An improved model for the kinetic description of the thermal degradation of cellulose

Abstract

In spite of the large amount of work performed by many investigators during last decade, the actual understanding of the kinetics of thermal degradation of cellulose is still largely unexplained. In this paper, recent findings suggesting a nucleation and growth of nuclei mechanism as the main step of cellulose degradation have been reassessed and a more appropriate model involving chain scission and volatilization of fragments has been proposed instead. The kinetics of cellulose pyrolysis have been revisited by making use of a novel kinetic method that, without any previous assumptions regarding the kinetic model, allows performing the kinetic analysis of a set of experimental curves recorded under different heating schedules. The kinetic parameters and kinetic model obtained allows for the reconstruction of the whole set of experimental TG curves.

Kinetics of Thermal Degradation of Cellulose: Analysis Based on Isothermal and Linear Heating Data

“…Perhaps that is the reason why most of the reported fittings are limited to a few experimental curves and, very often, do not include both isothermal and linear heating data (Conesa et al 1995;Lin et al 2009;Chen et al 2014). There are a few reports where, independent of the kinetic approach used, relatively good fittings of both isothermal and non-isothermal thermogravimetric curves of cellulose are displayed (Sánchez-Jiménez et al 2011). But even in the cited case, the quality of that fitting was worse than the fittings obtained in the present work.…”

“…Despite the enormous amount of reports, the kinetics of cellulose decomposition constitutes an ongoing debate. Assuming an Arrhenius dependence on the temperature, but not assuming that any kinetic model fit the reaction, cellulose pyrolysis was studied by the combined kinetic analysis method and master plots (Sánchez-Jiménez et al 2011). While the combined kinetic analysis allowed the reconstruction of experimental curves recorded under different heating profiles, the master plots allowed comparison of the results yielded by the analysis with different models to discriminate which kinetic model the reaction followed.…”

Kinetic study of regional agro-industrial wastes pyrolysis using non-isothermal TGA analysis

“…Therefore, the first peak is mainly linked to it decomposition. The temperature range and the peak temperature of the second DTG peak are very close to cellulose pyrolysis 50,51,52,53,54,55,56,57 . This indicates that the second DTG peak is mainly linked to the cellulose decomposition.…”

Limitations of model-fitting methods for kinetic analysis: Polystyrene thermal degradation

“…That model is especially suitable to polymeric degradation studies, and has a clear physical meaning. Actually, since its publication, we have found a number of polymers such as cellulose, polystyrene and polybutylen terephtalate, that decompose according to a random scission model (Sanchez-Jimenez et al , 2010, Sanchez-Jimenez et al , 2011, Sanchez-Jimenez et al , 2012. Here, we attempt to provide some insight about the use of model-fitting methods and highlight some of its limitations in order to clarify why in some cases the experimental data cannot be properly fitted by any kinetic model (Brems et al , 2011).…”