The Henry's law constant of N 2O and CO 2 in aqueous binary and ternary amine solutions (MEA, DEA, DIPA, MDEA, and AMP)

Abstract

This paper presents a new expression for the Henry's law constant of N 2O in aqueous binary and ternary amine solutions (monoethanolamine MEA, diethanolamine DEA, diisopropanolamine DIPA, N-methyldiethanolamine MDEA, and 2-amino-2-methyl-1-propanol AMP) as a function of temperature and amine concentration. The Henry's law constant of CO 2 is derived from the Henry's law constant of N 2O in the same solvents, assuming the N 2O–CO 2 analogy. The Henry's law constant of CO 2 in aqueous amine solvents is necessary while modeling gas sweetening and post-combustion CO 2 capture processes, i.e. the absorber and the solvent regeneration units. The parameters of the new expression were fitted to 992 data points up to 393 K, thus extending the model validity range to higher temperatures compared to most of the models found in the literature. The Henry's law constants at high temperatures are especially important in modeling the solvent regeneration step, since amine regenerations often occurs near 393 K, which is above the validity range of most existing correlations. The weighted average error calculated on all the studied binary solvents was 5%. The shape of our model enables the direct calculation of the Henry's law constant of N 2O in aqueous ternary amine solutions solely based on the Henry's law constants of N 2O in aqueous binary amine solutions with an average deviation of 9.4%. If solubility data in the aqueous ternary amine solutions of interest are available, an additional ternary parameter can be regressed and the model average error reduced to 6.4%.