Effect of petroleum coke expanding by perchloric acid on the performance of the resulted activated carbon
Abstract
Petroleum coke (PC) was expanded by using KMnO4 as oxidant and HClO4 as intercalator so as to decrease the amount of KOH needed for the successive activation. Activated carbon (AC) was prepared by activation of the expanded PC (EPC) at KOH/coke mass ratio of 3:1 (denoted as EAC-3). As a comparison, AC was also made by activation of PC at KOH/coke mass ratio of 3:1, 4:1 and 5:1 (denoted as AC-3, AC-4 and AC-5). Influence of expanding modification on the structure and performance of PC and AC was investigated. The results revealed that the expanding treatment increased the interplanar distance of PC microcrystalline from 0.344 to 0.362 nm and decreased the microcrystalline thickness from 2.34 to 1.57 nm. The specific surface area of EAC-3 and AC-5 was 3461 and 3291 m2⋅g-1, respectively. The average pore size of EAC-3 was 2.19 nm, which is 0.11 nm larger than that of AC-5. At a scan rate of 0.5 mV⋅s-1, EAC-3 and AC-5 achieved a specific gravimetric capacitance of 486 and 429 F⋅g-1, respectively. Supercapacitor based on EAC-3 possessed lower resistance and better power performance.
