Dynamic Spacer Installation of Multifunctionalities into Metal-Organic Frameworks for Spontaneous One-Step Ethylene Purification from a Ternary C2-Hydrocarbons Mixture

Simultaneous ethane and acetylene removal from a C2-gases mixture (C2H6, C2H4, and C2H2) through a one-step separation process for ethylene purification is of great importance yet challenging in petrochemical industry, owing to their similar molecule sizes and physical properties. Herein, a series of multifunctionalized metal-organic frameworks (MOFs), LIFM-XYY-1 similar to 8 (LIFM stands for Lehn Institute of Functional Materials, and XYY are the initials of the first author), are constructed via a dynamic spacer installation (DSI) approach to optimize the pore-nanospaces for efficient C2H4 isolation from the ternary C2-gases mixture. Installation of variable organic-spacers into the prototypical MOFs, LIFM28 or PCN-700, results in dramatically improved pore volume/surface area, contracted pore size, and functionalized pore surface, which in turn bring out high C2-gases uptake capacities, enhanced C2H6 and C2H2 adsorption selectivities over C2H4, and fast adsorption kinetics, providing an effective strategy to achieve delicate trade-off among these indexes for adequate separation performance. Specifically, optimized LIFM-XYY-7 presents four-times C2H6 and C2H2 adsorption capacities than proto-PCN-700. Dynamic breakthrough experiments reveal that poly-grade C2H4 (>99.9%) can be obtained from binary or ternary C2-hydrocarbon mixtures through a single separation process. Combined with the molecular simulations, this work demonstrates a promising protocol of porenanospace engineering via multi-functional optimization by the DSI approach to screen out MOFs for a formidable task.