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Aminosilane-Functionalized Hollow Fiber Sorbents for Post-Combustion CO2 Capture

Li, Fuyue Stephanie, Lively, Ryan P., Lee, Jong Suk, Koros, William J.
Industrial & Engineering Chemistry Research 2013 v.52 no.26 pp. 8928-8935
Fourier transform infrared spectroscopy, absorbance, carbon dioxide, cellulose acetate, chromatography, coal, crosslinking, engineering, flue gas, global warming, greenhouse gas emissions, heat transfer, mass transfer, mixing, nitrogen, oxygen, scanning electron microscopy, silicon, sorbents, sorption
Increasing carbon dioxide emissions are generally believed to contribute to global warming. Developing new materials for capturing CO₂ emitted from coal-fired plants can potentially mitigate the effect of these CO₂ emissions. In this study, we developed and optimized porous hollow fiber sorbents with both improved sorption capacities and rapid sorption kinetics by functionalizing aminosilane (N-(2-aminoethyl)-3-aminoisobutyldimethylmethoxysilane) to cellulose acetate hollow fibers as a “proof of concept”. A lumen-side barrier layer was also developed in the aminosilane-functionalized cellulose acetate fiber sorbent to allow for facile heat exchange without significant mass transfer with the bore-side heat transfer fluid. The functionalized cellulose acetate fiber sorbents were characterized by pressure decay sorption measurements, multicomponent column chromatography, FT-IR, elemental analysis, and scanning electron microscopy. The carbon dioxide sorption capacity at 1 atm is 0.73 mmol/g by using the pressure decay apparatus. Multicomponent column chromatography measurements showed that aminosilane functionalized cellulose acetate fiber sorbent has a CO₂ sorption capacity of 0.23 mmol/g at CO₂ partial pressure 0.1 atm and 35 °C in simulated flue gas. While this capacity is low, our proof of concept positions the technology to move forward to higher capacity with work that is underway. The presence of silicon and nitrogen elements in the elemental analysis confirmed the success of grafting along with FT-IR spectra which showed the absorbance peak (∼810 cm–¹) for Si–C stretching. A cross-linked Neoprene material was used to form the lumen-side barrier layer. Preliminary data showed the required reduction in gas permeance to eliminate mixing between shell side and bore side fluid flows. Specifically the permeance was reduced from 10 000 GPUs for the neat fibers to 6.6 ± 0.1 and 3.3 ± 0.3 GPUs for the coated fibers. The selected lumen layer formation materials demonstrated strong resistance to water and oxygen.