Katsuhisa Maruyama

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

Abstract 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.

Preparation of fibrous activated carbons from wood fiber

Short fibrous hollow activated carbons with a high aspect ratio were prepared by carbonization and carbon dioxide activation of softwood and hardwood fibers. The softwood activated carbon consisted mostly of micropores even though the degree of burn-off during the activation became higher. In the case of the hardwood fiber, on the other hand, meso- and macropores as well as micropores were formed and the ratio of these large pores increased with an increasing degree of burn-off. The adsorbed amount of water and toluene vapor on these fibrous activated carbons was compared with that of the commercial activated carbon fibers (ACFs). These fibrous activated carbons showed a high adsorption capacity comparable to that of the ACFs.

Carbonization and graphitization behavior of decacyclene

Decacyclene was carbonized in a glass tube or a molten salt at various temperatures and the products were analyzed by means of Raman spectroscopy, X-ray diffractometry, ESR and FT-IR spectroscopies in order to investigate the influence of contained pentagonal aromatic rings on the change of carbon structures with heat-treatment. It was found that the presence of the pentagonal rings disturbs the growth of planar aromatic layers at the early stage of carbonization and that the development of the layer stacking to c-axis with further heat-treatment is influenced predominantly by the phase during the carbonization stage rather than by the pentagonal rings.