(695b) Decarboxylated Crosslinked Polyimide Hollow Fiber Membranes for Natural Gas Purification

Natural gas processing is one of the largest industrial membrane gas separation applications, almost all for the removal of CO2. Polyimides are a widely studied class of polymers that have very high ideal CO2/CH4 selectivities. However, the performance of polyimide membranes is significantly below the intrinsic membranes under normal operating conditions (mixed gas with high CO2 partial pressure) due to membrane plasticization. High CO2 content can swell the membranes and thus cause drastic losses in selectivity.

Covalent crosslinking has been shown to increase plasticization resistance in dense films. This research focuses on extending success with dense films to asymmetric hollow fibers. Defect-free asymmetric hollow fiber membranes were successfully spun from a carboxylic acid containing polyimide and crosslinked by thermally-induced decarboxylation without damaging the selective skin layer on the hollow fibers. The crosslinked hollow fibers were tested with model natural gas feeds at high pressure and showed excellent plasticization resistance against CO2.