Microporous mixed-ligand metal–organic framework with fluorine-decorated pores for efficient C2H2/C2H4 separation

Abstract

The selective separation of C2H2 from C2H4 is a very important process for downstream industrial production, and porous metal-organic frameworks (MOFs) have shown great potential for such an application due to their tunable pore surroundings and adjustable building blocks. In this study, a new microporous MOF formulated as {(Et2NH2)[In(TBOT)(2,3-FDA)](DEF)(H2O)2}n (1, H3TBOT ​= ​4,4′,4’’-(((2,4,6-trimethylbenzene-1,3,5-triyl)tris(oxy))tris(methylene))tribenzoic acid, 2,3-HFDA ​= ​2,3-difluorobenzoic acid and DEF ​= ​N,N-diethylformamide) with 2-fold interpenetrated network and 1D fluorine-decorated pores has been prepared via using an acid-acid mixed-ligand strategy. The activated complex 1 (named as 1a) demonstrates apparently higher C2H2 uptake than C2H4 around room temperature, resulting in its relative high C2H2/C2H4 (v:v ​= ​1:99) IAST (Ideal Adsorbed Solution Theory) selectivity of 10.3 ​at 298 ​K and 1 ​bar. Furthermore, the GCMC (grand canonical Monte Carlo) simulation results indicate that the 2,3-FDA moieties serve as preferential binding sites for C2H2 via the multipoint F2⋯H–CC–H⋯F2 interactions, implying the feasibility of the mixed-ligand approach for building porous MOFs with the targeted applications.