Kinetic modelling of torrefaction of olive tree pruning

The objective of this study is the proposal of a pyrolysis kinetic model that describes the thermal decomposition of olive tree pruning in different torrefaction conditions via thermogravimetrical measurements in nitrogen atmosphere. First, the determination of activation energies was performed by isoconversional methods of Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Friedman. Three stages were distinguished in which the activation energy keeps approximately constant and were related to the thermal degradation of the different constituents of the material (cellulose, hemicellulose and lignin). Then, Coast-Redfern method was applied to determine the kinetic function. The kinetic function that seems to determine the mechanism of thermal degradation of main components of olive tree pruning was nth order reaction. Finally, a detailed pseudo-mechanistic model (using least squares fitting in a parallel reaction scheme) was analyzed. This model was appropriate to predict the pyrolysis behavior of the olive tree pruning in all torrefaction conditions studied. (C) 2016 Elsevier Ltd. All rights reserved.