(695e) Advanced Polyamide-Imide Membranes for Acid Gas Separations

Membranes provide more environmentally friendly and energy efficient separations as compared to conventional methods for acid gas removal such as amine absorption towers. In the case of acid gas purification, the key challenge for a membrane is to be able to show high CO2/CH4 selectivity in the presence of high pressure CO2. Plasticization and bulk flow effects occur when a highly condensable component, such as CO2 or heavy hydrocarbons strongly sorb into a membrane, and swell the polymer chains. These effects cause an increase in permeability and a drop in selectivity. A 6FDA based polyamide-imide polymeric membrane has been developed, which shows good permeabilities and selectivities, and mixed-gas data that approaches Robeson's upper bound. Also, the material shows excellent plasticization resistance, without additional material modification such as crosslinking. The material's overall performance is dependent upon film post-treatment conditions, such as solvent exchange, annealing time and temperature. The effects of solvent exchange in MeOH and annealing temperature will be reported, along with their subsequent effect on packing density, free volume, and intermolecular interactions. The post-treatment conditions that lead to optimal membrane performance and plasticization resistance will be reported and discussed.