Torlon® hollow fiber membranes for organic solvent reverse osmosis separation of complex aromatic hydrocarbon mixtures

Abstract

Abstract Defect‐free polyamide‐imide (Torlon®) hollow fiber membranes were fabricated to investigate the potential for polymer‐based organic solvent reverse osmosis (OSRO) separations. The quality of the membranes was assessed by gas permeation, and the membranes were found to be defect‐free. Low molecular weight cut‐offs of ~180 g/mol were obtained using a complex mixture of aromatic hydrocarbons relevant to refinery separations. We demonstrate bulk OSRO‐type separations of 80/20 (mol%) mixtures of toluene and 1,3,5‐triisopropylbenzene (TIPB, 204 g/mol). At an upstream pressure of 80–90 bar, we find that the permeate concentration was approximately 98.5–99.0 mol% toluene and that the TIPB rejection coefficient was approximately 90% in the permeate. We observed low solvent permeances of 0.01 L/m 2 hr bar, which can be attributed to the low OSRO driving forces and the low permeability of Torlon®. The membranes were found to provide stable performance up to pressures of 95 bar and temperatures of 60°C.