An Overview of Ammonia Separation by Ionic Liquids

Ammonia (NH 3 ) is an important chemical in several fields, such as agriculture, pharmaceutical, material, and chemicals manufacturing. However, NH 3 is a toxic gaseous pollutant and NH 3 release results in environment pollution. Minimizing NH 3 emission is of great significance for solving NH 3 -related environmental issues and promoting the reuse of NH 3 resources. Ionic liquids (ILs) are energy-saving gas absorbents, because of their low vapor pressure, good chemical stability, and high NH 3 solubility. The recent research progress of conventional, functionalized ILs and novel IL-based materials and solvents for NH 3 separation was summarized. The effects of anions and cations on NH 3 absorption capacity, as well as the absorption mechanism of ILs, were discussed in detail in this Review. The simulated dynamic parameters of NH 3 –IL systems including mass diffusivity, heat- and mass-transfer coefficient were also discussed. In addition, this Review summarized the industrial application achievement of ILs in NH 3 separation and recovery from NH 3 -containing tail gas, which spans from simulation, pilot plant to industrial applications. Finally, the research trends in NH 3 separation by IL-based systems were proposed based on existing research.