The pore structure determination of carbon aerogels

The detailed adsorption isotherms of nitrogen on carbon aerogels at 77 K were measured. The N-2 adsorption isotherm had a marked hysteresis. The adsorption isotherms were analyzed by high resolution alpha(s)-plots to evaluate their porosity. The alpha(s)-plots showed an explicit upward deviation from the linearity below alpha(s) = 0.5, suggesting the presence of micropores. The mesoporosity and microporosity were separately determined from the alpha(s)-plot. The predominant pores in carbon aerogels were mesopores and the percentage of micropores was in the range of 5 to 10% of the total pore volume. The N-2 adsorption hysteresis was analyzed with the Saam-Cole theory under the assumption of the cylindrical pore shape. The parameters determined from the Saam-Cole method were associated with the carbon aerogel structure.