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.