Characterization and kinetics of CO2 absorption in potassium carbonate solution promoted by 2-methylpiperazine

Abstract

In this work, the absorption performance of potassium carbonate (K2CO3) promoted by 2-methylpiperazine (2-MPZ) was examined for CO2 capture by using a stirred cell reactor at temperatures between 303 and 323 K. The density, viscosity and loading capacity of K2CO3 + 2MPZ solutions were experimentally measured. Moreover, Hatta number, enhancement factor, Henry’s constant and diffusivity of CO2 and N2O in K2CO3 + 2MPZ solution was also determined to check the fast pseudo-first-order reaction regime. Furthermore, kinetics of the reaction of CO2 with K2CO3 + 2MPZ solution was studied and described in detail using zwitterion mechanism. The CO2 absorption rate along with the reaction rate constant (k2) for the CO2 + K2CO3 + 2MPZ system were obtained and the results were compared with other systems. It was concluded that the CO2 absorption rate is first order with respect to both 2MPZ and CO2, the activation energy and k2 were found to be 62.45 kJ/mol and8.92×1014exp(−7511.8T), respectively. The results revealed that the K2CO3 + 2MPZ solution could be an attractive solvent for post-combustion CO2 capture due to its excellent characteristics such as the higher CO2 absorption rate and capacity compared to MEA.