Protic ethanolamine hydrochloride-based deep eutectic solvents for highly efficient and reversible absorption of NH3

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Ternary protic DES ethanolamine hydrochloride (EACl)/resorcinol (Res)/glycerol (Gly) is a promising material for NH 3 absorption and storage because of its high NH 3 absorption capacity, simple preparation process, good thermal stability, excellent reversibility and NH 3 /CO 2 selectivity. • A serial of protic deep eutectic solvents (DESs) were prepared for NH 3 absorption. • Ternary ethanolamine hydrochloride-based (EACl) DESs are superior to binary ones. • EACl/resorcinol (Res)/glycerol Gly DES possesses high up to 0.240 g NH 3 /g DES. • EACl/Res/Gly ternary DESs have multiple interaction sites with NH 3 molecules. Ammonia (NH 3 ) is essential for nitrogen fertilizer and is also considered as a promising energy carrier recently. In considering the role of NH 3 for energy storage, the health and environmental risks from NH 3 emission must be minimized and efficiently eliminated. To this end, a wide range of materials such as metal halides, ionic liquids and porous materials have been examined for NH 3 absorption. Deep eutectic solvents (DESs) with unique properties and low cost are considered as potential solvents for absorbing NH 3 . Herein, we report a DES composed of protic ethanolamine hydrochloride (EACl), weakly acidic resorcinol (Res) and neutral glycerol (Gly) can absorb 0.240 g NH 3 /g DES for EACl/Res/Gly (1:4:5) at 293 K and 0.1 MPa, which is much higher than most of reported DESs. The absorption mechanism of NH 3 is hydrogen-bonding interaction from the results of NMR and FT-IR spectra. The ternary DESs EACl/Res/Gly have abundant hydrogen-bonding sites to absorb NH 3 without structural damage, in which EACl and Res play a major role in the interaction with NH 3, while Gly is helpful for structural stability during NH 3 absorption. Besides, DES EACl/Res/Gly (1:4:5) has good reversibility, excellent NH 3 /CO 2 selectivity, is a potential NH 3 absorption and storage material for industrial application.