Absorption of CO2 into aqueous mixtures of glycerol and monoethanolamine

- The solubility of CO2 in various aqueous mixtures of MEA and glycerol at different temperatures and pressures was measured.
- Correlations of solubility as a function of CO2 partial pressure successfully fit the experimental data.
- Addition of 5 and 10 wt% glycerol improved the CO2 solubility of MEA at low pressures.
- The loading dependence of the isosteric heat showed the occurrence of different absorption mechanisms.
- The 5 wt% glycerol in the mixture yielded the optimum CO2 solubility and a potential solvent for post-combustion CO2 capture.

The solubility of CO2 in aqueous solutions 30 wt% monoethanolamine (MEA) mixed with various glycerol concentrations was measured. The CO2 absorption was performed at three different temperatures (313, 323, and 333 K), and pressures ranging from 500 to 1500 kPa with concentrations of glycerol in the mixture varying from 0 to 20 wt%. Correlations of solubility as a function of CO2 partial pressure were obtained with deviation of less than 2% over the pressure range investigated. The CO2 loading at various temperatures, pressures, and concentrations showed an agreement to the general trend of absorption (i.e., increasing the equilibrium loading with decreasing the temperature and increasing the pressure). The solubility of the MEA solution increased by adding glycerol up to a level of 10% at lower pressures. The findings showed that 5 wt% glycerol in the mixture was the concentration that yielded the optimum CO2 solubility as it could increase the CO2 solubility of MEA at low pressures and approximately maintain its capture performance at high pressures. It confirmed that the solvent is suitable for the absorption of CO2 under low pressures (below 1000 kPa) and can be applied in low-pressure CO2 absorption processes such as post-combustion CO2 capture.