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

Acetylene (C2H2) is a crucial industrial feedstock, but its production typically yields CO2-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 Å2) in the a-axis, which is decorated with uncoordinated carboxylate oxygen on the porous surface. These structural features enable STU-130 to preferentially adsorb C2H2 over CO2 through differential host–guest interaction strengths. Single-component gas adsorption tests revealed a significant difference in uptake capacities between C2H2 (106.8 cm3 g–1) and CO2 (80.84 cm3 g–1), with an IAST-predicted selectivity of 4.2 for equimolar C2H2/CO2 mixtures (50:50, 298 K, and 1 bar). Dynamic breakthrough tests further confirmed the C2H2/CO2 separation performance with the C2H2/CO2 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 C2H2 through strong C–H···O hydrogen bonds (32.6 kJ mol–1), playing a pivotal role in C2H2/CO2 selective separation.