Enhancement of Propadiene/Propylene Separation Performance of Metal-Organic Frameworks by an Amine-Functionalized Strategy.

Here, a hexanuclear Co 6 (μ 3 -OH) 6 cluster-based metal-organic framework (MOF), [Co 6 (μ 3 -OH) 6 (BTB) 2 (bpy) 3 ] n (JXNU-15) (bpy = 4,4'-bipyridine), with the 1,3,5-tri(4-carboxyphenyl)benzene (BTB 3- ) ligand was synthesized for the challenging propadiene/propylene separation. The combination of a large pore volume and a suitable pore environment boosts the significantly high propadiene (C 3 H 4 ) uptake (311 cm 3 g -1 at 298 K and 100 kPa) for JXNU-15. An amine-functionalized MOF of JXNU-15(NH 2 ) was further obtained with the 1,3,5-tri(4-carboxyphenyl)benzene analogue of 3,3″-diamino-5'-(3-amino-4-carboxyphenyl)-[1,1':3',1″-terphenyl]-4,4″-dicarboxylic ligand. The comparative studies of propadiene/propylene(C 3 H 4 /C 3 H 6 ) separation performance between isostructural JXNU-15 and JXNU-15(NH 2 ) are provided. JXNU-15(NH 2 ) exhibits an impressive C 3 H 4 capacity at low pressures with 69.1 cm 3 g -1 at 10 kPa, which is twice that of JXNU-15 under the same conditions. Moreover, the separation selectivity of JXNU-15(NH 2 ) is 1.3-fold higher as compared to JXNU-15. JXNU-15(NH 2 ) with enhanced C 3 H 4 /C 3 H 6 separation performance was elegantly illustrated by gas separation experiments and theoretical simulations. This work presents an amine-functionalized strategy for the enhancement of the C 3 H 4 /C 3 H 6 separation performance of MOF.