Analysis and insights of the second-generation ternary AMP-PZ-MEA solvents for post-combustion carbon capture: Absorption-regeneration performance

Abstract

This work comprehensively investigates absorption and regeneration performance of the second-generation AMP-PZ-MEA in comparison with the first-generation AMP-PZ-MEA, the benchmark 5 M MEA, and the conventional MEA at the same amine concentration. The performance indicators include CO2 absorption capacity, mass transfer coefficient, CO2 removal percentage, amount of desorbed CO2, initial CO2 desorption rate, and regeneration heat duty. Both 6 M (i.e., 2:2.5:1.5, 1.3:3.2:1.5, and 0.95:3.55:1.5) and 7 M (i.e., 2:2.5:2.5, 1.3:3.2:2.5, and 0.95:3.55:2.5) second-generation blends show more promising overall absorption and regeneration performance than 5 M, 6 M, and 7 M MEA. In comparison with the first-generation blend, 6 M and 7 M second-generation blends deliver more favorable mass transfer rate. Interestingly, an increase of PZ:AMP molar ratio accelerates mass transfer and absorption capacity but unfavorably affects solvent regeneration. Also, high viscosity of the second-generation 7 M blend (especially, at its equilibrium CO2 loading) retards the solvent regeneration. The key success for a formulation of AMP-PZ-MEA is appropriate PZ:AMP molar ratio and total amine concentration. Too high and too low PZ:AMP molar ratio lead to (i) solvent precipitation and (ii) imbalance of absorption and regeneration performance. Three standouts are recommended. 2.5:0.5:3 is attractive due to its low regeneration heat duty (42.1% lower than that of 5 M MEA). In terms of mass transfer coefficient, 0.95:3.55:1.5 shows 148.6% higher than 5 M MEA. 2:2.5:1.5 is also favorable according its high mass transfer coefficient (91.3% greater respecting 5 M MEA) and low regeneration heat duty (16.3% less than 5 M MEA).