DFT Calculations on the Role of Base in the Reaction between CO2 and Monoethanolamine

DFT calculations using a PCM solvation model were carried out to examine the reaction pathways for the formation of carbamate from CO 2 and monoethanolamine (MEA) in the presence of an additional proton acceptor, MEA or H 2 O. In both cases, the zwitterionic species [HO(CH 2 ) 2 NH 2 + —COO − ] has a lower energy than the reactants. Proton transfer from the zwitterionic species to the base (MEA) produced a carbamate product with an accompanying gradual decrease in energy. However, a similar process for the water case resulted in an implausible increase in energy, which suggests that MEA is suitable as a base but H 2 O is not.