Introducing pyrazole-based MOF to polymer of intrinsic microporosity for mixed matrix membranes with enhanced CO2/CH4 separation performance

The performance of mixed matrix membranes (MMMs) substantively depends on the intrinsic structure and composition of the introduced nanofillers. In this work, pyrazole-based metal-organic frameworks (termed as MOF-303) were introduced into polymer of intrinsic microporosity (PIM-1) through a physical blending approach. Thanks to the well CO2-philic capability, high porosity, and appropriate pore structure of the incorporated MOF-303, the obtained MMMs exhibited remarkable separation performance. The improved CO2 permeability and well-maintained CO2/CH4 selectivity were achieved. Specifically, MMMs introducing 30 wt% MOF-303 loading exhibited a CO2/CH4 selectivity of 27.6 and a high-CO2 permeability of 7528.2 Barrer, which were 2.2 and 1.9 times greater than those of the unfilled PIM-1 membranes, respectively. Furthermore, a 33-h continuous separation test verified the excellent stability of the manufactured MMMs. More importantly, the MMMs showed significant resistance against physical aging, retaining up to 92.8% of their original CO2 permeability after 150 days, compared to just 33.0% for control PIM-1 over the same period. Meanwhile, the plasticization resistance of the MMMs was reinforced compared to the unfilled PIM-1 membrane. This study potentially provides a novel approach for the rational design of MMMs in CO2 separation applications.