Optimization of the preparation conditions of KOH-activated, PAN-based carbon ellipsoids by orthogonal experimental analysis

The optimal preparation conditions for activated carbons from polyacrolynitrile ellipsoid powder by KOH activation were investigated by orthogonal experimental analysis. Results indicate that the activation temperature, holding time, KOH/carbon mass ratio all have a significant impact on the specific surface area, but a small impact on the total pore volume and mean pore size. The importance of factors determining (a) specific surface area are activation temperature > activation time > KOH/carbon mass ratio, (b) total pore volume are activation temperature > KOH/carbon mass ratio > activation time, and (c) the mean pore size are activation time > KOH/carbon mass ratio > activation temperature. The optimal combination of conditions (activation temperature of 800 ℃, holding time of 4 h and KOH/carbon mass ratio of 4:1) from orthogonal experimental analysis was validated experimentally. Under these conditions the specific surface area, total pore volume and mean pore size of the PAN-based porous carbon reached 2 517 m² g^-1, 1.07 cm³ g^-1 and 1.70 nm, respectively.