Unraveling a novel biphasic CO2 capture process through rigorous modeling

Abstract

Modification of the chemical absorbent is a crucial aspect in the field of CO2 capture. Nevertheless, the consequences arising from the utilization of modified solvents have not been thoroughly examined on a process scale. This study investigates a biphasic chemical absorption process for CO2 capture using a blended solvent composed of 2-ethylamino ethanol (EAE), diethylene glycol diethyl ether (DEGDEE), and water. The design was based on rigorous consideration of the physical properties of the pure components and the solution, as well as chemical equilibrium. Our results indicate that the proposed biphasic process reduces specific regeneration energy by 6.45 % compared to the conventional method using monoethanolamine (MEA) solution as a solvent (biphasic: 3.41 GJ/Ton; conventional: 3.63 GJ/Ton). Furthermore, it presents the advantage of utilizing low-temperature waste heat for solvent stripping, resulting in a notable 56 % decrease in indirect emissions (biphasic process: 0.119 Ton/Ton, conventional: 0.274 Ton/Ton). When processing flue gases that are more diluted in CO2, the CO2-e of the biphasic process was only slightly increased. Finally, the techno-economic analysis demonstrated that the biphasic process exhibits minimum required treatment prices (MRTPs) comparable to those of conventional methods for treating flue gases with CO2 concentrations ranging from 10 to 19 mol% (biphasic: 0.755 to 1.452 USD/kg, conventional: 0.756 to 1.455 USD/kg). This finding highlights the economic potential of the biphasic process. Overall, this investigation sheds light on the potential of intensifying the CO2 capture process in a biphasic environment.