Molecular Sieving of C₂‐C₃ Alkene from Alkyne with Tuned Threshold Pressure in Robust Layered Metal–Organic Frameworks

Abstract

C2‐C3 alkyne/alkene separation is of great importance; however, designing materials for an efficient molecular sieving of alkenes from alkynes remains challenging. Now, two hydrolytically stable layered MOFs, [Cu(dps)2(GeF6)] (GeFSIX‐dps‐Cu, dps=4,4′‐dipyridylsulfide) and [Zn(dps)2(GeF6)] (GeFSIX‐dps‐Zn), can achieve almost complete exclusion of both C3H6 and C2H4 from their alkyne analogues. GeFSIX‐dps‐Cu displays a notable advanced threshold pressure for alkynes adsorption and thus substantial uptakes at lower pressures, providing record C3H4/C3H6 uptake ratios and capacity‐enhanced C2H2/C2H4 sieving for a wide composition range. Metal substitution (Zn to Cu) affords fine tuning of linker rotation and layer stacking, creating slightly expanded pore aperture and interlayer space coupled with multiple hydrogen‐bonding sites, allowing easier entrance of alkyne while excluding alkene. Breakthrough experiments confirmed tunable sieving by these MOFs for C3H4/C3H6 and C2H2/C2H4 mixtures.

Tuning Gate‐Opening of a Flexible Metal–Organic Framework for Ternary Gas Sieving Separation

“…[4] Forsmaller gas molecule,t he gate-opening pressure is also lower as smaller degree of structural change is needed to accommodate smaller molecule in the pore. [5] Selective gate-opening adsorption has realized several important binary gas separation [6] with high sieving performance that is comparable to those of rigid sieving MOFs.…”

An Unprecedented Pillar‐Cage Fluorinated Hybrid Porous Framework with Highly Efficient Acetylene Storage and Separation

“…The N 2 isotherm exhibits typical type I adsorption behavior characteristic of microporous materials (Figure 3 a). The BET surface area was calculated to be 1330 m 2 g −1 , which is distinctly higher than those of most ultra‐microporous fluorinated MOFs, including famous SIFSIX‐1‐Cu (1178 m 2 g −1 ), [8e] SIFSIX‐2‐Cu‐i (685 m 2 g −1 ), [8e] UTSA‐200a (612 m 2 g −1 ), [8c] UTSA‐300a (311 m 2 g −1 ) [8d] and GeFSIX‐dps‐Cu (382 m 2 g −1 ) [13] . The pore volume was calculated to be 0.52 cm 3 g −1 , which matches well with the theoretical value of 0.51 cm 3 g −1 .…”

Crystal engineering of porous coordination networks for C3 hydrocarbon separation

“…116,117 In 2017, Li et al 96 reported C , exemplified by ZJUT-1, SIFSIX-14-Cu-i (UTSA-200), TIFSIX-14-Cu-i (ZU-13), and GeFSIX-dps-Cu/Zn. 58,[119][120][121]…”

“…The selectivity towards C 3 H 4 was attributed to C−H···F hydrogen bonds between propyne molecules and the F atoms of the linker ligands. Other reports of selective adsorption of C 3 H 4 over C 3 H 6 have focused on hybrid porous materials with inorganic anionic pillars of SiF 6 2− , TiF 6 2− , and GeF 6 2− , exemplified by ZJUT‐1, SIFSIX‐14‐Cu‐i (UTSA‐200), TIFSIX‐14‐Cu‐i (ZU‐13), and GeFSIX‐dps‐Cu/Zn 58,119–121 …”