UiO-66-polyether block amide mixed matrix membranes for CO2 separation

Mixed matrix membranes containing metal-organic frameworks have attracted large attention owing to the combined advantages of high separation performance and easy processability. In this work, CO2-philic zirconium metal organic framework UiO-66 and UiO-66-NH2 nanocrystals were synthesized and embedded into polyether block amide (PEBA) polymer membranes for CO2 separation. It can be found that amine-functionalization endowed UiO-66-NH2 nanoparticles with stronger CO2 affinity compared with that of UiO-66. Also, the hydrogen bonding frameworks between UiO-66-NH2 and PEBA were enhanced, leading to improved dispersibility in polymer matrix. Both the UiO-66-PEBA and UiO-66-NH2-PEBA mixed matrix membranes showed much higher CO2 separation performance than that of pure PEBA membrane. Especially, amine functionalization of the porous frameworks provided the so-prepared UiO-66-NH2-PEBA mixed matrix membrane with higher CO2/N2 selectivity and slightly decreased CO2 permeability than those of UiO-66-PEBA membrane. The developed UiO-66-NH2-PEBA mixed matrix membrane (with MOFs loading of 10 wt%) was tested in humid state and showed excellent and stable CO2/N2 separation performance (CO2 permeability of 130 Barrer, CO2/N2 selectivity of 72) surpassing the upper bound of polymer membranes. This type of UiO-66 based mixed matrix membranes featuring with excellent structural stability and significantly improved gas separation performance offer promising potential for CO2 capture.