Effect of elemental sulfur in precursors on the pore structure and surface chemical characteristics of high-surface area activated carbon

Analog sulfur-containing precursors (ASCPs) have been prepared by adding a certain amount of elemental sulfur (ES) into petroleum coke (PC) for synthesis of high-surface area activated carbon (HAC). ASCPs make it feasible to control the speciation and content of sulfur in ASCPs, so as to accurately investigate the influence of ES on the pore structure and surface chemical characteristics of the resultant HAC. The results indicate that ES in ASCPs can react with activator KOH and consume a part of KOH amount, thus leading to the deficiency of actual KOH amount for PC activation, eventually making a decrease in the specific surface area and pore volume of HAC. Interestingly, some of ES in ASCPs is transformed into organic sulfur thioether (C-S-C) and sulfate (C-SO4-C) or sulfonate (C-SO3-C) on HAC surface during the activation process. Therefore, the surface chemical characteristics of HAC are modified correspondingly.