Experimental study on phase change solvents in CO2 capture by NMR spectroscopy

2-(Diethylamino)ethanol (DEEA) and 3-(Methylamino) propylamine (MAPA) in combination may represent a promising absorbent system for CO2 capture due to high CO2 loading capacity, high equilibrium temperature sensitivity, low energy requirement for regeneration and relatively high reaction rate. Three different systems: DEEA–CO2–H2O; MAPA–CO2–H2O and DEEA–MAPA–CO2–H2O were studied quantitatively by NMR spectroscopy and the data are reported in the present work. The main products quantified for these systems are: carbonate-bicarbonate for the DEEA–CO2–H2O system; primary, secondary carbamate, dicarbamate for the MAPA–CO2–H2O system, and primary/secondary carbamate, dicarbamate, carbonate/bicarbonate in blended DEEA–MAPA–CO2–H2O. The speciation data of the three systems were measured and reported in the present work. The blended system of 5M DEEA–2M MAPA can form two liquid phases after being loaded with CO2 and both phases were analyzed quantitatively by NMR spectroscopy. The experimental data shows that the lower phase is rich in CO2 and MAPA while the upper phase was lean in CO2 and rich in DEEA. The ratio DEEA–MAPA in the lower phase increases with increasing partial pressure whereas for the upper phase the opposite is true. •Aqueous solution of loaded DEEA, MAPA, DEEA/MAPA studied quantitatively by NMR.•Blended system of DEEA/MAPA forms two phases when CO2 added to the solution.•Lower phase rich in CO2 and upper phase lean in CO2.•Potential for significant regeneration energy reduction.•Main products of these systems were identified and speciation reported.