Model-free and model-fitting approaches to kinetic analysis of isothermal and nonisothermal data

Biomass pyrolysis kinetics: A comparative critical review with relevant agricultural residue case studies

The kinetic analysis of non-isothermal data

The thermal effect of a reaction makes the temperature inside the reaction system deviate from a prescribed heating program. To take into account the effect of such temperature deviations on kinetic evaluations, a computational method applicable to an arbitrary variation in temperature has been developed. The method combines the isoconversional principle of evaluating the activation energy with numerical integration of the equation, dα/dt = k[T(t)]f(α), over the actual variation of the temperature with the time, T(t). Details of the numerical algorithm are reported. A model example has been used to verify the reliability of this method as compared to an analogous method which does not account for the deviations of the temperature from a prescribed program. The method has been tested for tolerance for noise in the temperature. © 1997 by John Wiley & Sons, Inc.

Evaluation of activation energy of thermally stimulated solid‐state reactions under arbitrary variation of temperature

Master plot methods based on the integral and/or the differential forms of the kinetic equation describing solid-state reactions have been redefined by using the concept of the generalized time, θ, introduced by Ozawa. This redefinition permits the application of these master plots to the kinetic analysis of solid-state reactions, whatever the type of temperature program used for recording the experimental data. In isothermal conditions, a single curve is enough to construct the experimental master plots. In nonisothermal conditions, the knowledge of both α as a function of temperature and activation energy is required for calculating the master plot curves from the experimental data. Practical usefulness of the present master plot methods is examined, and exemplified by being applied to the thermal decomposition of ZnCO3 under isothermal, linear nonisothermal, and nonlinear nonisothermal conditions.

Kinetic Analysis of Solid-State Reactions: The Universality of Master Plots for Analyzing Isothermal and Nonisothermal Experiments

Rational approximations have been derived for the integral of the Arrhenius function
 
$$\int\limits_0^T {\exp ( - E/RT)}$$

 
dT which is important in the kinetic analysis of thermogravimetric data. The first degree rational approximation is found to be equivalent to the Gorbachev approximation, i.e., RT2
exp (−E/RT)/(E+2RT). The second degree rational approximation is more accurate than the Zsako empirical approximation when E/RT 5. The third and higher degree rational approximations are found to be more accurate than any other previous approximation.

G. I. Senum

Papers

Rational approximations of the integral of the Arrhenius function