Steam Activation of Brown Coal Char

Abstract

The conditions to prepare active carbon from brown coal were investigated. Brown coal used was Kashima, Taiheiyo or Yallourn. Experimental conditions were as follows, carbonization temperature: 600°C, activation temperature: 700∼900°C, activation time: 0.5∼15 hours, steam rate 1.3 g/hr, respectively. Specific surface area of Kashima or Taiheiyo coal showed a maximum at about 50% weight loss and decreased rapidly with further activation. Values of specific surface area were less than 500 m²/g. But specific surface area of active carbon from HCl treated Kashima or Taiheiyõ char increased monotonously with weight loss. Active carbons with specific surface area of 600 m²/g were prepared. Effect of activation temperature on specific surface area was negligible. The reactivity of HCl treated chars against steam was smaller than that of untreated ones. Yield of active carbon from HCl treated chars was higher than that from untreated chars under the same activation conditions. Specific surface area of Yallourn coal char was 400 m²/g which is about two times larger than other chars.
Active carbons with specific surface area of 900 m²/g were prepared from Yallourn coal.
The reactivity of brown coal against steam was much higher than that of bituminous coal.