Autocatalytic decomposition reactions, hazards and detection

Abstract

In the chemical industry, estimation methods based on dynamic Differential Scanning Calorimetry (DSC) measurements have been developed for a preliminary screening of the risk associated to a chemical operation. An important point for the assessment of thermal risk is the identification of autocatalytic reactions. These types of reactions require our special attention and should be clearly distinguished from nth order reactions. Until today, the most reliable tool for the identification of autocatalytic decompositions was an isothermal DSC measurement. A new screening method based on dynamic DSC measurements for the identification of autocatalytic decompositions has been developed. The method consists of fitting a first order kinetic model to the measured heat release rate curve (from dynamic DSC measurement) and determining the apparent activation energy. If the apparent activation energy is higher than 220 kJ/mol, the decomposition is autocatalytic. By taking into account the cases with the border value of the apparent activation energy (180–220 kJ/mol), as well as the exception to this method, it should be possible to apply our new screening tool to about 80% of the cases.