Hui Zhang,Qiang Fu,Hongyun Qin,Xia Chen,Qicheng Zhang,Zixu Dong,Haoyuan Li,Shoudong Wang,Ming Wang
Hydrogen recovery from ammonia purge gas is a desirable method to relieve the pressure of increasing demand for hydrogen. Metal-organic frameworks (MOFs) are promising adsorbents for the separation of the H 2 –N 2 mixture. However, the separation of the H 2 –N 2 mixture using MOFs remains challenging due to the lack of adsorptive mechanism. Herein, the adsorption mechanism of the H 2 –N 2 mixture in SIFSIX-2-Cu-i has been systematically investigated with the method of a combination of excess adsorption experiments, molecular simulations , and DFT calculations. In the Grand Canonical Monte Carlo (GCMC) simulations, the polarizable force field was first applied to the adsorption of pure H 2 or N 2 and H 2 –N 2 mixture in SIFSIX-2-Cu-i. Ab Initio Molecular Dynamics (AIMD) was performed to investigate the distribution of the guest molecules in the pores of SIFSIX-2-Cu-i. Finally, Density functional theory (DFT) calculations were performed to predict the transfer of charge between MOF and guest molecules. Results revealed two binding sites of H 2 or N 2 in SIFSIX-2-Cu-i. A relatively high thermodynamic adsorption selectivity for N 2 over H 2 has been observed in SIFSIX-2-Cu-i. Furthermore, SIFSIX-2-Cu-i also exhibits a greater affinity with N 2 than with H 2 , which is probably because of the stronger induction interactions between F2 atoms and N 2 molecules. These findings are of significance to guide the design of the new highly selective adsorbents for the separation of H 2 /N 2 .
Separation and purification of light hydrocarbons have been the critical processes for producing basic chemicals and polymers in petrochemical industry. Adsorbents with high performance are highly demanded for the separation of light hydrocarbons. However, the adsorbents filling in the packed bed when evaluated will inevitably induce reduced performance and increased pressure drop that considerably impede their application. Herein, mixed-matrix fiber adsorbents with anion-pillared hybrid microporous materials (SIFSIX-2-Cu-i) embedded within poly (ether sulfone) (PES) are constructed to enable an energy-efficient propylene/propyne separation. Owing to the sufficient binding sites and abundant channels for selective gas transfer, the fiber adsorbents achieve high C 3 H 4 uptake capacity of 0.963 mmol g −1 in the propylene/propyne (99/1) mixture breakthrough experiments. Moreover, fiber adsorbents exhibit good tolerance toward high gas velocity and show distinctively low pressure drop, which will be advantageous in industrial applications. This work provides a strategy for fabricating high-performance mixed-matrix fiber adsorbents.
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