Enhancing CO2/N2 adsorption selectivity via post-synthetic modification of NH2-UiO-66(Zr)

Abstract A metal organic framework (MOF) modified with amino group (NH2-UiO-66) was functionalized with glycidyl methacrylate (GMA) via ring opening reaction between the amine species in the framework and epoxy groups in GMA. The products were characterized by X-ray powder diffraction (XRD), nuclear magnetic resonance (NMR) spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and N2 adsorption–desorption measurements to monitor their textural properties before and after functionalization. The BET surface area, pore volume, and pore diameter of NH2-UiO-66 were reduced after treatment with GMA. However, the crystalline structure, morphology, and thermal stability were retained. Single-gas adsorption isotherm measurements exhibited that CO2 adsorption capacity of GMA-UiO-66 was enhanced comparatively due to the presence of many polar functional groups including primary and secondary amines, ester, alkene, and hydroxyl groups. Moreover, GMA-UiO-66 showed higher adsorption selectivity against CO2 in CO2/N2 mixture than NH2-UiO-66.