The Reaction of CO2 absorption in MEA(monoethanolamine) aqueous Solution: A Theoretical Study on the Effect of Neighboring Molecules

Abstract

Objectives : CO2 is one of the greenhouse gases that cause the global warming. Alkanolamine aqueous solutions are frequently used as a chemical absorption solvent for post combustion capture process. The reaction of CO2 and MEA(monoethanolamine) was studied by theoretical analysis to describe the effect of neighboring molecules.Methods : The reaction of CO2 absorption in MEA aqueous solution was investigated using DFT (density functional theory) method. The 14 reaction models were designed according to the arrangement of reactant and neighboring molecules.Results and Discussion : The structures of reactant, TS (transition state) and product were analyzed in perspective of the geometry, thermodynamics and kinetics. The neighboring molecules stabilized the structures of reactant complex due to increasing intermolecular interaction (hydrogen bond) between reactants and these molecules. The structures of reactant complex were change to the arrangement that MEA can easily react with CO2 . However, the neighboring molecules would slightly affect the reaction pathway of the structures of TS and product. The activation energy and TS structure were differed according to the type of hydrogen atom transfer, not the effect of neighboring molecules. The neighboring molecules seems to work slightly in the aspect of chemical kinetics of the reaction between CO2 and MEA in aqueous solution.