Thermo-kinetic analysis of reactions involved in the manufacture of o-nitroaniline

Exothermic reaction processing must be concerned with potential consequence s when heat released by the reaction exceeds that removed by the reactor co olant,system, a situation known commonly as a runaway reaction. We have inv estigated a complicated reaction process in which two exotherms can occur - the process of making the desired product, o-nitroaniline (o-NA), from amm onia and o-chloronitrobenzene (T Onset around 140 degrees C), and the decom position of the product, o-NA (T Onset around 225 degreesC. A severe indust rial loss occurred in 1971 at a plant-producing o-nitroaniline, an incident that has been the subject of several AlChE loss prevention presentations a nd papers. In this article, we take a closer look at the chemistry, involve d, and the ability, to use thermo-kinetic analyses to understand the reacti ons involved, and how these influenced the accident that occurred. Further, we present the progress we've made towards predictive models for the kinet ics and the pressure-time data. Several useful generalizations have evolved . First, is the need to include experiments that use stoichiometric mixture s when assessing exothermic reactions. Second, is the need to understand th e role of reaction intermediates, and how they may influence the operation of the plant.