Cross-Linkable Polyimide Membrane for Natural Gas Purification and Carbon Dioxide Plasticization Reduction

The ability of propanediol monoester cross-linkable (PDMC) polymer to effectively separate CO 2 from CH 4, and the polymer's stability against plasticization under high CO 2 pressures, was investigated. The cross-linked PDMC membranes were found to have significantly higher CO 2 permeability and slightly higher selectivity for the CO 2 /CH 4 separation than the un-cross-linked PDMC membranes. Cross-linking temperature was found to have a significant impact on the permeation properties of the membranes. The PDMC membrane permeation results are compared with previous research that uses other cross-linking agents for CO 2 plasticization resistance and found to offer an excellent balance between extent of cross-linking and tradeoff between mechanical and transport properties. The cross-linked membranes not only outperform the un-cross-linked membranes with their enhanced transport properties but also provide vastly superior plasticization resistance against aggressive CO 2 steams. Un-cross-linked and cross-linked PDMC membranes were characterized via permeation (pure and mixed gas), density, T g, and sorption measurements.