A Porous MOF Containing Accessible Open Metal Sites with Low Steric Hindrance for Selective Separation of
Shi-Hui Zhang1,2, Xiu-Yuan Li1,3, Shu-Yu Zhang1
1Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Materials Science, Northwest University. Xi'an 710127, P. R. China.
Abstract:
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 CO2 and C2H2 over C2H4 and CH4, as well as high ideal adsorbed solution theory (IAST) selectivities for C2H2-CO2, C2H2-C2H4, C2H2-CH4, and CO2-CH4 mixtures. Experimental breakthrough curves further validated the potential of Ni-MOF for industrial C1/C2 hydrocarbon purification. Grand canonical Monte Carlo (GCMC) simulations revealed that the low-steric resistance OMSs could interact strongly with more C2H2 and CO2 molecules, leading to higher affinities and separation abilities.
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