Deep eutectic solvents as attractive media for CO2 capture

Abstract

We report a family of deep eutectic solvents (DESs) consisting of various hydrogen bonding donor–acceptor pairs as CO₂ capturing media. These DESs capture CO₂via carbamate formation upon reaction between their hydrogen bonding donor units and CO₂. Among the members tested herein, a DES made up of monoethanolamine hydrochloride–ethylenediamine exhibits an unprecedentedly high gravimetric uptake of 33.7 wt% with good initial kinetics (25.2 wt% uptake within 2.5 min) and recyclability. The given DES also shows sustainable performance in the presence of water, decent tolerance against temperature rise, and a relatively low heat of absorption which is attractive for regeneration. Even with the high gravimetric uptake, the DES has a far more suppressed corrosiveness compared to its pure monoethanolamine and ethylenediamine counterparts due to low oxygen/moisture permeability and the hydrogen bonding network that alleviates the corrosion redox cycle. The observed excellent properties in various key aspects of CO₂ capture suggest that DESs are strong candidates to replace the conventional monoethanolamine-based scrubbing technology and are worth further exploration.