Analysis of the impact of TG data sets on activation energy (Ea): Case study applied to torrefaction of biomasses by means of isoconversional methods

This work reports the results of an extended kinetic study involving both experimental measurements and modelling elaborations. It is specifically dedicated to investigate the thermal behaviour of biomasses undergoing to torrefaction treatment. Three biomasses, representative of the hardwood family, have been considered: ash-wood, beech-wood and hornbeam. As main purpose, this work evaluates the impact of the TG measurements on the Activation Energy (Ea) results achieved by implementing the so called isoconversional “model free” methods on both their differential and integral version. Considering the heterogeneous nature of the biomasses and the thermo-chemical factors conditioning the involved solid state reactions, several replicates of the TG data sets have been carried out and their impact on the Ea reliability has been evaluated. An extended sensibility analysis of the adopted models allows to identify a Confidential Boundary Range (CBR) of the TG measurements and, in correspondence, an Activation Energy Boundary Range (EaBR) for the Ea results. Considering the “model free” nature of these methods, a preliminary selection of a kinetic scheme is not required, making particularly attractive this approach to match the purpose of this research. This study provides even a comparison among the models performances and a review of their application limits. Applied to heterogeneous materials, the proposed approach could be considered a general methodology to test the impact of the TG measurements on the Activation Energy results reliability