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. • A high heating rate can delay pore merging during the two-step method. • Better adsorption properties are generated by the one-step method with a high heating rate. • The heating rate but not the carbonization temperature can enhance the functional groups. • Carbonization does not positively affect the specific surface area but is beneficial to the microporous at 20℃/min. • The pore diameter, but not the specific surface area, plays a decisive role in adsorbing iodine. [ABSTRACT FROM AUTHOR]