Absorption of carbon dioxide in piperazine activated concentrated aqueous 2-amino-2-methyl-1-propanol solvent

In this work new experimental data on the rate of absorption of CO₂ into piperazine (PZ) activated concentrated aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) over the temperature range 303–323 K are presented. The absorption experiments have been carried out in a wetted wall contactor over CO₂ partial pressure range of 5–15 kPa. PZ is used as a rate activator with a concentration ranging from 2 to 8 wt% keeping the total amine concentration in the solution at 40 wt%. The physical properties such as density and viscosity of concentrated aqueous AMP+PZ, as well as physical solubility of CO₂ in concentrated aqueous AMP+PZ, are also measured. New experimental data on vapor liquid equilibrium (VLE) of CO₂ in these concentrated aqueous solutions of AMP+PZ in the temperature range of 303–323 K have also been presented. The VLE measurements are carried out in an equilibrium cell in CO₂ pressure range of 0.1–140 kPa. A thermodynamic model based on electrolyte non-random two-liquid (eNRTL) theory is used to represent the VLE of CO₂ in aqueous AMP+PZ. Liquid phase speciations are estimated considering the nonideality of concentrated solutions of the amines and the calculated activity coefficients by eNRTL model. The CO₂ absorption in the aqueous amine solutions is described by a combined mass transfer-reaction kinetics model developed according to Higbie's penetration theory. The model predictions have been found to be in good agreement with the experimental results of the rates of absorptions of CO₂ into aqueous AMP+PZ.