Thermodynamic studies for improving the prediction of CO2 equilibrium solubility in aqueous 2-dimethylamino-2-methyl-1-propanol

In this work, CO2 equilibrium solubility in aqueous 2-(dimethylamino)-2-methyl-1-propanol (2DMA2M1P) solution was investigated by varying temperature, CO2 partial pressure and amine concentration. Dissociation constant (pKa) and CO2 absorption heat of 2DMA2M1P were calculated. Results show that the CO2 equilibrium solubility increases with the CO2 partial pressure but decreases with the increase of temperature. It was also revealed that the CO2 equilibrium solubility declines when the concentration of 2DMA2M1P increases from 1 to 2 mol/L. In addition, a new extended Cf model was proposed for predicting the CO2 equilibrium solubility, and the predicted results show a good agreement with the experimental measured data with an average absolute deviation (AAD) of 2.08%. Furthermore, the proposed model was validated with the published data of tertiary amines, and the results indicate that the developed model has a good universality in predicting the CO2 equilibrium solubility. Finally, a comparison with other reported amines was also made in terms of the CO2 equilibrium solubility and the CO2 absorption heat. All of them proved that the 2DMA2M1P could be a competitive amine solvents for CO2 capture.

Automated summary

This work investigates the CO2 solubility in aqueous 2-(dimethylamino)-2-methyl-1-propanol (2DMA2M1P) solution by varying temperature, CO2 partial pressure, and amine concentration. The results show that the CO2 solubility increases with the CO2 partial pressure but decreases with the increase in temperature. A new extended model is proposed to predict the CO2 solubility with good agreement with experimental data and universality with tertiary amines.