A Highly Stable Microporous Calcium-Based MOF for C₂H₂/CO₂ Separation with Low Regenerative Energy

Most of the porous materials used for acetylene/carbon dioxide separation have the problems of poor stability and high energy requirements for regeneration, which significantly hinder their practical application in industries. Here, we report a novel calcium-based metal-organic framework (NKM-123) with excellent chemical stability against water, acids, and bases. Additionally, it has exceptional thermal stability, retaining its structural integrity at temperatures up to 300 °C. This material exhibits promising potential for separating C₂H₂ and CO₂ gases. Furthermore, it demonstrates an adsorption heat of 29.3 kJ mol^-1 for C₂H₂, which is lower than that observed in the majority of MOFs used for C₂H₂/CO₂ separations. The preferential adsorption of C₂H₂ over that of CO₂ is confirmed by dispersion-corrected density functional theory (DFT-D) calculations. In addition, the potential of industrial feasibility of NKM-123 for C₂H₂/CO₂ separation is confirmed by transient breakthrough tests. The robust cycle performance and structural stability of NKM-123 during multiple breakthrough tests show great potential in the industrial separation of light hydrocarbons.