Recent progress on fabrication methods of polymeric thin film gas separation membranes for CO2 capture

Membrane technology has been recognized as an attractive and environment-friendly technology for carbon capture due to its low expense (capital and operating), ease of operation as well as low energy consumption. Traditionally, the membrane materials are cast into dense membranes with a thickness of 50-150 mu m and their gas separation properties are evaluated by the trade-off between permeability and selectivity. However, permeance (gas flux), rather than permeability, is more emphasized recently because the increase of the real gas flux through a membrane without the loss of selectivity has been recognized to be more important in industrial scenarios. The permeance is inversely proportional to the membrane thickness, and thus the thin film membranes with sub-micro scale selective layers as part of a composite membrane has drawn particular interests. In thin film membranes, the membrane fabrication technique as well as the membrane configuration design are more important than the membrane materials. However, the recent progress on membrane fabrication techniques, especially the bottom-up approaches for composite membranes, have not been fully reviewed and compared. This review focuses on the recent progress in fabrication techniques and approaches of the thin film (sub-micron) polymeric membranes for CO2 capture, the state-of-art performance of those membranes will be summarized, and future direction of thin film composite membrane will be discussed.