Dense Packing of Acetylene in a Stable and Low‐Cost Metal–Organic Framework for Efficient C2H2/CO2 Separation

Abstract Porous materials for C 2 H 2 /CO 2 separation mostly suffer from high regeneration energy, poor stability, or high cost that largely dampen their industrial implementation. A desired adsorbent should have an optimal balance between excellent separation performance, high stability, and low cost. We herein report a stable, low‐cost, and easily scaled‐up aluminum MOF (CAU‐10‐H) for highly efficient C 2 H 2 /CO 2 separation. The suitable pore confinement in CAU‐10‐H can not only provide multipoint binding interactions with C 2 H 2 but also enable the dense packing of C 2 H 2 inside the pores. This material exhibits one of the highest C 2 H 2 storage densities of 392 g L −1 and highly selective adsorption of C 2 H 2 over CO 2 at ambient conditions, achieved by a low C 2 H 2 adsorption enthalpy (27 kJ mol −1 ). Breakthrough experiments confirm its exceptional separation performance for C 2 H 2 /CO 2 mixtures, affording both large C 2 H 2 uptake of 3.3 mmol g −1 and high separation factor of 3.4. CAU‐10‐H achieves the benchmark balance between separation performance, stability, and cost for C 2 H 2 /CO 2 separation.