Hydration structure around CO 2 captured in aqueous amine solutions observed by high energy X-ray scattering

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 CO2 absorption. Difference distribution functions around captured CO2 were derived by applying a difference analysis method and by subtracting intramolecular interactions within CO2-bound molecules. Otained difference distribution functions showed a peak at r=0.35nm for each solution. This peak is attributable to C(CO2)⋯O(water) interaction. It can be concluded that captured CO2 forms hydrogen bond with neighboring water molecules.