Efficient C2H2/CO2 and C2H2/C2H4 separations in a novel fluorinated metal–organic framework

Separating acetylene (C2H2) from carbon dioxide (CO2) and ethylene (C2H4) presents a significant challenge in the industry due to their closely similar physical properties. Herein, we synthesized a novel [NbOF5]2- pillared microporous metal–organic framework ZNU-11 with abundant electronegative sites for efficient C2H2/CO2 and C2H2/C2H4 adsorption separation. The uncoordinating fluorine atoms in the confined pores selectively capture C2H2 from CO2 and C2H4 by hydrogen bonding interactions. The C2H2 capacity of ZNU-11 is 45.5 cm3/g at 298 K and 100 kPa, over three folds of the C2H4 uptake and two folds of the CO2 uptake. The relatively modest C2H2 adsorption heat of 36.1 kJ/mol facilitates the straightforward desorption and regeneration of ZNU-11. Furthermore, density functional theory (DFT) calculations confirmed the stronger binding of C2H2 compared to CO2 and C2H4. Experimental breakthroughs with C2H2/CO2 and C2H2/C2H4 gas mixtures, coupled with excellent recyclability, validated the practical separation performance of ZNU-11. Notably, the dynamic separation factor of 4.2 for equimolar C2H2/CO2 mixture rivals those of many benchmark materials.