Combined differential and integral method for analysis of non-isothermal kinetic data

Abstract

The generally accepted integral and differential forms for analysis of non-isothermal kinetic data are ▪ and dα d T = A β exp(− E/RT) f(α) Very often, these equations do not clearly and unambiguously indicate the reaction mechanism involved. The general trend to determine the mechanism on the basis of goodness of mathematical fit of data makes the task more formidable. Two other forms of integral and differential methods have been proposed to obviate this difficulty. These, in logarithmic forms, are ▪ and ▪ The analysis, based on these two equations, requires a logical choice of the functions f(α) and g(α) by trying out in turn all the known forms available in literature. Amongst all the logical possibilities, the one with comparable E and A obtained for both the forms is suggestive of the possible reaction mechanism. The equation (valid for linear rate of heating, β) is derived by replacing the time of reaction, t, by ( T − T O))/β. The differential form is solved by an iterative method to obtain consistent values of E and A. Experimental data of thermal dehydroxylation of Mg(OH) 2, as published by Fong and Chen, are re-analyzed by these two methods. The results indicate that a diffusion-controlled mechanism is involved.