A chemically stable nanoporous coordination polymer with fixed and free Cu2+ ions for boosted C2H2/CO2 separation

Safely and highly selective acetylene (C2H2) capture is a great challenge, because of its highly explosive nature, as well as its nearly similar molecule size and boiling point toward the main impurity of carbon dioxide (CO2). Adsorption separation has shown a promising future. Herein, a new nanoporous coordination polymer (PCP) adsorbent with fixed and free Cu ions (termed NTU-66-Cu) was prepared through post-synthetic approach via cation exchanging from the pristine NTU-66, an anionic framework with new 3, 4, 6-c topology and two kinds of cages. The NTU-66-Cu shows significantly improved C2H2/CO2 selectivity from 6 to 32 (v/v: 1/1) or 4 to 42 (v/v: 1/4) at low pressure under 298 K, along with enhanced C2H2 capacity (from 89.22 to 111.53 cm(3).g(-1)). More importantly, this observation was further validated by density functional theory (DFT) calculations and breakthrough experiments under continuous and dynamic conditions. Further, the excellent chemical stability enables this adsorbent to achieve recycle C2H2/CO2 separation without loss of C2H2 capacity.