Constructing ternary deep eutectic solvents with multiple sites for ammonia storage

Abstract

Ammonia is a key chemical raw material and a promising carrier for the store and transportation of renewable energies. The absorption or adsorption of ammonia is an important part for the current air pollution control and the forthcoming green ammonia synthesis. Deep eutectic solvent (DES) has the advantages of excellent designability and environmental friendliness, and has thus been actively investigated in gas absorption. Herein, we report a type of ternary DESs with multiple active sites for binding NH3, that are consisting of 4-Amino-4H-1,2,4-triazole (Atri), glycerol (Gly), and resorcinol (Res). The effects of DES composition, temperature, and NH3 partial pressure on the NH3 absorption performance were systematically investigated. A high ammonia capacity of 0.193 g NH3 per g DES is achieved over the ternary DES Atri/Res/Gly (1:5:4) at 313.15 K and 0.1 MPa, which is superior to most previously reported DESs. NMR and FT-IR spectroscopy characterizations suggest that the formation mechanism of DESs and the absorption mechanism of NH3 are based on the formation of hydrogen bonds, and the multiple absorption sites of DESs enable them to obtain high NH3 absorption capacities.