Energy valorization of cassava residual biomass for high-energy value precursors: pyrolysis case

Abstract

The present work studied the pyrolysis of cassava residues through a thermogravimetric analysis (TGA). For this purpose, the selected biomass (cassava) was characterized by its calorific value, immediate analysis, and elemental analysis. For the experiments, three heating rates (50, 75, and 100 K/min) were used under in an inert atmosphere with a heating ramp from room temperature (~25 °C) to 900 °C. The initial characterization results showed an ash content of 1.8% by mass and a calorific value of 15.2 MJ/kg, making this residue a promising candidate for energy use through thermochemical conversion processes. On the other hand, during heat treatment under an inert atmosphere, the cassava residue experienced a major mass loss event at 339.57 °C for 50 and 75 K/min (the greatest mass loss was at 50 K/min, resulting in 12.15% of the char) and displaced 34 °C when the sample was treated at 100 K/min.  From the kinetic analysis, it was observed  that the activation energy increases as the conversion increases, whereas the Friedman method which presents high activation energies of 93.98, 190.98 and 182.1 kJ/mol at 0.15, 0.85 and 0.95 respectively. OFW and KAS methods present a similar behavior for the activation energy dependence on conversion, and the variation is minor between the results obtained with each of them.