Stability of Supported Amine Adsorbents to SO2 and NOx in Postcombustion CO2 Capture. 2. Multicomponent Adsorption

Abstract

Packed bed CO2 adsorption breakthrough experiments using both amine-impregnated and amine-grafted silica adsorbent materials in the presence of SO2, NO and NO2 impurities are reported. The effects of temperature, feed concentration and adsorbent amine loading on the dynamic adsorption capacity of the adsorbents are evaluated by performing dual component SO2/CO2, NO/CO2 and NO2/CO2 coadsorption experiments as well as three component SO2/NO/CO2 adsorption experiments. Although SO2 is found to significantly influence the dynamic CO2 capacity of aminosilica adsorbents, the obtained results confirm the long-term stability of the adsorbents during SO2/CO2 coadsorption runs when the bed is not allowed to fully saturate with SO2. On the other hand, little competitive effect of NO on CO2 adsorption is observed in any case. This is due to the decreased affinity of amine-based adsorbents toward NO as opposed to SO2. The more reactive nitrogen oxide, NO2, is shown to have a minimal impact on CO2 adsorption when it is present at low levels in the simulated flue gas. Among the adsorbents investigated, the results demonstrate that secondary amine containing adsorbents are more stable to SOx and NOx impurities in CO2 capture processes than those that contain primary amine groups.