The Effect of CO2 Partial Pressure On Capture with Ion Exchange Resins

Wednesday, October 19, 2011
Exhibit Hall B (Minneapolis Convention Center)
W. Richard Alesi, Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA and John R. Kitchin, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA

Ion exchange resins (IER), especially polymeric resins with primary amine functionality have been used to scrub CO2 from breathing air, and have potential for application in CO2 capture from fossil energy power plant flue gas. To assess this potential, one must evaluate the role that temperature and pressure have on the CO2 capacity and kinetics of capture for the resins. We investigated the CO2 capture capacity of an IER in a packed bed reactor as a function of adsorption temperature and CO2 partial pressure. A series of adsorption and desorption experiments using thermogravimetric analysis and a packed bed reactor were used to determine the CO2 capture capacity of an IER under different adsorption and desorption conditions. As expected, lower adsorption temperatures result in increases in the adsorbed capacity of CO2. This result is contrary to that found in many impregnated polymeric amine sorbents, where temperature increases are necessary to offset the diffusional resistance of CO2 travel within the pores. Additionally, the role of CO2 partial pressure for capture is investigated with experiments of adsorption under atmospheric concentrations of CO2 and regeneration under 100% CO2. A thermodynamic model is developed to relate the changes in CO2 capacity to the thermodynamic driving forces for CO2 – resin interaction, whereby the resultant capacities under a series of experimental conditions can facilitate predictions of capacities under alternate conditions.

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