CO2 solubility and liquid phase ion speciation determined by C NMR13 technique in IPAB-CO2-H2O system

A newly developed alkanolamine (4-isopropylamino-2-butanol (IPAB)), with a high carbon dioxide (CO2) loading capacity and low regeneration energy, as a potential CO2 absorbent was studied in this work. The accurate quantitative C NMR13 techniques were selected to investigate the ion speciations in aqueous IPAB-CO2-H2O system. Calibration equations were established to quantify the exact ion concentrations of free amines and protonated amines in the IPAB-CO2-H2O system. The results show that the NMR method can be used to obtain both qualitative and quantitative information of the amine-CO2-H2O system. IPAB had a larger capacity for CO2 than MEA because of the dominant formation of bicarbonate rather than carbamate. No significant carbon peak of carbamate was observed at various CO2 loadings in the IPAB solutions, which can be explained by the sterically hindered effects on the forming of an unstable carbamate.