Fe-Based Microporous Metal–Organic Framework for C2H2/CO2 Separation

Acetylene (C 2 H 2 ) is a crucial industrial feedstock, but its production typically yields CO 2 -contaminated mixtures, posing a significant separation challenge. To overcome this critical separation challenge, we synthesized an iron-based metal–organic framework named STU-130 with a brn-1 underlying net. It features a 1D channel (6.4 × 5.8 Å 2 ) in the a -axis, which is decorated with uncoordinated carboxylate oxygen on the porous surface. These structural features enable STU-130 to preferentially adsorb C 2 H 2 over CO 2 through differential host–guest interaction strengths. Single-component gas adsorption tests revealed a significant difference in uptake capacities between C 2 H 2 (106.8 cm 3 g –1 ) and CO 2 (80.84 cm 3 g –1 ), with an IAST-predicted selectivity of 4.2 for equimolar C 2 H 2 /CO 2 mixtures (50:50, 298 K, and 1 bar). Dynamic breakthrough tests further confirmed the C 2 H 2 /CO 2 separation performance with the C 2 H 2 /CO 2 elution time gap of 25 min g –1 . Density functional theory calculations and grand canonical Monte Carlo simulations revealed that the uncoordinated carboxyl oxygen atoms can selectively bind C 2 H 2 through strong C–H···O hydrogen bonds (32.6 kJ mol –1 ), playing a pivotal role in C 2 H 2 /CO 2 selective separation.