MIL-101(Cr) loaded simple ILs for efficient ammonia capture and selective separation

Capture and recovery of ammonia (NH3) from industrial exhaust is a win–win strategy for resource utilization and contaminants control. [CAM][Cl]@MIL-101(Cr) composite designed and prepared based on ionic liquids (ILs, carbamide chloride: [CAM][Cl]) and metal–organic frameworks (MOFs, MIL-101(Cr)) has exhibited potentials for NH3 capture capacity (11.61 mmol/g) and NH3/CO2 separation (SNH3/CO2 = 3,266). The selectivity is 3.13 times as high as that of the parent MIL-101(Cr) and higher than the highest values in literature. Not only that, the breakthrough experiment of NH3/CO2 mixture further proves that high-purity NH3 can be obtained in one step (Separation Factor is about 1518). Such excellent performance originates from the synergistic effect of various types of interaction sites and adsorption spaces. The theoretical calculation reveals that the hydrogen bond (HB) interaction between ILs and NH3 plays a greatly significant role in enhancing NH3 adsorption and separation selectivity of NH3/CO2 for the composite. In addition, the composite exhibits good structural stability and regenerability. More importantly, the novel design-strategy can avoid the challenge for precise control of the microstructure and channel environment of adsorbents, which is beneficial to the development of novel materials.