Efficient absorption of low pressure NH3 by non-ionic phenol-based deep eutectic solvents with multiple acidic sites

In chemical industry, efficient absorption of ammonia (NH 3 ) from industrial exhaust remains a challenge and significant issue for resource utilization and pollution control. Present study proposed a new strategy to design non-ionic deep eutectic solvents (DESs) using phenolic analogues. Several phenol-based DESs with multiple acidic sites were constructed by paring catechol (Cat) or resorcinol (Res) with phenol (PhOH) and investigated as feasible NH 3 absorbents from physical property, NH 3 absorption performance, and mechanism analysis. Among the as-obtained DESs, Res/PhOH (1:3) demonstrated attractive NH 3 absorption capacity at 303.15 K (11.862 mol/kg at 101.3 kPa, and 6.391 mol/kg at 5.0 kPa), surpassing most DESs and ionic liquids (ILs) reported in the literatures. Meanwhile, it displayed good reversibility, satisfactory thermal stability, and high NH 3 /CO 2 selectivity. The mechanism of NH 3 absorption was further elucidated using FTIR and NMR spectra, and Quantum chemistry calculation, and inferred as the strong and multiple interaction between NH 3 and weakly acidic sites of DESs.