Kinetics of the pyrolysis of arundo, sawdust, corn stover and switch grass biomass by thermogravimetric analysis using a multi-stage model

• Multistage biomass decomposition model using single TGA experiment was developed.
• The pyrolysis decomposition of the biomass could be divided into three stages.
• Temperature range for the 1st, 2nd, and 3rd stages determined for each biomass.
• Multistage linearization gave very good fits (0.955 < R2 < 0.999) for conversions >80%.
• All kinetic parameters determined for each of the three stages for the four biomass.

A new multi-stage kinetic model has been developed for TGA pyrolysis of arundo, corn stover, sawdust and switch grass that accounts for the initial biomass weight (W0). The biomass were decomposed in a nitrogen atmosphere from 23 °C to 900 °C in a TGA at a single 20 °C/min ramp rate in contrast with the isoconversion technique. The decomposition was divided into multiple stages based on the absolute local minimum values of conversion derivative, (dx/dT), obtained from DTG curves. This resulted in three decomposition stages for arundo, corn stover and sawdust and four stages for switch grass. A linearized multi-stage model was applied to the TGA data for each stage to determine the pre-exponential factor, activation energy, and reaction order. The activation energies ranged from 54.7 to 60.9 kJ/mol, 62.9 to 108.7 kJ/mol, and 18.4 to 257.9 kJ/mol for the first, second and the third decomposition stages respectively.