Metal chlorides-promoted ammonia absorption of deep eutectic solvent

• Published in: International journal of hydrogen energy 2022-04, Vol.47 (36), p.16121-16131
• Main Authors: Sun, Xiaoxue, Wang, Qinghua, Wu, Shenghan, Zhao, Xinyu, Wei, Ligang, Li, Kunlan, Hao, Jingai, Wei, Li, Zhai, Shangru, An, Qingda
• Format: Article
• Language: English
• Subjects: Deep eutectic solvents; Hydrogen–bonding interaction; Lewis acid–base interaction; Metal chlorides; NH3 absorption
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2022.03.101

Ammonia is considered as a promising hydrogen or energy carrier. Ammonia absorption or adsorption is an important aspect for both ammonia removal, storage and separation applications. To these ends, a wide range of solid and liquid sorbents have been investigated. Among these, the deep eutectic solvent (DES) is emerging as a promising class of ammonia absorbers. Herein, we report a novel type of DES, i.e., metal-containing DESs for ammonia absorption. Specifically, the NH3 absorption capacity is enhanced by ca. 18.1–36.9% when a small amount of metal chlorides, such as MgCl2, MnCl2etc., are added into a DES composed of resorcinol (Res) and ethylene glycol (EG). To our knowledge, the MgCl2/Res/EG (0.1:1:2) DES outperforms most of the reported DESs. The excellent NH3 absorption performances of metal–containing DESs have been attributed to the synergy of Lewis acid–base and hydrogen bonding interactions. Additionally, good reversibility and high NH3/CO2 selectivity are achieved over the MgCl2/Res/EG (0.1:1:2) DES, which enables it to be a potential NH3 absorber for further investigations. [Display omitted] •Metal-based deep eutectic solvents (MDESs) were prepared for ammonia absorption.•MDESs significantly improve ammonia absorption capacity.•MgCl2/Res/EG possesses a high NH3 capacity up to 0.239 g NH3/g DES at 313 K.•MgCl2/Res/EG exhibits a good recycling performance.•MDESs are potential NH3 absorbers for further investigations.