Construction of MOF-based mixed matrix membranes with multiple fluorine sites for low concentration CO2 separation under humid conditions

Metal-organic framework (MOF) is widely used in MOF-based mixed matrix membrane (MMMs) for gas separation, however, their separation in low concentration CO 2 and humid environment is a challenging problem to overcome. Herein, a MOF-based MMM with multiple fluorine sites was constructed for efficient separation of CO 2 /N 2 separation system with low concentration CO 2 under humid conditions. Introducing fluorine element sites into membrane materials can not only enhance the affinity between the membrane material and CO 2 molecules, but also make the membrane material hydrophobic, making it suitable for low concentration CO 2 separation under humid conditions. The optimized membrane composed of 10 wt% PIM-2/PIM-1 as blend polymer matrices and 25 wt% fluorinated UiO-66 as fillers exhibited CO 2 permeability of 9234 Barrer and CO 2 /N 2 selectivity of 32.97 under humid conditions of relative humidity of 65% and low CO 2 /N 2 volume ratio of 1:99. This work may provide a feasible way for the design of high-performance gas separation membranes in practical applications.