Analyzing the pyrolysis kinetics of several microalgae species by various differential and integral isoconversional kinetic methods and the Distributed Activation Energy Model

The pyrolysis kinetics of the microalgae Chlorella vulgaris (CV), Isochrysis galbana (IG), Nannochloropsis gaditana (NG), Nannochloropsis limnetica (NL), Phaeodactylum tricornutum (PT), and Spirulina platensis (SP) were studied by non-isothermal thermogravimetric analysis conducted at nine different constant heating rates. The kinetic parameters of each microalgae species were calculated using several kinetic methods, such as those of Kissinger, Friedman, Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), Vyazovkin, and the simplified Distributed Activation Energy Model (DAEM). The results show that the kinetic parameters calculated from the integral isoconversional methods OFW, KAS and Vyazovkin are similar to those determined by applying the simplified DAEM. In contrast, application of the differential isoconversional method of Friedman led to moderate deviations in the activation energies and pre-exponential factors computed, whereas the unique values of the kinetic parameters determined by the Kissinger method resulted in the highest deviations.