Quasi-Orthogonal Configuration of Propylene within a Scalable Metal-Organic Framework Enables Its Purification from Quinary Propane Dehydrogenation Byproducts

Propylene production via nonoxidative propane dehydrogenation (PDH) holds great promise in meeting growing global demand for propylene. Effective adsorptive purification of a low concentration of propylene from quinary PDH byproducts comprising methane (CH₄), ethylene (C₂H₄), ethane (C₂H₆), propylene (C₃H₆), and propane (C₃H₈) has been an unsolved academic bottleneck. Herein, we now report an ultramicroporous zinc metal-organic framework (Zn-MOF, termed as 1) underlying a rigid one-dimensional channel, enabling trace C₃H₆ capture and effective separation from quinary PDH byproducts. Adsorption isotherms of 1 suggest a record-high C₃H₆ uptake of 34.0/92.4 cm³ cm^-3 (0.01/0.1 bar) at 298 K. In situ spectroscopies, crystallographic experiments, and modeling have jointly elucidated that the outstanding propylene uptakes at lower pressure are dominated by multiple binding interactions and swift diffusion behavior, yielding quasi-orthogonal configuration of propylene in adaptive channels. Breakthrough tests demonstrate that 30.8 L of propylene with a serviceable purity of 95.0-99.4% can be accomplished from equimolar C₃H₆/C₃H₈ mixtures for 1 kg of activated 1. Such an excellent property is also validated by the breakthrough tests of quinary mixtures containing CH₄/C₂H₄/C₂H₆/C₃H₆/C₃H₈ (3/5/6/42/44, v/v/v/v/v). Particularly, structurally stable 1 can be easily synthesized on the kilogram scale using cheap materials (only $167 for per kilogram of 1), which is important in industrial applications.