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.