Volatility of amines for CO2 capture

Volatility is a critical criterion for amine selection for CO2 capture from low pressure gas streams. The Henry's law constant (Ham) in water of 24 novel amines, including 18 tertiary amines, 3 hindered amines, 2 ether amines, and 1 pyridine derivative was measured at 40 °C using a hot gas FTIR. 14 of them have a Ham less than 2-amino-2-methyl-1-propanol (AMP). A group contribution model that correlates Ham to molecular structure was developed based on the data from this work and data from literature. Non-cyclic groups and cyclic groups have significant effect on the volatility of the amine. The amine partial pressure (Pam) of tertiary and hindered amines was also measured in a blend with PZ at 40 °C and their normal CO2 loading range for flue gas CO2 capture. With increased pKa, the Pam of tertiary and hindered amines becomes a stronger function of CO2 loading. These results at nominal lean loading were correlated with Ham of the amine.