Tailoring the CO2 permeation of Pebax1657/polyether imide thin film composite membrane via embedding Ag-based metal-organic framework

Abstract

Thin-film composite/nanocomposite (TFC/TFN) membranes count as the latest version of carbon capture membranes characterized by their excellent gas permeance, great selectivity, cost-effectiveness, and the ability to separately manage and tune the constituents of the individual layer. In this regard, Pebax®1657 embedded with synthesized Ag-BTC metal-organic frameworks (MOFs) was coated on the polyether imide (PEI) support layer to produce TFNs. To assess the impacts of Ag-BTC particles (carboxyl-rich surface particles) on the features of the constructed TFC/TFN membranes and their gas permeation qualities, several CO2/N2 and CO2/CH4 separation experiments (mixed and pure gas testing) were carried out. Ag-BTC particles were distributed appropriately within the Pebax1657 matrix, improving the gas permeability (particularly for CO2) and enhancing CO2/N2 and CO2/CH4 separation factors. A simultaneous increase in CO2 permeability and gas pair selectivities was observed with rising feed pressure. A 394.97 Barrer CO2 permeability and 38.20 CO2/N2 and 21.25 CO2/CH4 selectivities were obtained for the TFN filled with 3 wt% Ag-BTC at 10 bar and 30 °C. A mixed gas test also showed a similar trend but lower values than a pure one. The results for the humidified conditions exhibited higher CO2 permselectivities in comparison with the dry gas given the water molecules facilitate the CO2 transportation through the Pebax®1657 matrix. Finally, enhancing Ag-BTC filler content and increasing the input pressure provided excellent conditions for approaching Robeson’s limit.