Free Energies of Activation for Viscous Flow of Different Amine Mixtures in Post Combustion CO2 Capture

Abstract

The viscosity of ternary mixtures of N-methyldiethanol amine (MDEA) + monoethanol amine (MEA) + H2O, Nmethyldiethanol amine (MDEA) + diethanol amine (DEA) + H2O and 2-amino-2-methyl-1-propanol (AMP) + diethanol amine (DEA) + H2O were correlated using Eyring’s viscosity model based on absolute rate theory. The correlations were capable of representing viscosity data within AARD 1.9%, 1.4% and 2.1% for the mixtures MDEA + MEA + H2O, MDEA + DEA + H2O and AMP + DEA + H2O respectively. These accuracies are acceptable in engineering calculations. The excess properties of volume 𝑉����, viscosity 𝜂���� and free energy of activation for viscous flow Δ𝐺����∗ were studied to understand the intermolecular interactions in the mixtures. The study shows that all mixtures have a negative sign for 𝑉����, 𝜂����and a positive sign for Δ𝐺����∗. This indicates weak intermolecular interactions in mixtures compared to the pure liquids and strong molecular attractions like H-bonds in the mixtures.