TG-DSC同時測定による鉱物の熱分解反応の解析-とくにマグネサイトについて

Abstract

The use of simultaneous TG and DSC data to evaluate kinetic parameters of decomposition reactions has been investigated. The procedure is described as below.1) Based on the method proposed by Achar et al., some probable kinetic equations (Function f(α), α is the fraction reacted) are found from TG or DSC data by trial and error. Then, kinetic parameters (activation energy Eand frequency factor Z) for each mechanism are evaluated. Theoretical TG or DSC curve is calculated from the obtained f(α), E, Z and heating rate q. The above results are examined from the degree of superimposition of the theoretical and experimental curves.2) Activation energy E is calculated by applying the Ozawa's method in a series of TG data obtained under different heating rates.3) The most probable mechanism and kinetic parameters are determined from the results obtained in 1) and 2).The above procedure has been applied to thermal decomposition of magnesite, giving the following results; the most probable kinetic equation R3(α), dα/dtk(1-α)2/3 (the phase boundary reaction of spherical symmetry): activation energy, 40 kcal/mol: frequency factor, about 109. The results are supported by those obtained by the Šatáva and Škvára's method, and are in good agreement with literature data.