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 cm3·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.