Introducing high concentration of hexafluorosilicate anions into an ultra-microporous MOF for highly efficient C2H2/CO2 and C2H2/C2H4 separation

Abstract

Tremendous effort has been endeavored to improve the C2H2 separation performance of porous solid materials from CO2 and C2H4, aiming to gain high purity of C2H2 for producing various downstream commodities. Herein, an ultra-microporous interpenetrated MOF, SIFSIX-DPA-Cu-i, featuring multiple functional hexafluorosilicate anions, has been constructed for efficient C2H2 separation from C2H2/CO2 and C2H2/C2H4 gases mixture. Significantly, SIFSIX-DPA-Cu-i presents good C2H2/CO2 and C2H2/C2H4 separation performance, especially for C2H2/CO2, with the value of 9.34 at 298 K and 1 bar due to the introduction of a high concentration of hexafluorosilicate anions capable of preferentially capturing C2H2 through forming a strong C2H2 nano-trap arising from the strong C-H∙∙∙F and C≡C∙∙∙H interactions confirmed by in situ IR and molecular modeling. Moreover, the consecutive transient-breakthrough experiments further demonstrate the outstanding potential of SIFSIX-DPA-Cu-i for practical C2H2/CO2 and C2H2/C2H4 separation applications.