Pyridine derivatives as hydrogen bond acceptors to prepare deep eutectic solvents for ammonia storage

Ammonia is a liquid-phase hydrogen storage medium, and the development of ammonia storage and transportation technology is a great challenge to the utilization of hydrogen energy and green ammonia synthesis technology. In the present work, a series of pyridine derivatives-based deep eutectic solvents (DESs) using pyridine derivatives as novel hydrogen bond acceptors were designed and synthesized for ammonia storage and separation. The experimental and characterization results demonstrated that the DESs composed of binary solid components of 2-aminopyridine (2-NH2Py) and resorcinol (Res) exhibited ideal thermal stability, high ammonia absorption capacity (0.185 gNH3/gDES at 303.15 K) and good NH3/CO2 selectivity (92.2 at 313.15 K and 0.1 MPa). The formation and ammonia absorption mechanisms of DESs were analyzed by NMR, FT-IR spectroscopies and quantum chemical calculations. Pyridine derivatives as novel hydrogen bond acceptors enrich the family of DESs, and provide opportunities for the development of efficient materials for ammonia storage and separation.