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

Abstract

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.