The assessment of honeycomb structure UiO-66 and amino functionalized UiO-66 metal–organic frameworks to modify the morphology and performance of Pebax®1657-based gas separation membranes for CO2 capture applications

Abstract

A new type of honeycomb structured UiO-66 metal–organic frameworks (MOF) was synthesized and amino functionalized followed by employing them to prepare mixed matrix membranes (MMM). The influences of dimethylformamide (DMF) and H2O/ethanol (70/30 wt.%) blend were firstly investigated on morphology, structure, and CO2/CH4 separation efficiency of Pebax®1657 membranes. Based on the transmission electron microscopy (TEM) analysis, the synthesized MOF has 15 nm in diameter. DMF led to the formation of a more crystalline (based on X-ray diffraction (XRD) analysis) and more porous structure. Higher CO2 permeability and CO2/CH4 selectivity were observed as DMF was employed to fabricate neat membranes. Scanning electron microscopy (SEM) exhibited MOF agglomeration as the UiO-66 was used while the nanoparticle dispersion was enhanced when UiO-66-NH2 was exploited. Fourier transform infrared spectroscopy (FTIR) confirmed the successful MOF incorporation into the MMMs. Ultimately, the gas separation experiments showed that CO2 permeability was enhanced compared to the neat membrane by 44.7% and 49.4% as 10 wt.% UiO-66 and UiO-66-NH2 were used, respectively. Moreover, the Pebax®1657-UiO-66-NH2 MMMs exhibited 71.7% and 34.5% improvement in selectivity of CO2/N2 and CO2/CH4, respectively, owing to enhancing CO2–OH interactions while the CO2/O2 was declined by 8.8%.