Physical Solubility and Diffusivity of N₂O and CO₂ into Aqueous Solutions of (2-Amino-2-methyl-1-propanol + Monoethanolamine) and (<i>N</i>-Methyldiethanolamine + Monoethanolamine)

Abstract

In this work, the physical solubility of N2O in (monoethanolamine + water), (N-methyldiethanolamine + monoethanolamine + water), and (2-amino-2-methyl-1-propanol + monoethanolamine + water) and the diffusivity of N2O in (N-methyldiethanolamine + monoethanolamine + water) and (2-amino-2-methyl-1-propanol + monoethanolamine + water) have been measured at (293, 298, 303, 308, and 313) K. For the binary mixture, the amine concentration ranges studied are (2.0, 2.5, and 3.0) kmol·m-3. For the ternary mixtures, the total amine strength in the solution was kept at 30 mass %, in view of the recent interest in using concentrated amine solutions in gas treatment. A solubility apparatus was used to measure the solubility of N2O in amine solutions. The diffusivity was measured with a wetted wall column absorber. The accuracy of the measurement is estimated to be ±2%. A semiempirical model of the excess Henry's constant was used to correlate the solubility of N2O in amine solutions. The parameters of the correlation were determined from the measured solubility data. The experimental N2O solubility and diffusivity data have been correlated. Comparison with the experimental results indicates that the models for solubility and diffusivity will be useful in estimating the solubility of N2O in (MEA + H2O), (MDEA + MEA + H2O), and (AMP + MEA + H2O) as well as the diffusivity of N2O in (MDEA + MEA + H2O) and (AMP + MEA + H2O) solvents. The "N2O analogy" is then used to estimate the solubility and diffusivity of CO2 in the aqueous alkanolamine solutions.