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This work studies the potential of using the tertiary amines 3-dimethylamino-1-propanol (3DMA1P), 3-diethylamino-1-propanol (3DEA1P) and 1-(2-hydroxyethyl)pyrrolidine (1-(2HE)PRLD) as an alternative to 2-(diethylamino)ethanol (DEEA) in the blend with 3-(methylamino)propylamine (MAPA). Vapour pressure of the three tertiary amines and vapour-liquid equilibrium (VLE) of the binary mixtures 3DMA1P/H2O, 3DEA1P/H2O and 1-(2HE)PRLD/H2O at T = (353, 363 and 373) K were measured in a modified Swietoslawski ebulliometer. The vapour pressure of the pure amines was fitted to the Antoine equation, and the P - T - x - y data were fitted to NRTL equations. VLE of the CO2 loaded blended amines were measured in the temperature range of T = 313 to 393 K, and speciation data of equilibrated samples at different CO2 loadings were obtained by NMR spectroscopy. The study showed that the tertiary amines 3DMA1P, 3DEA1P and 1-(2HE)PRLD in the binary amine/H2O system were less volatile than DEEA in aqueous solution. The CO2 loaded blended amines showed comparable VLE behaviour, as well as speciation, and obtained a cyclic capacity higher than that of 30 wt% MEA but similar to most of the blended amines studied in the literature. The overall results indicated that the tertiary amines studied in this work can be used as an alternative to DEEA.
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