3. Performing an isoconversional analysis#

To perform an isoconversional analysis:

Make sure you loaded the data
Select an isoconversional method
Fill the required parameters

You’ll find a description of the isoconversional methods in: Isoconversional methods module

If you’re wondering why you should perform an isoconversional analysis here a some reasons:

Reasons to perform isoconversional analysis#

Estimation of Activation Energy#

By applying isoconversional methods such as the Vyazovkin or Friedman methods, it is possible to estimate the activation energy of a reaction without assuming a specific reaction mechanism. This is particularly useful when the mechanism is unknown or complex.

Determination of Reaction mechanism#

Isoconversional analysis can help elucidate the reaction mechanism. For instance, significant changes in activation energy with conversion may indicate transitions between different rate-determining steps or the involvement of different species at different stages of the reaction.

Prediction of Reaction Kinetics#

Isoconversional analysis allows for the prediction of reaction kinetics parameters. For example, if one assumes that a reaction follows a Kamal model:

\[\frac{d\alpha}{dt} = \left( A_1 e^{ \left( \frac{-E_1}{RT} \right)} + A_2 e^{ \left( \frac{-E_2}{RT} \right) } \alpha^m \right) (1-\alpha)^n\]

Then, the apparent activation energy (on the isoconversional plot) is equal to [1] :

\[E_{app}(\alpha) = \frac{\frac{A_1}{A_2}*exp(-\frac{E_1}{RT})*E_1 + exp(-\frac{E_2}{RT})*E_2*\alpha^m}{\frac{A_1}{A_2} exp(-\frac{E_1}{RT}) + exp(-\frac{E_2}{RT})*\alpha^m}\]

And when the extent tends to 0, the apparent activation energy is equal to \(E_1\).

Additional insights#

Isoconversional analysis can also be used to assess the quality of kinetic data or the thermal stability when studying thermal degradation or decomposion reactions.