A simple, sensitive graphical method of treating thermogravimetric analysis data

TLDR

Thermogravimetric analysis is increasingly used to study pyrolysis and combustion, but complex reactions and experimental imperfections make kinetic parameter extraction difficult, leading to many analytical methods, many of which rely on inaccurate graphical techniques; a linear plot method exists but its sensitivity to experimental issues has been underappreciated. This paper aims to illustrate the application of the linear graphical procedure to a hypothetical first‑order pyrolysis representative of cellulose TGA behavior. The authors demonstrate the method by applying it to a simulated first‑order pyrolysis model of cellulose, showing how the linear plot can be used to extract kinetic parameters.

Abstract

Thermogravimetric Analysis (TGA) is finding increasing utility in investigations of the pyrolysis and combustion behavior of materials. Although a theoretical treatment of the TGA behavior of an idealized reaction is relatively straight-forward, major complications can be introduced when the reactions are complex, e.g., in the pyrolysis of cellulose, and when experimental imperfections arise. Consequently, a fairly large number of analytical methods have been proposed for obtaining kinetic parameters from TGA curves. Among the proposed methods are several graphical procedures, mostly involving relatively inaccurate tehniques, such as obtaining slopes on a rapidly changing curve. Included among the proposed procedures is one which permits a linear plot of TGA data. The sensitivity with which such a plot can be used to identify and correct for a variety of experimental complications seems to have escaped even the proponents of the techniques. This paper provides an illustration of the use of this graphical procedure in a hypothetical first-order pyrolysis typical of those occurring in the TGA behavior of cellulose.