Gate-Opening Effect in a Flexible Metal–Organic Framework for Sieving Acetylene

Abstract

High Resolution Image Download MS PowerPoint Slide Adsorptive separation employing porous materials is one of the most promising alternative technologies for C 2 H 2 purification due to its energy-efficient and environmentally friendly advantages. Herein, we present the design and synthesis of a dicopper-paddle-wheel-based metal–organic framework (termed JNU-5-Me) with a carboxylate-azolate organic linker. The use of such a linker results in the axial positions of the dicopper paddle wheels being occupied by azolates, and therefore, a much-improved chemical stability of the framework structure. JNU-5-Me shows negligible adsorption of C 2 H 4, C 2 H 6, and CO 2 at 1.0 bar and 298 K, while a gate-opening effect for C 2 H 2 and a large C 2 H 2 adsorption (4.7 mmol g –1 ) at 1.0 bar and 298 K. Dynamic breakthrough studies on JNU-5-Me demonstrate its excellent C 2 H 2 separation performance from C 2 H 2 /CO 2 (50/50, v/v) and C 2 H 2 /CO 2 /C 2 H 4 /C 2 H 6 (70/10/10/10, v/v/v/v) mixtures. Additionally, in-situ infrared spectroscopy and Grand canonical Monte Carlo (GCMC) simulation reveal that the carboxylate oxygens and methyl groups on the framework are involved in the strong binding of C 2 H 2, which may be attributed to the gate-opening effect of JNU-5-Me.