A stable metal-organic framework with oxygen site for efficiently trapping acetylene from acetylene-containing mixtures

Highly selective separation of acetylene from various other gases (e.g., carbon dioxide and methane) is of great importance in the petrochemical industry but remains a challenge due to their similar sizes and physical properties. Herein, we reported a microporous metal − organic framework Zn₄O(NTB)₂ (H₃NTB = 4,4′,4″-nitrilotribenzoicacid acid), features oxygen binding sites explored for C₂H₂ capture and separation. A high C₂H₂ uptake of 2.62 mmol g⁻¹ combined with excellent selectivity of C₂H₂/CO₂ (4.8) and C₂H₂/CH₄ (21.6) under ambient conditions (i.e., 50:50 mixture at 298 K and 1 bar) was realized. Moreover, the grand canonical Monte Carlo (GCMC) simulations and first-principles density functional theory (DFT) calculations have identified that the high C₂H₂ capture and selectivity ascribe to oxygen sites on the pores (C–H…O interaction). Dynamic breakthrough experiments comprehensively demonstrate that Zn₄O(NTB)₂ is a promising adsorbent for practical C₂H₂/CO₂ and C₂H₂/CH₄ separation.