A novel cage-based metal–organic framework for efficient separation of light hydrocarbons

Abstract

The development of effective physical adsorbents for the separation of light hydrocarbon gas mixtures is a challenging and prime step in the petrochemical industry. In this work, we designed and synthesized a novel cage-based metal–organic framework, SDU-CP-8, featuring an ellipsoid-shaped cage and a 3-nodal (4,6,8)-connected network. SDU-CP-8 displays remarkable adsorption capacities for C₃H₈ (148.9 cm³ g⁻¹) and C₂H₆ (126.3 cm³ g⁻¹), significantly higher than that for CH₄ (16.6 cm³ g⁻¹) at 273 K and 100 kPa, while the gas uptake value for C₂H₂ (116.1 cm³ g⁻¹) is higher than that for CO₂ (61.8 cm³ g⁻¹) at 273 K and 100 kPa. Moreover, breakthrough experiments demonstrate that SDU-CP-8 can effectively separate C₃H₈/C₂H₆/CH₄ and C₂H₂/CO₂ gas mixtures. Theoretical calculations show that multiple interactions (C–H⋯O and C–H⋯π) within the cage of SDU-CP-8 significantly contribute to the high gas uptake by the framework. These results show that SDU-CP-8 is a promising adsorbent for both CH₄ and C₂H₂ purification.