Quantitatively modelling kinetics through a visual analysis of the derivative thermogravimetric curves: application to biomass pyrolysis

Analytic relations are developed that directly link visually observable features of differential thermogravimetric (DTG) curves (e.g., peak temperature, height, width, skewness and conversion at the peak) to the parameters of chemical reaction kinetics models (e.g., activation energy and prefactor), which can be used to study the thermal decomposition of solid fuels. General expressions suitable for any reaction model are provided, as well as explicit expressions for nth order reactions with a rate constant given by the Arrhenius equation. This approach is illustrated for the pyrolysis of biomass, where it is found to provide a rapid and accurate estimate of the relative contributions of cellulose, hemicellulose, and lignin to the volatile yield, as well as their kinetic parameters. The method offers a simple way to obtain the model reaction kinetics parameters from thermogravimetric data and saves computing time by providing sensible initial values and bounds of the fit parameters.