The Benito-Perez Model

The Benito-Perez model [6] also includes a first reaction, called the initiation reaction, producing some product, which then enters into an autocatalytic reaction similar to the schema described above (Section 12.2.3.1). It can be described by a formal kinetic model as 

This model comprises eight parameters, that is, two frequency factors, two activation energies, three exponents for the reaction orders, and the initial conversion. It is often used in a simplified form, with all reaction orders equal to one  

Figu re 12.4 Comparison of a strongly autocatalytic reaction with a weak autocatalytic reaction (dashed line). Isothermal DSC experiment at 200°C. The heat release rate for the strong autocatalytic reaction is zero at the beginning of the exposure. 

Systems with a faster initiation reaction provide an initial heat release rate which detects them earlier. These systems are called weak autocatalytic.  

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It can be shown that this model is equivalent to the Benito-Perez model by setting... 

To obtain a more realistic estimation of the behavior of an autocatalytic reaction under adiabatic conditions, it is possible to identify the kinetic parameters of the Benito-Perez model from a set of isothermal DSC measurements. In the example shown in Figure 12.11, the effect of neglecting the induction time assumes a zero-order reaction leading to a factor of over 15 during the time to explosion. Since this factor strongly depends on the initial conversion or concentration of catalyst initially present in the reaction mass, this method must be applied with extreme care. The sample must be truly representative of the substance used at industrial scale. For this reason, the method should be only be applied by specialists. 

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