Activated carbon production from low ash subbituminous coal with CO₂ activation

Activated carbon was prepared by physical activation in CO₂ from a low-ash subbituminoits coal. The preparation process consisted of carbonization of the coal in N₂ followed by activation of the resulting chars in CO₂. Tlte activation temperature ranged from 700 to 950°C. Experimental results revealed that the surface area, pore volume and average pore diameter of the activated carbon generally increased with the amount of carbon bumojf carried out at the same temperature. Tiiese surface characteristics were also influenced by the variation of the activation temperature. It was found that the porosity of the carbon passed through a maximum at a temperature of 750°C. The activation energy for the carbon gasification in CO₂ was calculated to be in a range of 130-180 kJ/mol, based on the assumption that the reaction rate was proportional to the surface area of the carbon. Ttie apparent order with respect to CO₂ partial pressure for the gasification was found to be within the range of 0.15-0.25.