High Performance UV-Irradiated PIM-1-Based Mixed-Matrix Membranes for Carbon Capture

A series of mixed-matrix membranes (MMMs) consisting of zeolitic imidazolate framework-71 (ZIF-71, Zn(dcIm)₂) and polymer of intrinsic microporosity (PIM-1) were investigated before and after ultraviolet (UV) irradiation for various gas separations. Well compatible MMMs are formed between ZIF-71 nanoparticles and PIM-1. The incorporation of ZIF-71 considerably enhances the gas permeability without compensating the gas pair selectivities of O₂/N₂, CO₂/N₂ and CO₂/CH₄. The PIM-1 comprising 30 wt% ZIF-71 exhibits a 154% increase in CO₂ permeability. FESEM and PAS confirm the formation of an ultrathin dense layer at the membrane surface after the UV treatment. The UV-irradiated PIM-1 has CO₂/CH₄, CO₂/N₂ and O₂/N₂ selectivities of 34.1, 29.8 and 6.7, respectively. The UV-treated MMMs possess much higher permeability compared to that of pristine UV-irradiated PIM-1 with similar gas pair selectivities. Under mixed gas tests, the UV treated PIM-1 containing 20 wt% ZIF-71 has a CO₂ permeability of around 2000 barrers and a CO₂/CH₄ selectivity of 32. This performance outperforms PIM-1 and UV treated PIM membranes. The UV-PIM-1/ZIF-71 membranes have superior separation performance with both high permeability and selectivity for CO₂/CH₄ or other gas pair separation.