Investigation of slow pyrolysis mechanism and kinetic modeling of Scenedesmus quadricauda biomass

Bioenergy potential of microalage Scednedesmus quadricuda through pyrolysis was investigated using kinetic and thermodynamic analyses. From model-free isoconversional methods, the estimated average activation energies were 152.37 (+/- 20.93), 174.98 (+/- 22.38), and 153.00 (+/- 21.23) kJ/mol, using Friedman, OFW and advance Vyazovkin methods, respectively. Avrami-Erofeev's A1/4 reaction model was the most probable single-step re-action mechanism determined from the combined kinetic analysis. The activation energy profile, however, indicated a complex degradation process in the active pyrolysis zone. Two independent parallel reactions were considered in the active pyrolysis zone. Average activation energy for low temperature conversion was 77.95 (+/- 3.12) kJ/mol, pre-exponential coefficient 4.86E4 (+/- 2.24E4) s(-1), and n = 1.51 (+/- 0.10), whereas for high temperature conversion, the activation energy was 73.26 (+/- 17.93) kJ/mol, pre-exponential coefficient 1.32E3 (+/- 2.61E3) s(-1), and n = 1.21 (+/- 0.16). Thermodynamic analysis of pyrolysis in terms of enthalpy, Gibbs free energy, and entropy indicated the feasibility of conversion.

Automated summary

The bioenergy potential of microalgae Scednedesmus quadricuda through pyrolysis was investigated using kinetic and thermodynamic analyses. The results indicated a complex degradation process in the active pyrolysis zone, with two independent parallel reactions considered. The activation energies for low temperature and high temperature conversions were found to be 77.95 kJ/mol and 73.26 kJ/mol respectively, with thermodynamic analysis showing the feasibility of conversion.