Anchoring LiCl in the Nanopores of Metal-Organic Frameworks for Ultra-High Uptake and Selective Separation of Ammonia

Ammonia (NH3) is an important chemical raw material and a unique carbon-free fuel with high hydrogen energy density. Thus, NH3 capture, storage, and desorption are of significant importance. However, high capacity capture, low energy desorption, and selective separation of NH3 are still challengs so far. Here, we report high-performance hybrid sorbents by anchoring LiCl in the nanopores of MIL-53-(OH)(2) metal-organic frameworks (MOFs). It is found that the optimal composite shows a capture capacity of 33.9 mmol g(-1) NH3 at 1.0 bar and 25 degrees C, which far exceeds the current record among the reported porous materials. Notably, the excellent capture capacity at low pressure and high temperature makes it possible to selectively capture NH3 from NH3/N-2, NH3/CO2, and NH3/H2O. It is revealed that synergistic action of NH3 coordination to the highly dispersed Li+ in the MOF nanopores and hydrogen bonding of NH3 with Cl- account for such an excellent capture and selectivity performance.

Automated summary

In this study, high-performance hybrid sorbents were reported, which were prepared by anchoring LiCl in the nanopores of MOFs. The sorbents exhibited excellent NH3 capture capacity at low pressure and high temperature, and could selectively separate NH3 from complex gas mixtures.