(45f) Amine Modified Polymer of Intrinsic Microporosity for Highly Selective Olefin/Paraffin Separation

Cryogenic distillation is a common practice in the current refinery industry to purify light hydrocarbon gases from crude oil streams, but it is a thermally intensive process with overwhelming energy consumption. In order to lower the carbon footprint associated with industrial distillation processes, membrane gas separation processes can be implemented to reduce energy consumption up to 90%. However, membranes have limitations on their gas separation efficiency, as it is dependent on the intrinsic properties of the material. The gas permeability and solubility in a polymeric membrane can be fine-tuned by designing the structure of the polymer. Polymer of Intrinsic Microporosity (PIM-1) is well known for its bulky, ladder-shaped backbone that creates high free volume, leading to high gas permeability, but suffers from a low gas selectivity. This study proposes to develop a novel membrane separation system to selectively separate hydrocarbon gases by using amine functional groups. By introducing amine groups into the PIM-1 backbone, the hydrogen bonding forces creates tighter packing in the membrane, creating new gas separation characteristics and efficiency. Initial investigation of amine-modified PIM-1 (PIM-NH₂) shows higher propylene/propane separation performance than PIM-1. PIM-NH₂ has a C₃H₆/C₃H₈ selectivity of 16, compared to PIM-1’s C₃H₆/C₃H₈ selectivity of 3. However, long-term testing of PIM-NH₂ shows significantly faster physical aging compared to PIM-1, losing up to 75% of its C₃H₆ permeability. This project explores the olefin/paraffin separation efficiency of different amine composition in PIM-1 and future plans for PIM-NH₂ aging mitigation, including the potential crosslinking pathway and linkers to study the optimization between permeation performance and lifetime of PIM-NH₂.