Hydrogen Peroxide Decomposition Analysis by Screening Calorimetry Technique

Abstract

In a study of Nolan and Barton in 1987 it was already underlined that process safety is primarily based on an accurate and detailed knowledge of the thermo-chemistry of the reaction and afterwards on a correct scale up and management.
In this work the experimental analysis of hydrogen peroxide decomposition is proposed by the use of a modified pseudo-adiabatic and non differential thermal analysis screening calorimeter.
The objective of the work is to study the decomposition of this peroxide and its effects in different operating conditions, particularly when a runaway reaction occurs and may be the cause of incidents leading to fires and explosions and losses of chemicals in general. Runaway reactions have the potential to inflict considerable damage if appropriate emergency measures are not in place.
Hydrogen peroxide is liable to decompose exothermically at also at ambient temperature. According to the Major Accident Reporting System (MARS) data bank, in the last 30 years there have been several major accidents involving peroxides and in particular almost 70 % of these accidents were caused by hydrogen peroxide. This is the main reason for which we focused our study on this substance.
The Thermal Screening unit (TS^u) used to carry out the experiments permitted us to find easily useful results such as onset temperature (the temperature at which the decomposition starts), time to maximum rate (the time at which the rate of temperature is maximum) and maximum pressure reached during the reaction. Adding an expansion vessel to the instrument made possible to study the reaction in different initial conditions of pressure (up to 12 bar), and so to evaluate the consequences of it on some critical parameters used to identify runaway reactions. The experimental data obtained by this simple and cost efficient technique have to be validated by experiments run in more complex calorimeters, such as adiabatic and reaction calorimeters, but the use of the TS^u makes it possible to reduce the number of experiments and to have a first step in risk analysis studies as key in scaling up of processes.
An Early Warning Detection System (EWDS) based on divergence criterion is finally applied off-line to the data regarding the decomposition. Both temperature and pressure profiles have been evaluated in order to compare the efficiency of the method to these parameters in terms of advance in detecting the runaway reaction.