Mathematical Models for Physicochemical Properties of Different Amine-based Solvents in Post combustion CO2 Capture

Abstract

In order to reduce global CO₂ emissions, CO₂ capture based on absorption in an amine/water mixture is an established method. To develop such processes, correct physicochemical properties like densities and viscosities are important.

The first objective of this work is to explore mathematical correlations for fitting viscosity data for aqueous Monoethanolamine (MEA) and Methyldiethanolamine (MDEA). A second objective is to evaluate the prediction of viscosity based on parameters independent of viscosity measurements.

13 developed correlations have been evaluated by comparing the maximum deviation of fitted models to the measured property, and by determining the average absolute relative deviation (AARD%). Python 3.6, MATLAB R2020b and Excel were used as the tools for regression.

The results indicated that viscosity for aqueous amines was better correlated by Eyring’s viscosity model based on NRTL (Non-Random-Two Liquid model) rather than a Redlich-Kister correlation. The achieved AARD% of aqueous MEA were 2.39 for Redlich-Kister, 1.87 for Eyring-NRTL and 1.88 for the segment-based Eyring-NRTL model. The same trend was achieved for aqueous MDEA with AARD% of 3.04, 2.23 and 1.88 for different approaches.

The possibility of using data from vapor/liquid equilibrium parameters to predict viscosity in MEA/water and MDEA/water was evaluated. Using parameters in the equilibrium model NRTL from the simulation program Aspen HYSYS in a model from Karunarathne indicated that it is possible to predict viscosity reasonably well without experimental viscosity data.