COAL-BASED ACTIVATED CARBONS PREPARED WITH ORGANOMETALLICS AND THEIR MESOPOROUS STRUCTURE

The preparation of a mesoporous carbon was attempted by a steam activa tion of a mixture of coal and metal acetylacetonate at 900 degrees C. The resultant porosity of the activated carbon was influenced more by the type of acetylacetonate [Al(acac)(3), Y(acac)(3), TiO(acac)(2), or Zr(acac)(4))] than by the rank of the coal (Miike, Taiheiyo, and Morw ell). Samples obtained from TiO(acac)(2) showed a particularly high me soporosity even at an early stage of activation, as evaluated by the B ET and BJH analysis of the N-2 adsorption isotherm. To clarify the inf luence of TiO(acac)(2) on the mechanism of formation of a remarkable a mount of mesopores, the structure of the activated carbon derived from the Ti complex was investigated by X-ray diffraction measurements and observations with a transmission electron microscope (TEM). The carbo n matrix was composed of small graphite-like crystallites with mesopor es and TiO2 (rutile and brookite) particles dispersed homogeneously th roughout the whole matrix. The shape of the characteristic mesopores r esembled that of the TiO2 particles. The particle size distribution de termined by image analysis of a TEM photograph quantitatively shows th e similarities in the average size of TiO2 particles and pores. It is believed that the formation of mesoporosity in the activated carbon is closely related to the migration of TiO2 from the carbon matrix.