Activated carbon production from low ash subbituminous coal with CO2 activation

Activated carbon was prepared by physical activation in CO, from a low‐ash subbituminous coal. The preparation process consisted of carbonization of the coal in N, followed by activation of the resulting chars in CO2. The 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 burnoff carried out at the same temperature. These 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. The apparent order with respect to CO2 partial pressure for the gasification was found to be within the range of 0.15–0.25.