Enhancement\nof Propadiene/Propylene Separation Performance\nof Metal–Organic Frameworks by an Amine-Functionalized Strategy

Abstract

Here, a hexanuclear Co₆(μ₃-OH)₆ cluster-based metal–organic framework (MOF),\n[Co₆(μ₃-OH)₆(BTB)₂(bpy)₃]_<i>n</i> (JXNU-15) (bpy =\n4,4′-bipyridine),\nwith the 1,3,5-tri(4-carboxyphenyl)benzene (BTB^3–) ligand was synthesized for the challenging propadiene/propylene\nseparation. The combination of a large pore volume and a suitable\npore environment boosts the significantly high propadiene (C₃H₄) uptake (311 cm³ g^–1 at\n298 K and 100 kPa) for JXNU-15. An amine-functionalized MOF of JXNU-15(NH₂) was further obtained with the 1,3,5-tri(4-carboxyphenyl)benzene\nanalogue of 3,3″-diamino-5′-(3-amino-4-carboxyphenyl)-[1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic\nligand. The comparative studies of propadiene/propylene(C₃H₄/C₃H₆) separation performance\nbetween isostructural JXNU-15 and JXNU-15(NH₂) are provided.\nJXNU-15(NH₂) exhibits an impressive C₃H₄ capacity at low pressures with 69.1 cm³ g^–1 at 10 kPa, which is twice that of JXNU-15 under the\nsame conditions. Moreover, the separation selectivity of JXNU-15(NH₂) is 1.3-fold higher as compared to JXNU-15. JXNU-15(NH₂) with enhanced C₃H₄/C₃H₆ separation performance was elegantly illustrated by gas separation\nexperiments and theoretical simulations. This work presents an amine-functionalized\nstrategy for the enhancement of the C₃H₄/C₃H₆ separation performance of MOF.