(535f) Impact of Water Vapor and Oxygen On Amine Sorbents for Post-Combustion CO2 Capture
AIChE Annual Meeting
Wednesday, November 6, 2013 - 5:49pm to 6:11pm
Amine sorbents such as polyethyleneimine/SiO2 are being considered for post-combustion CO2 capture from coal-fired power plants. A successful sorbent must be stable under moist conditions present during adsorption and regeneration steps. Also, the presence of oxygen in flue gas may have an impact on the amine sorbents; thus understanding its impact on the amine in the presence of CO2 is required. In this work, we are evaluating the stability of amine sorbents under steam during regeneration and the impact water and oxygen have on the sorbent during adsorption
The sorbent used in this work was synthesized by wet impregnation of SiO2 (Fuji Silysia Cariact grade G-10 HPV) with polyethyleneimine (Aldrich PEI Mn-423). CO2 adsorption-desorption cycling was conducted in a fixed bed reactor. The sorbent was tested prior and subsequent to O2 pretreatment using dry cycles (10 vol. % CO2/He at 60°C) to assess any change in its performance. Gas analysis of the reactor effluent was conducted using mass spectrometry.
The impact of 5% O2/He on the sorbent was investigated at 80 °C. The sorbent was held at these conditions for 5 h, resulting in a decrease in CO2 capture of 7 mol%. The impact of 5% O2/He at 80 °C in the presence of water was also investigated. The sorbent was cycled ten times through 5% O2-8% H2O/He at 80 °C with the total time adding up to 5 h and regenerated under helium at 80°C. The sorbent was tested under dry conditions prior to and after exposure to O2/H2O to assess their impact on its performance. The CO2 loading was found to decrease by 19 mol% compared to the fresh sorbent. However when the sorbent was exposed to 8% H2O/He, the decrease in CO2 loading was found to be only 9 mol %. Clearly the combination of H2O and O2 at 80 °C has the greatest negative impact on the sorbent.
The impact of O2 in the presence of CO2 on this sorbent and a silanated sorbent will be discussed as well. Characterization of the fresh and spent sorbents prior to and following O2/H2O/CO2/He exposure will be presented.