Monoalkylcarbonate formation in the system monoethanolamine–water–carbon dioxide

Abstract In a recent study, we have shown by NMR spectrocopy that monoalkylcarbonates are formed in substantial amounts in aqueous solutions of the tertiary alkanolamine methyldiethanolamine (MDEA) upon loading with carbon dioxide ( CO 2 ). These species had been overlooked by most authors previously. In the present work, this study was extended to the primary alkanolamine monoethanolamine (MEA). Also here monoalkylcarbonates were found, but only at CO 2 loadings above 0.5 mol CO 2 per mol MEA. Both the amine and its carbamate form monoalkylcarbonates. The concentration of the monoalkylcarbonates was determined with 13 C NMR spectroscopy in a wide range of CO 2 loadings, MEA concentrations, and temperatures. Based on this comprehensive data the chemical equilibirium constants of the formation of the monoalkylcarbonates were determined.