(68e) Integrated Membrane Material and Process Development for Gas Separation
The popularization of membrane systems for gas separation has been realized by effective process designs and high performance membrane materials, achieving low cost and high energy efficiency. This presentation will highlight three areas of the research, based on our experience. First, the importance of membrane process designs will be illustrated by examples of sweep/countercurrent designs to seamlessly integrate membrane units into process trains to enhance energy efficiency. This approach is particularly useful for separations with low feed‑to‑permeate pressure ratios such as CO2 capture from flue gas. Second, polymeric membranes with high permeability and selectivity are preferred. However, there exists a tradeoff, i.e., materials with higher permeability often have lower selectivity and vice versa. The selection of membrane materials will be dictated by process designs with judicious balance of permeability and selectivity. The presentation will give examples of optimal membranes identified for O2/N2 separation and CO2/CH4 separation. Finally, high performance polymers need to be made into thin film composite membranes to achieve high flux and establish industrial relevancy. Thin films of many hydrocarbon polymers often show decreasing permeability with time. Interestingly, thin film perfluoropolymers show stable permeability over time, which may shed some light on the molecular level understanding of thin film polymer aging.