On the thermal decomposition of tert.-butyl hydroperoxide, its sensitivity to metals and its kinetics, studied by thermoanalytic methods

The decomposition of hydroperoxides like tert.-butyl hydroperoxide (TBHP) due to reactions with reactor materials (wall reactions) is an important issue in the frame of industrial processes and the analysis of such compounds. Because of the high surface-volume ratio such heterogeneous reactions are also especially important in case of thermo-analytical measurements. Therefore, the decomposition of TBHP has been studied for the first time extensively by Differential Scanning Calorimetry (DSC) using differently coated high pressure stainless steel crucibles (uncoated, gilded, silicon coated) and a medium pressure stainless steel crucible. Furthermore, the interaction of such crucible materials with TBHP has been measured for the first time by Thermal Activity Monitoring (TAM). The material of the gilded copper blowout disc turned out to be the reason for the very different DSC curves published in literature and had the highest influence compared to the crucible body material and the pressure. To protect the sample against the blowout disc, an aluminium foil has been placed below the blowout disc. This changed the shape of the DSC curve completely. It became more similar to that obtained with the medium pressure crucible. Furthermore, the reaction mechanism, kinetics and chemical aspects of the decomposition of TBHP at different conditions have been discussed and kinetics has been investigated for the first time by an overall evaluation of the DSC curves and a model free kinetics approach. Using the linear relationship between the kinetic activation parameters the published values are compared to those of the present work.