The Activator Mechanism of Piperazine in Aqueous Methyldiethanolamine Solutions

Piperazine (PZ) is added to aqueous methyldiethanolamine (MDEA) solutions to achieve a greater CO₂ absorption in CO₂ capture technology. It is referred to as “activated MDEA solutions” in the industry. However, does PZ really activate rate the CO₂ absorption of MDEA, or do PZ and MDEA just have parallel reactions with CO₂, the mechanism is not clear. In this work, a semi-batch stirred cell with CO₂ continuous operation was used to investigate the “activation” mechanism of PZ in aqueous MDEA solutions. As a comparison, kinetics of CO₂ absorbed in MDEA + MEA solution and PZ aqueous solution respectively were performed at the same conditions as MDEA + PZ solution.