Kinetic models of complex reaction systems

In this work, the desired N-oxidation of β-picoline (3-methylpyridine), 2,6-lutidine, 3,5-lutidine and 2,4,6-collidine and the undesired hydrogen peroxide decomposition accompanying the syntheses reactions have been studied by means of reaction calorimetry. The power generation measurements have been used for the development of a kinetic model that will represent satisfactorily the N-oxidation of this family of reactions and it can be used towards the prediction of selected runaway scenarios of the respective reactions. Their kinetic study was based on the kinetic model of Sempere et al. [Sempere, J., Nomen, R., Rodriguez, J. L., & Papadaki, M. (1998). Modelling of the reaction of 2-methylpyridine using hydrogen peroxide and a complex metal catalyst. Chemical Engineering and Processing, 37, 33–46.], which was improved and refined. It was found that the model represents well the N-oxidation of methylpyridines. Due to limited miscibility of di- and trimethylpyridines with hydrogen peroxide, water and catalyst only partial agreement with the model was achieved. These reactions need further study under conditions where homogeneous mixtures can be formed. A simple methodology was employed for the evaluation of the model coefficients. Accurate evaluation of the kinetic model constants can be achieved if the noise of measurements is reduced, or conditions where it is less pronounced are employed.