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

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 SO_x and NO_x impurities in CO₂ capture processes than those that contain primary amine groups.