Conversion of SOD zeolite into type I porous liquid and preparation of mixed matrix membrane with AO-PIM for efficient gas separation

Abstract

Low-silica SOD zeolites are among the most promising inorganic materials for mixed matrix membranes (MMMs). However, the gas separation performance is severely hindered by the non-selective voids formed by both the zeolite and polymer membranes, as well as the rigid layer. In this work, SOD-liquid-M2070 PL type I porous liquid was synthesized and subsequently filled into an Amidoxime-functionalized polymer of intrinsic microporosity (AO-PIM) to prepare MMMs. The fillers and MMMs were characterized using FTIR, SEM, TGA, XRD, and gas permeation techniques. SOD-liquid-M2070 PL facilitates the rapid diffusion of CO2 and H2 gas molecules for efficient gas separation. The liquid-like fluidity of SOD-liquid-M2070 PL improves the formation of non-selective pores in the SOD and polymer matrix membranes to enhance gas permeability and selectivity. The CO2, H2 permeability and CO2/N2, H2/N2 selectivity of MMMs composed of 5 wt% SOD-liquid-M2070 PL with optimal filling ratio were increased by 248%, 246%, and 173%, 222%, respectively, compared with pure membranes. It exceeds the 2008 Robeson limit for H2/N2 and approaches much closer to the 2019 Robeson limit for CO2/N2. The field of green environment presents a promising development prospect for low silica SOD zeolite, which exhibits high separation efficiency.