A pacs-type metal-organic framework with high adsorption capacity for inverse CH/CH separation

• Published in: New journal of chemistry 2024-06, Vol.48 (23), p.1577-1583
• Main Authors: Zhang, Kuo, Pang, Jing-Jing, Lian, Xin, Song, Zi-Han, Yuan, Yue-Chao, Huang, Hongliang, Yao, Zhao-Quan, Xu, Jian
• Format: Article
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d4nj00605d

Separation of the mixture of ethylene (C 2 H 4 ) and ethane (C 2 H 6 ) to produce polymer-grade C 2 H 4 is of prime importance in the petrochemical industry. In this context, metal-organic frameworks (MOFs) featuring tunable pore metrics and surface chemistry, especially those with inverse C 2 H 6 /C 2 H 4 adsorption selectivity, hold great promise in energy-effective purification of C 2 H 4 by adsorptive separation, but often encounter the well-known trade-off between adsorption selectivity and capacity. In this work, we report two new MOFs by deploying the pore-space-partition (PSP) strategy for the purpose of reducing the pore aperture size while retaining the gas-accessible pore volume. As a result, Ni-bodc-tpt (bodc = bicyclo[2.2.2]octane-1,4-dicarboxylic acid, tpt = 2,4,6-tri(4-pyridyl)-1,3,5-triazine) by combining optimal pore size, large cage pore volume, and rich C-H binding sites exhibits concurrently high C 2 H 6 adsorption capacity (131.65 cm 3 g −1 ) and C 2 H 6 /C 2 H 4 selectivity (1.8) at 298 K and 1 bar, which is superior or comparable to many benchmark C 2 H 6 -selective MOFs. A dynamic breakthrough experiment demonstrates that high-purity C 2 H 4 (>99.9%) can be harvested in one step from a binary mixture of C 2 H 6 /C 2 H 4 (50/50, v/v), attesting to the feasibility of this new MOF as a prospective C 2 H 4 purification agent. A pacs-type MOF shows a decent inverse adsorption of C 2 H 6 over C 2 H 4 for one-step C 2 H 4 purification by addressing the trade-off between adsorption selectivity and capacity.