Study on the preparation of high value-added activated carbon from petroleum coke: Comparison between one- and two-step methods for carbonization and activation

To study the effects of carbonization on the preparation of activated carbon, petroleum coke-based activated carbon was prepared via a one-step method involving carbonization and activation as well as a two-step method involving carbonization followed by activation. In addition, the effects of carbonization temperature (550–750 °C) and activation heating rate (10 °C/min and 20 °C/min) on the surface morphology and pore structure of the activated carbon were investigated, and the adsorption performance of the activated carbon for iodine was analyzed. The results showed that precarbonization did not increase, but rather decreased, the number of surface oxygen-containing functional groups. In addition, increasing the heating rate to 20 °C/min effectively increased the number of oxygen-containing functional groups and delayed the merging of pores. Carbonization of activated carbon did not result in an increase in its specific surface area; rather, its specific surface area was reduced by up to 55.5 %. However, at a heating rate of 20 °C/min, the activated carbon prepared by carbonization exhibited a better microporous structure. Based on the iodine adsorption values, it was found that the adsorption performance of iodine was determined by the micropore diameter of the activated carbon but not the specific surface area.