Superior energy-saving splitter in monoethanolamine-based biphasic solvents for CO₂ capture from coal-fired flue gas

A monoethanolamine/1-propanol aqueous biphasic absorbent with rapid absorption rate and low regeneration energy was proposed to enhance the CO₂ capture technology. 1-propanol was used as a physical solvent and phase splitter, which increased the mass transfer coefficient from 1.83 to 2.36 × 10⁻¹⁰ mol cm⁻² s⁻¹ Pa⁻¹ and triggered the liquid–liquid phase separation due to the salting-out effect. CO₂ capture process was modeled using an Aspen plus simulator by incorporating a decanter according to experimental results of phase separation. Energy consumption was analyzed considering the solvent circulation rate, lean loading, operating pressure, and biphasic solvent concentration. Because only the CO₂-rich phase was required to be regenerated, a decreased stripping volume and high m_CO2/m_H2O were achieved. Sensible and vaporization heats substantially decreased by 80% and 75%, respectively, and the total regeneration energy decreased by 39.85%. Moreover, the cyclic capacity was increased from 1.01 to 2.51 mol/kg, which substantially reduced the equipment footprint. This study provides new insights into biphasic solvents with considerable energy saving for CO₂ capture.