Two-Dimensional Metal-Organic Framework with Ultrahigh Water Stability for Separation of Acetylene from Carbon Dioxide and Ethylene.

Highly selective separation and purification of acetylene (CH) from ethylene (CH) and carbon dioxide (CO) are daunting challenges in light of their similar molecule sizes and physical properties. Herein, we report a two-dimensional (2D) stable metal-organic framework (MOF), ([Cu(Hmpba)]·1.5DMF) (Hmpba = 4-(3,5-dimethyl-1-pyrazol-4-yl)benzoic acid), with topology, stacked together through π-π interactions for efficient separation of CH from CH and CO. The 2D-MOF material offers high hydrolytic stability and good purification capacity; especially, it could survive in water for 7 months, even longer. This stable MOF selectively captures CH from mixtures containing CH and CO, as determined by adsorption isotherms. The ideal adsorbed solution theory selectivity calculations and transient breakthrough experiments were performed to verify the separation capacity. The low isosteric heat of - (desolvated -) (18.24 kJ mol for CH) validates the feasibility of adsorbent regeneration with low energy footprint consumption. Furthermore, Grand Canonical Monte Carlo simulations confirmed that the pore surface of the - framework enabled preferential binding of CH over CH and CO via multiple C-H···O, C-H···π, and C-H···C interactions. This work provides some insights to prepare stable MOF materials toward the purification of CH, and the water-stable structure, low isosteric heat, and good cycling stability of - make it very promising for practical industrial application.