A Scalable Pore-space-partitioned Metal-organic Framework Powered by Polycatenation Strategy for Efficient Acetylene Purification

Abstract

Efficient separation of acetylene (C₂H₂) from carbon dioxide (CO₂) and ethylene (C₂H₄) is a significant challenge in the petrochemical industry due to their similar physicochemical properties. Pore space partition (PSP) has shown promise in enhancing gas adsorption capacity and selectivity by reducing pore size and increasing the density of guest binding sites. Herein, we firstly employ the 2D→3D polycatenation strategy to construct a PSP metal-organic framework (MOF) Ni-dcpp-bpy, incorporating functional N/O sites to enhance C₂H₂ purification. The polycatenated framework with optimized pore size and regularity, exhibiting significant improvements over traditional PSP MOFs by resolving the critical contradiction of balancing C₂H₂ uptake (98.5 cm³ g^-1 at 298 K, 100 kPa) and selectivity of C₂H₂/CO₂ (3.4), C₂H₂/C₂H₄ (5.9), and C₂H₂/CH₄ (96.4) in a MOF. Breakthrough experiments confirm high-purity C₂H₄ (>99.9 %) and high C₂H₂ productivity from binary and ternary mixtures. Notably, Ni-dcpp-bpy exhibits excellent water stability, scalability, and regenerability after 20 cycles for separating C₂H₂/CO₂. Theoretical calculations verify that the strong binding of C₂H₂ is mainly attributed to the C-H⋅⋅⋅O/N interactions between host Ni-dcpp-bpy and guest C₂H₂ molecules. The polycatenation strategy not only improved industrial C₂H₂ purification efficiency but also enriched the design diversity of customized MOFs for other gas separation applications.

Keywords: acetylene purification; gas adsorption and separation; metal-organic framework; polycatenation strategy; pore space partition.