CO۲/CH۴ separation performance by innovative polyethylene glycol modified ZIF-۸ membrane

PEG/ZIF-۸/PES was synthesized for enhancement in CO۲/CH۴ separation. The layer by layer growth method of membrane fabrication was applied for the synthesis of ZIF-۸ on polyethersulfone (PES) support. The samples were characterized by XRD and SEM analysis to investigate the crystal structure and morphology of ZIF-۸ coated layer respectively. Pure gas permeation tests showed that the PEG incorporated ZIF-۸ membranes have superior CO۲/CH۴ ideal selectivity (۲۲.۱) compared with pristine ZIF-۸ membrane. Due to the flexibility of polyether chains of incorporated PEG, the brittleness of the modified ZIF-۸ membrane decreased remarkably and a flexible and operable ZIF-۸ selective layer has been fabricated. Mixed gas permeation results showed an unpredictable trend of change of CO۲/CH۴ real selectivity mainly due to the competing effect in penetration of CO۲ and CH۴ through pores of ZIF-۸ modified membranes.