Thin film nanocomposite membranes based on renewable polymer Pebax® and zeolitic imidazolate frameworks for CO2/CH4 separation

This study investigates the impact of integrating Pebax® Rnew® 30R51, a sustainable elastomer-type copolymer material, with zeolitic imidazolate frameworks (ZIFs) to develop advanced membranes for CO 2 /CH 4 gas separation. The fabrication process of ZIF/Pebax® Rnew® 30R51 thin films was optimized to achieve uniform and defect-free thin film composite (TFC) membranes. Crucial membrane properties, including permeability, selectivity and separation efficiency, were analyzed with variations in ZIF type, loading levels, film thickness and operating conditions. Additionally, the resulting TFC and ZIF/Pebax® Rnew® 30R51 thin film nanocomposite (TFN) membranes were subjected to characterization via FTIR, XRD, TGA and SEM to evaluate their physicochemical properties. Nanoparticles of ZIF-8, NH 2 -ZIF-8 and ZIF-94 were individually added (at 5–15 wt% loadings) to the Pebax® Rnew® 30R51 matrix to develop the CO 2 separation efficiency. The pristine TFC membrane showed a 66 GPU CO 2 permeance and a 37.5 CO 2 /CH 4 separation selectivity, primarily due to improved CO 2 mass transport. Upon inclusion of ZIFs, the CO 2 permeance with 5 wt% loadings of ZIF-8, NH 2 -ZIF-8 and ZIF-94 increased to 148, 99 and 125 GPU, respectively, despite this, the CO 2 /CH 4 separation selectivity maintained at 29.4, 37.0 and 27.0, respectively.