Preferential adsorption of ethane over ethylene on a Zr-based metal–organic framework: impacts of C–H⋯N hydrogen bonding

Abstract

The separation of ethylene/ethane mixtures using energy-efficient technologies is important but challenging. In this study, we prepared a Zr-based metal–organic framework (MOF-545) possessing a high Brunauer–Emmett–Teller (BET) surface area of 2265.4 m² g⁻¹, and investigated its adsorption performance for ethylene/ethane separation. Isotherm measurements show that MOF-545 exhibits preferential adsorption of ethane over ethylene. The mechanism underlying the selective adsorption of ethane over ethylene was revealed by the calculations of preferential adsorption sites, interaction energies and adsorption density distributions of ethane and ethylene in MOF-545 via the Metropolis Monte Carlo method. Results show that the strong C–H⋯N hydrogen bonding between ethane molecules and porphyrin rings gives rise to the selective adsorption of ethane over ethylene. Thermal, air and cycling stability tests, adsorption selectivity and adsorption enthalpy calculations, and breakthrough experiments comprehensively validate the potential of MOF-545 as an efficient ethane-selective adsorbent for ethane/ethylene separation.