Effective ammonia separation by non-chloride deep eutectic solvents composed of dihydroxybenzoic acids and ethylene glycol through multiple-site interaction

• Published in: Separation and purification technology 2023-03, Vol.309, p.123136, Article 123136
• Main Authors: Zheng, Lu, Zhang, Xinyue, Li, Qiuke, Ma, Yongde, Cai, Zhenping, Cao, Yanning, Huang, Kuan, Jiang, Lilong
• Format: Article
• Language: English
• Subjects: Absorption capacity; Chloride free; Deep eutectic solvent; Gas separation; Multiple site
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2023.123136

Novel non-chloride dihydroxybenzoic acids based deep eutectic solvents (DESs) have been designed for effecitve separation of NH3. High NH3 absorption capacity, selectivity and excellent reversibility were achieved by the designed DESs. [Display omitted] •A new series of non-chloride DESs composed of DHBAs and EG were prepared.•DHBA + EG DESs can absorb up to 5.64 mol/kg of NH3 at 298.2 K and 0.1 bar.•DHBA + EG DESs also demonstrate selective and reversible absorption of NH3.•The high performance of NH3 separation originates from multiple-site interaction. The effective separation of ammonia (NH3) has important implication for the conversion improvement and pollution control during the synthesis of NH3. In the present work, a novel kind of non-chloride deep eutectic solvents (DESs) were constructed from dihydroxybenzoic acids (DHBAs) and ethylene glycol (EG). The DHBA + EG DESs exhibit several weak acidic sites and hydrogen-bond sites, thus were proposed for NH3 separation. We found that the amounts of NH3 absorbed by DHBA + EG DESs are quite impressive, particularly at reduced pressures. The capacities can reach 5.64 and 11.69 mol/kg at 0.1 and 1 bar respectively, when the temperature of 298.2 K is considered. Besides, after five absorption–desorption cycles, the DHBA + EG DESs can preserve the excellent NH3 absorption performance. The DHAB + EG DESs can also selectively absorb NH3 from N2 and H2 in the mixed gas. The NH3 absorption mechanism of DHBA + EG DESs was further deeply illustrated by spectroscopic techniques and theoretical calculations.