In this work, we studied the CO2 absorption mechanism by nonaqueous solvent comprising hindered amine 2-[(1,1-dimethylethyl)amino]ethanol (TBAE) and ethylene glycol (EG). The NMR and FTIR results indicated that CO2 reacted with an -OH group of EG rather than the -OH of TBAE by producing hydroxyethyl carbonate species. A possible reaction pathway was suggested, which involves two steps. In the first step, the acid-base reaction between TBAE and EG generated the anion HO-CH2-CH2-O-; in the second step, the O- of HO-CH2-CH2-O- attacked the C atom of CO2, forming carbonate species.
Keywords: capture; carbon dioxide; greenhouse gas; hindered amine; water lean.