Mathematical modelling and numerical simulation of aromatic nitrations by mixed acid in discontinuous reactors

This work deals with the mathematical modelling and numerical simulation of aromatic nitrations in discontinuous reactors, and the experimental work carried out to characterise the model, as well as to verify the simulated results. The model employed, based on the effective interfacial area between the two liquids and the description of mass transfer with reaction using the film model is used. Theoretical model predictions are compared with experimental results and the effect of the different parameters is discussed. From the comparisons between model and experimental results it can be concluded that it is possible to extrapolate data from homogeneous nitration experiments and to interpret the dynamic behaviour of discontinuous nitration processes of benzene, toluene and chlorobenzene in the different reaction regimens. Furthermore, the accumulation of unreacted nitric acid in semibatch aromatic nitrations can be dangerous if accompanied by a phase inversion due to the fact that the heat rate production may increase suddenly, since the conversion rate is usually mass transfer controlled under industrial operating conditions. The main parameter responsible for this increase is the interfacial area that increases if the continuous phase changes to acid phase.