Novel assessment of highly efficient polyamines for post-combustion CO2 capture: Absorption heat, reaction rate, CO2 cyclic capacity, and phase change behavior

Energy consumption is one of the crucial factors in determining the suitability of the chemical absorbents for capturing carbon dioxide (CO2). Polyamines have attracted increasing attention in recent years because of the existence of several amino functional groups that could effectively capture CO2 in their molecules. In this work, the structures of seven polyamines with excellent CO2 capture performance were investigated in relation to reaction rate and the CO2 absorption heat. A high-precision microcalorimeter was applied to analyze the ab-sorption heat of CO2 directly, and a parameter defined as the CO2 quasi-cycle capacity was employed to assess the cyclic capture capacity of CO2, absorption rate, and desorption rate. Experimental results revealed that for the selected polyamines, the increase in the ratio of the secondary amino functional group to the primary-one in the molecule leads to a decrease in the CO2 absorption heat and an increase in the CO2 cyclic capacity.The Delta Habs of the eight amines give out the order of HMDA (92.22 kJ/mol) > MAPA(90.91 kJ/mol) > AEEA (87.62 kJ/mol) > MEA (86.36 kJ/mol) > TEPA (82.95 k/mol) > AEP (82.36 kJ/mol) > 2MPRZ (77.08 kJ/mol) > PZ (74.41 kJ/ mol). The CO2 quasi-cycle capacity of 2MPZR is about twice that of the MEA. In addition, 2MPRZ was found to be an absorbent with phase change potential. The effective phase change solvent system, 2MPRZ + Triethylene glycol monobutyl ether (TGBE) + H2O, was developed in this work. Compared to the 5 M MEA aqueous solution, its sensible heat was reduced by 56.3 %, indicating that 2MPRZ is a promising absorbent.