A Porous MOF Containing Accessible Open Metal Sites with Low Steric Hindrance for Selective Separation of Hydrocarbons

Conventional hydrocarbon production yields impure products, while solvent-based purification techniques emit volatile pollutants and are energy-intensive. Metal–organic frameworks (MOFs) with open metal sites (OMSs) offer an energy-efficient and eco-friendly alternative, yet steric hindrance from OMSs with traditional geometries restricts multimolecule adsorption. Herein, a stable Ni-MOF incorporating novel seesaw-geometry OMSs was constructed using a 1,3,5-tris(pyrazolyl)benzene ligand. Owing to the presence of accessible low-steric resistance OMSs, the activated MOF displays exceptional binding affinities for CO 2 and C 2 H 2 over C 2 H 4 and CH 4, as well as high ideal adsorbed solution theory (IAST) selectivities for C 2 H 2 –CO 2, C 2 H 2 –C 2 H 4, C 2 H 2 –CH 4, and CO 2 –CH 4 mixtures. Experimental breakthrough curves further validated the potential of Ni-MOF for industrial C 1 /C 2 hydrocarbon purification. Grand canonical Monte Carlo (GCMC) simulations revealed that the low-steric resistance OMSs could interact strongly with more C 2 H 2 and CO 2 molecules, leading to higher affinities and separation abilities.