A Thermodynamic Robust Model to Assess Hybrid Solvents for CO2 Capture

Abstract

Abstract The molecular-based soft-SAFT equation of state has been applied to describe the chemisorption of CO2 in non-aqueous hybrid solvents of mixtures of AMP and glycols. The reactive nature of the CO2 absorption process in non-aqueous amines was implicitly modelled by the formation of CO2-amine physical aggregates bounded by strong and localised intermolecular interactions. This modelling framework only required VLE data on the absorption of CO2 in amine solvents, without the need for additional information such as speciation reactions or equilibrium constants. Subsequently, the developed models were used to examine the CO2 capture performance of these hybrid solvents in terms of absorption cyclic capacity and heat of regeneration as key performance indicators using a simple and short-cut estimation method. Results show that for the same total amine mass concentration, non-aqueous AMP solvents possess a 30-40% decrease in total heat of regeneration compared to their aqueous counterparts at the expense of a 20-50% reduction in cyclic capacity. These results validate the reliability of the molecular modelling approach as an attractive and valuable tool for the screening of chemical solvents and process modelling.