Water-Stable Metal−Organic Framework with a Tuned Pore Microenvironment for Selective Acetylene Separation

Abstract

Due to the highly similar molecular dimensions, polarizability, and physicochemical properties among C₂H₂, CO₂, C₂H₆, and C₂H₄, these gas molecules always exhibit analogous adsorption behaviors in conventional porous adsorbents. Therefore, the precise and high-efficient separation of C₂H₂ from multi-component light hydrocarbon mixtures remains a formidable challenge in practical industrial separation processes. In this work, we have synthesized a metal−organic framework denoted ZJNU-412, which possesses one-dimensional channels functionalized with uncoordinated O atoms and aromatic rings. These functional groups serve as high-affinity recognition sites toward C₂H₂. At 298 K and 1 bar, the C₂H₂ uptake capacity of ZJNU-412 reaches 49.6 cm³ g⁻¹, markedly exceeding those of CO₂ (21.8 cm³ g⁻¹), C₂H₆ (21.6 cm³ g⁻¹), and C₂H₄ (21.0 cm³ g⁻¹). Ideal adsorbed solution theory (IAST) calculations revealed that the considerable separation selectivity for equimolar C₂H₂/CO₂, C₂H₂/C₂H₆, and C₂H₂/C₂H₄ mixtures is 10.8, 10.0, and 11.7, respectively. Fixed-bed breakthrough experiments verified that ZJNU-412 can efficiently isolate C₂H₂ from binary C₂H₂/CO₂, C₂H₂/C₂H₆, and C₂H₂/C₂H₄ mixtures as well as a complex quaternary C₂H₂/CO₂/C₂H₆/C₂H₄ system, accompanied by outstanding cycling stability. Impressively, this material retained its outstanding separation performance even under 50% relative humidity. Collectively, these results reveal that ZJNU-412 exhibits great potential for broad industrial applications in acetylene separation.