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

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 N-2 and H-2. The underlying mechanism of prepared DESs for NH3 absorption was finally investigated by theoretical calculations and spectroscopic characterizations.