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

Abstract

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 C3H6capture and effective separation from quinary PDH byproducts. Adsorption isotherms of 1 suggest a record-high C3H6uptake of 34.0/92.4 cm3cm-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/C3H8mixtures 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.