Enhancing POlymer Crystallinity in MixEd Matrix Membranes by Incorporating Metal-Organic Framework Nanosheets for an Efficient CO2 Capture – POCEMON

The urgent demand for natural gas sweetening and flue-gas purification has prompted the development of different technologies for efficient CO2/CH4 and CO2/N2 separations, including adsorption, absorption, cryogenic distillation and membranes. Currently, amine-based absorption process using chemicals ranging from monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) dominates the CO2/CH4 separation market in natural gas industries owing to its high separation efficiency. However, this technology is largely limited by its large capital investment, high energy consumption and complicated maintenance. Adsorption and cryogenic distillation also experience similar challenges and they are particularly suitable for treating gases with a high CO2 content. Membranes offer more energy-saving alternatives by allowing mixtures to be continuously separated without a phase change. The energy savings of up to 50% can be realized in membrane-based separation processes compared to other technologies.
Materials play a key role in membrane technology. Therefore, the search for membrane materials with excellent separation performance and high resistance toward the harsh operational conditions has aroused great attention in recent years. Among various types of membranes, mixed matrix membranes (MMMs) have been proposed by using polymers as continuous phase and organic/inorganic fillers as dispersed phase to synergistically combine the merits of both components, i.e. a good processability and strong mechanic strength of polymeric materials; inherently high gas permeability and selectivity of filler materials.
The main objective of this proposed project is to design and fabricate robust MMMs composed of porous metal-organic framework (MOF) nanosheets and highly permeable polymers for efficient CO2 capture. Chemically-stable MOF nanosheets will be prepared in a bottom-up method, which guarantees their large production yield for future industrial applications. The intrinsic pores of CO2-selective MOF structures will provide fast gas permeation pathways, boosting the membrane gas permeation. Highly permeable polymers (> 3000 Barrer) can largely improve the gas treatment productivity in membrane units, possessing a huge potential of replacing current commercially available polymers with moderate or low gas permeability (< 100 Barrer). Efficient polymer-filler interactions, such as hydrogen bond interactions and/or covalent bonding, will be utilized to improve the interfacial compatibility and facilitate the homogeneous distribution of porous fillers inside the membranes.
Here, we expect that the high aspect ratio of MOF nanosheets will result in a large surface contact area between MOF nanosheets and polymers, leading to the increase in active sites where the polymer-filler interactions can take place. Hydrogen bonding and pi-pi interactions will be designed here, and MOF nanosheets can function as templates that induce the ordered packing of one dimensional polymer chains onto them, resulting in enhanced polymer crystallinity. Polymers with good crystallinity will feature size-selective gas permeation channels and demonstrate excellent gas pair selectivity. Therefore, we are strongly convinced that this strategy can be highly valuable to improve the membrane permeability and selectivity simultaneously owing to the high porosity of MOF fillers and size-selective channels in the polymer phase. Our proposed technology will play an important role in the efficient CO2 capture process and it can have far-reaching effects on mitigating worldwide climate change and achieving a sustainable development for the human society.