Deep eutectic solvents with multiple weak acid sites for highly efficient, reversible and selective absorption of ammonia

• Published in: Separation and purification technology Vol. 269; p. 118791
• Main Authors: Cheng, Ning-Ning, Li, Zi-Liang, Lan, Hong-Chao, Xu, Wen-Long, Jiang, Wen-Jing, Huang, Kuan, Peng, Hai-Long
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-08-2021
• Subjects: Ammonia synthesis; Chemical absorption; Deep eutectic solvent; NH3 separation; Weak acid site; Weak acid site; Deep eutectic solvent; Ammonia synthesis; Chemical absorption; NH3 separation
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2021.118791

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•Novel DESs with more than two different weak acid sites were prepared.•The DESs exhibit quite high NH3 solubilities, especially at low pressures.•The absorption of NH3 is highly reversible, and selective towards N2 and H2.•Theoretical calculations and spectroscopic characterizations were performed.
Developing new NH3 separation technology is very meaningful for the environmental protection related to ammonia synthesis process. In this work, we found that ethylamine chloride (EaCl) can form deep eutectic solvents (DESs) with resorcinol (Res) and phloroglucinol (Phl). The chemical and physical properties of new DESs were determined first, because they are the basic data for DESs. Considering that such kinds of DESs have multiple weak acid sites, we systematically investigated the NH3 absorption performance of prepared DESs. We found that the prepared DESs show chemical absorption for NH3, with quite high NH3 solubilities, particularly at reduced pressures. Specifically, the solubilities of NH3 in prepared DESs reach 9.00 mol/kg at 313.2 K and 102.1 kPa, and 3.73 mol/kg at 313.2 K and 4.7 kPa. The prepared DESs also show highly reversible absorption for NH3, and selective absorption towards N2 and H2. The underlying mechanism of prepared DESs for NH3 absorption was finally investigated by theoretical calculations and spectroscopic characterizations.