XRD evaluation of CO2 activation process of coal- and coconut shell-based carbons

Microporous carbons were prepared by CO2 activation of coal and coconut-shell chars. Specific surface area of the samples was determined by N2 adsorption as a parameter for surface structure, and was compared with some crystallographic parameters evaluated with X-ray diffraction (XRD) pattern. Number of aromatic layers increased linearly with increase of specific surface area in both series of samples, while interlayer spacing and fraction of stacking structure showed more complicated variation. This result was explained in terms of the earlier gasification of carbon atoms out of the stacking structure of aromatic layers. Results by TEM observation also supported this interpretation.