Mathematical modelling and kinetics of thermal decomposition of corn stover using thermogravimetry (TGA-DTG) technique
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Lignocellulosic biomass could be pyrolytically converted into value-added products and
one of the steps during the pyrolysis is thermal decomposition which involves multiple
reactions. Therefore, mathematical modelling of thermal decomposition could provide
molecular insight into thermal degradation reactions by providing accurate prediction of
the phases of the multi-component reactions in particular nucleation, growth and
boundary-phase reactions occurring under different working conditions. In this study, thermal decomposition behaviour of Corn Stover was explored using thermogravimetry
technique (TGA-DTG) at heating rates of 20, 30, 40 and 50 °C/min under nitrogen gas
flow (55 mL/min) and oxygen gas flow at 15 mL/min. The Flynn-Wall Ozawa (FWO) and
Kissinger Akahira Sunose (KAS) models were used to estimate the kinetic parameters
such as apparent activation energy, pre-exponential factor and order of reaction so as
to be able to design the pyrolytic reactor that could be used for the biomass conversion.
The hemicellulose maximum mass loss rate was at 300 °C, cellulose at 410 °C and
lignin decomposition from 190 °C to 620 °C. The apparent activation energies
calculated ranged from 44.39 -134.81 kJ/mol using the FWO method while the KAS
method gave 87.83 - 282.41 kJ/mol. The variation of the apparent activation energy
represents the four different stages occurring during the thermal decomposition process
for the corn stover. The Friedman's model was used with reaction- order model to
estimate the order of reaction. The predicted model fitted well with the experimental
data showing that the complex degradation process followed a first-order reaction.
Keywords
Q Science (General), T Technology (General), TP Chemical technology