CO2 absorption and desorption using phase-separation gel

Abstract

Phase-separation absorbent has attracted much attention to reduce energy consumption for CO2 capture, storage and utilization. In this work, to improve handling of the absorbents, we have developed a new semi-solid absorbent, phase-separation gel, which became clouded gel by CO2 absorption and returned to transparent by CO2 desorption. We measured amounts of CO2 absorption at 50 ˚C and desorption at 90 ˚C with 10 vol% CO2 gas mixed with N2 gas. A cyclic capacity defined by the CO2 desorption amount of a phase-separation gel with solvent of 2-(ethylamino)ethanol/diethylene glycol diethyl ether was larger than those of the other homogeneous gels with 2-(ethylamino)ethanol/diethylene glycol monoethyl ether or diethylene glycol. Furthermore, the initial desorption flux of the phase-separation gel was larger than that of the absorbent solvent, suggesting that the phase-separation absorbent fixed inside the gels improves the initial desorption flux because of the larger interfacial area between the CO2-rich and CO2-lean phases inside the gel.