Screening of Biphasic Solvents for Energy Efficient CO2 Capture

Abstract

Phase separation of biphasic solvent during CO2 absorption was investigated. Tested amine components were selected according to the molecular structure. Phase separation experiments shows the biphasic solvents comprised of polyamine and tertiary alkanolamine, such as DETA/DEEA and TMPDA/DEEA, may be suitable for the biphasic system due to easy phase separation. The CO2 absorption capacity of those biphasic solvents with different amine concentration was compared. The mixed amine solution of 3M DETA and 2.5M DEEA was the most potential blend in this screening study. CO2 absorption capacity of this biphasic solvent at 313K and 15kPa CO2 partial pressure was 201 gCO2/kg and CO2-rich phase volume fraction was 80%. Liquid solutions from the upper and lower phases were analyzed individually. The upper phase was mainly DEEA with very low CO2 loading, the lower phase was composed of DETA, DEEA and water with very high CO2 loading. The CO2 and amine distribution between the upper and lower phases were measured during CO2 absorption.