Investigations on Mediterranean biomass pyrolysis ability by thermogravimetric analyses: thermal behaviour and sensitivity of kinetic parameters

Abstract

A comparison of the thermal behaviours of different Mediterranean biomasses, based on the evaluation of their pyrolysis characteristic temperatures, their reactivity and kinetic parameters is presented. Parameters such as the activation energy and the pre-exponential factor of the pyrolysis reactions are determined by different methods (Kissinger, Kissinger–Akahira–Sunose [KAS], Coats–Redfern, nonlinear least-squares minimization [NLSM] and model distributed activation energy model [DAEM]). Furthermore, a sensitivity analysis of the kinetic parameters based on different methods is conducted. The comparison of this work with the literature, showed that thermal characteristic parameters determined using the thermogravimetric analysis (TGA) are often neglected and not used in biomass pyrolysis at laboratory scale. The kinetic parameters seem to be highly sensitive to the used kinetic methods. For a given biomass, such as the Aleppo pine husk residue, for example, the activation energy can vary from 65.80 to 197.08 kJ${\cdot }$mol$^{-1}$ depending on the used method. For this biomass, the highest average activation energy (190 kJ${\cdot }$mol$^{-1}$) was estimated by the KAS and DAEM methods. The Kissinger method yields to an activation energy close to that of cellulose calculated by the NLSM method. For all biomasses, the activation energy remains between 150 and 200 kJ${\cdot }$mol$^{-1}$ except for the Coats–Redfern method, where this value is in the range of 50–100 kJ${\cdot }$mol$^{-1}$. Therefore, it is important to have a means of recommending the most appropriate method for the determination of kinetic parameters.

Keywords

• Biomass
• Pyrolysis
• Thermogravimetric analysis
• Kinetic parameters
• Bio-oil