Ni-Based Anionic Metal–Organic Framework for Efficient Separation of C₂H₂ from C₂H₄ and CO₂ Mixtures

Selective separation of acetylene (C 2 H 2 ) from carbon dioxide (CO 2 ) and ethylene (C 2 H 4 ) remains a significant challenge in the field of gas separation. Non-thermally driven separation technology based on metal–organic frameworks (MOFs) offers an efficient and environmentally friendly approach. Herein, a Ni-based anionic MOF (iMOF-1A) was employed for gas separation for the first time. The differential recognition of various gas molecules is enhanced by suitable pore sizes, accessible aromatic rings, and cations outside the framework. Experimental results demonstrate that iMOF-1A exhibits exceptional uptake ratios for C 2 H 2 /CO 2 (2.27) and C 2 H 2 /C 2 H 4 (1.48), which surpass those of most previously reported MOF materials. Furthermore, the ideal adsorbed solution theory (IAST) selectivity calculations display a promising theoretical separation performance, which is supported by molecular simulations. Breakthrough experiments further validate that iMOF-1A not only effectively separates C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 mixtures but also exhibits excellent separation performance and humidity stability for C 2 H 2 /C 2 H 4 /CO 2 ternary mixtures.