A screening study of alcohol solvents for alkanolamine-based CO2 capture

The present study was aimed at developing a non-aqueous absorbent system that does not form any precipitate/solid upon exposure to CO2. More specifically, the non-aqueous absorbent system must be a homogeneous mixture (single phase) within the whole range of CO2 loading. At the same time, sufficient amine regeneration must occur at a low temperature of 80-90 degrees C compared to reference non-aqueous monoethanolamine (MEA)based absorbents. To achieve this target, 18 alcohols were investigated as solvents and 4 alkyl-linked alkanolamines were evaluated as absorbents. Several experiments mixing alkanolamines with alcohols were performed to evaluate their CO2 capture performance. High-performance non-aqueous liquid absorbents (without solid/precipitate formation) with the advantages of higher absorption rates, higher cyclic capacities, higher regeneration efficiencies, lower specific heats, and lower heats of reaction compared to reference MEA-based non aqueous absorbents were successfully developed herein. The favorable features of these absorbents will provide the basis for the discovery of potential non-aqueous amine-based absorbents.