(137f) Two Dimensional Nanosheets-Embedded Thin Film Composite Membrane for CO2 Cature Applications

The development of cost-effective CO₂ capture technologies for coal power plants will reduce the adverse impact of CO₂ emissions on global climate. Amine absorption technologies have been extensively studied and are regarded viable for post-combustion CO₂ capture. However, the energy comsuption for absorption technologies is still much higher than minimum requirement for large scale post-combustion flue gas. It seems clear that the membrane-based gas separations have presented a suitable alternative to the traditional separation processes for CO₂ capture, particularly for the treatment of flue gas streams including more than 15% CO₂. Membrane systems offer relevant gains in terms of flexibility, reliability, modularity and that they need energy intensity generally lower, or, at least, comparable with that of absorption technology. For competition with existing technologies, most of all, membrane materials with high permeability and high selectivity should be further developed with feasible processibility for real membrane platforms such as hollow fibers or thin-film composite membranes. According to recent report, the membrane systems can compete with existing technologies when membrane shows high CO₂ permeance (~4000 GPU, 1 GPU = 1×10^-10 cm³(STP)/cm².sec.cmHg) and high CO₂/N₂ selectivity (~50). However, to achieve this goal, many factors should be considered: selective layer thickness, gutter layer, and the porosity of support membrane in the form of thin-film composite membrane. In this study, we have developed high permeable, selective thin-film composite membrane for post-combustion CO₂ capture. Selective layers consist of high CO₂ permeable polymer and two-dimensional nanosheets. The nanosheets as dispersed phase in continuous polymer matrix help enhance CO₂/N₂ selectivity (~60) without any loss of CO₂ permeability. Also, such nanosheets at low content help prevent CO₂-induced plasticization, often leading to dramatic decrease in gas mixture. To develop high permeable, selective thin-film composite membranes, we have analyzed the effect of selective layer thickness, types of gutter layer (or gutter layer thickness), and support membrane properties, and these results were used for preparing optimized thin-film composite membranes. These thin-film composite membranes exhibited high CO₂ permeance and high CO₂/N₂ selectivity, even in the presence of water, which is close to the membrane criteria suitable for membrane-based CO₂ capture system. We have also prepared plate-to-frame modules, based on these membranes, showing high CO₂ flux of 5 m₃/h, for pilot plant demonstration.