One-Dimensional Channel with Side Pockets for Rapid Diffusion and Efficient C₂H₂ Purification

Efficiently separating acetylene (C₂H₂) from carbon dioxide (CO₂) has been a long-standing challenge due to their similar molecular dimensions and physical properties. Herein, we report a series of isostructural pillar-layered metal-organic frameworks (MOFs), named JNU-13, JNU-13-CH₃, and JNU-13-(CH₃)₂. These MOFs feature one-dimensional (1D) channels integrated with orthogonally arrayed side pockets, enabling dense packing of C₂H₂ molecules while maintaining rapid diffusion pathways. Specifically, JNU-13-CH₃ achieves a high C₂H₂ packing density of 360 g L^-1, a low adsorption enthalpy of 31.61 kJ mol^-1, and adsorption/desorption coefficients one to two orders of magnitude higher than other benchmark MOFs. Breakthrough experiments reveal a high C₂H₂ capture capacity of 3.46 mmol g^-1 from an equimolar C₂H₂/CO₂ mixture at 298 K and 1 bar, even under humid conditions. Moreover, we demonstrate the scale-up synthesis of JNU-13-CH₃ and gas-cylinder collection of high-purity C₂H₂, achieving >99.9% from a C₂H₂/CO₂ (95/5) mixture and >99.7% from a C₂H₂/CO₂/CH₄ (95/2.5/2.5) mixture. Overall, this study highlights the effectiveness of orthogonal-arrayed side pockets for balancing dense packing and mass transport, offering a promising strategy for energy-efficient C₂H₂ purification.