Synthesis of highly soluble zirconium organic cages by iodine substitution toward a CO/N separation membrane

• Published in: Chemical science (Cambridge) 2024-11, Vol.15 (45), p.1913-1921
• Main Authors: Dong, Junchao, Gai, Dongxu, Cha, Guocai, Pan, Qinhe, Liu, Jia, Zou, Xiaoqin, Zhu, Guangshan
• Format: Article
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d4sc05080k

Metal organic cages (MOCs) show promise as fillers in mixed-matrix membranes (MMMs) for gas separation; highly soluble MOCs are desirable for fabrication of high-compatibility membranes. Herein, we report an iodine substitution strategy to substantially increase the MOC solubility. The synthesized MOC of ZrT-NH 2 -I possesses over 10-fold higher solubility than the parent ZrT-NH 2 in organic solvents whilst retaining the original molecular structure and permanent porosity. Such enhanced solubility allows for the effective integration of ZrT-NH 2 -I with an amidoxime polymer of intrinsic microporosity (PIM-PAO), resulting in a compatible MMM with a uniform distribution of MOC. The ZrT-NH 2 -I@PIM-PAO MMM demonstrates a CO 2 permeability of 1377 barrer and a CO 2 /N 2 gas selectivity of 45 which is 45 times that of the membrane made from ZrT-NH 2 . The permeability-selectivity performance not only surpasses the 2008 upper bound, but also exceeds those of currently available MMMs. Iodine substitution is developed for solubility enhancement of metal organic cages of ZrT-NH 2 -I, and ZrT-NH 2 -I based membranes exhibit superior performance in CO 2 /N 2 separation.