CO₂ Solubility in a Mixture Absorption System of 2‑Amino-2-methyl-1-propanol with Ethylene Glycol

A mixture system of sterically hindered amine 2-amino-2-methyl-1-propanol (AMP) with ethylene glycol (EG) was developed. The solubility of CO₂ in mixture solutions of AMP–EG was measured at temperatures from 303.2 to 353.2 K and partial pressures of CO₂ from 5 to 120 kPa. The concentration of AMP ranged from 0.4 to 1.0 mol/L. A model based on a zwitterion mechanism concerned with parameters independent of temperature and ion strength was derived, which could fit the experimental data very well. The calculated heat of absorption of CO₂ in AMP–EG solution showed a decline compared to that in AMP–H₂O solution. Comparing the solubilities of CO₂ in different solvents with the same chemical absorber AMP, we found that the solvent has a significant influence on the solubility of CO₂. Two possible aspects make contributions to the influence: deprotonation process and ion strength. The study of the influence of the solvent provides guidance for a reasonable selection and good design of the absorption process for CO₂. Compared to AMP–DEG and AMP–TEG solutions, the loading of CO₂ in AMP–EG solution is higher especially at lower partial pressure of CO₂; the viscosity of AMP–EG solution is also lower. Compared to AMP–H₂O solution, AMP–EG solution has higher circular loading of CO₂ while the temperature changes especially at lower desorption temperature