Molecular Exclusion Separation of 1‐Butene Isomers by a Robust Metal–Organic Framework under Humid Conditions

Separating n-butene and i-butene by adsorption is an energy-efficient alternative, but designing porous adsorbents that distinguish the subtle differences between the isomers is extremely challenging. Currently, adsorbents that can sieve 1-butene isomers and are stable enough to withstand humid gas mixtures are largely unmet. Herein, we propose a robust ultramicroporous metal-organic framework (MET-Fe) that can separate 1-butene isomers through molecular exclusion. The pore aperture size (4.6 Å) precisely matches the kinetic diameters of the isomers, as verified by static and kinetic adsorption experiments and theoretical calculations. Furthermore, dynamic breakthrough experiments confirmed the excellent separation performance, easy regeneration, and remarkable reusability of MET-Fe in both dry and humid conditions. With its high selectivity, large breakthrough capacity, and outstanding stability, MET-Fe provides an ideal platform for industrial butene isomers separation.