Volatility of aqueous amines in CO2 capture

Abstract

The volatility of amines in amine-water was measured using a hot gas FTIR. The amine partial pressures are reported as their respective Henry’s constants. At infinite dilution in water, Henry’s constants are in the order: methyldiethanolamine (MDEA) < 2-aminoethoxyethanol (DGA©) < piperazine (PZ) < 2-Methyl Piperazine (2-MPZ) < 3-methylamino propylamine (MAPA) < ethylenediamine (EDA) < monoethanolamine (MEA) < 1,2-diaminopropane (DAP) < 1-Methyl Piperazine (1-MPZ) < 2-amino2-methyl-1-propanol (AMP). The amine Henry’s constant at 40 °C is correlated to molecular group contributions: lnH40°C=4.19−1.65(N) -0.21(NH) -1.55(R-O-R) + 0.7(Non Cyclic C- CH3) + 2.63(Cyclic N- CH3), where the number of each functional group is defined as: N = tertiary nitrogen, NH = secondary amine, R-O-R = ether, Non Cyclic C- CH3 = C- CH3 in a straight chained amine, Cyclic N- CH3 = N- CH3 in a cyclic amine. Predictions of Henry’s constants at 40 °C by the UNIFAC-DMD model in AspenPlus overestimate most measured values up to an order of magnitude except in the case of MEA.