Constructing Connected Paths between UiO-66 and PIM-1 to Improve Membrane CO2 Separation with Crystal-Like Gas Selectivity

Most metal-organic-framework- (MOF-) based hybrid membranes face the challenge of low gas permeability in CO2 separation. This study presents a new strategy of interweaving UiO-66 and PIM-1 to build freeways in UiO-66-CN@sPIM-1 membranes for fast CO2 transport. In this strategy, sPIM-1 is rigidified via thermal treatment to make polymer voids permanent, and concurrently polymer chains are mutually linked onto UiO-66-CN crystals to minimize interfacial defects. The pore chemistry of UiO-66-CN is kept intact in hybrid membranes, allowing full utilization of MOF pores and selective adsorption for CO2. Separation results show that UiO-66-CN@sPIM-1 membranes possess exceptionally high CO2 permeability (15433.4-22665 Barrer), approaching to that of UiO-66-NH2 crystal (65-75% of crystal-derived permeability). Additionally, the CO2/N-2 permeation selectivity for a representative membrane (23.9-28.6) moves toward that of single crystal (24.6-29.6). The unique structure and superior CO2/N-2 separation performance make UiO-66-CN@sPIM-1 membranes promising in practical CO2 separations.