Enhanced CO2 selectivity of polyimide membranes through dispersion of polyethyleneimine decorated UiO‐66 particles

Abstract Branched polyethyleneimine (PEI) functionalized UiO‐66 were synthesized and used as fillers to fabricated mixed‐matrix membranes (MMMs) for CO 2 /CH 4 separation. The purpose of introducing amino‐functional groups in the filler is to improve the interfacial compatibility of the filler with the polymer through the formation of hydrogen bonds with the carbonyl group of 6FDA‐ODA. Additionally, the amino group can facilitate CO 2 transport through a reversible reaction, enhancing the CO 2 /CH 4 separation properties of MMM. The chemical structure and morphology of fillers and membranes were characterized by employing X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FTIR), X‐ray diffraction (XRD), thermogravimetric (TGA), Derivative thermogravimetry (DTG) and scanning electron microscope (SEM). Furthermore, the effects of filler loading and feed pressure on CO 2 permeability and CO 2 /CH 4 selectivity have been investigated. MMMs present higher gas separation performance than pure 6FDA‐ODA due to the presence of amino groups and the improvement of interface morphology. In particular, the MMM with 15 wt% loading of UiO‐66‐PEI shows optimum CO 2 permeability of 28.23 Barrer and CO 2 /CH 4 selectivity of 56.49. Therefore, post‐synthetic modification of UiO‐66 particle with PEI is a promising alternative to improved membrane performance.