Evaluation of CO sub(2) solubility in potential aqueous amine-based solvents at low CO sub(2) partial pressure

The cyclic capacity of various potential aqueous amine-based solvents was determined by performing CO sub(2) absorption experiments at 30 degree C and 10 kPa CO sub(2) partial pressure and regeneration at 90 degree C and atmospheric pressure. By comparing selected solvents the effect of molecule structure on the cyclic capacity and reactivity at low CO sub(2) partial pressure was investigated in this work. 1,7-Diaminoheptane and 1,6-hexanediamine, N,N'-dimethyl showed a high cyclic loading of 0.81 and 0.85 moles CO sub(2)/moles amine respectively. Aqueous solutions of 1,6-hexanediamine, N,N'-dimethyl of 0.5 and 2.55 mole/L concentration were selected to study solubility of CO sub(2) at different CO sub(2) partial pressures ranging from 1 up to 40 kPa, 30 degree C and at 1 atm. The solubilities of CO sub(2) in aqueous 1,6-hexanediamine, N,N'-dimethyl at 30 degree C were compared with CO sub(2) solubility in aqueous solution of MEA of similar solvent molar concentrations. The solubility of CO sub(2) in 2.55 mole/L 1,6-hexanediamine, N,N'-dimethyl was found to be almost twice that of 2.5 mole/L MEA at lower CO sub(2) partial pressure.