kg·m^-3. For the EMEA + H₂O mixtures, the highest deviation was observed with AARD 0.23 % and AMD 8.38 kg·m^-3. Viscosity correlations showed a highest deviation for the EMEA + DEEA mixtures in which AARD was 5.2 % and AMD was 1.2 mPa·s. For the EMEA + H₂O mixtures, the highest deviation observed with AARD was 1.1% and AMD was 0.75 mPa·s.

McAllister’s kinematic viscosity model is a semi-empirical model based on Eyring’s theory for viscosity. The kinematic viscosity data were fitted to McAllister’s three-body model to investigate whether the suggested intermolecular interactions in the model are capable of describing the nature of the binary mixtures. The results indicated a good agreement between data and model with accuracies R² = 0.99 and AARD 2% for EMEA + DEEA mixtures and AARD 6% for EMEA + H₂O mixtures.