Preparation of activated carbon from needle coke via two-stage steam activation process

•Mesoporous activated carbon was prepared from needle coke via two-stage steam activation process.•The activated needle cokes treated by 1st steam activation exhibited the highest specific surface area of 643.3 m2/g.•2nd steam activation using the naphthalene makes the average pore diameter to increase.•The highest specific surface area and average pore diameter showed 1134.3 m2/g and 2.77 nm via two-stage steam activation.