Carbon Dioxide Adsorption on Activated Carbons Obtained from Polymeric Precursors

A series of activated carbons obtained from different polymers such as polypyrrole, sulfonated styrene divinylobenzene resin, polycarbonate, Kevlar (R). fibers, and poly(vinylidine fluoride) were included in the study. The polymeric precursors were carbonized in flowing nitrogen at a temperature from 350 to 700 degrees C and activated with KOH at the carbon:KOH ratio of 1:4 and 1:5 at 700 degrees C. Specific surface area of carbons obtained ranged from 1810 to 2920 m(2)/g, their total pore volume - from 0.87 to 1.64 cm(3)/g, volume of micropores and small nnesopores - from 1.07 to 1.47 cm(3)/g, and finally the ultramicropore volume varied between 0.44 and 0.72 cm(3)/g. Additionally, the commercial activated carbon Filtrasorb 400 was studied for the comparison purposes. The porous structure parameters for the carbons studied were on average about twice as large as those of the commercial carbon Filtrasorb 400. The polymer-derived carbons showed high adsorption capacities toward carbon dioxide at 0 C and under the pressure from about 2 to 900 mmHg. The maximum capacity for carbon dioxide adsorption under the aforementioned conditions varied from 4.31 to 7.58 mmol/g. The CO2 adsorption isotherms were fitted by the Dubinin-Radushkevich (DR) equation to evaluate the maximum CO2 uptake (a(0)) by the micropores as well as the B constant. It was demonstrated that the maximum CO2 uptake calculated by the DR equation correlated well with the volume of ultramicropores determined on the basis of pore size distribution by the DFT (density functional theory) analysis. Very good adsorption properties of the carbons obtained from polymeric precursors, including polymeric wastes, render them potentially useful materials for capture and storage of carbon dioxide.