Effects of KOH/MMB weight ratio on structure and morphology of activated mesophase carbon microbeads

In order to prepare the high surface area activated mesocarbon microbeads with high mesopore content, mesophase pitch microbeads were activated with KOH at 850 ℃ and the effects of the weight ratio of KOH/MMB to the structure and morphology of activated carbon microbeads were investigated in this paper. Both the total pore volume and the mesopore volumetric proportion of activated carbons increase with increasing the weight ratio KOH/MMB to a maximum, and then decrease with further increase of the weight ratio. The activated mesocarbon microbeads with the highest BET surface area (3 182 m2/g), the highest pore volume (245 cm3/g), and large percentage (62%) of mesopore volume were prepared with the KOH/MMB ratio of 8. With the increase of KOH/MMB ratio from 8 to 10, the total pore volume and surface area decrease to 239 cm3/g and 2 548 m2/g respectively, but the mesopore volume reach the highest value of 157 cm3/g. The results also indicate that, with increasing KOH/MCMB weight ratio, the sizes of the activated carbon microbeads can be reduced and the forms of the activated carbon microbeads change from sphere to ellipsoid, and then become smaller beads. On basis of the above results, the activation mechanism of MMB with KOH was discussed.