Comparison of equilibria and kinetics of high surface area activated carbon produced from different precursors and by different chemical treatments

Activated carbons prepared by chemical activation of coal and macadamia nutshell precursors with KOH and ZnCl2 have been studied in terms of their equilibrium and dynamic characteristics. These characteristics were then related to the micropore properties: surface area, volume, and half-width. Volumetric techniques were used for equilibria characterization and an FT-IR batch adsorber for dynamics. Carbons activated by KOH resulted in a more microporous structure, while those activated by zinc chloride were more mesoporous. High surface area samples were further studied in terms of their methane adsorption uptake. It was found that nutshell-derived activated carbons have a higher adsorption capacity per unit mass than those derived from coal; however, this was offset by lower particle density (mass/volume). High-pressure (2 GPa) pelletization of the carbons used for dynamic testing had a detrimental effect on capacity, presumably from pore collapse. Dynamic characteristics were found to be rather similar between the samples, with those treated with KOH displaying slower adsorption time scales.