Customizing Quasi-Discrete Pores with Gating Flexibility in 2D Supramolecular Isomers for Kinetic Propyne/Propylene Separation

Abstract

Adsorptive separation based on porous materials is highly favored as an attractive gas separation method. At present, the identification of small differences between similar gases is mainly achieved through thermodynamic and molecular sieve mechanisms, and there are still issues of low selectivity and slow kinetics. In this work, by fine-tuning the layer stacking mode of two-dimensional MOFs, we successfully constructed a flexible material, FJI-W3-AB, which can amplify the diffusion-rate disparity between C₃H₄ and C₃H₆, achieving efficient kinetic separation. In contrast to FJI-W3-AA equipped with discrete intrinsic pores, FJI-W3-AB with dynamic guest-gated quasi-discrete pores is beneficial for regulating gas diffusion behavior. Ultimately, FJI-W3-AB not only exhibits significantly fast C₃H₄ adsorption kinetics but also achieves record C₃H₄/C₃H₆ kinetic selectivity. The excellent separation performance was demonstrated through breakthrough experiments. Theoretical calculations further elucidate the exquisite mechanism of gating flexibility as well as the disparities in host–guest interaction sites and diffusion energy barriers.