Combustion reaction kinetics of guarana seed residue applying isoconversional methods and consecutive reaction scheme

This work aims the study of decomposition kinetics of guarana seed residue using thermogravimetric analyzer under synthetic air atmosphere applying heating rates of 5, 10, and 15 °C/min, from room temperature to 900 °C. Three thermal decomposition stages were identified: dehydration (25.1-160 °C), oxidative pyrolysis (240-370 °C), and combustion (350-650 °C). The activation energies, reaction model, and pre-exponential factor were determined through four isoconversional methods, master plots, and linearization of the conversion rate equation, respectively. A scheme of two-consecutive reactions was applied validating the kinetic parameters of first-order reaction and two-dimensional diffusion models for the oxidative pyrolysis stage (149.57 kJ/mol, 6.97 × 1010 1/s) and for combustion stage (77.98 kJ/mol, 98.61 1/s), respectively. The comparison between theoretical and experimental conversion and conversion rate showed good agreement with average deviation lower than 2%, indicating that these results could be used for modeling of guarana seed residue.