A DFT study on selective adsorption of NH3 from ammonia synthesis tail gas with typical aromatic boranes

Abstract

Adsorption of NH3 from ammonia synthesis tail gas is a kind of dry deamination technology that can avoid the environmental problems associated with discharging ammonia-containing wastewater with traditional scrubbing technique. Here, the adsorption properties of different aromatic boranes on NH3, N2, H2 and CH4 are examined by density functional theory (DFT). It is demonstrated that the adsorbents show superior adsorption performance on NH3 among the selected gas molecules. The magnitude of adsorption energy on NH3 for aromatic boranes decreases sharply as the number of benzene ring on borane increases. Meanwhile, the position of methyl on benzene ring does not heavily affect the adsorption performance of aromatic boranes. According to the selectivity coefficient, the adsorbents have high selectivity for NH3 and NH3 can be desorbed readily at elevated temperature or reduced pressure. This study has the potential to offer valuable insights into the mechanism of NH3 adsorption and provide guidance for the design and development of aromatic borane adsorbing materials.