Leveraging Surface Polarity in a Cost-Effective Metal–Organic Framework for Olefin Purification From Methanol-to-Olefin Products

Research over the years has revealed the immense potential of metal–organic frameworks (MOFs) for purifying olefins such as ethylene (C₂H₄) and propylene (C₃H₆). However, many of these MOFs face challenges in terms of economic viability, particularly in production scalability, long-term stability, and process capability. In this study, we present a low-cost and easily scalable synthesis of a robust MOF material (JNU-74a), featuring a balanced surface polarity that allows for one-step C₂H₄ and C₃H₆ purification from methanol-to-olefin (MTO) products. By incorporating highly electronegative atoms on the nonpolar surface, JNU-74a exhibits substantially larger absorption capacity and stronger binding affinity for C₃H₆ and ethane (C₂H₆) compared to C₂H₄, as evidenced by their gas adsorption isotherms and heats of adsorption measurements. In-depth analyses through in situ single-crystal X-ray diffraction (SCXRD) of gas@JNU-74a unveil multiple supramolecular bindings that favor C₃H₆ and C₂H₆, confirming their preferential adsorption over C₂H₄. Breakthrough experiments demonstrate that JNU-74a can efficiently produce polymer-grade C₂H₄ (≥99.95%) and C₃H₆ (≥99.5%) from C₂H₆/C₂H₄, C₃H₆/C₂H₄, and C₃H₆/C₂H₆/C₂H₄ mixtures of different ratios in a single adsorption-desorption cycle. With its impressive separation capability, high chemical stability, and cost-effective production, JNU-74a holds promise for olefin purification from MTO products and other challenging industrial separations.