Highly Efficient C ₃ H ₈ /C ₂ H ₆ /CH ₄ Separation Under Humidity Condition by a Metal–Organic Framework

Abstract The efficient purification of CH ₄ from multicomponent C ₃ H ₈ /C ₂ H ₆ /CH ₄ natural gas mixture under humid conditions is critical for optimizing the energy efficiency and safety of CH ₄ utilization, however, developing energy‐efficient separation technologies remains an urgent priority. In this work, the efficient separation of high purity CH ₄ (≥99.99%) from natural gas mixture is reported via adsorptive separation using a microporous metal–organic frameworks (MOFs) BUT‐315, which features high‐density C ₃ H ₈ /C ₂ H ₆ nano‐traps. BUT‐315 demonstrates outstanding separation selectivity for both C ₃ H ₈ /CH ₄ (545.8) and C ₂ H ₆ /CH ₄ (54.9), benefiting from its much higher C ₃ H ₈ /C ₂ H ₆ affinity over CH ₄ as indicated by the density functional theory (DFT) calculation. Notably, BUT‐315 achieves the highest separation potential (△Q) (26.54 mmol g ⁻¹ ) for C ₂ H ₆ /CH ₄ mixture of 10:85 ratio among reported benchmark adsorbents, ascribed to its unprecedented C ₂ H ₆ uptake at 0.1 bar along with its superior C ₂ H ₆ /CH ₄ selectivity. Besides, BUT‐315 also demonstrates exceptional CH ₄ productivity (10.76 mmol g ⁻¹ ) during the dynamic breakthrough experiment of ternary (C ₃ H ₈ /C ₂ H ₆ /CH ₄ = 5/10/85) gas mixture. Furthermore, its excellent separation performance can well maintain at least 10 adsorption–desorption cycles, even under the introduction of humidity (RH = 70%), which is a consequence of BUT‐315′s high C ₂ H ₆ /H ₂ O (28.8) and C ₃ H ₈ /H ₂ O (14.8) kinetic selectivity.