Influence of the carbonization heating rate on the physical properties of activated carbons from a sub-bituminous coal

The effect of the coal carbonization step heating rate on the reactivity of the chars obtained, as well as on their porous structure development in the subsequent activation step, was analyzed. Different types of carbonization process were investigated, combining a low heating rate (5 K/min) and high heating rate (hundreds of K per second) in this step. Chars obtained in these processes were activated at 1123 K with CO2 at three burn-off degrees. Chars from carbonization experiments at high heating rates showed a higher reactivity than those subjected to slow heating rates and yielded a slightly increased surface area of activated carbons. A mathematical model has been developed that is capable of simultaneously correlating the 77 K N-2 adsorption isotherms of all samples obtained as a function of the burn-off and the heating history in the carbonization step. Copyright (C) 1996 Elsevier Science Ltd