Plasticization-resistant hollow fiber membranes for CO2/CH4 separation based on a thermally crosslinkable polyimide

Decarboxylation-induced thermal crosslinking has been demonstrated to be effective for stabilizing membranes against plasticization in dense films. This study extends this promising crosslinking approach from dense films to industrially relevant asymmetric hollow fiber membranes. Crosslinkable asymmetric hollow fiber membranes were spun from a carboxylic acid containing polyimide, 6FDA-DAM:DABA. Dope and spinning conditions were optimized to obtain fibers with a defect-free selective skin layer. It is found that slightly defective fibers suffered severe selectivity loss after thermal crosslinking, suggesting that defect-free property is essential to the performance of the resulting crosslinked hollow fiber membranes. The crosslinked fibers were tested for CO2/CH4 separation. The excellent plasticization resistance under high pressure feeds (with highest CO2 partial pressure of 400 psia) suggests that these robust membranes are promising for aggressive natural gas purification.

► Transition of crosslinking approach from dense films to asymmetric hollow fibers.
► Defect-free hollow fiber membranes can be spun from a crosslinkable polyimide.
► Comparison study of thermal treatment on defect-free and slightly defective fibers.
► Post-spin thermal crosslinking is implemented to improve membrane stability.
► Crosslinked fiber membranes are promising for aggressive natural gas purification.