Regulation of Layer Torsion in Metal‐Organic Framework Adsorbent for High‐Purity and High‐Productivity Sieving Purification of 1‐Butene

ABSTRACT As a crucial petrochemical feedstock, adsorptive purification of 1‐Butene (1‐C ₄ H ₈ ) by removing trace butadiene (C ₄ H ₆ ) impurities is imperative. However, the scarcity of porous adsorbents with appropriate pore structures leads to undesired co‐adsorption and insufficient low‑pressure C ₄ H ₆ uptake. Herein, we regulate the torsion of metal‐organic frameworks via the coordination geometry to delicately control framework flexibility and pore architecture. Compared to the prototypical NCU‐628a with flexible open channels, the spatial repositioning of carboxylate groups in the pillar ligands largely restricts the torsion of 2D layers, yielding rigid NCU‐628b featuring a transformed multi‐cage architecture with contracted pore apertures. The tailored NCU‐628b enables molecular sieving of C ₄ H ₆ /1‐C ₄ H ₈ mixtures with exceptional C ₄ H ₆ uptake of 29.1 cm ³ g ⁻¹ at low‐pressure (0.01 bar), delivering a record C ₄ H ₆ /1‐C ₄ H ₈ uptake ratio (21.7) and ultrahigh selectivity (3336.8). Dynamic breakthrough experiments confirm its practical C ₄ H ₆ /1‐C ₄ H ₈ separation performance with excellent cyclability and stability. Notably, ultrahigh‐purity 5N‐grade 1‐C ₄ H ₈ (>99.999%) can be directly obtained with a high productivity of 121.01 L kg ⁻¹ .