Formation of a N/O/F-Rich and Rooflike Cluster-Based Highly Stable Cu(I/II)-MOF for Promising Pipeline Natural Gas Upgrading by the Recovery of Individual C3H8 and C2H6 Gases

Hongtao Cheng; Qian Wang; Liuli Meng; Pan Sheng; Zonghui Zhang; Min Ding; Yajun Gao; Junfeng Bai

doi:10.1021/acsami.1c11971

Formation of a N/O/F-Rich and Rooflike Cluster-Based Highly Stable Cu(I/II)-MOF for Promising Pipeline Natural Gas Upgrading by the Recovery of Individual C₃H₈ and C₂H₆ Gases

ACS Appl Mater Interfaces. 2021 Sep 1;13(34):40713-40723. doi: 10.1021/acsami.1c11971. Epub 2021 Aug 18.

Authors

Hongtao Cheng¹, Qian Wang¹, Liuli Meng¹, Pan Sheng¹, Zonghui Zhang¹, Min Ding¹, Yajun Gao², Junfeng Bai¹

Affiliations

¹ Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China.
² State Key Laboratory of Coordination Chemistry, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China.

PMID: 34405673
DOI: 10.1021/acsami.1c11971

Abstract

Due to the ultralow amounts of C₃H₈ and C₂H₆ gases, to design and synthesize water-stable MOFs that are promising for real-world efficient pipeline natural gas (NG) upgrading by the recovery of individual C₃H₈ and C₂H₆ gases is still a great challenge. Here, a N/O/F heteroatom-rich and rooflike [Cu(II)₄Cu(I)₂(COO)₄(tetrazolyl)₆] cluster-based ultra-microporous tsi-MOF (SNNU-Bai68) was afforded as a multiple heteroatom-rich and curved-surface-shaped cluster-based ultra-microporous MOF and the first porous MOF based upon such rooflike [Cu(II)_xCu(I)_y(tetrazolyl)_z]^(2x+y-z)+ cluster. In SNNU-Bai68, the rooflike cluster was further assembled into a 1D chain secondary building block (SBB), which led to a high density of accessible potential adsorptive sites. Very interestingly, it exhibited the most promising balance of high gas adsorption uptakes at 0.01, 0.03, and 0.05 bar, high C₃H₈/CH₄, C₃H₈/C₂H₆, and C₂H₆/CH₄ adsorption selectivities, moderate adsorption enthalpies, and high water and chemical stability for pipeline natural gas upgrading by the recovery of individual C₃H₈ and C₂H₆ gases, which was further confirmed by the breakthrough experiments of the gas mixtures with/without 74% RH. Furthermore, the SC-XRD and GCMC studies revealed that the successful separation of C₃H₈, C₂H₆, and CH₄ gases in SNNU-Bai68 is due to different synergistic effects of H-bonds between the frameworks at three adsorptive sites around each rooflike cluster and those different gas molecules, which were initially described systematically by the number of H atoms from the gas molecules, the total number of H-bonds within the synergistic H-bonds, and the binding energy of the framework at an adsorption site toward the gas molecules. In addition, this work may provide a method for the construction of a multiple heteroatom-rich and curved-surface-shaped cluster-based ultra-microporous MOF as a novel approach to build MOFs with polar pore surfaces, suitable pore sizes, and unique pore shapes to maximize the synergistic H-bonds between the framework and guests.

Keywords: C3H8 and C2H6 recovery; N/O/F-rich MOF; chemically stable; pipeline natural gas upgrading; rooflike cluster.