Metal modification in the Zr-MOF defect towards ultrahigh-selective MOF/polymer mixed matrix membrane for CO2 separation

Cu ions were introduced into defect sites of UiO MOF via post-functionalized modification. • The Cu-functionalized defective MOF synergistically improved gas separation performance of MMM under high pressure. • Experiments/simulation revealed the CO2 transport pathway, offering a new defect-engineered MOF design idea for separation. The incorporation of defect engineering in a metal-organic framework to prepare advanced MOF/Polymer mixed matrix membranes for CO 2 separation has become a new direction. However, the existence of defect engineering inevitably loses the selectivity enhancement of specific gas pair separation performance while opening the convenient door for gas diffusion. Herein, introducing Cu ions towards the UiO MOF defect to prepare functionalized defective UiO MOF materials. The Cu ions with CO 2 affinity maximize the proportion at the interface with the zirconia node, thus giving the material a higher CO 2 absorption capacity at high pressure. The prepared mixed matrix membranes (Cu/UiO-H 2 O/Pebax) break through the "trade-off" effect under high pressure (580.0 psi) and realize the synergistic improvement of CO 2 permeability and selectivity. Compared with low pressure (14.5 psi), the CO 2 permeability of Cu/UiO-H 2 O/Pebax mixed matrix membranes increased nearly two times, and the CO 2 /N 2 selectivity increased nearly 3.5 times. A thorough combined permeation test experiment/simulation characterization revealed the influence of the CO 2 transport pathway within the membrane, indicating the mechanism of Cu/UiO-H 2 O fillers on the permeability of mixed matrix membranes at high pressure. Notably, the post-functionalized of mixed matrix membranes with defect-engineered MOF materials provides a new idea for designing defect-engineered MOF materials in the separation field. Download: Download high-res image (247KB) Download: Download full-size image