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Initial kinetic parameters for the model-based kinetic method
Elena Moukhina
Model-based analysis uses the assumption of a kinetic model and needs the initial kinetic information to suggest the correct model with correct reaction types and parameters. In this article it is shown that model-free analysis can provide such initial information, which is necessary in searching for kinetic parameters by the non-linear regression method. In addition to the activation energy, the initial values of pre-exponential factor, step contributions and reaction types can be found. The simple method is proposed for checking whether acceleration is present. This method is based on model-free analysis for a set of dynamic measurements with different heating rates. It does not require any additional isothermal measurement. For single-step reactions, the method can be applied by drawing two iso-conversional lines: one for the maximum point and one for the half-maximum point. For multi-step reactions, the method can be applied by analyzing the direction of movement of the iso-conversional lines with the reaction progress. If the iso-conversional lines move up as the reaction progresses, then this is the indicator of the acceleration.
Keywords: Thermokinetics, kinetics, model-free, model-based, Friedman, acceleration test.