An anion-functionalized zinc-organic framework for efficient C2H2/C2H4 separation

Abstract

An anion-functionalized porous framework exhibits a 4,6-connected fsc topology with diamond channels along the b axis, which has high C 2 H 2 adsorption capacity and excellent separation selectivity for 1/99 C 2 H 2 /C 2 H 4 and 50/50 C 2 H 2 /C 2 H 4 . • An anion-functionalized porous framework FJI-W2 has been constructed using a four-connected TPB ligand. • FJI-W2 exhibits a 4,6-connected fsc topology with diamond channels along the b axis. • FJI-W2 manifests excellent separation selectivity for 1/99 C 2 H 2 /C 2 H 4 and 50/50 C 2 H 2 /C 2 H 4 . Separating acetylene from ethylene is a very significant process in the petrochemical industry. Herein, we have successfully synthesized an anion-functionalized porous framework [Zn(TPB)SiF 6 ] n (FJI-W2, TPB = 1,2,4,5-tetra(pyridin-4-yl)benzene). The single component gas sorption isotherms reveal that the adsorption capacity of C 2 H 2 can reach 95 cm 3 /g at 298 K and 1 bar. More notably, FJI-W2 has a high C 2 H 2 uptake of 28 cm 3 /g at 0.01 bar, significantly higher than that of C 2 H 4 (0.1 cm 3 /g). The isosteric adsorption enthalpies for C 2 H 2 and C 2 H 4 further prove that the adsorption affinity of FJI-W2 with C 2 H 2 is much stronger than C 2 H 4 . Ideal adsorbed solution theory shows that the separation selectivity of FJI-W2 for C 2 H 2 /C 2 H 4 (1/99, v/v) and C 2 H 2 /C 2 H 4 (50/50, v/v) can be up to 14.2 and 12.5, respectively.