Heat Capacities of Aqueous Polyamine (Ethylenediamine and Diethylenetriamine) Blends of Two Amine Absorbents: 2-Isopropylaminoethanol and 2-Amino-2-methyl-1-propanol

Abstract

Blended amine solutions are energy-efficient and cost-effective alternatives to traditional alkanolamine solvents for the removal of CO₂ from flue gases emitted from industrial processes. For such solvent systems, it is crucial that thermophysical properties like heat capacity be available to establish their suitability and estimate energy requirements in CO₂ absorption-stripping systems. In this study, experimental data on the heat capacity of aqueous blended sterically hindered amine/polyamine solutions (total amine concentrations: w = 0.3 and w = 0.4) were reported. The sterically hindered amines studied included 2-isopropylaminoethanol and 2-amino-2-methyl-1-propanol while the polyamines were ethylenediamine and diethylenetriamine. Using a differential scanning calorimeter, the experimental heat capacities were measured at atmospheric pressure and temperatures from 303.2 K to 353.2 K. Molar heat capacity differences were determined for each studied ternary system, and the heat capacity was then correlated with the total amine concentration and system’s temperature using a modified Söhnel and Novotný equation. The predicted heat capacities agreed very well with the experimental data as indicated by average absolute deviations ( 0.1 % for all systems. Therefore, it can be said that the applied model could be used to accurately calculate the heat capacity of the investigated CO₂ amine absorbents.