Complex process activation energy evaluated by combined utilization of differential and integral isoconversional methods

Abstract

Performance of the differential and integral isoconversional methods of kinetic analysis was evaluated for complex processes with overlapping independent or consequent reaction mechanisms. Novel way of combined interpretation of the activation energy dependences provided by both differential and integral methods was developed, enabling precise determination of the true activation energies of the overlapping sub-processes. Fundamental part of this evaluation method is based on the existence of point of inflexion following the overshoot effect on the differential isoconversional dependence of activation energy on the degree of conversion. This point of inflexion was found to very well coincide with the higher activation energy. The lower true activation energy can be always determined from the integral isoconversional dependence. Universal pattern for interpretation of the isoconversional kinetic methods behavior was confirmed for all sub-processes with asymmetry in the range of <-0.35; 0.35>, covering majority of real-life data.