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.