Diffusion‐Trap Mechanism‐Mediated Trace Propylene Capture in a Microporous Metal‐Organic Framework Enables Record Ethylene Purification From Cracking Gas

ABSTRACT Efficient separation of a propylene (C 3 H 6 ) and ethylene (C 2 H 4 ) mixture is very essential in the petrochemical industry but remains a major challenge due to their similar physicochemical properties. Herein, we report a diffusion‐trap mechanism in a metal‐organic framework (Cu‐TBDA) with one‐dimensional channels and functionalized side nanocages for excellent C 3 H 6 /C 2 H 4 separation. The suitable channels and confined cavities in Cu‐TBDA simultaneously boost the mass transfer efficiency and provide strong binding sites for C 3 H 6 molecule. Thus, at 298 K, Cu‐TBDA achieves ultrahigh C 3 H 6 uptake of 2.06 mmol g −1 at 0.01 bar, and record Henry selectivity of 44.0 and ideal adsorption solution theory (IAST) selectivity of 39.8 for C 3 H 6 /C 2 H 4 mixtures. The kinetic experiments proved Cu‐TBDA possesses fast C 3 H 6 adsorption kinetics (0.66 min −1 ) and high kinetic C 3 H 6 /C 2 H 4 selectivity (4.57). Dynamic breakthrough tests confirm Cu‐TBDA can gather high‐pure C 2 H 4 (> 99.95%) from C 3 H 6 /C 2 H 4 mixtures with benchmark C 2 H 4 productivities and C 3 H 6 /C 2 H 4 separation factors, along with efficient C 3 H 6 (> 99.90%) recovery during desorption. Additionally, Cu‐TBDA has good structure stabilities and can be synthesized through the simple reflux technique, which renders it a promising adsorbent for practical C 3 H 6 /C 2 H 4 separation. This work sets a new benchmark for achieving precise and efficient gas separation in industrial applications.