Immobilization of Amino-site into a Pore-Partitioned Metal–Organic Framework for Highly Efficient Separation of Propyne/Propylene

Adsorptive separation of propyne/propylene (C₃H₄/C₃H₆) is a crucial yet complex process, however, it remains a great difficulty in developing porous materials that can meet the requirements for practical applications, particularly with an exceptional ability to bind and store trace amounts of C₃H₄. Functionalization of pore-partitioned metal–organic frameworks (ppMOFs) is methodically suited for this challenge owing to the possibility of dramatically increasing binding sites on highly porous and confined domains. We here immobilized Lewis-basic (−NH₂) and Lewis-acidic (−NO₂) sites on this platform. Along with an integrated nature of high uptake of C₃H₄ at 1 kPa, high uptake difference of C₃H₄−C₃H₆, moderated binding strength, promoted kinetic selectivity, trapping effect and high stability, the NH₂-decorated ppMOF (NTU-100-NH₂) can efficiently produce polymer-grade C₃H₆ (99.95 %, 8.3 mmol ⋅ g⁻¹) at room temperature, which is six times more than the NO₂-decorated crystal (NTU-100-NO₂). The in situ infrared spectroscopy, crystallographic analysis, and sequential blowing tests showed that the densely packed amino group in this highly porous system has a unique ability to recognize and stabilize C₃H₄ molecules. Moving forward, the strategy of organic functionalization can be extended to other porous systems, making it a powerful tool to customize advanced materials for challenging tasks.