Hydration structure around CO2 captured in aqueous amine solutions observed by high energy X-ray scattering

Abstract High energy X-ray scattering measurements using synchrotron radiation were carried out for aqueous monoethanolamine, diethanolamine and 2-amino-2-methyl-1-propanol solutions before and after CO 2 absorption. Difference distribution functions around captured CO 2 were derived by applying a difference analysis method and by subtracting intramolecular interactions within CO 2 -bound molecules. Otained difference distribution functions showed a peak at r  = 0.35 nm for each solution. This peak is attributable to C(CO 2 )⋯O(water) interaction. It can be concluded that captured CO 2 forms hydrogen bond with neighboring water molecules.