One-Step Separation of Propylene From Ternary C₃ Mixtures in Amino Acid Functionalized Metal-Organic Frameworks

The low-cost C₃H₈/C₃H₆/C₃H₄ separation for high-grade C₃H₆ is of paramount importance but extremely difficult in the chemical industry. Here we report an economic strategy of functionalizing Zr-based metal-organic frameworks (MOFs) with amino acids for one-step C₃H₆ purification from ternary C₃ mixtures. The resulting UiO-67-AA exhibits exceptionally high C₃H₈ and C₃H₄ uptakes and benchmark selectivities for C₃H₈/C₃H₆ and C₃H₄/C₃H₆ separations, rivaling reported ternary C₃ separating MOFs. Breakthrough experiments confirm its excellent performance in producing high-purity C₃H₆ in one step. Crucially, the estimated over 2250 times the cost reduction among reported C₃H₈/C₃H₄-selective MOFs makes UiO-67-AA an ideal candidate for industrial C₃H₆ purification. In situ infrared spectroscopy, in situ neutron powder diffraction, and theoretical calculations indicate that amino acids offer selective binding to dually strengthen both C₃H₈ and C₃H₄ affinity over that of C₃H₆, with the amino group dictating the supramolecular interactions. Systematic evaluation across UiO-67 with diverse nitrogen moieties establishes a monotonic relationship between the separation performance and the specific nitrogen electronegativity, providing an element‑specific and quantitative electronegativity-driven design rule for next-generation MOF adsorbents for industrial olefin purification.