Experimental Modeling of CO2 Sorption/Desorption Cycle with MDEA/PZ Blend: Kinetics and Regeneration Temperature

CO2 sorption-desorption cycles with a methyldiethanolamine (MDEA)/piperazine (PZ) blend have been performed with a rotoevaporator. Similar to other CO2 separation technologies, the heating involved in MDEA/PZ solvent regeneration is the most energy-intensive step in the overall CO2 separation process. Thus, this study investigated the desorption kinetics under low-pressure (<200 mbar) and low-temperature conditions in the range from 308 to 363 K with the aim of reducing costs. The CO2 desorption time to unload the samples from similar to 2.35 mol/kg to below the threshold of 1 mol/kg was reduced from 500 s at 333 K to 90 s at 363 K. The Avrami-Erofoyev model was found to fit the experimental kinetic data accurately. The Arrhenius law calculations provided an activation energy of the CO2 desorption process equal to 76.39 kJ/mol. It was demonstrated that the combination of a pressure reduction and the increase in temperature resulted in an enhancement of the desorption kinetics, especially at low temperatures. The combined effect of these two factors resulted in higher desorption kinetics compared to the individual effects of either factor alone. Solvent regeneration at a low temperature was demonstrated to be a valid option when coupled with pressure reduction.

Automated summary

This study focused on the energy-intensive heating step in the MDEA/PZ solvent regeneration process for CO2 separation. By investigating the desorption kinetics under low-pressure and low-temperature conditions, it was found that the combination of pressure reduction and temperature increase significantly enhanced the desorption kinetics, especially at low temperatures.