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Highly promotion of NO separation selectivity from flue gas by the -NH2 functional group on Fe-Ni bimetallic MOF at ambient conditions

Hao Li, Han Zhang, Xinyu Yue, Jingshu Ban, Jie Hu, Fushun Tang

Abstract

In this paper, the bimetallic MOFs of FeNi-BDC and FeNi-BDC-NH2 with similar Fe/Ni molar ratio, crystal structure, porosity and thermal stability were synthesized by solvothermal method. The results of adsorption experiment at ambient conditions showed that the adsorptive uptake of NO, CO2, O2 and N2 on FeNi-BDC was all very small under different adsorption partial pressure with weak adsorption property because of their none unsaturated adsorption sites. On the contrary, at 100 kPa, the adsorption of NO by FeNi-BDC-NH2 was considerably higher than that by FeNi-BDC, indicating that the incorporation of NH2 on the ligand could effectively enhance the adsorption of NO. The adsorption capacity of FeNi-BDC-NH2 for NO reached 142.17 cc.g-1, which was considerably higher than its capacity for CO2 and O2 and N2 under the same conditions. IAST simulations calculated the adsorption selectivity for NO/CO2 and NO/O2 under mixed atmosphere to reach 1325 and 13346, respectively, demonstrating high adsorption selectivity. In situ infrared experiments and calculations of the enthalpy of adsorption, it was demonstrated that FeNi-BDC-NH2 adsorbed NO because NO can combine with NH2 in the material to form a NONOate structure, which preliminarily explored the mechanism of NO adsorption and the influence of NH2 functional groups on the adsorption and separation of NO, and revealed that the selectivity of adsorption was closely related to the variability of the enthalpy of adsorption. This also provided a new strategy for the adsorption and separation of NO in the flue gas environment.

CH24060  Accepted 03 July 2024

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