CORRELATION BETWEEN ARRHENIUS KINETIC-PARAMETERS IN THE REACTION OF DIFFERENT CARBON MATERIALS WITH OXYGEN

Correlation between Arrhenius kinetic parameters is often found in coa l and char reactions, to such an extent that Essenhigh and Misra have recently suggested (Essenhigh, R. H.; Misra, M. K. Energy Fuels 1990, 4, 171-177) that these parameters are autocorrelated. In order to thro w additional light on this point, a self-consistent set of kinetic dat a for the reaction of carbonaceous solids with oxygen, determined by t hermogravimetric analysis, is presented and analyzed in this work. The wide range of carbon materials under study allowed to broaden the sco pe of correlations with respect to numerous previous studies of this r eaction. A generalized correlation between Arrhenius parameters (appar ent activation energy and preexponential factor) was found. Unlike pre vious reports, existence of a systematic curvature in the correlation plot was detected. Thus, optimum fitting to a curve obeying a power eq uation rather than to a straight line was attempted. An active-centers model adapted to the graphite structure was used to justify the occur rence of compensation effect, differences in behavior among carbon mat erials being explained as a function of the relative predominance of t he various types of factors controlling the reactivity of these solids against oxygen.