(45b) Polyethyleneimine-Functionalized Polyamide-Imide Hollow Fiber Sorbents for Post-Combustion CO2 Capture

Carbon dioxide emitted from existing coal-fired power plants causes a major environmental concern due to possible linkages to global climate change. Therefore developing materials for capturing carbon dioxide has become an important issue for this application. In this study, we expand previous work focused on aminosilane-functionalized polymeric hollow fiber sorbents by introducing a new class of polyethyleneimine (PEI) functionalized polymeric hollow fiber sorbents for post-combustion carbon dioxide capture. The study proves that the open-walled porous morphology of the polymeric hollow fibers can be maintained after functionalizing with PEI. Different molecular weight PEIs were studied as modification reagents on polyamide-imide hollow fibers. This imide ring-opening modification introduces two amide functional groups and was confirmed via FTIR-ATR. The carbon dioxide equilibrium sorption capacities of PEI functionalized polyamide-imide materials were characterized using both pressure decay and gravimetric sorption methods. For equivalent PEI concentrations, polyamide-imide fibers functionalized with lower molecular weight PEI exhibited higher sorption capacities. Our hypothesis to explain this observation is that the imide ring opening event is substantially more prevalent in the low PEI molecular weight samples. Diffusional and steric limitations become significant hindrances for efficient tethering in the high PEI molecular weight samples. The effect of water in the ring-opening reaction was also studied. Up to a critical value, water in the reaction mixture enhanced the degree of functionalization. The optimal water concentration found in this reaction is 10% (w/w).