Aqueous amine solutions have been used extensively for the separation and capture of CO2 from gas streams.  The downsides of this method include high regeneration energy, solvent lost due to oxidation and high volatility of the amines. Several solid amine enriched sorbents have been recently synthesized and successfully tested to remove CO2; however, the high cost of these sorbents prohibits their large-scale application.  Consequently, the development of new economical amine-enriched sorbents will greatly benefit CO2 sequestration capabilities. To this end, chitosan (a polysaccharide manufactured from the waste shells of crab and shrimp on tonnage scale) is of prime interest due to its high amino nitrogen content. The reported investigation is designed to test our hypothesis that commercial chitosan materials have utility for separation and capture of CO2 from industrial flue gases. Several commercial chitosan samples were characterized for thermal stability, surface area, and water content. Isothermic CO2 sorption experiments were performed in a pressure vessel, with desorption analyzed by GC-MS. FTIR measurements confirmed CO2 sorption and interaction with chitosan amino-groups through the appearance of a unique peak in the CO2 region.  Selectivity studies using a gas mixture of CO2, O2, and N2, demonstrated that chitosan had little affinity for O2 and N2.  It was determined that increase of water level in chitosan significantly enhances CO2 sorption. Based upon these results, chitosan shows promise as an affordable and effective material for CO2 separation and capture. Even with a relatively low surface area, chitosan displays a sizable capacity for CO2 sorption that is enhanced in a humidified environment.

Chitosan for separation and capture of CO2 from flue gas

239th National Meeting (2010)

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