Different Approaches for the Development of Low-Cost CO2 Adsorbents

Different carbon materials were tested as precursors for the production of CO2 adsorbents. The chemical modification of the surface of the prepared adsorbents was studied by means of three different approaches: impregnation with amines, electrophilic aromatic substitution, and heat treatment in the presence of ammonia. The samples were chemically characterized and the porous texture was evaluated from the N-2 adsorption isotherms at -196 degrees C. The CO2 adsorption capacities of the adsorbents at 25 and 100 degrees C were evaluated in a thermogravimetric analyzer. In general, the incorporation of basic nitrogen functionalities enhanced the CO2 capture capacities of the modified carbons, but this increase depended on the textural properties of the support and the surface modification methodology. CO2 adsorption capacities of up to 111 mg CO2/g at room temperature were attained. All the tested samples were completely regenerated when subjected to heat treatment at 100 degrees C under inert atmosphere.