Enhanced O2/N2 separation performance of poly(phenylene oxide)/SBA-15/carbon molecule sieve multilayer mixed matrix membrane using SBA-15 zeolite particles

Multilayer composite membranes were composed using large-pore mesoporous silica molecular sieve SBA-15, PPO polymer, and CMS/Al₂O₃ substrate. The SBA-15 was used at different aging temperatures to transform into different crystal sizes. Membranes were characterized by field emission scanning electron microscopy (FESEM) to observe the morphology and cross-sectional images. FESEM images of these composite membranes indicate the existence of voids between the PPO/SBA-15 layer and CMS/Al₂O₃ if 110°C SBA-15 is added. The permeability and selectivity of PPO/SBA-15/CMS/Al₂O₃ membranes with different aging temperatures of SBA-15 were also investigated. The selectivity for O₂/N₂ separation increased remarkably from 6.2 to 8.8, which corresponded to the increase in aging temperature of SBA-15 for the PPO/SBA-15/CMS/Al₂O₃ composite membrane from 90 to 110°C, respectively. This phenomenon confirms that blockage and reduced mobility of polymer chains as a result of mixing the aging temperature of SBA-15 at 110°C with a PPO matrix may significantly improve the gas separation performance of composite membranes.