Preparation of KH560-UiO-66-NH2/Pebax mixed matrix membranes and CO2 separation

Metal–organic frame UiO-66-NH 2 was modified by 3-glycidyl ether oxypropyl trimethoxysilane (KH560), and KH560-UiO-66-NH 2 was synthetized and added to Pebax to prepare KH560-UiO-66-NH 2 /Pebax mixed matrix membranes (MMMs). The epoxy group of KH560 had an amine-epoxidation reaction with the  NH 2 in UiO-66-NH 2 , which prevented UiO-66-NH 2 from agglutinating in the MMMs. In addition, the N  H bond and  OH bond of KH560-UiO-66-NH 2 could theoretically form hydrogen bonds with CO and N  H bonds in the main chain of polymerization, respectively, so as to improve the interfacial compatibility between fillers and polymers. The structure and properties of the filler particles and MMMs were evaluated by Fourier transform infrared spectrometer, x-ray diffraction, scanning electron microscopy, and thermogravimetric analyzer. The results showed that the filler particles were successfully synthesized, and had good crystallinity, uniform size distribution, and good thermal stability. The inorganic and organic interfaces of MMMs had no obvious interface defects. The obtained KH560-UiO-66-NH 2 /Pebax MMMs showed CO 2 permeability of 111.52 Barre and CO 2 /N 2 selectivity of 92.16, which were 85.65% and 88.73% higher than that of pristine membranes, respectively. The gas separation performance of MMMs was significantly improved, exceeding the upper bound of 2008 Robeson.