Fluorine-Functionalized Pore-Space-Partitioned Metal–Organic Frameworks for One-Step Methane Purification

High Resolution Image Download MS PowerPoint Slide The efficient removal of ethane (C 2 H 6 ) and propane (C 3 H 8 ) from natural gas is vital for purification. A synergistic pore engineering integrating pore space partition and fluorine functionalization in metal–organic frameworks (MOFs), which may effectively promote the C–H···π and C–H···F interactions for effective methane separation. This strategy was validated using two fluorine-functionalized pore-space-partitioned MOFs (SNNU-707/-708) constructed by introducing varying numbers of −CF 3 groups on the pore surface. Single-component adsorption isotherms show high adsorption of SNNU-707/-708 for C 2 H 6 and C 3 H 8 were 94.9/63.6 cm 3 g –1 and 96.4/68.9 cm 3 g –1, significantly exceeding that of CH 4 (18.9/13.4 cm 3 g –1 ). Ideal adsorbed solution theory (IAST) indicated high selectivity values of 85.2/116.6 for C 3 H 8 /CH 4 (50/50) and 16.7/17.0 for C 2 H 6 /CH 4 (50/50). Notably, the actual breakthrough interval times of SNNU-707 for C 3 H 8 /CH 4 (5/95) and C 2 H 6 /CH 4 (10/90) can reach 502 and 78 min·g –1 and yield high-purity CH 4 (>99.5%) at 5.89 mmol g –1 from ternary mixtures. Grand Canonical Monte Carlo (GCMC) simulations attribute this performance to synergistic weak interactions (C–H···π, C–H···F, C–H···O/N) between MOF and alkane. Specially, thanks to the fluorine-functionalized pore environments, both MOFs maintain structural integrity and separation performance under harsh conditions up to 98% relative humidity, which is crucial for practical wet natural gas separation.