Physical Solubility and Diffusivity of N₂O and CO₂ into Aqueous Solutions of (2-Amino-2-methyl-1-propanol + Diethanolamine) and (N-Methyldiethanolamine + Diethanolamine)

In this work the physical solubility of N 2 O in (diethanolamine + water), (2-amino-2-methyl-1-propanol + water), ( N -methyldiethanolamine + water), ( N -methyldiethanolamine + diethanolamine + water), and (2-amino-2-methyl-1-propanol + diethanolamine + water) as well as the diffusivity of N 2 O in ( N -methyldiethanolamine + diethanolamine + water) and (2-amino-2-methyl-1-propanol + diethanolamine + water) have been measured at (293, 298, 303, 308, and 313) K. For the binary mixtures 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 treating. A solubility apparatus was used to measure the solubility of N 2 O in amine solutions. The diffusivity was measured with a wetted wall column absorber. The uncertainty of the measurement is estimated to be ±2%. A semiempirical model of the excess Henry's constant proposed by Wang et al. ( Chem. Eng. J. 1992, 48, 31−40) was used to correlate the solubility of N 2 O in amine solutions. The parameters of the correlation were determined from the measured solubility data. The experimental N 2 O 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 N 2 O in (DEA + H 2 O), (AMP + H 2 O), (MDEA + H 2 O), (MDEA + DEA + H 2 O), and (AMP + DEA + H 2 O) as well as diffusivity of N 2 O in (MDEA + DEA + H 2 O) and (AMP + DEA + H 2 O) solvents. The “N 2 O analogy” is then used to estimate the solubility and diffusivity of CO 2 in the aqueous alkanolamine solutions.