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

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)SiF6]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 C2H2 can reach 95 cm3/g at 298 K and 1 bar. More notably, FJI-W2 has a high C2H2 uptake of 28 cm3/g at 0.01 bar, significantly higher than that of C2H4 (0.1 cm3/g). The isosteric adsorption enthalpies for C2H2 and C2H4 further prove that the adsorption affinity of FJI-W2 with C2H2 is much stronger than C2H4. Ideal adsorbed solution theory shows that the separation selectivity of FJI-W2 for C2H2/C2H4 (1/99, v/v) and C2H2/C2H4 (50/50, v/v) can be up to 14.2 and 12.5, respectively.