A new UiO-66-NH2 based mixed-matrix membranes with high CO2/CH4 separation performance

A new UiO-66-NH2 based MOF named UiO-66-NH2@ICA has been prepared by grafting imidazole-2-carbaldehyde (ICA) to UiO-66-NH2 through a post-synthesis reaction via amine condensation. FESEM, XRD, 1H NMR, FT-IR and N2 adsorption were used to characterize the morphology and structure of UiO-66-NH2@ICA. The grafted ICA mainly reduces the pore volume of UiO-66-NH2 but increases the number of nitrogen atom as binding site of CO2. The UiO-66-NH2@ICA showed less BET surface area but a higher CO2/CH4 adsorption selectivity in comparison with UiO-66-NH2. UiO-66-NH2@ICA and UiO-66-NH2 crystals were dispersed in Matrimid®5218 to form mixed-matrix membranes (MMMs). Single gas permeation and mixed gas separation was carried out to investigate the effects of filler loading and feed gas pressure on the separation performances of the MMMs. The UiO-66-NH2@ICA/Matrimid® MMM with 10 wt % filler showed a high CO2/CH4 selectivity with a separation factor of 64.7, which is an increase by 40% in comparison with UiO-66-NH2/Matrimid® MMM.