Effect of alcohols on CO2 absorption, phase splitting, and desorption behaviors of biphasic anhydrous system: The primary amine-tertiary amine of DGA-PMDETA

Abstract

Chemical absorption with organic amine solution is the most mature technology for CO2 capture. Some biphasic anhydrous absorbents show potential in reducing regeneration energy consumption, but high viscosity of the CO2 rich phase hinders its practical application. Alcohols are commonly employed as dilutes to reduce viscosity reducers, while its effect on CO2 absorption and phase splitting behaviors are still unclear. In this study, the effects of alcohols on CO2 absorption and phase-splitting of biphasic anhydrous 2-(2-Aminoethoxy)ethanol (DGA) -N,N,N′,N″,N″-pentamethyl diethylenetriamine (PMDETA) -alcohol systems are investigates. Adding alcohol reduces the viscosity of the CO2-rich phase, enhances desorption rate, and decreases the phase splitting time. The rich phase entrainment stage and the rich phase thickening stage, can be distinguished along with during CO2 absorption. The majority DGA reacts with CO2 in the rich phase since the phase splitting begins. This work may provide some basis for further biphasic absorbent design and regulation.