(535f) Impact of Water Vapor and Oxygen On Amine Sorbents for Post-Combustion CO2 Capture

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.