Theoretical study of the equilibrium constants for solvents for CO2 capture

Calculated carbamate stabilities are presented for a broad range of solvents. These results are presented together with experimental basicity data. These two equilibrium constants do to a large extent determine how a solvent will perform in CO2 absorption. It is found that electron withdrawing groups in the molecular structure results in higher carbamate stability and lower basicity, while electron donor groups on the other hand result in weaker carbamate stability and higher basicity. Accessability of the solvent to the amine functionality results in both higher carbamate stability and higher basicity. The potential of different sterically hindered amines to form carbamates has been studied. The sterically hindered amine 2-amino-2 fluoro ethanol is predicted to form a more stable carbamate form than MEA, while most other stercially hindered amines are predicted to not form stable carbamate forms.