Boosting Acetylene Packing Density within an Isoreticular Metal–Organic Framework for Efficient C2H2/CO2 Separation

Porous solid adsorbents for C₂H₂/CO₂ separation are generally confronted with poor stability, high cost, or high regeneration energy, which largely inhibit their industrial implementation. A desired adsorbent material for practical implementation should exhibit a good balance between low cost, high stability, scale-up production feasibility, and good separation performance. An effective strategy is herein explored based on reticular chemistry through embedding methyl groups in a prototype microporous metal-organic framework (MOF) featuring low cost and high stability to effectively separate an C₂H₂/CO₂ mixture. The anchored methyl groups on the pore surfaces could strongly boost the C₂H₂ packing density and specifically enhance the C₂H₂/CO₂ separation performance, as distinctly established by single-component gas sorption isotherms. The CAU-10-CH₃ material exhibits an excellent C₂H₂ packing density of 486 g L^-1 and high adsorption differences between C₂H₂ and CO₂ uptake (147%), outperforming the prototype benchmark material CAU-10-H (392 g L^-1 and 53%). The highly selective adsorption of C₂H₂ over CO₂ was achieved by a lower C₂H₂ adsorption enthalpy (25.18 kJ mol^-1) compared to that with unfunctionalized CAU-10-H. In addition, dynamic column breakthrough experiments further confirm CAU-10-CH₃'s efficient separation performance for the C₂H₂/CO₂ mixture. CAU-10-CH₃ accomplishes the benchmark balance between cost, stability, scale-up, and separation performance for C₂H₂/CO₂ separation, establishing its promise for industrial implementation. This approach could further facilitate the development of advanced MOF adsorbents to address challenging separation processes. Thus, this study paves the route for the practical implementations of MOF materials in the gas adsorption and separation field.