Modulating the Pore Environment of a Hydrogen‐Bonded Organic Framework for Efficient Separation of a Ternary Mixture of Methanol‐to‐Olefin Products

ABSTRACT Developing energy‐efficient adsorbents for one‐step purification of ethylene (C 2 H 4 ) from ternary methanol‐to‐olefins (MTO) product mixture remains highly important but essentially unexplored in hydrogen‐bonded organic frameworks (HOFs). Herein, an ultramicroporous HOF, HOF‐36, with pyridine‐functionalized pore surfaces, was synthesized from 4,4′,4″,4‴‐(pyridine‐2,3,5,6‐tetrayl)tetrabenzoic acid. According to the single‐component sorption isotherm, the activated HOF‐36 (HOF‐36a) exhibits preferential adsorption toward ethane (C 2 H 6 ) and propylene (C 3 H 6 ) over C 2 H 4 , with IAST selectivities of 1.6 for C 2 H 6 /C 2 H 4 and 13.1 for C 3 H 6 /C 2 H 4 mixtures at 298 K, where the C 3 H 6 /C 2 H 4 selectivity surpasses those of all previously reported HOFs. Dynamic breakthrough experiments demonstrate that HOF‐36a enables one‐step purification of polymer‐grade C 2 H 4 (≥ 99.99%) from binary and ternary MTO‐related hydrocarbon mixtures. Notably, HOF‐36a affords a C 2 H 4 productivity of 1.1 L kg −1 for the challenging ternary C 3 H 6 /C 2 H 6 /C 2 H 4 (33.3/33.3/33.3, v / v / v ) mixture. Moreover, the separation performance remains nearly unchanged under humid conditions and repeated breakthrough cycles. Theoretical calculations reveal that the pyridine‐functionalized pore surface strengthens the binding affinity toward C 2 H 6 and C 3 H 6 through enhanced host–guest interactions. This work demonstrates the potential of HOFs for challenging multicomponent olefin separation and highlights pore environment engineering for regulating host–guest interactions.