Preparation and characterization of Matrimid® 5218 based binary and ternary mixed matrix membranes for CO2 separation

The effect of LMW polyethylene glycol (PEG 200) as a CO2-philic polymer on the gas separation properties of Matrimid®5218/ZSM-5 MMM was investigated. Hybrid ternary membranes were fabricated considering various compositions of PEG 200 and ZSM-5 zeolite via dense film casting method. The effect of the calcination of ZSM-5 was determined by FTIR analysis. Possible interactions in Matrimid/PEG 200/ZSM-5 system and phase changes in Matrimid microstructure were further studied by FTIR and XRD, respectively. According to FESEM images increment in PEG content (15 wt.%) resulted in nanoparticles agglomeration and formation of pores in the dense structure of Matrimid, while at lower content of PEG (<5 wt.%), a uniform dispersion of nanoparticles and a good compatibility between ZSM-5/polymers was observed. The results revealed that the CO2 permeability and CO2/CH4 selectivity of pure Matrimid was significantly enhanced with low-level loadings of calcined ZSM-5 and small portions of PEG in to the membrane structure. The CO2 permeability and CO2/CH4 selectivity of the best-yield hybrid ternary membrane (Matrimid/PEG (95:5) + 5 wt.% ZSM-5) increased about 50% (from 7.68 to 11.53 Barrer) and 72% (from 34.9 to 60.1) compared to pure Matrimid, respectively.