Synthesis of polyethylenimine-impregnated titanate nanotubes for CO₂ capture: Influence of porosity and nitrogen content on amine-modified adsorbents

Amine-modified adsorbents have been of interest due to their excellent performance for carbon dioxide (CO₂) capture. In this work, we have prepared titanate nanotubes (TNTs) with amine modification using polyethylenimine (PEI) for selective CO₂ capture under flue gas. TNTs were prepared by the hydrothermal reaction, and PEI-functionalized TNTs (P-TNTs) were prepared by the wet impregnation method. Enhanced CO₂ affinity through amine modification on TNTs allows for selective and favorable CO₂ adsorption onto adsorbents. To confirm the CO₂ capture in the post-combustion step, CO₂ adsorption performances were investigated by the gravimetric method under 15% CO₂ /85% N₂ (binary) and 15% CO₂/5% O₂/80% N₂ (ternary) gases as in flue gas conditions, respectively. Furthermore, our work provides evidence that the amine-modified adsorbents can be influenced by oxygen gas on CO₂ capture performances, including regeneration ability.