Investigation of Multi-Cycle Absorption Performance of Organic Amines under Low-Flux and Low-Partial-Pressure CO₂ Conditions

To evaluate the stability of amine absorbents in low-flow, low-concentration, and low-partial-pressure CO₂ absorption-desorption cycles, two key performance parameters were analyzed: the ratio of apparent cycle capacity to maximum cycle capacity (ACCR/MCCR) and the 20-cycle retention capacity. These metrics were applied to assess the absorption stability, desorption properties, and cyclical performance of ethanolamine (MEA), triethylenetetramine (TETA), N-methyldiethanolamine (MDEA), and the MDEA/TETA blend. Experimental results demonstrated that the ACCR/MCCR directly quantifies the divergence between CO₂ absorption efficiency under constrained operational conditions and the theoretical maximum capacity, while the 20-cycle retention capacity reflects the evolution of CO₂ transport capability during repeated cycles. The MDEA/TETA mixed absorbent achieved the highest ACCR/MCCR of 78.10%, indicating minimal efficiency loss under suboptimal conditions. Additionally, it maintained a stable 20-cycle capacity of 0.75 mol CO₂/mol amine, showcasing robust cyclical durability. This combination of high ACCR/MCCR and sustained capacity highlights the MDEA/TETA system’s potential for industrial applications, particularly in capturing CO₂ from flue gas generated by fossil fuel combustion, where stability under fluctuating low-concentration conditions is critical.