Hydrogen-bonded metal-nucleobase frameworks for highly selective capture of ethane/propane from methane and methane/nitrogen separation

• Published in: Nano research 2022-08, Vol.15 (8), p.7695-7702
• Main Authors: Liu, Ying, Xu, Qianqian, Chen, Lihang, Song, Changhua, Yang, Qiwei, Zhang, Zhiguo, Lu, Dan, Yang, Yiwen, Ren, Qilong, Bao, Zongbi
• Format: Article
• Language: English
• Subjects: Adsorption; Anions; Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Chemistry and Materials Science; Coalbed methane; Condensed Matter Physics; Density functional theory; Ethane; Gas mixtures; Hydrogen bonding; Low pressure; Materials Science; Methane; Nanotechnology; Natural gas; Polarizability; Research Article; Selectivity; Separation
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-022-4352-0

The separation of light hydrocarbons, including C 2 H 6 and C 3 H 8 , is essential to natural gas upgrading. Meanwhile, N 2 removal from CH 4 is also crucial to concentrating low-quality coalbed methane, but the adsorption process is challenging because of the close kinetic diameter. This work reports two hydrogen-bonded metal-nucleobase frameworks (HOF-ZJU-201 and HOF-ZJU-202) capable of efficiently separating C 3 H 8 /CH 4 , C 2 H 6 /CH 4 , and CH 4 /N 2 . Due to strong affinity for C 3 H 8 and C 2 H 6 , the low-pressure capacity for C 3 H 8 (5 kPa) and C 2 H 6 (10 kPa) of HOF-ZJU-201a exceeds most adsorbents. The ideal adsorbed solution theory (IAST) selectivity of C 3 H 8 /CH 4 and C 2 H 6 /CH 4 is 119 and 45 at ambient conditions. According to density functional theory calculations, surface polarization environments formed by electron-rich anions and electron-deficient purine heterocyclic rings contribute to the selective capture of C 3 H 8 and C 2 H 6 with greater polarizability. Furthermore, the high CH 4 adsorption capacity (1.73 mmol/g for HOF-ZJU-201a and 1.50 mmol/g for HOF-ZJU-202a at 298 K and 1.0 bar) and excellent CH 4 /N 2 selectivity (6.0 for HOF-ZJU-201 at 298 K), as well as dynamic breakthrough experiments of binary CH 4 /N 2 gas mixture implied their efficacy in the concentration of low-quality coalbed methane.