Zinc Pyrazolate Framework with Knotted‐Like Chains for Separation of Propylene/Ethylene Mixtures

Ethylene and propylene are important raw chemicals that are in high demand. Methanol-to-olefins (MTO) is a promising alternative approach for producing ethylene from non-petroleum feedstocks, in which the separation of propylene/ethylene is particularly crucial. In this study, a metal azolate framework (MAF) [Zn₇(μ-H₂O)(tppa)₄(HCOO)₂] (MAF-68, where H₃tppa = tris(4-(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)phenyl)amine) has been synthesized with rare zinc pyrazolate chains comprising μ-H₂O bridges, namely Zn₇(μ-H₂O)(Rpz)₁₂(HCOO)₂ (Rpz^- denotes pyrazolate groups), for the separation of propylene/ethylene mixtures. Sorption experiments indicated that MAF-68 shows a remarkable uptake of 4.19 mmol g^-1 for propylene (at 10 kPa), which is significantly higher than those of many other reported porous materials for C₃H₆/C₂H₄ separation. MAF-68 also shows a high selectivity of 9.5 for 2/5 C₃H₆/C₂H₄. Breakthrough experiments further confirm the separation potential of this material for high-purity C₃H₆ (99.9999%) and C₂H₄ (99.9999%).